Star Formation Newsletter#376 1-15
KASI

The Asymmetric Bipolar [Fe II] Jet and H2 Outflow of TMC1A
Resolved with JWST’s NIRSpec IFU

K. D. Assani1 , D. Harsono2 , J. P. Ramsey1 , Z.-Y. Li1 , P. Bjerkeli3 , K. M. Pontoppidan4 , Ł. Tychoniec5 , H. Calcutt3 , L.
5 , and L. Francis5al.: TheofAsymmetric
Bipolarwith[Fe II]
Jet andH
E. Kristensen7 , J. K. Jørgensen7 , A. Plunkett8 , M. L. van Gelder
K. D. Assani
et al.: The Asymmetric Bipolar [FeK.II]D.JetAssaniand H2etOutflow
TMC1A Resolved
JWST’sNIR
A&A proofs: manuscript no. main
Department of Astronomy, University of Virginia, Charlottesville, VA 22903, USA
2
Institute of Astronomy, Department of Physics, National Tsing Hua University, Hsinchu, Taiwan
3
Chalmers University of Technology, Department of Space, Earth and Environment, SE-412 96 Gothenburg, Sweden
4
Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109, USA
5Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
6
Leiden Observatory, Leiden University, PO Box 9513, 2300RA, Leiden, The Netherlands
7
Niels Bohr Institute, University of Copenhagen, Øster Voldgade 5–7, DK 1350 Copenhagen K., Denmark
8
National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903, USA••• Class I

rXiv:2404.18334v1 [astro-ph.SR] 28 Apr 2024

1

TMC1A,Received
JWST,
NIRSpec IFU 1-5 µm, H22024, Accepted 2024

, [Fe II], 0.1"

30
[Fe II]
ABSTRACT(a2G, a4D, a4P, a2P, a2HContext. Protostellar; ToutflowsK)structure depending on the observed gas emission. To understand theexhibit large variations in their
up=2,400-26,100
origin of the observed variations, it is important to analyze di↵erences in the observed morphology and kinematics of the di↵erWebb Space Telescope (JWST)• H226 (S, Q, L ent tracers.
; TTheupJames=6,000-17,500
K)allows us to study the physical structure of the protostellar outflow through
•

•
•
•

well-known near-infrared shock tracers in a manner unrivaled by other existing ground-based and space-based telescopes at thesewavelengths.
A&A proofs: manuscript no. main
Aims. This study analyzes the atomic jet and molecular outflow in the Class I protostar, TMC1A, utilizing spatially resolved [Fe ii] andH2 lines to characterize morphology and identify previously undetected spatial features, and compare them to existing observations
Fig. 2. Detected [Fe ii] emission lines in order of increasing wavelength. Each panel shows a spectrum taken in the northern part of the outfloof TMC1A and its outflows observed at other wavelengths.
alongwithin
the jetthe
axisG140H,(⇠0.5 arcseconds
away
fromgratings
the protostar).
The location
Methods. We identify a large number of [Fe ii] and H2 lines
G235H, andG395H
of the NIRSpec
IFUof the spaxel is shown as an "x" in the panel of the 1.644 µm line oFig. 3. Meanwhile,the 4.889
extracted
from athelocationthat is marked by "x" in the panel for the 4.889 µm in Fig. 3 to avoid thobservations. We analyze their morphology and position-velocity(PV) diagrams.
Fromµmthespectrum
observedis[Feii] line ratios,
extinction
contamination by the CO fundamental ro-vibrational line. Velocities are calculated independently for each line with respect to the rest waveleng
toward the jet is estimated.
(seeA.1).time,The
wavelength
given
inleft ofandNIRSpec
the transition
et al.:The
Asymmetric
Bipolar[Fe II]in
Jetmicrons
H2 is
Outflowof theTMC1A
Resolved
withpanel,
JWST’sIFU terms are given in the upper right an
Results. We have detected the bipolar K.
FeD.
jetAssaniby revealing,
forTable
the
first
the
presenceofa andred-shifted
atomicjet.upper
Similarly,
theeachsummarized
in BothTable[FeA.1.
µm line isemission
blendedexhibitwith theH2 1-0 S(7) line and each are labeled in the inset. Similarly the Br 18 hydroge
red-shifted component of the H2 slower wide-angle outflow
is observed.
ii]Theand 1.749
H2 red-shifted
significantly
recombination
is denotedin theline.
Fig. 3. Each lower
panel fluxshows
the peakflux density
mapblue-shiftedof the detected[Feii] lines
with line
an SNR
3 andbad1.534
pixelsµm
maskedout. The black"x" withdensities
comparedto theircounterparts.
Additionally,
we report
detectionofa collimatedhigh-velocity
white borders(⇠in100
the kmpanel
the 1.644 µmHline
denotesthe spaxeltheusedto extract
1D spectra
2.to
A the
di↵erent
spaxelis usedto extract
The
uncertainty
includinga 5%calibrations 1for), blue-shiftedsuggestingpresenceof athemolecular
jet 1in Figure
additionwell-known
wider
angle
low-uncertainty is shown by the shaded region.
2 outflow,
4. Linealong
profilesofthedetectedHemission
inwithorderof increasing
wavelength. Each spectrum is taken in the northern part of theline profile
since itTheis a↵ectedby H
contamination
closer tointensity
the Fig.
protostar.
The
red-shiftedorwhichsouthernthelines
outflow
discussedindyn the 4.89 µm velocity
2 partstructure.
[Fe ii] and
peaks
the
jet
axis,
may
be of
associatedongoingor
2 jets show multiple
Articlenumber,
page
4
of
16
5.at
Peak
flux2.122
densityofoftheto because
Fig. 3. The
with whitein the2.122 µm
2 linesmarkedby theblack"x"
in velocity
theµmmapspanel
Fig.
5. structure.
This Hlocation
is chosen
thisblackregion"x"
is bright
in H2borders, while thecontaminatio
later sectionsrecent(see Sect.
3.2) events.
will notInappear
in thesesinceinweplotintensities,
theflux density
maps
thecorresponding
to detected
the
peak
line
flux
outburst
additionto themaps
variation
theirthe
H2 Fig.
wide-angle
outflow
exhibitsa "ring"-like
Thesimilarthespaxelwherethespectra
in
Fig.
4
are
taken.
scattered
light
that
is
worse
at
longerwavelengths
isminimized,
easingthedetectionofweakerline
emission.
for a spaxel locatedin theHblue-shiftedsideof thea left-rightjet. The rest
wavelengthin micronsof dueeachtoline
is over-plottedin theupper leftambientof each medium
panel.
blue-shiftedshowsbrightness
asymmetrylikelyinteractions
with thesurrounding
2 outflow also
and molecular outflows. Using the [Fe ii] line ratios, the extinction along the atomic jet is estimated to beArticle
between
AV = 10–30
number,page 5onofthe
16
blue-shifted side, with a trend of decreasing extinction with distance from the protostar. A similar AV is found for the red-shifted side,
line
and
line
ratio
respect
to Thistheµm lineIn addition >to2thisIn Figures
4 andweobserved
present the26
Hemissionlines
that2.122
strongerat wavelengthsµm blue-shiftedcompared tocomponent,
the 1–2 µm
2withsupporting the argument for an intrinsic red-blue outflow lobe asymmetry
ratherthan5,theenvironmentale↵ectssuch
as extinction.
are reported
inthe
the
AppendixA.
red-shifted
the jet on
soutdetect.suggests
Figure4 shows
1D
spectrafor exhibita bright
in where most of
the [Fe ii]component
lines are ofdetected.
Asthe
was
do
intrinsic di↵erence revealed by the unprecedented sensitivity weof JWST,that
younger
outflows
already
thespaxel
red-blue
tostarin the1.257,
1.644&shown1.803 at
µmthe
lines
side asymmetry more commonly observed towards jets associatedwith Class II
disks. of the H2 outflow (see the black "x" in the [Fe ii], the flux
the north-east
sectiondensitymaps
in Fig.
5 are
vel[Fe II] 1.644 µm
1.257, 1.644, 1.803 µm
t =4, 6, 7

that thejet ininTMC1A
is bipolar.
2.122 µm map in Fig. 5). The chosen spaxel is taken from one of given by the peaklineatomic
intensities
Fig. 4. The
H2 lines d
TheofBipolar
the brightest 3.2.
regions
the H2Atomic
outflow.JetThis location also ben- include the S, Q, and O rotational transition branches, with
Figure6, Kweto showdensityoefits from being far from the protostar to minimize contamina- energies spanningInfrom
6,000
17,500theK. flux
The details
investigate
and velocity
structureis of the bright µm [Fe ii] line across several velocity bins,tion from the We
brightscatteredthe
dustspatial
continuum.
The continuum
using state-of-the-art
such as the James
Webb jetSpace
1.644 µm [Feinstrumentsii] line to characterize
the atomic
emanating tours at several flux levels with signal-to-nTelescope(JWST).
from
TMC1A. Harsono et al. (2023) revealed a bright blue- At 1.644 µm, the width of each velocity bin
1
Article number,
page 6atomicof
16of theshiftedjet 1.644
to theµmnorthernof thein2.5,TMC1A.
Fig. 6.
Channelmaps[Fe ii] line.side
Contours
are protostar
plotted at 1.5,
5, and 15 µJy.km s . The flux density of the blue-shifted

Key words. Atomic data, Molecular data, Line:identification, Techniques: imaging spectroscopy, Stars: jets

1. Introduction

ne, peaks
trinsic ratios tabulated in Giannini et al. (2015), and then using
The Asymmetric Bipolar [Fe II] Jet and H2 Outflow of TMC1A
ructing a
the parameterized extinction curve from Cardelli et al. (1989) toe highest
Resolved with JWST’s NIRSpec IFU
determine the visual extinction, AV , in magnitudes.
normal1 , D. Harsono2 , J. P. Ramsey1 , Z.-Y. Li1 , P. Bjerkeli3 , K. M. Pontoppidan4 , Ł. Tychoniec5 , H. Calcutt3 , L.
K. of
D. Assani
We use Equation 21.1
Draine(2011), which
describes how
hat there
E. Kristensen7 , J. K. Jørgensen7 , A. Plunkett8 , M. L. van Gelder5 , and L. Francis5
the extinction at a given wavelength, A , reduces the observedd H2 jet.
0.4 AVflux Fobs ( ) = Fint ( )⇥10 0.4A
= FofintAstronomy,( )⇥10, whereFint VA 22903, USA
Department
University of Virginia,
Charlottesville,
the proInstitute of Astronomy, Department of Physics, National Tsing Hua University, Hsinchu, Taiwan• His2the
2.803µm
intrinsic flux and = Chalmers
A /AVUniversity. Theof Technology,
terms Department
are determinedof Space, Earth and Environment, SE-412 96 Gothenburg, Sweden
ect. 3.2).
Jet Propulsion
Laboratory, et
California
Instituteof Technology,
using the extinction curve from
Cardellial.
(1989),
which4800 Oak Grove Drive, Pasadena, CA 91109, USA•Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
dentified
canObservatory,
be determinedsolelyon Leiden, The Netherlands
Leiden University,
PO Boxbased
9513, 2300RA,• demonstrated that extinctionLeiden
distances
Niels Bohr Institute, University of Copenhagen, Øster Voldgade 5–7, DK 1350 Copenhagen K., Denmark
the parameter RV that describes
the Astronomy
slope Observatory,of the extinction
atCharlottesville, VA 22903, USA
National Radio520 Edgemont Road,
mescalesvisible wavelengths. We adopt
V =5.5
Received R
2024,
Acceptedas
2024in McClure (2019).
eaks are
Given the well-established intrinsic flux ratios for certain [Fe ii]
nel, Figlines (Giannini et al. 2015), it is useful to take the ratio of ABSTRACT
thei] peaks,
Fig.
9.
Channelmapsofthe
2.122 (toppanels) on& 2.803µm (bottom
panels) HTolines.
Contours
Context. Protostellar outflows exhibit large variations in their structure
dependingthe observed
gas emission.
understandthe are plotted at flux levels of 3 ,5,10, and 30 µJy
previous equation at two ofthese
specific
wavelengths
toshown
by the cyanlines.thenoriginoftheobservedvariations,itisimportanttoanalyzedi↵erencesintheobservedmorphology
andkinematics
ofthedi↵er•
eded fortracers. The James Webb Space Telescope (JWST) allows us to study the physical structure of the protostellar outflow throughsolve for AV (Giannini et al.ent
2015):
well-known near-infrared shock tracers in a manner unrivaled by other existing ground-based and space-based telescopes at these•• row)CO[O I], OH! of the 1.644 µm [Fe ii] (Top Row) and 2.803 µm H (Bottom
Fig. wavelengths.
8. PV diagrams
lines at di↵erent locations in the bipolar jet. The distance
Aims.
study
the atomic
jet and amolecular
outflow
the Class
TMC1A,
resolved [Fe ii]o↵setobs,
from This
the jetaxisanalyzes
is calculated
by adopting
distance of
140 pcinwithout
de-projection
since the utilizing
slices arespatiallytaken perpendicular
to andthe jet. The
Fobs, 1 /F
2 to characterize morphology•I protostar,Class
IIcompare
H linesandleft
identify
undetectedfeatures,andthem to existingobservations
de-projectedo↵setsare shown in )the 1bottomof eachpreviously
panel. In (1)eachpanel, spatial
theintegrated
flux
densityor moment-0
maps areshown in the inset
AV = 2.5 log10
(
,
1that
2observed
TMC1A
and its
outflows
otherwavelengths.
alongofwith
the region
the PV
diagram at
was
taken
which has a width of 4-spaxels.
Fint, 1 /F
int,
1
• G235H, and G395H gratings of the NIRSpec IFU
Methods.
We identify a large number of [Fe ii] and H lines within the G140H,
1
2
3

rXiv:2404.18334v1 [astro-ph.SR] 28 Apr 2024

4
5
6
7
8

2

2

2

2

• βwhere 1 and 2 represent
intrinsic
feeding arm
epresentthe ratio of A( )/A(V) calculated•nd dust,extinction
et al. 17(1989) (their eq. 1).
• from the200
au 2curve of Cardelli
A =14,
e extincin the extintion, we propagate uncer• To estimate the uncertainty
AV=21-23H
htness of tainties in the standard way for the intrinsic ratio (F/F)
such as using the standard deviations reported in Giannini et al. (2015),
e extinc- and the observed peak flux (F,F).
• 110,
190wekm/s
150, 260 km/s [Fe II]
he intenDue to the lines spanning only 3-5 velocity
bins,
de- H
As discussed in Harsono et al. (2023), extended molecular hyepisodic
originate termine the ratio of observed
intensities
by takingtheratioof ⇠Key
200words.
AU (seeFigure7).Molecular
The second
feature (2F)
Atomicdata,
data,emission
Line:identification,
Techniques:
spectroscopy,
Stars: jets
drogenimaging(H2 ) emission
is detected
towards TMC1A with a nearlyFig.
10. Lineof jet’s
the 1.644 µm [Fe ii] (Left) and 2.803 µm H (Right) lines at di↵erent locations. The spectra are color-coded and correspondis only visible inbrighter line
[Fe ii]lines
and profiles
istheconsiderably
rature or of the maximum flux densities
oftheeach
along
•
t
<10
yr
conical shape that appears to enclose the blue-shifted [Fe ii] jet.
dyn
to
the
locationsmarkedby"x" in the moment-0 maps shown in the insets. The spectra are extracted in di↵erent locations for the [Fe ii] and H lines
smaller than the other two, located at a distance of approxiSimilar
ourpanel,
analysisthe [Fe ii]tolines,
investigate
thealong
mor-the blue-shifted jet axis (blue, steel blue,
Einstein axis at several di↵erent 1.locations/spaxels.
The
intrinsic
ratiosoftohighlight
particularcharacteristics.
In thetolefttheseofcorrespondthe 3webrightness
peaks
mately270 AU from the protostar. The third emission feature using
phology
of
two
of
the
brightH
lines(2.122&2.803µm)
in velocity emission detected (purple), thestate-of-the-art
instruments
such
as
the
James
Webb
Space
Introduction2
purple) and red-shifted jet (red). In the right panel, the spectra correspond to the central spine with higher(3F) is observedin several [Fe ii]
lines
and is located close to
the Telescope
Giannini the 1.257/1.644, 1.321/1.644,
1.533/1.677,
andµmdetail.
For
both lines,
the structureof the outflow
depends(JWST).
left1.599/1.712(steel blue) and right (blue)
wings
of thering-likestructureand the red-shifted
outflow(red). on veobservations. We analyze their morphology and position-velocity (PV) diagrams. From the observed [Fe ii] line ratios, the extinction
towardthe 1.810
jet is estimated.
1.257,
1.644,µm) on the northern side of the atomic jet, Theoretically, protostellar outflows are expected to rotate, andResults.
We
have7.detected
the bipolar
Fe jetshow
by revealing,forµm
the first
time, thepresenceof a red-shifted
atomicjet. Similarly,
as shown in Figure
For brevity,
we only
the 1.644
indeedthere
is evidence
to support
it (e.g.
Frank et theal. 2014).
componentof the ofH2 theslowerwide-angle
outflow
is observed.
Both[Fe expectii] and Htheemission
exhibitsignificantly
2 red-shifted
line red-shifted
and note thatthelocation
peaks
does
not
changesigWe
wouldrotation
to
show
up
as
an
increasing or deV
lower flux densities compared to their blue-shifted counterparts. Additionally, we report the detection of a collimated high-velocity
nificantlyin the other lines. We determine the location of these creasing velocity gradient perpendicular to the jet axis, as seen in(⇠ 100 km s 1 ), blue-shifted H2 outflow, suggesting the presence of a molecular jet in addition to the well-known wider angle lowpeaks
byfitting
Gaussian
profilesnormalized 1D flux den- some sources (e.g., DG Tau,
2 Zapata et al. 2015; De Valon et al.
velocity structure.
The [Feii] andtoHthe
2 jets show multiple intensity peaks along the jet axis, which may be associated with ongoing orsity profiles.
The distanceseach peakreportedin AUfrom 2020).
In
these
observations,the avelocity
at peak
flux Thedensity rerecent outburst
events. In of
additionto thearevariation
theirintensities,theHwide-angle
outflow
exhibits"ring"-likestructure.
int, inint,
2
1
2
the central
starandde-projecting
each
point
along
the
jet
adoptmains
constant
acrossthejetaxis
withinthevelocity
resolution
blue-shifted H2 outflow also shows a left-right brightness asymmetry likely due to interactions with the surrounding ambient medium
ing anwith respect
the skyof ⇠ 35 along
andthedoes
not jetchangesignificantly
from one
to on
thethenext.
andinclination
molecular outflows.
Usingtothethe[Feplaneii] lineofratios,the extinction
atomicis estimatedto be between
AV =peak
10–30
for thejet, based
onwiththea disk⇠ 55 (where
90 from the protostar. A similar AV is found for the red-shifted side,
blue-shiftedside,
trendinclinationof decreasingofextinction
with distanceobs, for1 argument
2 etanal.
supportingtheintrinsic
wouldbeobs,
edge-on)(Harsono2021).red-blue outflow lobe asymmetry rather than environmental e↵ects such as extinction. This
3.3.
Jetoutflows
and Wider
Angle
Outflow
2 The Molecular
intrinsic
di↵erence
revealedbythesensitivitywith
of JWST,suggeststhat younger
already
exhibitthe red-blue
The first peak (1F) appears as asunprecedented
an extended structureside
asymmetrymorecommonlyobserved
towardsjets
associated
with
Class
II
disks.
a maximum in its flux density profile at a de-projected distance22edge of the FOV at ⇠370 au from the protostar. Adopting a de-locity. To examine the kinematic structure of the H2 emission,Self-similarity of the magnetic field at different scales:
The case of G31.41+0.31
M. T. Beltrán1 , M. Padovani1 , D. Galli1 , N. Áñez-López2 , J. M. Girart3,4 , R. Cesaroni1 , D. Dall’Olio5,1 ,G. Anglada6 , C. Y. Law7 , A. Lorenzani1 , L. Moscadelli1 , Á. Sánchez-Monge3,4 , M. Osorio6 , and Q. Zhang81•• G31.41+0.31••

INAF – Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italye-mail: maria.beltran@inaf.it
2
Université Paris-Saclay, Université Paris Cité, CEA, CNRS, AIM, 91191 Gif-sur-Yvette, France
3
Institut de Ciències de l’Espai (ICE, CSIC), Can Magrans s/n, 08193 Cerdanyola del Vallès, Catalonia, Spain
4
Institut d’Estudis Espacials de Catalunya (IEEC), 08034 Barcelona, Catalonia, Spain
5
Department of Space, Earth and Environment, Chalmers University of Technology, Onsala Space Observatory, Observatorievägen
90, 43992 Onsala, Sweden
6
Instituto de Astrofísica de Andalucía, CSIC, Glorieta de la Astronomía s/n, 18008 Granada, Spain
7
Department of Space, Earth & Environment, Chalmers University of Technology, 412 96 Gothenburg, Sweden
8
Center for Astrophysics | Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138, USA

ALMA 1.3 mm, 3.1 mm, 0.068" (250 au)

Beltrán, M. T., et al.: A&A, 686, A281 (2024)~10 mG

90°

Received 12 December 2023 / Accepted 10 April 2024
ABSTRACT

A-D:

1.4, 3.5 mm+: UC HII

Context. Dust polarization observations of the massive protocluster G31.41+0.31 carried out at ⇠100 (⇠3750 au) resolution with the

SMA at 870 µm have revealed one of the clearest examples to date of an hourglass-shaped magnetic field morphology in the high-mass
regime. Additionally, ⇠0.00 24 (⇠900 au) resolution observations with ALMA at 1.3 mm have confirmed these results. The next step is toinvestigate whether the magnetic field maintains its hourglass-shaped morphology down to circumstellar scales.
Aims. To study the magnetic field morphology toward the four (proto)stars A, B, C, and D contained in G31.41+0.31 and examine
whether the self-similarity observed at core scales (100 and 0.00 24 resolution) still holds at circumstellar scales, we carried out ALMA
observations of the polarized dust continuum emission at 1.3 mm and 3.1 mm at an angular resolution of ⇠0.00 068 (⇠250 au), sufficient
to resolve the envelope emission of the embedded protostars.
Methods. We used ALMA to perform full polarization observations at 233 GHz (Band 6) and 97.5 GHz (Band 3) with a synthesized
beam of 0.00 072 ⇥ 0.00 064. We carried out polarization observations at two different wavelengths to confirm that the polarization traces
magnetically aligned dust grains and is not due to dust self-scattering.
Results. The polarized emission and the direction of the magnetic field obtained at the two wavelengths are basically the same, except
for an area between the embedded sources C and B. In such an area, the emission at 1.3 mm could be optically thick and affectedby dichroic extinction. In the rest of the core, the similarity of the emission at the two wavelengths suggests that the polarized emission is due to magnetically aligned grains. The polarized emission has been successfully modeled with a poloidal field with a small
toroidal component on the order of 10% of the poloidal component, with a position angle = 63 , an inclination i = 50 , and a
mass-to-flux ratio = 2.66. The magnetic field axis is oriented perpendicular to the NE–SW velocity gradient detected in the core.
The strength of the plane-of-the-sky component of the mean magnetic field, estimated using both the Davis-Chandrasekhar-Fermi andthe polarization-intensity gradient methods, is in the range ⇠10–80 mG, for a density range 1.4 ⇥ 107 –5 ⇥ 108 cm 3 . The mass-to-flux
ratio is in the range ⇠1.9–3.0, which suggests that the core is “supercritical”. The polarization-intensity gradient method indicatesthat the magnetic field cannot prevent gravitational collapse inside the massive core. The collapse in the external part of the core is(slightly) sub-Alfvénic and becomes super-Alfvénic close to the center.
Conclusions. Dust polarization measurements from large core scales to small circumstellar scales, in the hot molecular coreG31.41+0.31 have confirmed the presence of a strong magnetic field with an hourglass-shaped morphology. This result suggests thatthe magnetic field could have a relevant role in regulating the star-forming process of massive stars at all scales, although it cannot
prevent the collapse. However, it cannot be ruled out that the large opacity of the central region of the core may hinder the study of themagnetic
field atcircumstellar
scales.
Therefore,high-angularresolution observations at longer wavelengths, tracing optically thinnerFig. 1. Stokes I and polarized intensity at both wavelengths in G31. Top panels:
ALMA Stokes
I mapof the G31 HMC
at 1.3mm (left) and3.1 mmneededconfirm
this(right). The contours are 5, 5, 10, 30, 60, 120, 160, and 200 times at 1.3emission,
mm and 5,are
5, 10,
30, 60,to120,
160, 240
andself-similarity.
320 times at 3.1 mm,

I A, BP D

1.3 mm

•

• P

Beltr

Self-similarity of the magnetic field at different scales:
The case of G31.41+0.31
M. T. Beltrán1 , M. Padovani1 , D. Galli1 , N. Áñez-López2 , J. M. Girart3,4 , R. Cesaroni1 , D. Dall’Olio5,1 ,G. Anglada6 , C. Y. Law7 , A. Lorenzani1 , L. Moscadelli1 , Á. Sánchez-Monge3,4 , M. Osorio6 , and Q. Zhang8

Beltrán, M. T., et al.: A&

Beltrán, M. T., et al.: A&A, 686, A281 (2024)
1

INAF – Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italye-mail: maria.beltran@inaf.it
2
Université Paris-Saclay, Université Paris Cité, CEA, CNRS, AIM, 91191 Gif-sur-Yvette, France
3
Institut de Ciències de l’Espai (ICE, CSIC), Can Magrans s/n, 08193 Cerdanyola del Vallès, Catalonia, Spain
4
Institut d’Estudis Espacials de Catalunya (IEEC), 08034 Barcelona, Catalonia, Spain
5
Department of Space, Earth and Environment, Chalmers University of Technology, Onsala Space Observatory, Observatorievägen
90, 43992 Onsala, Sweden
6
Instituto de Astrofísica de Andalucía, CSIC, Glorieta de la Astronomía s/n, 18008 Granada, Spain
7
Department of Space, Earth & Environment, Chalmers University of Technology, 412 96 Gothenburg, Sweden
8
Center for Astrophysics | Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138, USA

4°-6°

•

• 0.24", 1"• A, B• 10 BC
Received 12 December 2023 / Accepted
April 2024•

⾒àdichroic extinction
<2%,
>10%

Fig
fun
ma
of

ABSTRACTshoContext. Dust polarization observations of the massive protocluster G31.41+0.31 carried out at ⇠100 (⇠3750 au) resolution with the

SMA at 870 µm have revealed one of the clearest examples to date of an hourglass-shaped magnetic field morphology in the high-mass
regime. Additionally, ⇠0.00 24 (⇠900 au) resolution observations with ALMA at 1.3 mm have confirmed these results. The next step is toFig. 5. Comparison of magnetic field orientations at 1.3 mm and 3.1 mm. Left: Magnetic field segments
at 1.3 mmwhether(blue) and 3.1(red). Segments
investigate
themmmagnetic
field maintains its hourglass-shaped morphology down to circumstellar scales.
shown every ten pixels. Contours show the 5 -level dust continuum emission at 1.3 mm. The synthesized beam is shown in the lower left corner.
To study
the magnetic
The black rectangle indicates the zoomed region shown in the right panel. Right: Close-upAims.
of the central
region towardsources A, B, field
and C. morphology toward the four (proto)stars A, B, C, and D contained in G31.41+0.31 and examine
Segments are shown every five pixels. The green rectangle shows the region where the polarization
segments
at 1.3 mm and 3.1 mmobserved
are almost at core scales (100 and 0.00 24 resolution) still holds at circumstellar scales, we carried out ALMA
whetherthe self-similarity
perpendicular.
observations of the polarized dust continuum emission at 1.3 mm and 3.1 mm at an angular resolution of ⇠0.00 068 (⇠250 au), sufficient
to resolve the envelope emission of the embedded protostars.
observations at 1.3 mm by Beltrán et al. (2019). For this reason, inclinations for optically thin emission, so the new results in
Methods.
Wewithusedto perform
full polarization observations at 233 GHz (Band 6) and 97.5 GHz (Band 3) with a synthesized
we decided to use the same model used by these authors. The absolute value arein agreement
the ALMA
previous ones.
The
00
model is based on Li & Shu (1996) and Padovani & Galli (2011) situation is less clear
3.1 0.
mm,and⇥ asin Fig.
8, the out polarization observations at two different wavelengths to confirm that the polarization traces
beamat of072
0.00shown
064. We
carriedand describes an axially symmetric singular toroid threaded by a distribution of ¯ 2magneticallyis much flatter. The
minimum¯ 2 isquite shalaligned
dust
grainsand is not due to dust self-scattering.
poloidal magnetic field. In order to take into account the impact low and is obtained for a positive value of ', in contrast to the13
Results.
The
polarized
emissionand theof rotation, we incorporated a modified force-free toroidal mag- expected orientation of G31. However, this 3
discrepancy can eas3 direction of the magnetic field obtained at the two wavelengths are basically the same, except
netic field component as described in Padovani et al. (2013). ily be explained because
regionis not uniformly
sampled at sources C and B. In such an area, the emission at 1.3 mm could be optically thick and affected
for an thearea
betweenthe embedded
While we refer to Sect. 4.1 of Beltrán et al. (2019) for the details 3.1 mm. As shown
the right panelof Fig.
3, the7-8-3of the core, the similarity of the emission at the two wavelengths suggests that the polarized emisbyindichroic
extinction.
In observations
the restof the model, here pos
we recall the main parameters such as the are not sensitive to the polarization of the northern and westernsion
to magneticallyalignedmass-to-flux ratio ( ), the ratio between the toroidal and poloidal regions of the core
andisthedue
magnetic
field morphology
cannot grains. The polarized emission has been successfully modeled with a poloidal field with a small
component of the magnetic field (b0 ), the orientation of the pro- be properly modeled.
To possibly
increase theof 10% of the poloidal component, with a position angle
toroidalcomponent
onsignal-to-noise
the order of= 63 , an inclination i = 50 , and ajection of the magnetic axis on the plane of the sky measured the 3.1 mm observations
and checkwhether=we
couldThe
recovermass-to-flux
ratio
2.66.
magnetic field axis is oriented perpendicular to the NE–SW velocity gradient detected in the core.
from north to east ('), and the inclination of the magnetic field some low-intensity extended emission, we applied a uv-taper ofThestrengththerunningplane-of-the-sky
visibility
dataofwhen
tclean. The component of the mean magnetic field, estimated using both the Davis-Chandrasekhar-Fermi andwith respect to the plane of the sky (i), which is assumed to be 0.00 15 ⇥ 0.00 15 to thethe polarization-intensity
positive (negative) if the magnetic field in the northern sector resulting synthesized
beam of the maps is 0.00 19 ⇥gradient0.00 16. Aftermethods, is in the range ⇠10–80 mG, for a density range 1.4 ⇥ 107 –5 ⇥ 108 cm 3 . The mass-to-flux
points toward (away from) the observer.
performing the uv-tapering,
distribution¯ 2 remainswhichflat
ratio is inthethe
range of
⇠1.9–3.0,
suggests that the core is “supercritical”. The polarization-intensity gradient method indicates
To begin with, we fixed the values of and b0 at = 2.66 over the same range of inclinations, although the minimum valuethat thefield
gravitational collapse inside the massive core. The collapse in the external part of the core isand b0 = 0.1, as done in Beltrán et al. (2019), and used DustPol of ¯ 2 is now obtained
for a magnetic
negative valueof 'cannot(see Fig.prevent
B.1),(slightly)
sub-Alfvénic
becomes(Padovani et al. 2012) to create images of the Stokes parameters in agreement withthe observations
at 1.3 mm andand thepredic- super-Alfvénic close to the center.
I, Q and U for each combination of i and '. Models were then tions of Beltrán etal. (2019). For allDust
these reasons,we decided
Conclusions.
polarization
measurements from large core scales to small circumstellar scales, in the hot molecular corefed into the simobserve and simanalyze tasks of the CASA to model only the 1.3 mm observations. The best fit model has
G31.41+0.31
presence of a strong magnetic field with an hourglass-shaped morphology. This result suggests thatsoftware, using the same antenna configuration as in our obser- been obtained withb0 = 0.1, = have
2.66, iconfirmed= 50 , and the= 63
the magnetic field could have a relevant role in regulating the star-forming process of massive stars at all scales, although it cannot
vations. Finally, the convolved models have been compared to (see Fig. 9).
the two new sets of observations by computing the reduced chi
prevent the collapse. However, it cannot be ruled out that the large opacity of the central region of the core may hinder the study of thesquared, ¯ 2 .
magnetic field at circumstellar scales. Therefore, high-angular resolution observations at longer wavelengths, tracing optically thinner
Figure 7 shows the distribution of ¯ 2 at 1.3 mm as a func- 4.2. Magnetic fieldstrengthemission,
are needed to confirm this self-similarity.
tion of i and '. Since the model is symmetric with respect to•toroid threaded by a poloidal field + force-free toroidal field.
Beltrán, M. T., et al.: A&A, 686, A281 (2024)• DustPol, simobserve 1.3 mm
the thermal contribution to the veloc•
M/Φ=2.66, toro/polo=0.1, PA= 63°, i=50°
for the temperatures >⇠100 K estimat
Beltrán et al. 2018). Using V ' 5.
•
CH CN, CH CN
DCF
ofis 2.4 ± 0.06 km s . This vaof 2.1 km s estimated by Beltrán etions of CH CN carried out with ALM• B / cos i = 13-78 mG
10 cm
Cruchter '12
⾒1
losFig. 6. Polarization fraction at both wavelengths.
Top: Polarization frac1
tion p (colors) and dust continuum emission map (contours) at 1.3 mm.
The synthesized beam is shown in the lower
left corner. Contours and3
00 Bottom: Same as top panel, at 3.1 mm.
symbols are the same as in Fig. 1.

Figbyof ⇠0. 22 by Beltrán et al. (2018).
deBeltrán et al. (2019) used a value usothe 5 contour level to focus only on the Main core. The averresponding
tothevolumedensityoage uncertainty
on the observed polarization angles
is obs = izapofbeam⇠1001 .isThis
radius
0.5 QU / Q2 + U 2 ,insidewhere aQUradius= 15 µJy
the noise
(
Main
core
the 5 iscontour
on the observed Stokes
Q and
U. insideThis expression
valid for levehigh (> 5) signal-to-noise
ratioswith(e.g., Vaillancourt2006), which baa(2021),
ALMA observations
is the case of our data. 00
As seen in Fig. 1 (bottom right panel), Al
1, estimatedaveragevaluesof t
the linearly polarized⇠0.
intensity,
P, of the G31
core is &5
QU =anembedded
continuum
0.07 mJy beam 1 in thethe region
inside the
5 contoursourcesof the A
1.3 mm dust continuum
map,
and
in
such
a
region.
4,
obs these a(see their Table 4). Because
Bp
therefore, we used a histogram bin of 6 .
the embedded sources, these values
The average value of the distribution of residuals is=of ±thedensities
in thethewhole
inner whre7.18 ± 38.41 or limits= 5.3221.45
considering
range ofor only containingthat where | sources| < 45 , respectively.
In theC, of
A, B, andw
area between sources B and C, the 1.3 mm polarization observa- theorderofmagnitude
lower,
n⇠5⇥
tions are likely affected by dichroic extinction (see Sect. 5.2).7 turof innumberof 1.4⇥10
If so, the 1.3 mm datathat areadensities
do not properly
trace the –5⇥Osensity,
0, 30,
areas
modbution
range
lines

n the
s and
., theobs <et al.

tions
angusight
max13
3 CN
2. To
estithen019),

intensity gradient method developed and successfully The
appliedtomagnetic
field strength in theFig.
plane11.of Magnetic
the sky is given
field sobservations by Koch et al.Self-similarity(2012a,b, 2013,2014).
Based
onoftheinterms⌃Bdifferentbyof themagnetic
field
atscales:Fig. 10. Mapof ⌃B atuses
1.3 mm(color)superimposed
to intensity con- intensity gradient method.
MHD force equation,
this method
the casemeasurable
angle
The
of G31.41+0.31
p 160, 200 times
tours. Contour
levelsare 5,
10,intensity
30, 60, gradient,120,( = uniform density n = 1.4 ⇥ 1
between the direction
of
the
field
and
the
M. T. Beltrán 1, M. Padovani , D. Galli , N. Áñez-López
D. Dall’Olio,(rP ,+R. Cesaroni
Bpos = , J. M.
⌃BGirart⇢r ) ,4⇡R
(3)
c,
sity
contours.
Contours
leve
0.15
mJy
beam
).
G.
Anglada
,
C.
Y.
Law
,
A.
Lorenzani,
L.
Moscadelli,Á.
Sánchez-Monge,
M.
Osorio
,
and
Q.
Zhang
together with the direction of gravity, to derive a local magnetic
Beltrán, M. T., et al.: A&A, 686, A281 (2024)
1( = 0.15 mJy beam ).
field strength at every location
wherepolarization
INAF – Osservatorio
Astrofisico di
Arcetri, Largo E. Fermi
5, is50125detected.
Firenze,
Italy
(Koch
et
al.
2012a,b),
where
rP
is
the
pressure gradient, r ise-mail: maria.beltran@inaf.it
The
relative importanceof magnetic
andforcesisof
Université
Paris-Saclay, Université
ParisgravitationalCité, CEA, CNRS,
AIM,gravity
91191
Gif-sur-Yvette,
France•Ψ magnetic
αin
theacceleration,
and Rc is the radius of curvature of the
The
plane
the sky
Institut de Ciències de fieldl’Espai (ICE,strength
CSIC), Can Magranss/n, the08193 Cerdanyola
del Vallès,
Catalonia,
Spain is given
Institutd’Estudis Espacialsquantity
de Catalunya (IEEC),
08034
Barcelona, Catalonia,
Spain
represented
by the non-dimensional⌃Chalmers, definedby fieldd
ΔPA
DCF
⾒ latter is defined byB
magnetic
line. The
DepartmentofSpace,
EarthandEnvironment,
UniversityofTechnology,
Onsala Space Observatory, Observatorievägenin terms of⌃byand 3.5. The decrease wit
B90, 43992 Onsala, Sweden
Instituto de Astrofísica de Andalucía, CSIC, Glorieta de la Astronomía s/n, 18008 Granada," Spain#the optical depth of total d
Department of Space, Earth & Environment, Chalmers University of Technology, 412 96 Gothenburg, Swedenp
1Street, Cambridge,
2 MA 02138,
1 USA
sin
Center for Astrophysics | Harvard & Smithsonian, 60 Garden
PA) ,
one
⌃B =
Bpos = Received⌃B12(rP+ ⇢r ) 4⇡Rc , R = d cos(2)2 (⇡(3) 2017), but in this case(4)December 2023 / Accepted 10 April 2024
sin ↵
c
1

1

6

1

7

2

1

1

3,4

1

5,1

3,4

6

8

1
2
3
4
5
6
7
8

emission is optically thin
(Koch et al.Dust2012a,b),
where
rP whereis thegradient,r is of the polarization fract
dpressureiscarriedtheoutdistancepolarization
observations
ofbetween
the massive protocluster
G31.41+0.31
at ⇠1 (⇠3750 au)between
resolution with thetwo contiguous magnetic field
where is the angle in SMA
theat 870
plane
of
the
sky
the
directionµm have revealed one of the clearest examples to date of an hourglass-shaped magnetic field morphology in the high-mass
withwavelength.
This hathe gravity
acceleration,and observationsRtheradiusofconfirmed
curvaturethesegments,PA
betweentheir position
Additionally,⇠0. 24 (⇠900 au) resolution
with
ALMA
at 1.3 mmand
havethese isresults.theThe ofnextdifference
step
is to
c is
of the local gravity
andregime.
theintensity
gradient,
and
↵
is
the
angle
investigate whether the magnetic field maintains its hourglass-shaped morphology down to circumstellar scales.
To study themagneticThefield morphology
towardfour (proto)stars The
A,C, andD containedof
in G31.41+0.31
and examine
angles.
radiuscurvature
is calculated
averagingthenary diskbyaroundthe lowmagnetic
field
line.
latterisandthedefined
byB,holds
betweenthepolarization
direction
andtheintensity
gradient.
The
whethertheself-similarity
observedatcore
scales(10.
24resolution)
stillatcircumstellar
scales,wecarriedout
ALMA• 13 mG, R=1", M=90 Mo
M/Φ~1.9
observations of the polarized dust continuum emission at 1.3local
mm and 3.1curvaturesmm at an angular resolutionof ⇠0. 068 (⇠250au), sufficient
betweentwo
adjacentetsegmentsoverallinnearest
al.
2018)
and
the H
local
gravity
direction
computedthroughthe
distributionoftois
resolvetheenvelope
emissionof the embedded
protostars.
"#
Fig. 11. Magnetic field strength estimated with the polarization•
78 mG, R=0.3", M=57
Mo
M/Φ~3.0
We used ALMA to perform full polarization observationsat 233 GHz (Bandand 97.5 (3),GHz (Band3) witha synthesized that local changes in temperneighbors.
Into6) Eq.
weassumeintensity
gradientof B derived
from Eq.
(3) for a
1mass,2atbeamany
1⇥ 0. 064.Fig.
theMaporiginof thisincreasMap⌃
at 1.3observations
mm(color)superimposed
intensity
conallsurrounding
map
position,undertheassumptionof 0. 072
We10.
carriedoutof
polarization
at twodifferent wavelengths
to confirm
that thepolarization
traces method.
•>60%
uniform density
n = 1.4 ⇥ 10 cm (color map) superimposed to intentours.
Contour
5, 10,
30,
60,
120,
160,
200
times
(
=
magneticallyaligneddust
grainsand is notlevels
due
to aredust self-scattering.
=
cos
(⇡
PA)
,
(4)
atureValues
and density
are minor
compared
to gravity
andtherefore
The polarized0.15
emissionand thedirectionof themass.
magnetic fieldobtained at theof
two wavelengths are basicallysame, except
that
the
dust
emissionis
proportional
thesity thecontours.
Contours studies
levels are 5, 10,30, 60,more
120, 160, observa
200 times
and
mJyto
beam
). gasRd2c•for an area between the embedded sources C and B. In such an area, the emission at 1.3 mm could be optically
andmJyaffected( thick= 0.15beam ).
thepressure
gradientrP
tobenegligible
compared
tothegravby dichroic indicate
extinction. In the whether
rest of the core, theor
similarity
ofthe
the emission
at the two wavelengths suggests that the polarized emis⌃B greater or less than unity
notmagnetic
characterize
theincreasesion is due to magnetically aligned grains. The polarized emission has been successfully modeled with a poloidal field with a small
The magnetic
field strength
in theplaneof angle
the sky
is givenitational
force
⇢r
Using
averagevalue of ⌃B , r and Rc
component on the orderof 10% of the poloidal component,with a position= 63., an
inclination ithe
= 50 , andaforce is able towhere
preventdtoroidal
gravitational
collapse.
wavelengths.
in
terms
of
⌃
by
3.5.infieldThe
decrease with radius, could be due to the decrease of
mass-to-flux
ratio distance= 2.66. The magnetic
field axis is oriented
perpendicular
to the NE–SW velocity
gradient anddetected
the core.
is thebetweentwo
contiguous
magnetic
over
the
map
(3)
and
(4), and a uniform value of ⇢The strengthof theplane-of-the-sky
componentof the meanmagnetic
field,
estimatedusing forboth the Eqs.
Davis-Chandrasekhar-Fermi
andtheopticaldepth
The map ofsegments,⌃B at 1.3
mm
is
shown
in
Fig.
10.
For
this
calpmethods, is in the range ⇠10–80 mG, for a density range 1.4 ⇥ 10 –5 ⇥ 10 cm . The mass-to-flux of total dust (Hildebrand et al. 2000; Yang et al.
the polarization-intensity
gradientand BPA= whichis⌃ (rP
the+ ⇢rdifference
betweentheir
position2017),
butin this case
expectcore,similar values) 4⇡R(3)density
to therange
ofone
thewouldMainn = where
1.4 the⇥ratio is in the range ⇠1.9–3.0,
suggeststhat thecorecorresponding
is, “supercritical”. The polarization-intensity
gradient
methodindicates
culation we have reduced
thenumberofpixelscontainedineach
emissionis
opticallythin.
Therefore,
thissuggestsanincreasethat the magnetic field cannot prevent gravitational collapse insidethemassivecore.
Thecollapseintheexternal
part
of
the
core
is
7calculated
8
3 averaging theangles.
Theradiusofet al.curvature
isrPpolarizationby(slightly)
sub-Alfvénicand becomessuper-Alfvénic
to 10
the
center.
–5
10
cm
, we
Bpos = 9–55
mG.
resultisconof the polarization
fraction,or ofThis
the polarization
efficiency,(Koch
2012a,b), closewhereisthe⇥pressure
gradient,r isobtainbeam surface to<3, andwehaveconsidered
only
5.2.
Dichroic
extinction
Dust polarization measurements from large core scales to small circumstellar scales, in the hot molecular corewithwavelength.
hasalso been
observedinin Sect.
the circumbithe gravity
acceleration,
andsistent
R field
is theradiusofthe
curvatureof theobtained
have confirmed
the presenceof a strongadjacentmagnetic
with segments
anhourglass-shaped
morphology.
This
resultsuggeststhat Thisbetween
two
over
all
nearest
with
range
with
the
DCF
method4.2
measurements local
abovecurvatures
5 G31.41+0.31.
diskitaroundmagnetic
fieldroleline.
The latter
defined process
by of massive stars at all scales,nary
the magnetic field could
have a relevantin regulating
the isstar-forming
althoughcannot the low mass YSO binary BHB2007-11 (Alves
prevent the collapse. However, it cannot be ruled out that the(Blarge opacity=of thecentral regionmG).
of the core may
study thatofand
the inonly
et temperal.the2018)
theFigure
HL values
Tau disk5(Linet⌃al.B2023).
8.3–50
We
note
of
< the
2However,have
neighbors.
In Eq. (3), we
that
local
changes
inhinderpos observationsshowsma" assume#magnetic field at circumstellar scales. Therefore,high-angularresolution
at longer wavelengths, tracing optically thinner1
2
1
the origin of this increase is not understood. Further theoretical
ABSTRACT

00

Context.

00

Aims.

Methods.

00

00

00

00

00

B

7

3

pos

1

Results.

1

B

7

pos

B

Conclusions.

emission, are needed to confirm= thiscosself-similarity.
(⇡
PA)

8

3

c

c

, been considered to avoid(4)
artificially high values of the magnetic

Thermal Structure and Millimeter Emission from a Protoplanetary Disk with Embedded
Protoplanets from Radiative Transfer Modeling
Felipe Alarcón

and Edwin A. Bergin

Department of Astronomy, University of Michigan, 323 West Hall, 1085 S University Ave., Ann Arbor, MI 48109, USA; falarcon@umich.edu
Received 2023 October 2; revised 2024 April 9; accepted 2024 April 9; published 2024 May 29

•
•
•
•
•
•
•
•
•

Abstract

PDSThe70,
AB ofAur,HD and169142
Figure2.circumplanetary
Input spectraof provides
the model
for opportunity
different toplanetaryrates,
discovery
protoplanets
disks
a uniquecharacterizeaccretion
planetThe Astrophysical Journal, 967:144 (11pp), 2024 June 1

UV, Hα3D HD, FARGO3D, RADMC-3D, λ=1.3 mm, θ=3 au
DSHARP HD 163296
α=10M =2.1 Mo.
10, 48, 86 au 0.7, 2.18, 0.14 MJ distribution
mm of an accretion
150disk
au (Calvet
2 MJet al. 1994):
0.69x10 7 Mo/yr
3GM M ⎡
R
⎛
⎞ ⎤.
=
q
1
(1 )
99
amax=2.5 mm, 1
5 µm
visc
3
the
best-ﬁt 2D model of the dust continuum
emission⎢⎥
preplicatedR
R
Uniﬁed Astronomy Thesaurus concepts: Protoplanetary disks8(1300);
Submillimeter
astronomy(1647);
Planetary⎝⎠from HD 163296⎣ from the DSHARP survey⎦ (Andrews et al.
interactions
2018; Zhang et al. 2018). We also embedded a planet beyond
d/g disk10^
2,(2204)
3, 4
the edge of the observable millimeter disk for the other run. We
8We
to calculate
thermalequilibrium.
decidedto replicate the HD the
163296 disk
as our starting
point
1200 K
10^used5, 10
6, photons
7 MJ/yr
because it presents a well-known and thoroughly characterized
formation through observations.
Massive protoplanets
shape thephysicalandstructure shocks.
of theirhostwhich include
the circumplanetary
andchemical
the accretion
includingdisk
the blackbody
emissionfrom a protoplanet,accretion The stellar
circumstellar disk by accretion, localized emission, and disk depletion.
In thethisspectrum
work, ofwea study
the thermalchanges
shocks, andcircumplanetary
disk. Wethenof accretion
the HD and
163296staris alsoshown
forreferencetheandcomparison
producedsynthetic
continuum
emission images of simulations
hosting
induced within the diskspectrum
by protoplanet
synthetic
predictions
throughhydrodynamical
disk
at
λ
=
1.3
mm
observable
by
ALMA
at
typicalangularwithtransfer
the protoplanetary
spectra.
with postprocessed radiativewith an emphasis onradio resolutions
millimeteremission. We explored distinct growthof dust continuum emission, ∼3 au (Andrews 2020).
conditions and varied both planetary accretion rates and the local dust-to-gas mass
3 ratios for a protoplanet at* circumplanetary
1200 K. The radiative transfer models show that beyond the effect of disk2.1.
gaps,
in most cases,theHydrodynamical
Simulation
Setup
disk (CPD) and the planet’s emission locally increase the disk temperature.
Moreover,dependingon the local dustWe ran two 3D hydrodynamical simulations with FARGO3D
to-gas depletion and accretion rate, the presence of the CPD may(Benítez-Llambay
have detectablesignatures
millimeter& Masset2016), inwhich
is built byemission.
expanding the FARGO(Masset2000), which Thus,
is particularly
It also has the power to generate azimuthal asymmetries that are important
foralgorithm
continuum
subtraction.
if other
1 wavelengths
2 disks. Using
efﬁcient for advection ﬂows in Keplerianmeans of detection of protoplanets are proven, the lack of corresponding
evidenceatother
can aset
dedicated
P P hydrodynamics codeP provides a more realistic
limits on their growth timescales through a combined analysis ofphysicalthe local
dust-to-gas
ratio
and
the
accretion
rate.
setup for the radiative transfer models. One of them

2. The emission cominusing the viscous heHill sphere of the plwill be dependent oplanetary accretion r
the radius of the pla
the star and the plan
3. The shock emission
tion of Calvet & Gu
temperature of the sh
Alarcón & BerginTsh =3 mm H 2
vs = 316 k

where mH, μ, and kmolecular weight, atively; vs is the freef

The Astrophysical Journal, 967:144 (11pp), 2024The
June
1
AstrophysicalJournal, 967:144 (11pp), 2024 June 1
The Astrophysical Journal, 967:144 (11pp), 2024 June 1
Alarcón & Bergin

Alarcón & Bergofgas and
dust(Szulágyi
al. 2014,
2022;
al.
disk,
particularly
at highetresolution
in millimeter
The stellar spectrum ﬂows
isprotoplanetary
theone
corresponding
to Dong
the etHD
wavelengths
as part elevateof both thethe
DSHARPand MAPS
2019)
and locallytemperature
insurveys
the surrounding
The observational detection of 163296
protoplanets through(Andrews
et al. 2018;
et al. 2021).
163296 disk
star different
given disk,
that
wesetÖbergup
theinThetheHDhydrodynamical
potentiallyinducingchangeschemical⎛ 2GM
presents
a rich substructurein dust emission
withcrescents,composition=v
means has become a reality in the present decade. A handful ofs(Cleeves
et al.
2015).
Muchof theextantinthe references
dark disk.
dust
gaps,
and
brightemissionrings(Isellawork
et al. 2018).
based
The
input
spectraforthe star
protoplanets have been conﬁrmedsimulations
or nominated throughdirect on that
Given
structure,
has been proposed
literature
⎝ RP
above
is thisbased
on itALMA
images inofthe gas
andthatdust in disk
the HD 163296 disk hosts several protoplanets, which are
imaging methods, including PDSand
70 b theand cprotoplanet(Keppler et al. are
combinedtheoretical
additional
observashownin
Figurepredictedwith
via simulations
thatmodels.
match2.
the However,structures seen
in dust2018; Haffert et al. 2019), AB Aur b (Currie et al. 2022), andtionalconstraintsare(Isella
becoming
available.
example, thecontinuum
emission
et al. 2018;
Zhang etAs
al. an2018;
with G the gravitatio
HD 169142
b (Gratton et al. 2019;We
Hammondet al. 2023).
modeledthe dust
opacity
dust
48 au
5 au
Garrido-Deutelmoser
et al.the2023). disk
Additional
evidence70fortwo
detectionof UV incontinuum
toward using
PDS
b supplies
protoplanets is found in the gas kinematics acting as planetary
Additionally, a larger number of protoplanet candidates haveand Ri the inner radi
information
itsal.accretionrate
and possibly
about
populations
radiativemodeling.
Theits CPD
ﬁrst
footprints about(Pintetransferet2019, 2020;
Teagueet al. 2019;
been proposed through velocity “kinks”
and footprintsfor
in diskthe (Zhoud/get al.et2022).
a chemical
point fromof view,
Izquierdo
al. 2022,From2023) andfrom the emission
atomicdetermining
gas kinematics (Pinte et al. 2019,population2020) and more recently
via
tracers(Alarcónet grains
al. rate2022).isInimportantparticular,
for ourhydrocorresponds
tolarge
holding
99%ofthethe effective
accretionfordetermining
the UVWe added an extra em
dynamical run, we located three planets of 0.7, 2.18, and 0.14
150 audetections of circumplanetary
10disks
au
25(CPDs)in K
gas or dustandHαluminosity,
which
sets
up
the
thermalandphoto48, and 86 au respectively,
although we focusonlyon
M at 10, population
disk
dust
mass,
and
the
other
represents
smallemission (Benisty et al. 2021; Bae et al. 2022). While existingtransfer modeling to explor
chemicalequilibrium
theau,planet-feeding
where atomic
the effectof the planet of
at 48
which is the mostgas,
massive
150 aud/g (e.g., Atacama Largegrains
insidethemillimeterdisk.
facilities
Millimeter/submillimeter
tracers dust
may bemass.
dominantThe(Alarcónet al.
2022).
with 1% of the disk
twopopulations
havea massive protoplanet, the C
In our second modeling setup, we analyze the effects of aArray/ALMA, the James Webb Space Telescope/JWST, andIncircumstellar
this investigation,
we explore
the thermal
disk with a massive
planet locatedbeyond theeffects of athesamecomposition,
which
corresponds
to
a
water
ice
mass
48
au
in
the
HD
163296model and for the same
numbersourceofground-based optical/infrared telescopes) will continue to pushgrowing
anddusttheemissionat millimeteredge of planet
the millimeter
disk,expectedi.e., where dust
emission falls
additional
point
corr
orbits for the model with one planet at 150 au. An aspect ratio
below
a
given
sensitivity
limit.
In
thismodel,
weembeddeda2
this ﬁeld, the upcoming large ground-based
opticalobservawavelengths
bypostprocessing
modelswithdifferent
accretionof 0.08with a ﬂaring index ψ = 0.08 was considered in thefraction of 20%, 40%
in planetorganics,
astrosilicates,
andat 150 au beyond 33%
the observablemillimeter disk. It
Mthe same location as the hydtories, such as the European Extremely Large Telescope, theinitial density distribution of the disk. The planets were input in
ratesis and
local
of in
dust
bothnoticeable
inside and outside
expected
thatlevels
the effects,
this depletion
case, will be more
ﬁxed circularorbits using the planet-to-star mass ratio, q,Thirty Meter Telescope, and the∼7.8%
Giant Magellan
Telescope, Thetheopacity
in troilites.
values
were
taken
from
and
easier to decouple
fromthestellar-disk
interactionsas predictions
the Warren
millimeter/pebble
disk.
We thenuse thesetoforHD
163296mode. We show
the dust
density
assuming a stellar mass of
2.1 Mthediskthebecomescolder inprotoplanet
the outer regions.
A mass tapering
will further revolutionize our knowledge of planet formation.
study
effective
footprint
withinfor the ﬁelds
currentofour
3Dhydrodynamical
simulationofHD
163296inplanetary
growthHenningin both models was&included
over the ﬁrst 100& Brandt(2008)
ice,
Stognienko(1996)
one.
The
This increased observational capacity
can potentiallyhelp tofor water
Figure 1. In the simulation,
we see thedensityspectral
depletion in theenergy dicapabilities
of ALMA.
orbits.
as expected at the location of the massive planets along
achieve characterization of young
systemsatmodelsassumeaDraineconstant as
α-viscosity
prescription
ThisOur paper
isorganized
follows:
we present
forplanet-forming
organics
andtroilite,and(2003)
forgaps thethe
1. Introduction

⎜

•
•
•
•

Jup

Figure 1. Top: density ﬁeld in the midplane of the disk after 500 orbits of the
HD 163296 model using the FARGO3D code (Benítez-Llambay &Masset 2016). Bottom: meridional cut of the density ﬁeld along the azimuthof the planet at 48 au showing the gap and density structure of the disk in theradial and vertical directions.

JupeThermal Structure and Millimeter Emission from a Protoplanetary Disk with Embedded
Protoplanets from Radiative Transfer Modeling
Felipe Alarcón

•
•
•
•
•
•

and Edwin A. Bergin

The AstrophysicalJournal,June 1
Department of Astronomy, University of Michigan, 323 West Hall, 1085 S University
Ave., Ann Arbor,
MI 967:144
48109,(11pp),
USA;2024
falarcon@umich.edu
Received 2023 October 2; revised 2024 April 9; accepted 2024 April 9; published 2024 May 29

d/g
d/g=0.01
d/g=0.01
à
150 aud/g

The Astrophysical Journal, 967:144 (11pp), 2024 June 1

Alarcón & Bergin

Abstract

The discovery of protoplanets and circumplanetary disks provides a unique opportunity to characterize planet
formation through observations. Massive protoplanets shape the physical and chemical structure of their hostcircumstellar disk by accretion, localized emission, and disk depletion. In this work, we study the thermal changes
induced within the disk by protoplanet accretion and synthetic predictions through hydrodynamical simulations
with postprocessed radiative transfer with an emphasis on radio millimeter emission. We explored distinct growth
conditions and varied both planetary accretion rates and the local dust-to-gas mass ratios for a protoplanet at
1200 K. The radiative transfer models show that beyond the effect of disk gaps, in most cases, the circumplanetary
disk (CPD) and the planet’s emission locally increase the disk temperature. Moreover, depending on the local dustAlarcón &to-gas
Bergindepletion and accretion rate, the presence of the CPD may have detectable signatures in millimeter emission.
It also has the power to generate azimuthal asymmetries that are important for continuum subtraction. Thus, if othermeans of detection of protoplanets are proven, the lack of corresponding evidence at other wavelengths can set
limits on their growth timescales through a combined analysis of the local dust-to-gas ratio and the accretion rate.

PDS 70c ⾒
⾒

mm

d/g

Uniﬁed Astronomy Thesaurus concepts: Protoplanetary disks (1300); Submillimeter astronomy (1647); Planetarydisk interactions (2204)
1. Introduction
The observational detection of protoplanets through different
means has become a reality in the present decade. A handful of
protoplanets have been conﬁrmed or nominated through direct
imaging methods, including PDS 70 b and c (Keppler et al.
2018; Haffert et al. 2019), AB Aur b (Currie et al. 2022), andHD 169142 b (Gratton et al. 2019; Hammond et al. 2023).
Additionally, a larger number of protoplanet candidates havebeen proposed through velocity “kinks” and footprints in disk
gas kinematics (Pinte et al. 2019, 2020) and more recently via
detectionsof ofcircumplanetary disks (CPDs) in gas or dust
Figure 10. Expected deviations in brightness temperaturein our suitemodels with respect to the baseline emission comparedemission
with deep(Benisty
high- et al. 2021; Bae et al. 2022). While existing
resolution continuum data from ALMA programs. Black squares show that ourfacilities(e.g.,
Atacama Large Millimeter/submillimetermodels predict localized deviations with a brightness temperature lower than
2 K. Blue triangles show the 3σ levels from the Andrews Array/ALMA,et al. (2021) limits, the James Webb Space Telescope/JWST, andoptical/infrared telescopes) will continue to pushwhile the red triangle is the one from Pérez et al. (2020) andground-based
the red circle is theobserved emission from PDS 70 c.
this ﬁeld, the upcoming large ground-based optical observatories, such as the European Extremely Large Telescope, themechanisms and/or physical instabilities (see Thirty
Bae et Meteral. 2023
Telescope, and the Giant Magellan Telescope,for a detailed overview of substructure-formingwill
mechanisms).
further revolutionize our knowledge of planet formation.
Many of these instabilities will lead to structures
This resembling
increased observational capacity can potentially help tothe ones produced by massive planets, i.e., gaps,
rings,
andachievecharacterizationof young planet-forming systems at• CPD
artifact
• CPD

kink

ﬂows of gas and dust (Szulágyi et al. 2014, 2022; Dong et al.
2019) and locally elevate the temperature in the surrounding
disk, potentially inducing changes in the chemical composition(Cleeves et al. 2015). Much of the extant work in the references
above is based on ALMA images of gas and dust in disk
combined with theoretical models. However, additional observational constraints are becoming available. As an example, thedetection of UV continuum toward PDS 70 b supplies
information about its accretion rate and possibly about its CPD(Zhou et al. 2022). From a chemical point of view, determining
the effective accretion rate is important for determining the UV
and Hαsets
up continuum
the thermalandphotoFigure
8. Comparison
synthetic
mm dustmodel
continuum
imagesusing SIMIO
between t
Figureluminosity,
8. Comparison of which
synthetic 1.3
mm dustimages using
SIMIO
betweenthe differentofmodels
and1.3a standard
without
protoplanetary
emissionfor ∼1of
hrthe
integration
time. Apartwhen
from onecase,isthere
is no depleted
strong additionalsignaturefor ∼1 equilibrium
hr integration time.ofApart
one case, there is no strong
CPD. Furthermore,
the CPD
severelyof large grains,theof thechemicalthefromplanet-feedinggas, additional
where signature
atomicmillimeteremission
is lowerthat inferfrom thatthe surroundings.
From the momillimeter emission from dust is lower than that from the surroundings. Fromthe models
withfrom
low dust
accretion
rate than
we alsothe 1200 K blackbody
tracersprotoplanetary
may be dominant(Alarcón et al. 2022).
protoplanetary
spectrum does not produce a signiﬁcant change in synthetic ALMA
images. spectrum does not produce a signiﬁcant change in synthetic ALMA image
In this investigation, we explore the thermal effects of aby thecould
protoplanetemission,
the CPD,fromand otherpossibleaccretion
growing
andemission,
the expected
emission
millimeterby theplanet
protoplanet
the CPD, andpossible ataccretion
be probed
by the emission
tracers
such as SO cou
onto theTherefore,changesstill2023).
be traceable
onto the planet.
Therefore, suchmodels
changes may
be traceable
or planet.
CI (Alarcón
et al.such
2022;
Law may
et al.
A tentative or C
wavelengths
by postprocessing
withstilldifferent
accretionby other means;increases
have
thehaspotential
todeteincreases havepotentialof temperature
a CPD beyond
the pebble
disk
been suggested
rates byandotherlocalmeans;levelstemperatureof dust depletion
both theinsideand tooutsidedetection
to thethermaldesorptionof thereotherwiseabsentvolatiles,of the in thlead to thermal desorption of otherwise absent volatiles, lead in
AS 209disk, whereis a local
enhancement
the millimeter/pebble
We duethentousepredictions
topredictedmakingthem easier
to observeto theweak increase
continuumin the predmaking them easier disk.
to observe
the these
weak continuumgas density,
butduealso
a slight
emissionand isolated
emission.
Moreover,
theby
local
of
tem
studyemission
the effective
protoplanet
footprint
withinthecurrent
and isolated emission. Moreover, the local density oftemperatureof theemissionmeasured
COdensity
isotopologues
can beenoughthat the millimeteremission
is is a (Badust canof be
low enough that the millimeter emission is dust (Baeet al.low2022).
The measurementof this thermal
increase
capabilities
ALMA.
while making
the CPD brighter
thanmass,
its surroundings
negligible
the CPDasbrighter
than itswe
surroundings
in determining
the CPDand therefore the keyThispaperwhile
is makingorganized
follows:
presentnegligible
thekey ingredientd/g

I. Bešlić1 , S. Coudé2, 3 , D. C. Lis4 , M. Gerin1 , P. F. Goldsmith4 , J. Pety1, 5 , A. Roue↵6 , K. Demyk7 ,Received 24 October
2023;4 , accepted
2024 9 , F. Levrier10 , J. Orkisz5 , N. Peretto11 , M. G. Santa-Maria9 ,8 January
C. D. Dowell
L. Einig5, 20, J. R. Goicoechea
N. Ysard7, 12 , and A. Zakardjian7

1

ABSTRACTLERMA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, 75014 Paris, France
2
Department of Earth, Environment, and Physics, Worcester State University, Worcester, MA 01602, USA
Context. Star formation
drivesthe evolutionof &galaxies
and60thecycling
matter between
phases of the interstellar medium
3
Centerfor Astrophysics| Harvard
Smithsonian,
GardenStreet,ofCambridge,
MA 02138,di↵erentUSA4and stars. The supportJetof
interstellar
cloudsagainstgravitational
collapse
magnetic
fields has
been USAproposed as a possible explaPropulsion
Laboratory,
California
Instituteof Technology,
4800 Oakby
Grove
Drive, Pasadena,
CA 91109,5
IRAM, 300
rue dela Piscine, 38406
Saint Martind’Hères, France
nation for the low observed
starformation
efficiency
ingalaxies
and
the
Milky
Way.
The
Plancksatellite
provided the first all-sky
6de Toulon, Aix Marseille Univ, CNRS, IM2NP, Toulon, France0
map of the magnetic7 Université
field
geometryinthedi↵useinterstellar
mediumonangularscalesof
5-15.
However,higher spatial resolution
IRAP, CNRS, Université de Toulouse, 9 avenue du Colonel Roche, 31028 Toulouse Cedex 4, France
8
observations are required
to understandtheCNRS,transitionfromdi↵use,gas France
to dense, gravitationally unstable filaments.
Université
Grenoble Alpes,
GIPSA-lab,
Grenoble
INP,subcritical
Grenoble, 38000,
9Institutode Física
Fundamental(CSIC). Calle
Serranoin
121-123,28006, Madrid,
Spain
Aims. NGC 2024, also
known
as
the
Flame
nebula,islocatedthenearbyOrion
B molecular cloud. It contains a young, expanding
10
Laboratoire de Physique de l’ENS, ENS, Université PSL, CNRS, Sorbonne Université, Université Paris Cité, Observatoire de
HII region and a dense
supercriticalfilament.
Thisfilament
harbors
embedded
protostellar
objects and is likely not supported by theParis, F-75005 Paris, France
11
magnetic field againstCardi↵
gravitational
collapse.Research
Therefore,
NGC 2024
anAstronomy,
excellentCardi↵
opportunity
studyBuildings,
the role of magnetic
Hub for Astrophysics& Technology,
Schoolprovidesof Physics &University,toQueensTheevolution,
parade, Cardi↵
CF24
3AA, UKof dense filaments, the dynamics of young HII regions, and the e↵ects of mechanicalfields in the formation,andcollapse
12
Université Paris-Saclay, CNRS, Institut d’Astrophysique Spatiale, 91405, Orsay, France

iv:2401.17171v2 [astro-ph.GA] 7 Feb 2024

arXiv:2401.17171v2 [astro-ph.GA] 7 Feb

Laboratoire de Physique de l’ENS, ENS, Université PSL, CNRS, Sorbonne Université, Université Paris Cité, Observatoire deParis, F-75005 Paris, France
11
Cardi↵ Hub for Astrophysics Research & Technology, School of Physics & Astronomy, Cardi↵ University, Queens Buildings,
The parade, Cardi↵ CF24 3AA, UK
The magnetic field in the Flame nebula
12
Université Paris-Saclay, CNRS, Institut d’Astrophysique Spatiale, 91405, Orsay, France

and radiative feedback from massive stars on the surrounding molecular gas.
Received
24 October
2023;
accepted
20 January
2024
Methods. We combinednew
154 and216µm dustpolarization
measurements carried out using the HAWC+ instrument aboard SOFIA
with molecular line observations of 12 CN(1–0) and HCO+ (1–0) from the IRAM 30-meter telescope to determine the magnetic field
ABSTRACTgeometry, and to estimate the plane of the sky magnetic field strength
across the NGC 2024 HII region and the surrounding molecular
cloud.
Context. Star formation drives the evolution of galaxies and the cycling of matter between di↵erent phases of the interstellar medium
Results. The HAWC+
observations
an clouds
orderedmagnetic
field
geometryin fields
NGChas2024
that follows
the morphologyof theand stars.
The support of showinterstellar
againstgravitational
collapseby magnetic
been proposed
as a possible
explanation
for thethe low
observedof
startheformation
in galaxiesTheand theMilky Way.
TheofPlancksatellite
provided field
the firststrength
all-sky is moderate,
expanding HII region
anddirection
main efficiency
dense filament.
derivedplane
the0 skymagnetic
the magnetic
field geometry
in the di↵use
angularscalesof 5-15
spatial resolution
ranging from 30 tomap
80ofµG.
The strongest
magnetic
field interstellar
is foundmedium
at the oneast
edge
of theHII. However,region, higher
characterized
by the highest gas
observations are required to understand the transition from di↵use, subcritical gas to dense, gravitationally unstable filaments.
densities and molecularline2024,
widths.
In contrast,
the nebula,
weakestfield inisthe
foundmain,cloud.
dense
filamentin NGC
2024.
Aims. NGCalso known
as the Flame
is locatednearbytoward
Orion B themolecular
It contains
a young,
expanding
HII region
and amagnetic
dense supercriticalfilament.
This filament harbors
embedded
objects andlikelynot supportedby theConclusions. We findthat thefield hasa non-negligible
influenceon protostellar
the gas stability
atistheedgesof the expanding
HII shellmagnetic
field againstandgravitational
collapse.(siteTherefore,
NGC 2024
providesan excellent opportunity to study the role of magnetic(gas impacted by stellar
feedback)
thefilamentofcurrent
star
formation).
fields in the formation, evolution, and collapse of dense filaments, the dynamics of young HII regions, and the e↵ects of mechanicalradiative feedback from massive stars on the surrounding molecular gas.
Key words. ISM:andmagnetic
fields – ISM: molecules – Galaxies: star formation
Methods. We combined new 154 and 216 µm dust polarization measurements carried out using the HAWC+ instrument aboard SOFIANGC 2024with molecular line observations of 12 CN(1–0) and HCO+ (1–0) from the IRAM 30-meter telescope to determine the magnetic field
geometry, and to estimate the plane of the sky magnetic field strength across the NGC 2024 HII region and the surrounding molecular
cloud.
Results. The HAWC+ observations show an ordered magnetic etfieldal.
geometryin NGC
2024 thatthe morphologyof the1. Introduction2006),
turbulentorfollowsmagneticpressure
gradients are strong
expanding HII region and the direction of the main dense filament. The derived plane of the sky magnetic field strength is moderate,enoughtomaintaincloudsinapproximatehydrostatic equilibranging from 30 to 80 µG. The strongest magnetic field is found at the east edge of the HII region, characterized by the highest gas
densities and molecular line widths. In contrast, the weakest field rium
is found on
toward
the
main,
dense
filament
in
NGC
2024.
all spatial scales for tens of free-fall times. In other
The question of what Conclusions.
controls We
thefindstar
formation
efficiency
in influence on thethat themagnetic field
has a non-negligible
gas stability at the edges of the expanding HII shellhigh-density regions are rapidly contracting, converting(gas impacted
filament(site of currentmodels,star formation).
molecular clouds has long
beenbyatstellar
thefeedback)center and
ofthe
star
formation

30

B

HII
SOFIA HAWC+ IRAM30
80μG
HII

fraction (as high as 40%; Bonnell et al. 2011) of theirwords. ISM: magnetic
fields1974)– ISM: molecules
formation
research. Early studiesKey(Zuckerman& Evans
showed– Galaxies:
that astarlarge
if all the gas within dense interstellar clouds were to collapse mass into stars in only a few free-fall times. However, the low-

HII

Germany,
Université Paris-Saclay, Université Paris Cité, CEA, CNRS, AIM, 91191, Gif-sur-Yvette, France,
3
Université Paris-Saclay, ENS Paris Saclay, 91191, Gif-sur-Yvette, France,
4
Inefficientstar formationin high Mach
numberenvironments
Universität Heidelberg,
Interdisziplinäres
Zentrum für Wissenschaftliches
Rechnen,Im Neuenheimer
Feld 205, 69120 Heidelberg,
Germany

II. Numerical simulations and comparison with analytical models

Received April 29, 2024; accepted
April 29, 2024
1

Noé Brucy , Patrick Hennebelle2 , Tine Colman2 , Ralf S. Klessen1, 4 , and Corentin Le Yhuelic2, 3

Universität Heidelberg, Zentrum für Astronomie, Institut
für Theoretische Astrophysik, Albert-Ueberle-Str 2, D-69120 Heidelberg,
ABSTRACT
Germany,
2
Université Paris-Saclay, Université Paris Cité, CEA, CNRS, AIM, 91191, Gif-sur-Yvette, France,
Context. Predicting
the star formation rate (SFR) in galaxies is crucial to understand their evolution and morphology. To do so requires
3
Université Paris-Saclay, ENS Paris Saclay, 91191, Gif-sur-Yvette, France,
4
a fine understandingof howHeidelberg,
dense structuresof gasZentrum
are createdand collapse.
In that,and205,
gravitya major role.
Universität
Interdisziplinäres
für Wissenschaftliches
Rechnen,
Im turbulence
Neuenheimer Feld
69120 play
Heidelberg,
Germany
Aims. Within the gravo-turbulent framework, we assume that turbulence shapes the ISM, creating density fluctuations that, if gravita1

Xiv:2404.17374v1 [astro-ph.GA] 26 Apr 2024

iv:2404.17374v1 [astro-ph.GA] 26 Apr 2024

2

tionally unstable,Received
will collapsestars.
goal of this work is to quantify how di↵erent regimes of turbulence, characterized
April 29,and
2024;form
accepted
AprilThe29, 2024
by the strength and compressibility of the driving, shape the density field. We are interested in the outcome in terms of SFR and how
it compares with existing analytical models for the SFR.
ABSTRACT
Methods. We run a series of hydrodynamical simulations of turbulent gas. The simulations are first conducted without gravity, so that
Context. Predicting the star formation rate (SFR) in galaxies is crucial to understand their evolution and morphology. To do so requires
the density and velocity
are shaped by the turbulence driving. Gravity is then switched on, and the SFR is measured and compareda fine understanding of how dense structures of gas are created and collapse. In that, turbulence and gravity play a major role.
with analytical models.
Thethephysics
includedin thesesimulations
is veryclose
to theonedensity
assumedin theAims. Within
gravo-turbulent
framework,
we assumethat turbulence
shapesthe ISM,creating
fluctuations
that,classicalif gravita- gravo-turbulent
tionally unstable,collapseform stars. The
goal of this work is to quantify how di↵erent regimes of turbulence, characterized
SFR analytical models,
which will
makes
theandcomparison
straightforward.
by thestrength
and compressibilityof themodels
driving, shapethe density field.
Wewithare interested
in the outcome
terms ofnumber,
SFR and how
Results. We foundthat
the existing
analyticalconvincingly
agree
simulations
at lowin Machbut we measure a
it compares with existing analytical models for the SFR.
much lower SFRMethods.
in the simulation
with
a
high
Mach
number.
Wedevelop,inacompanion
paper,
anupdatedphysically-motivatedWe run a series of hydrodynamical simulations of turbulent gas. The simulations are first conducted without gravity, so thatthe density andwell
velocity
shaped by the
turbulence
then switched on, and the SFR is measured and compared
SFR model that reproduces
theareinefficienthighMach driving.
regimeGravityof theis simulations.
analyticalmodels. Thethat
physics
includedestimationsin these simulations
is very
close to the one assumed
in the classicalConclusions. Ourwith
work
demonstrates
accurateoftheturbulent-driven
replenishment
timegravo-turbulentof dense structures and the
SFR analytical models, which makes the comparison straightforward.
dense gas spatialResults.
distribution
arenecessarytocorrectly
predict
the
SFR
in
the
high
Mach
regime.
The
inefficient
high-MachregimeWe found that the existing analytical models convincingly agree with simulations at low Mach number, but we measureamuch lowerfor
SFR
in low
the simulation
with ainhighMachandnumber.
We develop,
in a companion
paper,
updatedphysically-motivatedis a possible explanation
theSFR founddense
turbulentenvironments
suchasanthecentersof our Milky Way and other
SFR model that reproduces well the inefficient high Mach regime of the simulations.
galaxies.
Conclusions. Our work demonstrates that accurate estimations of the turbulent-driven replenishment time of dense structures and thedense gas spatial distribution are necessary to correctly predict the SFR in the high Mach regime. The inefficient high-Mach regime
Key words. stars:
formation — ISM: clouds — physical processes: turbulence
is a possible explanation for the low SFR found in dense and turbulent environments such as the centers of our Milky Way and other

SFR galaxies.

Key words. stars: formation — ISM: clouds — physical processes: turbulence

1. Introduction
1. Introduction

How fast a self-gravitating gaseous system converts its mass into
How fast athat
self-gravitating
system converts
its mass intostars is a major questionneeds to gaseous
be addressedto understandstars is a major question that needs to be addressed to understandthe history of ourtheUniverse.
Determining
the startheformation
rate
history of ourUniverse. Determining
star formation
rate(SFR),
which
the massof starsper
formedof time,led(SFR), which is themassofisstars
formedunitperofunit
time,hashasledtoavast
numberofobservational
studies(e.g.
Schmidt
1959;
to a vast number of observational studies (e.g. Schmidt 1959;
Lada et al. 2010; Kennicutt & Evans 2012; Sun et al. 2023).
Lada et al. 2010;From
Kennicutt& side,Evans2012;e↵orts
Sunhave
et alsoal. been2023).
the theoreticalnumerous
dedi-

SFR

ally determined by invoking a density or a scale for gravitational
SFR
instability.
ally determined by invoking a density or a scale for gravitational
instability.
Turbulence is thought to be a key player in the generation of
Turbulenceis thought
to be a keyFrom
player thein thenumericalgeneration ofsimulation side,
self-gravitating
structures.
self-gravitating structures. From the numerical simulation side,studiesthat
investigate
role of on
turbulence
studies thatinvestigate
the roletheof turbulence
the SFR canon
be the SFR can bedividedintosimulations
with large-scalea prescribed large-scale
divided into
two twotypes:types:
simulations
with a prescribed
drivingandsimulations
that
explicitly
treatvariousstellarfeeddriving and simulations that explicitly treat various
stellar feedback processes. When large-scale driving is employed (Mac Low
backprocesses.
Whenlarge-scale
driving
isemployed(Mac Low& Klessen 2004; Padoan & Nordlund 2011; Federrath & Klessen&
Klessen
2004;
PadoanNordlund2011;& Klessen
2012,2013), thegoal hasusually &been
to understandbasicFederrath
phys-

SFR

2 Universitäts-Sternwarte, Fakultät für Physik, Ludwig-Maximilians-Universität München, Scheinerstr. 1, 81679 München, Germany
3 Max-Planck-Institut für extraterrestrische Physik, Giessenbachstrasse 1, 85748 Garching, Germany

Impacts of Energetic Particles from T Tauri Flares on Inner Protoplanetary
Discs

5 INAF-Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy

V. Brunn,1? Ch. Rab,2,3 A. Marcowith,1 C. Sauty,1,4 M. Padovani,5 and C. Meskini1

1 Laboratoire Univers et Particules de Montpellier, Université de Montpellier/CNRS, place E. Bataillon, cc072, 34095 Montpellier, France

Accepted XXX. Received
YYY; in originalFakultät
form ZZZ
2 Universitäts-Sternwarte,für Physik, Ludwig-Maximilians-Universität München, Scheinerstr. 1, 81679 München, Germany
3 Max-Planck-Institut für extraterrestrische Physik, Giessenbachstrasse 1, 85748 Garching, Germany

4 Laboratoire Univers et Théories, Observatoire de Paris, Université PSL, Université Paris Cité, CNRS, F-92190 Meudon, France

ABSTRACT

arXiv:2404.16459v1 [astro-ph.HE] 25 Apr 2024

T

iv:2404.16459v1 [astro-ph.HE] 25 Apr 2024

4 Laboratoire Univers et Théories, Observatoire de Paris, Université PSL, Université Paris Cité, CNRS, F-92190 Meudon, France

5 INAF-Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy

T Tauri stars are known to be magnetically active stars subject to strong flares observed in X-rays. These flares are likely
Accepted XXX. Received
YYY; in originalevents
form ZZZ during which a part of the stored magnetic energy is converted into kinetic
due to intense magnetic
reconnectionenergy of supra-thermal particles. Since T Tauri stars are surrounded by an accretion disc, these particles may influence the
ABSTRACT
disc dynamics andchemistry. This work continues on a previous stationary model, which showed that energetic particles
T Tauri stars are known to be magnetically active stars subject to strong flares observed in X-rays. These flares are likely
accelerated during flares can produce a strong ionisation rate at high column densities in the inner accretion disc. The
due to intense magnetic reconnection events during which a part of the stored magnetic energy is converted into kinetic
present model includes
non-stationaryof flaring
eventsbysampled
a theseChandraX-ray
surveytheof nearby young
energy of supra-thermal
particles.sequences
Since T Tauri stars
are surrounded
an accretionby
disc,particles
may influence
disccalculate
dynamics andThisionisation
work continues
onexpected
a previous stationarymodel,
whichfromshowedthattoenergeticstellar objects. We
thechemistry.
averagedrate
in a radius
range
0.08
0.6 auparticles
from the central star.
accelerated
duringflarescanproduceastrongionisation
rate
at
high
columndensities
in
the
inner
accretion
disc.
The
We confirm that energetic particles produced by the flares dominate the ionisation of the disc up to column
densities ofpresent
model
includesnon-stationary
sequencesofflaring
eventssampledbyaChandraX-ray
surveyofnearbyyoung
25°2
10 cm . We further
studyWethemaintheconsequencesof thisadditionalsourceof from
ionisation
the accretion rate,
stellar objects.
calculate
averaged ionisation
rate expected
in a radius
range
0.08 to 0.6on
authe
fromviscosity,
the central star.
We confirm
thatandenergetic
particles producedby the flares
dominate
the ionisation ofdiscs.
the disc up to column densities ofthe volumetric heatingrate
the chemicalcomplexityof inner
protoplanetary1025 cm°2 . We further study the main consequences of this additional source of ionisation on the viscosity, the accretion rate,
Key words: acceleration
ofheatingparticles– magnetic
reconnection– stars:
flare – accretion,accretion discs
the volumetricrate andthe chemicalcomplexity of innerprotoplanetary
discs.

X

Key words: acceleration of particles – magnetic reconnection – stars: flare – accretion, accretion discs

1 INTRODUCTION
1 INTRODUCTION

10^25 cm^-2

0.08

0.6au

T Tauri stars
are typically
young stars,oftypicallya few million
years
old,
T Tauri stars are youngstars,
a fewofmillion
years
old,
still contracting and accreting material from their surrounding
still contracting andaccreting material from their surrounding
circumstellar discs. The way T Tauri stars accrete the surrounding
circumstellar discs.
The matter
way Tis Tauristarssubject
accretethe surrounding
infalling
still an open
in astrophysics(Venuti et al.
2014;
Hartmann
et
al.
2016;
Manaraetal.
2016).
All
mechanisms
infalling matter is still an open subject in astrophysics (Venuti et al.
that describe accretion-ejection processes involve the interaction
2014; Hartmann etal. 2016; Manara et al. 2016). All mechanisms
between magnetic fields and ionised disc matter (e.g., Shakura &that describe accretion-ejection
processes
the interaction
Sunyaev 1973; Blandford& Payne involve
1982).
The
magnetic
field
geometry
of
these
stars
is muchmore combetween magnetic fields and ionised disc matter (e.g.,
Shakura&plex than those of non-accreting cool stars (Donati et al. 2007;
Sunyaev 1973; Blandford&
Payne1982).
Gregory et al. 2008). Some field lines might become twisted due

pectedto produce
particle
fluxesarefive orders of magnitude
pectedto produce
particle
fluxes thatare fivethat
ordersof magnitude
higherthan
those
producedby the Sunby(Feigelson
et al.
2002; Rab et al. 2002; Rab
higherthan
those
producedthe Sun(Feigelson
et al. 2017). The high-energy particle flux produced by T Tauri stars
et al. 2017). The high-energy particle flux produced by T Tauri stars
strongly impacts the surrounding environment (Rodgers-Lee et al.
strongly
the etsurrounding
environment(Rodgers-Lee et al.
2017;
Rab etimpacts
al. 2017; Offner
al. 2019; Waterfall
et al. 2020; Brunnetal. 2023).
theseparticles
can2019;
ionise Waterfall
the gas in theet al. 2020; Brunn
2017;
RabInetparticular,al. 2017;
Offneret al.
surrounding
disc
et al. 2023).
Discparticles
ionisation isa criticalet al. 2023).
In(Brunnparticular,
these
can
ionise the gas in theprocess in T Tauri discs, as it couples the disc material to magsurrounding
et al.
Disc
is a critical
neticfields, which discaffects(Brunn
the dynamics
and2023).
chemistryof theionisation
whole
disc
(Cleeves
2013; Offner
al. 2019;
Waggoner& Cleevesprocess
inetTal.Tauri
discs,etas
it couples
thedisc material to mag2022)
jets (Sauty
2019;
Jacquemin-Ide
et al. 2019;
Ray& Ferneticand
fields,which
affects
the dynamics
andchemistryof the wholereira 2021). Magnetic fields can also trigger instabilities in the gas
disccan(Cleeves
et al.of2013;
Offneretthe
al.star2019;
Waggoner & Cleeves
that
drive accretion
disc material
onto(Hartmann

V. V. Bobylev, How
A. T. common
Bajkova can the origin of clusters Cha I, Cha II, ϵ Cha andη Cha be?

arXiv:2404.00669v1 [astro-ph.GA] 31 Mar 2024

arXiv:2404.00669v1 [astro-ph.GA] 31 Mar 20

η Cha be?

Pulkovo Astronomical Observatory, St.-Petersburg 196140, Russia; bob-v-vzz@rambler.ru
V. Bobylev,
T. Bajkova
G Received 20XXV.Month
Day;A.
accepted
20XX Month Day
Pulkovo Astronomical Observatory, St.-Petersburg 196140, Russia; bob-v-vzz@rambler.ru
G Received 20XX Month Day; accepted 20XX Month Day

Abstract The trajectories of the clusters η Cha, ϵ Cha and Cha I, Cha II, constructed
Abstract
Thebeentrajectoriesof theclusters
η Cha, ϵ that
Cha andI, Cha II, constructedbackward in time,
havestudied.
We
concluded
theChahypothesis
about the joint
backward
in
time,
have
been
studied.
We
concludedthatthehypothesisabout
the jointformation of all
four of these clusters from one molecular cloud cannot be completely
exformation of all four of these clusters from one molecular cloud cannot be completely excluded. However,
10–15
Myr
ago,Myrallago,these
fourfourclusters
locatedat approximately
thecluded.
However,
10–15
all theseclusterswere
were locatedat approximatelythesame height
above theplaneGalaxy.
of the Galaxy.
Thus,
gas-dust clouds
fromfrom
whichwhich
all theseall thesesame height above
the planeof theThus,
thethegas-dustcloudsfour
clusters
wereformedwerelocated
on
one
broad
front.
Itis
possiblethat
theappearfour clusters wereformed were located on one broad front. It is possible thatthe appearance of the Cha I, Cha II, ϵ Cha and η Cha clusters may be associated with the impact onance of the Cha
I,
Cha
II,
ϵ
Cha
and
η
Cha
clustersmaybeassociatedwiththeimpact onsuch a front of shock waves formed after supernova explosions in the Scorpius-Centauri
New estimates
the kinematic
ages ofexplosions
the clusters Cha
and Scorpius-Centauri
Cha II are obsuch a front ofassociation.
shock waves
formedof after
supernova
in Ithetained
as
0.12
±
0.19
and
0.05
±
0.15,
respectively.
It
is
shown
that
the
minimum
size IIof are obassociation. New estimates of the kinematic ages of the clusters Cha I and Cha
the Cha I-north and Cha I-south clusters corresponded to the time of 0.55 ± 0.24 Myr andtained as 0.12 0.04
± 0.19and± 0.15, respectively.
It is1.5shownthat
the minimum± 0.18Myr0.05
ago, respectively,
and approximately
Myr agothe distance
between size ofthetrajectories
of
these
two
groupings
wasminimal.
the Cha I-north and Cha I-south clusters corresponded to the time of 0.55 ± 0.24 Myr and0.04 ± 0.18 Myr ago, respectively, and approximately 1.5 Myr ago the distance between
Key words: (Stars:) distances: open clusters and associations (Galaxy:) kinematics andthe trajectoriesdynamics
of these two groupings was minimal.
Key words:(Stars:) distances: open clusters and associations (Galaxy:) kinematics and
1 INTRODUCTION
dynamics

η Cha ε Cha Cha Close
I toChaII(at a distance of about 100–250 pc), the fourth galactic quadrant
10is occupied
15 by thethe SunScorpius-Centauri OB association (Blaauw 1946, 1964). It has three main structural components LCC:
(Lower Centaurus Crux), UCL (Upper Centaurus Lupus) and US (Upper Scorpius). A large number of
1 INTRODUCTION
publications have been devoted to the study of the stellar composition and kinematics of the Sco–Cen OB
association (de Geus et al. 1989; de Geus 1992; Bruijne 1999; de Zeeuw et al. 1999; Sartori et al. 2003;
et al. 2008;ofPöppel
et al.
2010; Rizzuto
al. 2011;
Pecautet al. 2012;
Pecaut is& Mamajek
Close to the SunFernández(at a distanceabout
100–250pc), etthe
fourthgalactic
quadrant
occupied by the
2016; Bobylev & Bajkova 2020, 2023). The association has a complex morphology and evolutionary
Scorpius-Centauri
OB association (Blaauw 1946, 1964). It has three main structural components LCC:
history — some of its components (LCC, UCL, etc.) have an age of 10–25 Myr, in which the star
(Lower Centaurus
Crux),process
UCLhas(UpperLupus)
andstructures
US (Upper
Scorpius).
Aanlarge
formation
already Centaurus
completed. There
are also(for example,
US withage ofnumber of
∼5
Myr),
where
star
formationisstilloccurring.
publications have been devoted to the study of the stellar composition and kinematics of the Sco–Cen OB
The star formation process in the Sco–Cen OB association generally fits well with the sequential
association (de Geus
et al. 1989; de Geus 1992; Bruijne 1999; de Zeeuw et al. 1999; Sartori et al. 2003;
star formation model (Preibish & Zinnecker 1999). This model is based on the assumption that shock
Fernández et al.waves
2008;
Pöppelet al.
2010;stars
Rizzutoet al.
2011;
Pecaut2012; Pecaut& Mamajek
fromexplosionsof massive
in one partof theassociation
leadettoal.
compressionof hydrogencloudsin anotherpart, thus
triggering
process of starhas
formation.
2016; Bobylev &Bajkova
2020,2023).
Thetheassociation
a complex morphology and evolutionary

Cha I Cha II
1.50.12±0.19
Cha I-north Cha I-south

0.05±0.15

1Hamburger Sternwarte, Universität Hamburg, Gojenbergsweg 112, 21029 Hamburg, Germany
e-mail: raghav.arora@hs.uni-hamburg.de2
Research
Schoolof Astronomy
and Astrophysics,
The Australian
University,spiralCanberra,arm
ACT 2611,
AustraliaTherole
of magnetic
fieldsin discNational
galaxies:
instability

1

Hamburger Sternwarte, Universität Hamburg, Gojenbergsweg 112, 21029 Hamburg, Germany
e-mail: raghav.arora@hs.uni-hamburg.de
ABSTRACT
2
Research School of Astronomy and Astrophysics, The Australian National University, Canberra, ACT 2611, Australia

Context. Regularly-spaced, star-forming regions along the spiral arms of nearby galaxies provide insight into the early stages andinitial conditionsof xxxx;
star formation.
The regular separation of these star-forming regions suggests spiral arm instability as their origin.
Received
accepted xxxx
Aims. We explore the e↵ects of magnetic fields on the spiral arm instability.
Methods. We use three-dimensional global magnetohydrodynamical
simulations of isolated spiral galaxies, comparing three di↵erent
ABSTRACT
initial plasma values (ratios of thermal to magnetic pressure) of = 1, 50, and 10. We perform Fourier analysis to calculate theRegularly-spaced,along
the spiralspiral armsof nearbyWe
galaxies
provide insight
into the earlywith
stagesobservations.
andseparation ofContext.
the over-dense
regionsstar-forming
formed asregions
a resultof theinstability.
then compare
the separationsof star formation.
Thehydro
regularcase
separationthesesuggestsspiral arm
instability
as their origin.
Results. Weinitialfind conditions
that the spiralarms in the( =of1)
arestar-forming
unstable, regionswith thefragments
initially
connected
by gas streams,
Aims. We explore the e↵ects of magnetic fields on the spiral arm instability.
reminiscent Methods.
of Kelvin-Helmholtz
instability.
In the= 50 case, the spiralarmsofalso
fragment,
but thecomparing
fragments
separate
We use three-dimensional
globalmagnetohydrodynamical
simulations
isolatedspiral galaxies,
three
di↵erent earlier andtend to be slightly
elongatedinthedirection
perpendiculartothespiralarms.
However,
in
the
=
10
run
the
arms
are stabilised
initial plasma values (ratios of thermal to magnetic pressure) of = 1, 50, and 10. We perform Fourier analysis to calculate theagainst fragmentation
Despitethe di↵erencein the initial
magnetic
strengthswithof the= 50 and 10 runs,
separation ofby
themagnetic
over-dense pressure.
regions formed
as a resultof the spiral instability.
We thencomparefield
the separations
observations.
find that thein the thehydrocase arms( = 1)
unstable,fragments
connectedcases
by gas(hydrostreams,and = 50)
the magneticResults.
field isWe
amplified
to spiral
1 insidespiralforarebothruns. with
Thethespiralarms initiallyin the unstablearm ⇠arms
reminiscentof Kelvin-Helmholtz
instability.
In the= 50 case, thespiralarms also fragment,
separateearlierand kpc in the
fragment into
regularly-spaced,over-dense
regions.
We determine
theirseparation
to be ⇠ but
0.5thekpcfragmentsin the hydroand⇠ 0.65tend to be slightly elongated in the direction perpendicular to the spiral arms. However, in the = 10 run the arms are stabilised= 50 case,against
both inagreementby
withthe observed
foundin nearby
We findsmaller medianfragmentation
magneticpressure. values
Despitethe di↵erencein thegalaxies.
initial magnetic
fielda strengthsof the =characteristic
50 and 10 runs,wavelength
+0.49
+0.31
of the over-densities
along
the
spiral
arms
of
0.73
kpc
in
the
hydro
case,
compared
to
0.98
kpc
in
the
50 case.
the magnetic field is amplified to arm ⇠ 1 inside0.36
the spiral arms for both runs. The spiral arms in the unstablecases (hydro=and= 50) Moreover,
0.46
we find a higher
growthrate of the over-densities
in theWe=determine
50 run comparedto therun.inWe
fragment
into regularly-spaced,over-dense regions.
their separation
to behydro⇠ 0.5 kpc
the observehydro andmagnetic⇠ 0.65 kpchills
in theand valleys= 50 case,arms
both ininagreement
the observed
found in nearby
galaxies.
Weinstability.
find a smaller median characteristic wavelength
along the fragmented
the = with50 run,which isvalues
characteristicof theParker+0.49+0.31

v:2311.16266v1 [astro-ph.GA] 27 Nov 2023

:2311.16266v1 [astro-ph.GA] 27 Nov 2023

Raghav Arora1 , Christoph, Federrath2, , Robi Banerjee1 , and Bastian Körgten1 ,Received xxxx; accepted xxxx

of the over-densities along the spiral arms of 0.73 0.36 kpc in the hydro case, compared to 0.98 0.46 kpc in thealong the fragmented arms in the= 50 run, which is characteristic of the Parker instability.

Key words. ISM – magnetic fields – star formation – Magnetohydrodynamics (MHD) – Instabilities

1. Introductionβ=β== 50 case. Moreover,find a–higher
growthfields
rate of–the= 50 run compared to the(MHD)
hydro run.
We observe magnetic hills and valleys
Key words.weISM
magnetic
starover-densities
formation in– theMagnetohydrodynamics– Instabilities

3

netic fields out of the plane of the galaxy with a wavelength twice
thattheoutadjacentseparationof withthese
regions (Efremov
2009,
1. Introduction
netic offieldsof the planeof the galaxy
a wavelength
twice2010). This indicates that magnetic fields could play an impor50Star 10
formation in spiral galaxies is driven by their spiral arms that of the adjacent separation of these regions (Efremov 2009,2010).
Thisinindicatesthat magnetic fields could play an imporrole
their formation.
formationin spiral galaxies
is drivenby their spiralarms tant(Nguyen et Star
al. 2017).
Star-forming
regions
that resemble
beads0.5kpc
β=50
0.65kpc
β=50
tantrole in their formation.
al. ubiquitous
2017). Star-forming
regions
that ofresemblebeadson-a-string (Nguyen
pattern etarein spiralarms
numerous
Beads-on-a-string patterns have been observed along spion-a-string pattern are ubiquitous in spiral arms of numerous
patterns have been observed along spinearby galaxies,
despite having a broad range of morphological ral Beads-on-a-stringarms in numericalsimulations (e.g. Chakrabarti et al. 2003;
nearby galaxies, despite having a broad range of morphological ral arms in numerical simulations (e.g. Chakrabarti et al. 2003;
features andfeaturesphysicalproperties(e.g.
Elmegreen&
Elmegreen
Wada
&
Koda
2004;
Kim
& Ostriker
2006;& Shetty
and physical properties (e.g. Elmegreen & Elmegreen Wada & Koda 2004; Kim & Ostriker
2006; Shetty
Ostriker& Ostriker
1983; Elmegreen
et al. 2006).
also also
seenseen
in in
rings
Wada2008;
2008;
Renaudal. 2013).
The mechaphysical mecha1983; Elmegreen
et al. Recently,
2006). Recently,
ringsofof 2006;
2006; Wada
Renaudet al. et2013).
The physicalbarred& Shimanovskaya
lenticulargalaxgalax- nism
nism responsible,
however,
has been
It was hypothebarred (Gusev& (Gusev
Shimanovskaya2020)2020)
and andlenticularresponsible,
however,has debated.
been debated.
It was hypotheieset(Proshina
et al.These
2022). star-forming
These star-forming
regions
found sized
sized totobebe
thetheKelvin-Helmholtz(KH) hydrodynamical
instabil- instabilies (Proshina
al. 2022).
regions
arearefoundKelvin-Helmholtz(KH) hydrodynamical
to be bright in IR (Elmegreen et al. 2006, 2018; Elmegreen & ity (Wada & Koda 2004), an artifact of numerical noise (Hanawa
to be brightElmegreen
in IR (Elmegreen
ettimesal. 2006,
Elmegreen& ity(Wada &
Kodaan artifact
numerical
noise2019), and at
also in2018;
FUV andH↵ (Efremov& Kikuchi
2012)
or 2004),of infinitesimallyflatof2D
discs (Kim
& (Hanawa
Elmegreen 2019),
and
at
times
also
in
FUV
and
H↵
(Efremov&
Kikuchi2012)
orof
infinitesimally
flat
2D
discs
2009, 2010; Gusev & Efremov 2013; Gusev et al. 2022) emis- Ostriker 2006), a magnetic-jeans instability (MJI) (Kim & Os- (Kim &3 Observatorio Astronómico Nacional (OAN-IGN), Calle Alfonso XII, 3, 28014 Madrid, Spain
4 Observatorio de Yebes (OY-IGN), Cerro de la Palera SN, Yebes, Guadalajara, Spain
5 European
First detection
space of thehigh-energy
isomerofVitacura,cyanomethanimine:
H2CNCNSouthernin
Observatory,
Alonsode Córdova,
3107,
Santiago 763-0355,
Chile
6 Joint ALMA Observatory,
1
1
1
Alonso de Córdova,
3107, Vitacura,Santiago 763-0355, Chile1

David San Andrés , Vı́ctor M. Rivilla , Laura Colzi , Izaskun Jiménez-Serra ,7 Department of Physics,1 Astronomy, and Geosciences,
Towson University,
Towson,MD
21252, USA ,1Jesús Martı́n-Pintado , Andrés Megı́as ,1 Álvaro López-Gallifa,1 AntonioMartı́nez-Henares
1
2
1
3, 4
4
8
Sarah
Massalkhi, Shaoshan
Zeng School, Miguel
Sanz-Novo, Belén Tercero
Pablo
VicenteDepartmentof Astronomy,
Graduateof Science,
The Universityof Tokyo,, Tokyo
113de0033,
Japan,
5, 6
7
8
9 Departamento de Quı́mica
SergioOrgánica
Martı́n e, Inorgánica,
Miguel Angel
Requena
Torres Universidad, Germán de
Molpeceres, andFacultadde Ciencias,
Extremadura,
E-06006 Badajoz, Spain
Juan Garcı́a de la Concepción 9, 10

arXiv:2404.03334v2 [astro-ph.GA] 9 Apr 2024

arXiv:2404.03334v2 [astro-ph.GA] 9 Ap

2 Star and Planet Formation Laboratory, Cluster for Pioneering Research, RIKEN, 2–1 Hirosawa, Wako, Saitama, 351–0198, Japan

10 IACYS-Unidad de Quı́mica Verde y Desarrollo Sostenible, Facultad de Ciencias, Universidad de Extremadura, E-06006 Badajoz, Spain
1 Centro de Astrobiologı́a (CAB), INTA-CSIC, Carretera de Ajalvir km 4, Torrejón de Ardoz, 28850, Madrid, Spain
2 Star and Planet Formation Laboratory, Cluster for Pioneering Research, RIKEN, 2–1 Hirosawa, Wako, Saitama, 351–0198, Japan(Received2023 December 24; Revised 2024 March 21; Accepted 2024 April 3)
3

Observatorio Astronómico Nacional (OAN-IGN), Calle Alfonso XII, 3, 28014 Madrid, Spain
4 Observatorio de Yebes (OY-IGN), Cerro de la Palera SN, Yebes, Guadalajara, Spain
5 European Southern Observatory, Alonsode Córdova, 3107, Vitacura, Santiago 763-0355, Chile
ABSTRACT
6 Joint ALMA Observatory, Alonso de Córdova, 3107, Vitacura, Santiago 763-0355, Chile
We report thefirst detectionin the interstellar medium of N -cyanomethanimine (H CNCN), the7 Departmentof Physics, Astronomy, and Geosciences, Towson University, Towson, MD 21252, USA 2
8
stable dimer ofDepartment
HCN ofofhighest
energy,themost complex
organic
molecule
Astronomy,
Graduateand
Schoolof Science,
The Universityof Tokyo,Tokyo 113identified
0033, Japan in space con9 Departamento de Quı́mica Orgánica e Inorgánica, Facultad de Ciencias, Universidad de Extremadura, E-06006 Badajoz, Spaintainingtheprebiotically
relevant
NCN
backbone.
We
have
identifiedaplethoraof a-type rotational
10 IACYS-Unidad de Quı́mica Verde y Desarrollo Sostenible, Facultad de Ciencias, Universidad de Extremadura, E-06006 Badajoz, Spaintransitions with 3  Jup  11 and Ka  2 that belong to this species towards the Galactic Center G+0.693-0.027 molecular
cloud,
the onlyinterstellar
sourceshowingthethree(Received 2023
December24; Revised
2024 March
21; Accepted
2024
April
3) cyanomethanimine
isomers (including the Z- and E- isomers of C-cyanomethanimine, HNCHCN). We have derived a
ABSTRACT
12
total column density for H2CNCN of (2.9 ± 0.1)⇥10cm 2 , which translates into a total molecular
11 medium of N -cyanomethanimine (H2CNCN), thereportthe first
in ±the0.3)⇥10
interstellar
abundanceWe
withrespect
to detection
H2 of (2.1
. We have also revisited the previous detection of
stable dimer of HCN of highest energy, and the most complex organic molecule identified in space conE- and Z-HNCHCN,
and found a total C/N -cyanomethanimine abundance ratio of 31.8 ± 1.8 and ataining the prebiotically relevant NCN backbone. We have identified a plethora of a-type rotational
Z/E-HNCHCN
ratio
0.2. While the latter can be explained on the basis of thermodynamictransitions
withof3 4.5
 J±
up  11 and Ka  2 that belong to this species towards the Galactic Cenequilibrium,chemical kinetics
arecloud,more
responsible
forshowing
the observed-cyanomethanimine
ter G+0.693-0.027
molecular
thelikely
only interstellar
sourcethe three C/Ncyanomethanimine
isomers
the gas-phase
Z- and E- reactionisomers ofbetween
C-cyanomethanimine,
HNCHCN).
Weand
havethederivedaabundance
ratio,(including
where themethanimine(CH2NH)cyanogenradtotal column density for H2CNCN of (2.9 ± 0.1)⇥1012 cm 2 , which translates into a total molecular
ical (CN) arises as the primary formation route. 11
abundance with respect to H2 of (2.1 ± 0.3)⇥10 . We have also revisited the previous detection ofE- and Z-HNCHCN, and found a total C/N -cyanomethanimine abundance ratio of 31.8 ± 1.8 and a
Keywords:
Pre-biotic ratio
astrochemistry(2079);
Galactic
Interstellar
Z/E-HNCHCN
of 4.5 ± 0.2. While theAstrochemistry(75);latter can be explained on
the basiscenter(565);
of thermodynamic
equilibrium,chemicalkinetics
aremorelikelyresponsiblefortheobserved
C/N-cyanomethanimine
clouds(834); Interstellar molecules(849); Spectral line identification(2073)
abundance ratio, where the gas-phase reaction between methanimine (CH2NH) and the cyanogen radical (CN) arises as the primary formation route.

N-

H2CNCN

G+0.693-0.027
3
H2CNCN
1. INTRODUCTION
so-called RNA-world(Gilbert 1986), which(2.9±0.1)×10^12
cm 2 H2(2.1±0.3)×10^
11 suggeststhat this macromolecule
may Interstellar
have performed both the
Keywords:
Pre-biotic
astrochemistry(2079);
Galactic
center(565);
How life originatedon Earthis oneof the key openAstrochemistry(75);
C/N31.8±1.8
Z/E-HNCHCN
metabolicand genetic functions that in present-day livInterstellar molecules(849);
Spectralline identification(2073)
questions still lingering inclouds(834);
the astrobiologicalcommu4.5±0.2
ing organisms are carried out by proteins and DNA,nity. One of the most accepted hypothesis is the
1. INTRODUCTION

How life originated on Earth is one of the key open
questionslingeringin the astrobiological commuCorresponding author:stillDavid
San Andrésso-called
RNA-world(Gilbert
which processes
suggests forming
respectively.
Althoughthe1986),
chemicalthat this macromolecule may have performed both thethe first RNA molecules remain unknown, numerous
metabolic and genetic functions that in present-day liv-

EL
Izidoro330

arXiv:2404.19390v1 [astro-ph.EP] 30 Apr 2024

EL meteorites do date the giant planet instability
Chrysa Avdellidou1,2⇤ , Marco Delbo’1,2 , David Nesvorny3 ,Kevin J. Walsh3 & Alessandro Morbidelli1,41

Laboratoire Lagrange, CNRS, Observatoire de la Côte d’Azur, Université Côte d’Azur,
Nice 06304, France
2

Athor
60 7RH, UK
Universityof Leicester, School of Physics and Astronomy, LE1
3

Athor

4

Southwest Research Institute, Boulder, CO, USA

Collège de France, CNRS, PSL Univ., Sorbonne Univ., Paris 75014, France⇤

Corresponding author. E-mail: c.avdellidou@leicester.ac.uk

60

2

In our recent work (1), we combined dynamical simulations, meteoritic data and thermal
models as well as asteroid observations to argue that the current parent body of the EL meteorites, i.e. asteroid Athor, was implanted into the asteroid belt not earlier than 60 Myr after the
beginning of the Solar System and that the most likely capture mechanism was the giant planet
orbital instability. This provides a lower limit of 60 Myr to the time of the instability, while
an upper limit of 100 Myr is given by the survival of the Patroclus-Menoetious Jupiter Trojan
binary system (2).
In the study “The link between Athor and EL meteorites does not constrain the timing of
the giant planet instability” that appeared in arXiv (3), Izidoro and collaborators argue that the
implantation of Athor into the asteroid belt does not necessarily require that the giant planet
orbital instability occurred at the implantation time. They show some simulations where the50

I. First results from multi-band near- and mid-infrared imaging
3 , A. Noriega-Crespo3 , P. Guillard4 , D. Van De Putte3 , A.N. Witt5 , N. Ysard6, 1 ,A. JWST
Abergel1 , K.
Misselt2 , K.D. Gordonof
observations
the Horsehead photon-dominated region
78
9
M. Baes , H. Beuther , P. Bouchet , B.R. Brandl10 , M. Elyajouri1 , O. Kannavou1 , S. Kendrew12 , P. Klassen13 , and B.
3
I. First results from multi-bandnearand mid-infrared imaging
Trahin4 , D. Van De Putte3 , A.N. Witt5 , N. Ysard6, 1 ,can be found3 ,after
the references)
A. Abergel1 , K. Misselt2 , K.D. Gordon3 ,(Affiliations
A. Noriega-Crespo
P. Guillard
7
8
9
10
1
1
12
13
M. Baes , H. Beuther , P. Bouchet , B.R.
Brandl, M.2024
Elyajouri, O.
Received
9 January; accepted
10Kannavou
April 2024 , S. Kendrew , P. Klassen , and B.
Trahin3

ABSTRACT(Affiliations can befound after the references)

Received
9 Januarythe2024; accepted
10 April
2024
Context. The James Webb Space Telescope (JWST)
has captured
sharpest
infrared
imagesever taken of the Horsehead nebula, a prototypicalmoderately irradiated photon-dominated region (PDR) that is fully representative of most of the UV-illuminated molecular gas in the Milky Way
and star-forming galaxies.
ABSTRACT
Aims. We investigate the impact of far-ultraviolet (FUV) radiation
emitted by a massive star on the edge of a molecular cloud in terms ofphotoevaporation, ionization, dissociation, H2 excitation, and dust heating. We also aim to constrain the structure of the edge of the PDR and its
Context. The James Webb Space Telescope (JWST) has captured the sharpest infrared images ever taken of the Horsehead nebula, a prototypicalillumination conditions.
moderately irradiated photon-dominated region (PDR) that is fully representative of most of the UV-illuminated molecular gas in the Milky Way
Methods. We used NIRCam and MIRI to obtain 17 broadband and 6 narrowband maps of the illuminated edge of the Horsehead across a wideand star-forming galaxies.
spectral range from 0.7 to 28 µm. We mapped the dust emission, including the aromatic and aliphatic infrared (IR) bands, scattered light, andAims. We investigate the impact of far-ultraviolet (FUV) radiation emitted by a massive star on the edge of a molecular cloud in terms ofseveral gas phase lines (e.g., Pa↵, Br↵, H 1-0 S(1) at 2.12 µm). For our analysis, we also associated two HST-WFC3 maps at 1.1 and 1.6 µm,
photoevaporation, ionization, dissociation,2H2 excitation, and dust heating. We also aim to constrain the structure of the edge of the PDR and its
along with HST-STIS spectroscopic observations of the H↵ line.
illumination conditions.
Results. We probed the structure of the edge of the Horsehead and resolved its spatial complexity with an angular resolution of 0.1 to 100 (equivalent
Methods. We
used NIRCam and MIRI to obtain 17 broadband and 6 narrowband maps of the illuminated edge of the Horsehead across a wide
to 2 ⇥ 10 4 to 2 ⇥ 10 3 pc or 40 to 400 au at the distance of 400 pc). We detected a network of faint striated features extending perpendicularly
spectral range from 0.7 to 28 µm. We mapped the dust emission, including the aromatic and aliphatic infrared (IR) bands, scattered light, andto the PDR front into the H II region in NIRCam and MIRI filters sensitive to nano-grain emission, as well as in the HST filter at 1.1 µm, which
several gas phase lines (e.g., Pa↵, Br↵, H2 1-0 S(1) at 2.12 µm). For our analysis, we also associated two HST-WFC3 maps at 1.1 and 1.6 µm,
traces light scattered by larger grains. This may indeed figure as the first detection of the entrainment of dust particles in the evaporative flow.
along with HST-STIS spectroscopic observations of the H↵ line.
The filamentary
structure of the 1-0 S(1) line of H2 at the illuminated edge of the PDR presents numerous sharp sub-structures on
as smallResults.
to scales
100 (equivalent
00 We probed the structure of the edge of the Horsehead and resolved its spatial complexity with an angular resolution of 0.1 00
as
1.5
.
An
4 excess of 3H2 emission compared to dust emission is found all along the edge, in a narrow layer (width around 1 , corresponding
to 2 ⇥ 10 3to 2 ⇥ 10 pc or 40 to 400 au at the distance of 400 pc). We detected a network of faint striated features extending perpendicularly
to the2 ⇥PDR
10 front
pc orinto
400theau)Hdirectly
illuminatedbyand-Orionis.
The sensitive
ionizationto front
and theemission,
dissociation
front
at distances
1 µm,
200 behindtoII region
in NIRCam
MIRI filters
nano-grain
as wellas appearin the HST
filter at 1.1
which
the externaledge of the
PDR andseem
to spatiallycoincide,very smallof the ofneutralatomic layer(below
100 au).flow.
All
traceslight scatteredby larger
grains.
This
may indeed
figure indicating
as the firstadetectionof thickness
the entrainment
dust particles
in theevaporative
broadband
mapsstructure
present strong
variations
betweenthe illuminated edge and the internal regions. This can be explained by dust attenuation
The
filamentaryof the color
1-0 S(1)line of H
2 at the illuminated edge of the PDR presents numerous sharp sub-structures on scales as small
in a1.5
scenario
where oftheHilluminatingstar -Orionis is slightly inclined compared to the plane of the sky, so that the Horsehead is 00illuminated from00as
. An excess
2 emission compared to dust emission is found all along the edge, in a narrow layer (width around 1 , corresponding
behindat an3 pc
obliqueangle.
The deviations
frombypredictionsof thethedissociation
H↵, Pa↵, andfrontBr↵ appear
lines alsoto2 ⇥ 10or 400au) directly
illuminated-Orionis.
Themeasured
ionizationemissions
front andinthe
at indicate
distancesdust
1 attenuation.
200 behind
With
a
very
simplemodel,
we
used
the
data
to
derivethemainspectralfeaturesoftheextinction
curve.
A
small
excessofextinctionat
3 µm
the external edge of the PDR and seem to spatially coincide, indicating a very small thickness of the neutral atomic layer (below 100au).mayAll
be attributed
to icyH2 O mantles
onto grains
formedin dense
We edgealso derived
profilesfrom
25 µm acrossthe attenuation
PDR. In all
broadbandmaps
present
strong color
variations
betweenthe regions.
illuminatedand theattenuationinternal regions.
This
can0.7
betoexplainedby dustlines
of sight wherecrossing
inner regions
the Horsehead,especiallythe IR
position,
appears
thatthedust
attenuation
is non-negligibleina scenario
thetheilluminating
starof -Orionis
is slightly
inclinedaroundcompared
to peak
the planeof theit sky,
so thatHorseheadis illuminatedfromover theatentire
spectralrange
ofdeviations
the JWST.from predictions of the measured emissions in the H↵, Pa↵, and Br↵ lines also indicate dust attenuation.
behindan obliqueangle.
The

MIRI

With
a very simple
model,
weHorsehead,
used the data
to extinction,
derive the main
spectralfeaturesof the photon-dominatedextinction curve. Aregion
small excess
3 µm may
Key words.
Infrared:
ISM:
dust,
molecules,
lines
and bands,(PDR),of
H extinction
II regions,atTechniques:beattributed
to
icy
H
O
mantles
onto
grainsformedindense
regions.
We
also
derivedattenuation
profiles
from
0.7
to
25
µm
acrossthe
PDR.
In all2
photometric, spectroscopy, Methods: observational, data analysis
lines of sight crossing the inner regions of the Horsehead, especially around the IR peak position, it appears that dust attenuation is non-negligible
over the entire spectral range of the JWST.

JWST0.71 Key
17dust, extinction, molecules,6lines thewords. Infrared: ISM: Horsehead,and order
bands, ofphoton-dominatedregion distances(PDR), H IIofregions,Techniques:
1. 28μm
Introduction
 1 at the typicalthe most
studied 18
photometric, spectroscopy, Methods: observational, data analysis
Galactic PDRs). This indicates that the physical conditions vary 19
σ on small spatial scales, dependent on both the lo- 20
2 Photon-dominated regions (PDRs) are predominantly neutral re- dramatically
3 gions of the interstellar medium (ISM) in which the heating and cal structure of the molecular cloud as well as the input radiation 21
PDR
2number,chemistry
are mainly regulated by far ultraviolet (FUV)
photons the
14 1.
Introductionof  1
1on attypicalsize,
distancesof andthe spectral
most studied
fieldorder(dependent
thethedistance,
types 18
22
00

5
26
37
48
5

from massive stars (e.g., Hollenbach & Tielens 1999; Wolfire
Photon-dominatedneutralreet al. 2022). Theseregions
regions(PDRs)
form atarethepredominantly
broad interface
betweengions
the andinterstellar
medium
(ISM)
in UV
which
the heating
youngofstars
molecular
clouds,whereradiation
heatsandgaschemistry
are drives
mainlychemical
regulatedevolution.
by far ultraviolet(FUV) photons
and dust and
The interactionof stelfrom massive stars (e.g., Hollenbach & Tielens 1999; Wolfire

00

Galactic
PDRs). This
indicatesthat thephysical conditions varyof the surroundingstars
undergoing
excitation).
dramatically on small spatial scales, dependent on both the local structure of the molecular cloud as well as the input radiation
formation(CO, size,
H2 , etc.)
andandchemistry,grain
fieldMolecule(dependent
on the number,distance,
spectral types

19
23
20
21
24
22

NIRCamUniversité Paris Cité, Université Paris-Saclay, CEA, CNRS, AIM, F-91191, Gif-sur-Yvette, France
Université Paris-Saclay, Université Paris Cité, CEA, CNRS, AIM, 91191, Gif-sur-Yvette, France
3
Univ Lyon, Ens de Lyon, Univ Lyon 1, CNRS, Centre de Recherche Astrophysique de Lyon UMR5574, 69007, Lyon, France2

Formation of low mass protostars and their circumstellar disks

Received 25/01/2024; accepted 21/04/2024
A. Ahmad1 , M. González1 , P. Hennebelle2 , and B. Commerçon3
ABSTRACT

Université Paris Cité, Université Paris-Saclay, CEA, CNRS, AIM, F-91191, Gif-sur-Yvette, France
2
Université Paris-Saclay, Université Paris Cité, CEA, CNRS, AIM, 91191, Gif-sur-Yvette, France
Context. Understanding
circumstellar
isCNRS,of prime
importancein Astrophysiqueastrophysics,dehowever,their birth
process
remains poorly con3
Univ Lyon, Ens
de Lyon, Univdisks
Lyon 1,
Centrede Recherche
Lyon UMR5574,
69007,
Lyon, France

strained due to observational and numerical challenges. Recent numerical works have shown that the small-scale physics, often
Received
25/01/2024;
accepted
wrapped into
a sub-gridmodel,
play a21/04/2024
crucial role in disk formation and evolution. This calls for a combined approach in which boththe protostar and circumstellar disk are studied in concert.
Aims. We aim to elucidate the small scale physics and constrain
sub-grid parameters commonly chosen in the literature by resolving
ABSTRACT
the star-disk interaction.
Context. Understanding circumstellar disks is of prime importance in astrophysics, however, their birth process remains poorly conMethods. We
carry out a set of very high resolution 3D radiative-hydrodynamics simulations that self-consistently describe thestrained due to observational and numerical challenges. Recent numerical works have shown that the small-scale physics, often
collapse of wrapped
a turbulent
molecular
cloud
corerole
toinstellar
densities.
study This
the calls
birthforofatheprotostar,
the incircumstellar
into adense
sub-grid
model, playa crucial
disk formation
andWe
evolution.
combined
approachwhich both disk, andits early evolution(< 6andyr circumstellar
after protostellar
the protostar
disk areformation).
studied in concert.
Aims. We aim
elucidatethe small scalecollapse,
physics andconstrain
sub-grid
parameters
commonlychosenin the velocity
literature byresolving
Results. Following
the tosecond
gravitational
thenascent
protostar
quicklyreachesbreakupandsheds its surface
the star-diskmaterial, thus
forminginteraction.
a hot (⇠ 103 K), dense, and highly flared circumstellar disk. The protostar is embedded within the disk, such
Methods. We carry out a set of very high resolution 3D radiative-hydrodynamics simulations that self-consistently describe thethat material
can flow
withoutdensecrossing
any cloudshockcore
fronts.
Thedensities.
circumstellar
mass
exceeds
that of the
protostar,and its
collapseof a turbulent
molecular
to stellar
We studydisk
the birthof quickly
the protostar,
the circumstellar
disk,
and
kinematics its
areearly
dominatedbyself-gravity.
Accretion
onto
the
disk
is
highlyanisotropic,
andaccretion
onto
theprotostar
mainlyoccursevolution (< 6 yr after protostellar formation).
Results.
Following
the thesecondcollapse,
nascent
quicklyinreachesbreakup velocity
and sheds
its surface
through material
thatslides on
diskgravitationalsurface. The
polarthemass
fluxprotostar
is negligible
comparison.
The radiative
behavior
also displays
material, thus
forminga hot(⇠ 103 K),
dense,
highlycircumstellar whereas
disk. The protostar
is embedded
within thesucha strong anisotropy,
as thepolar
accretionshock
is andshown
toflaredbe supercriticalits equatorial
counterpart
is disk,
subcritical.
We alsothat material can flow without crossing any shock fronts. The circumstellar disk mass quickly exceeds that of the protostar, and its
find a remarkable convergence of our results with respect to initial conditions.
kinematics are dominated by self-gravity. Accretion onto the disk is highly anisotropic, and accretion onto the protostar mainly occurs
Conclusions.
These
results
thethestructureandThekinematics
theis smallest
scalesThe
relevant
tobehavior
protostellar
and circumstellar
throughmaterial
thatreveal
slides on
disk surface.
polar massin
flux
negligible spatialin comparison.
radiative
also displays
disk evolution.
They
can
be
used
to
describe
accretion
onto
regions
commonlydescribed
bysub-grid
modelsinsimulations
a strong anisotropy, as the polar accretion shock is shown to be supercritical whereas its equatorial counterpart is subcritical. We also studyinga remarkable convergence of our results with respect to initial conditions.
larger scalefind
physics.

Xiv:2404.14496v1 [astro-ph.SR] 22 Apr 2024

iv:2404.14496v1 [astro-ph.SR] 22 Apr 2024

1

Conclusions. These results reveal the structure and kinematics in the smallest spatial scales relevant to protostellar and circumstellar

diskStars:
evolution.
They can -beStars:
used toProtostars
describe accretion
onto
regions
commonlydescribed
by sub-gridmodels in simulations
studying transfer Key words.
Formation- Stars:
Low
mass- Methods:
Numerical- Hydrodynamics- Radiative
scale physics.
Gravitationlarger- Turbulence- Disks - Accretion Disks

3DKey words. Stars: Formation - Stars: Protostars - Stars: Low mass - Methods: Numerical - Hydrodynamics - Radiative transfer -6
1. Introduction

Gravitation - Turbulence - Disks - Accretion Disks

1. Introduction

Circumstellar disks form as a result of the conservation of anCircumstellar
disks
as a resultof the conservationof angular momentum
duringtheform
collapseof gravitationaly
unstable
gular
momentum
duringthecollapseofgravitationaly
unstablepre-stellar cloud cores. Understanding the formation of thesepre-stellar cloud cores. Understanding the formation of thesedisks and theirevolutionis ofisfundamental
disks subsequentand their subsequentevolutionof fundamentalimporimportance in astrophysics,
as they asarethey
thearebirthplaceof planets.
tance in astrophysics,
the birthplaceof planets.This
This
task is heavily
however heavily
impededby numerous
challenges inintask is however
impededby numerous
challenges
observingstar forming
the dense
infallingenvelope
envelope
observing star
forming
regions,regions,as theasdense
infalling
obscures the nascent disk during the class 0 phase. As such,
obscures thenascent disk during the class 0 phase. As such,
most observational constraints come from more evolved classmost observational
constraints
come from
more evolved
class
I and II disks.
From a theoreticalstandpoint,
the prohibitive
I and II disks.
Fromatheoreticalstandpoint,theprohibitive
time-stepping constraints in numerical simulations has madeAlthough necessary to study the global evolution of the disk,
reducingnecessary
the innerregions(whichcontainof the
protostar) to a
Althoughto study
the global
evolution
the disk,
sub-gridthemodel
can produce
nonphysicalresults,
reducing
inner regions(which containthe protostar)
to a especiallysub-grid
modelofcan
nonphysicalresults,
especiallywhen muchthe produce
actual sub-grid
physics
thathas been encodedwhen
muchpoorlyof the actual
sub-grid physics that has been encoded
remains
constrained.
remains poorly constrained.
Inthisthisrespect,respect,
Machidaal. (2014)
investigatedthe e↵ects ofIn
Machidaet al. et(2014)
investigatedthe e↵ects ofsinkparametersontheformationofcircumstellar
sink parameters on the formation of circumstellar disks. Theydisks. They
foundthethechoiceof theofsink
its accretion
foundthat
that
choicetheradius
sink andradiusand its threshaccretion thresholdcan,inconjunction
withthephysicalmodel
old can, in conjunction with the physicalemployed,model employed,
dictate the formation and evolution of a circumstellar disk.
dictate the formation and evolution of a circumstellar disk.
Vorobyov et al. (2019) lead a similar study, this time focusing
Vorobyovet al. (2019)lead
similarthis time focusingon
the mass transport
rate fromtheasink
cell tostudy,
the protostellar
on the They
massfoundtransport
rate fromwith
thea sink
totransthe protostellar
surface.
that simulations
slowercell
mass

E

Extinction values towards embedded planets in protoplanetary disks
estimated from hydrodynamic simulations
Extinction
valuesplanets
in protoplanetarydisks 1
FelipeAlarcón towards,1 Edwinembedded
A. Bergin,1 andGabriele Cugno
estimated from hydrodynamic simulations

1 Department of Astronomy, University of Michigan, 323 West Hall, 1085 S University, Ave., Ann Arbor, MI 48109, USA,1 Edwin A. Bergin,1 and Gabriele Cugno

1

1 Department of Astronomy, University of Michigan, 323 West Hall, 1085 S University, Ave., Ann Arbor, MI 48109, USA

ABSTRACT

arXiv:2404.05788v1 [astro-ph.EP] 8 Apr 2024

iv:2404.05788v1 [astro-ph.EP] 8 Apr 2024

Felipe Alarcón

The upcoming new coronographs with deeper
contrast limits, together with planned and current
ABSTRACT
high-contrast
imaging
campaigns
will
push
the
detectability
limittogetherof protoplanets.
These
planet-hunting
The upcoming new coronographs with deeper contrast limits,with plannedand current
campaigns
present aimaging
new opportunity
topushcharacterize
protoplanetsand their Thesesurrounding
environments.
high-contrast
campaigns will
the detectability
limit of protoplanets.
planet-hunting
present
new opportunityastoto
characterize
and their
surrounding
environments.
However,campaigns
there areclearauncertainties
what areprotoplanets
the extinctionlevelsat di↵erent
regions of protoHowever,
there
are
clear
uncertainties
as
to
what
are
the
extinctionlevelsatdi↵erent
regionsofplanetary disks, which will impede our ability to characterize young planets. A correct protounderstanding
planetary disks, which will impede our ability to characterize young planets. A correct understandingof the expected extinction together with multiple photometric observations will lead to constraints onof the expected extinction together with multiple photometric observations will lead to constraints on
the extinctionlevels,levels,
dust dust
growth,disk
andprotoplanetary
protoplanetary
accretion
In this work,
the extinction
growth,diskevolution
evolution andaccretion
rates. rates.
In this work,
we used wehydrodynamic
simulations
anddisk
observational
constraints
fromused hydrodynamic
simulations
andprotoplanetary
protoplanetary disk
observational
constraints
obtainedobtained
from
both
dust
and
gas
emissiontoexplorethe
expected
extinction
mapsfor
continuum
filters
associatedboth dust and gas emission to explore the expected extinction maps for continuum filters associatedwith hydrogenstrong hydrogenas tracers
accretion andphotometricfilters. We
providewith stronglineslines
as tracers
ofofaccretion
andkeykeybroadband
broadband
photometricfilters.
We provide
a scaling relationship for the extinction as a function of planetary separation and disk mass for threea scalingdi↵erent
relationshipfortheextinctionasafunctionofplanetary
separation
and
disk
mass
for threegas giant masses. We also report values for a subset of disks of interest targetted by multipledi↵erent imaging
gas giantmasses.The
Wedescribed
also reportfor a for
subsetof disksof interest
targetted by multiple
campaigns.
valuesvalues
will be useful
the optimal
designof future planet-hunting
imaging surveys
campaigns.
described
valueswill be usefulfor the optimal
designof futurefluxes
planet-hunting
and forThegivingcontext to
non-detectionsin protoplanetarydisks andthe observedofpoint
sources
along
with
the
birth
conditions
ofprotoplanets.
surveys and for giving context to non-detections in protoplanetary disks and the observed fluxes ofpoint sources along with the birth conditions of protoplanets.
Keywords: planet–disk interactions — protoplanetary disks — — accretion disks – direct imaging
1. INTRODUCTION
extinction
from–theirhostdisk canKeywords: planet–diskinteractions — protoplanetaryconstraints
disks — in
— theaccretion
disks
directimaging

As dedicated algorithms for high-contrast imaging arebeing appliedin planet-hunting campaigns, the detec1. INTRODUCTION
tion of protoplanets through direct methods has started
As dedicatedalgorithms
areto becomea reality for(e.g.high-contrast
Keppler et al. imaging
2018; Ha↵ert
being applied
planet-hunting
campaigns,
et al. in
2019;
Currie et al. 2022;
Zhou et al. the2022;detecHammond et al. through2023). However,many dedicatedsurveystion of protoplanets
direct methods
has started
shown that
detection etrateplanetary
comto becomehave
a reality(e.g.theKeppleral.of 2018;
Ha↵ertpanions in circumstellar disks is quite low (Cugno et al.
et al. 2019; Currie et al. 2022; Zhou et al. 2022; Ham2019; Zurlo et al. 2020; Jorquera et al. 2021; Asensiomond et al.
2023).
many
dedicatedsurveysTorreset al. However,2021; Huélamo
et al.
2022; Cugno
et al.
have shownthat
the etdetection
rate ofplanetarycom2023;
Follette
al. 2023, among
others).
This low
detection
rate
may
be
the
resultofhighextinction
atoppanions in circumstellar disks is quite low (Cugno et al.

provide key parameters to understanding the formation
environments of protoplanets, and might be particularly
constraints in the extinction from their host disk can
useful for the design of future campaigns.
providekey upcoming
parameters
to understanding
the formation
Current andfacilities
have devoted instruenvironments
of protoplanets,
andasmight
be particularly
ments
for high-contrast
imaging such
MagAO-X,
ELT-METIS,
and design
the Nancy
Space Teleuseful for theof Grace
futureRoman
campaigns.
scope
for
example.
In
additiontobetterinstruments
Current and upcoming facilities have devoted instruwith deeper contrast limits, improved adaptive optics
ments for high-contrast imaging such as MagAO-X,(AO) algorithms/techniques are also pushing the achievELT-METIS,
andthe Nancy
Gracesuch
Roman
able
contrast. Image
processing
techniques
as Ref-Space TelescopeDi↵erential
for example.
addition
betterinstruments
erenceImagingIn(Grady
et al. to1999),
AngularDi↵erential
Imaging(Maroisetal.
2006),
Polarizawith deeper contrast limits, improved adaptive opticstionDi↵erential
Imaging (Kuhn et al.
and Spec-the achiev(AO)
algorithms/techniquesare2001),
also pushingNaira Azatyan1*
1* Byurakan Astrophysical Observatory, 0213 Aragatsotn Prov., Armenia.

Corresponding author(s). E-mail(s): 1*nayazatyan@bao.sci.am;
Naira Azatyan

1* Byurakan Astrophysical Observatory, 0213 Aragatsotn Prov., Armenia.

Abstract

arXiv:2404.05413v1 [astro-ph.GA] 8 Apr 2024

Xiv:2404.05413v1 [astro-ph.GA] 8 Apr 2024

Search and study of young infrared stellar clusters

The main aim of this paper is to study both the Interstellar Medium (ISM)
Corresponding author(s). E-mail(s): nayazatyan@bao.sci.am;
and the young stellar population in the three star-forming regions, namely
IRAS 05137+3919, 05168+3634, and 19110+1045. The study of the ISM includes
determination of the hydrogen column
density (N(H2 )) and dust temperature
Abstract(Td ) inThethemainregions
using
Modifiedblackbodyfitting.
The mainparametersof
aim of this paper is to study both theInterstellar
Medium(ISM)
identified
andclassified
youngstellarobjects(YSOs)
belongingtotheregions
and the young stellar population in the three star-forming regions, namely
IRAS 05137+3919,
05168+3634,
study ofmodels.
the ISM includes
were determinedcomparing
withandthe19110+1045.
radiation The
transfer
We also condeterminationofthehydrogencolumndensity
(N(H
))
and
dust
temperature2
structed a colour-magnitude diagram to compare the parametersof the YSOs
(Td ) in the regions using Modified blackbody fitting. The main parameters ofwith theresultsoftheradiative
transfermodels.
The
threestellarpopulations
identified and classified young stellar objects (YSOs) belonging to the regions
appear were
to haveformedcomparing
under di↵erent
In the casesof IRAS
determinedwith thescenarios.
radiation transfer
models.
We also05137+3919
conand IRAS
05168+3634,
the agediagram
spreadto iscompare
considerably
wider,of suggesting
structeda colour-magnitude
the parameters
the YSOs thatwith population
the results of likely
the radiativetransfermodels.
The three condensations.
stellar populationsIn conthe stellar
emergedfromindependent
appeartohaveformedunderdi↵erent
scenarios.
In
the
cases
of
IRASregions
05137+3919
trast, the third region comprises a pair of ultra-compact HII(UCHIIs),and IRAS 05168+3634, the age spread is considerably wider, suggesting that
G45.12+0.13
andG45.07+0.13,
withanotablysmallerage
spread.
Thishints atthe stellar population likely emerged from independent condensations. In conthe possibility
that
these
clusters
originatedfromasingletriggering
event.
trast, the third region comprises a pair of ultra-compact HII regions (UCHIIs),
G45.12+0.13 and G45.07+0.13, with a notably smaller age spread. This hints at

Keywords:stars: pre-main
sequence– infrared:fromstars– radiativetransfer
the possibility
that theseclusters originateda single
triggering
event.- Interstellar
medium (ISM)stars: pre-main sequence
IRAS 05137+3919 05168+3634 Keywords:
19110+1045
3 – infrared: stars – radiative transfer - Interstellar
medium (ISM)
Td
⾒05137+3919

N(H2)1 Introduction
1 Introduction
IRAS 05168+3634
G45.12+0.13
The processofstarformation
remains
ongoing
throughout
variousstagesofevoluprocess of star formation remains ongoing throughout various stages of evoluHII tion of The
our ofgalaxyand andothergalaxies,in thethepresent
present
Ambartsumiantion
our galaxy
othergalaxies,even
even inera eraAmbartsumian(1947). (1947).
It standsof themostpivotalprocesses
processes thatobservableoutcomes
within within
It stands
as oneasofonethe
mostpivotalthatyield
yield
observableoutcomes
galaxies.
Giantmolecular
cloudsarebirthplacesofstellarpopulation(Soderblom,galaxies. Giant molecular clouds are birthplaces of stellar population (Soderblom,2010). Stellar clusters that remain embedded within their original molecular clouds2010). Stellar
clusters
that remain
embedded
their original
molecular clouds
hold a special
significance.
They provide
insights within
into distinguishing
the characteristics
hold a special significance. They provide insights into distinguishing the characteristics

YSO
IRAS
G45.07+0.13

Department of Physics & Electronics, CHRIST (Deemed to be University), Bangalore 560029, India

2 Department of Astronomy and Astrophysics, Tata Institute of Fundamental Research Homi Bhabha Road, Colaba, Mumbai 400005, India

3 Academia Sinica Institute of Astronomy & Astrophysics, 11F of Astro-Math Bldg., No. 1, Sec. 4, Roosevelt Road, Taipei 10617, Taiwan, Republic of China
4 Max Planck Institute for Radio Astronomy, Auf dem Hügel 69, 53121 Bonn, Germany

HAeBe
Chandra1¢

1 V. Jithesh,1 Sreeja S. Kartha,1 P. Manoj,2 Mayank Narang3

HemaYYY;
Anilkumar,
BlessonAccepted XXX. Received
in original form
ZZZ Mathew,and Mahathi Chavali,41 Department of Physics & Electronics, CHRIST (Deemed to be University), Bangalore 560029, India

ABSTRACT

2 Department of Astronomy and Astrophysics, Tata Institute of Fundamental Research Homi Bhabha Road, Colaba, Mumbai 400005, India

3 Academia Sinica Institute of Astronomy & Astrophysics, 11F of Astro-Math Bldg., No. 1, Sec. 4, Roosevelt Road, Taipei 10617, Taiwan, Republic of China

4 Max Planck Institute for Radio Astronomy, Auf dem Hügel 69, 53121 Bonn, Germany
Herbig Ae/Be (HAeBe)stars are intermediate-mass pre-main sequence stars, characterized by infrared excess and emission lines.
They are observed to emit X-rays, whose origin is a matter of discussion and not settled yet. X-ray emission is not expected in
HAeBe stars, as
theyXXX.
lackReceived
the sub-surface
zone. In this study, we retrieved observations from the Chandra archive
Accepted
YYY; in originalconvective
form ZZZ
for 62 HAeBe stars, among which 44 sources (detection fraction ⇠71%) were detected in X-rays, with 7 being new detections.
We use this sample
as a test bed to conduct a comparative analysis of the X-ray properties of HAeBe stars and their low-mass
ABSTRACT
counterparts, THerbig
TauriAe/Be
Stars(HAeBe)(TTSs).
Further,
we comparepre-main
the X-rayproperties
of HAeBe
and
TTSs
opticalstars
are intermediate-masssequencestars, characterized
by stars
infraredexcessand withemissionlines. and IR
Theyare
observed
toemit
X-rays,whose
originisamatterofdiscussion
andnotsettledyet.
X-rayemissionisnotexpected
properties to constrain the X-ray emission mechanism in HAeBe stars. We found no correlation between X-ray emissioninand disk
HAeBe stars,
they lack thethat
sub-surface
zone. Intothisaccretion
study, we shocks.
retrieved observations
the Chandra
properties of HAeBestars,asconfirming
X-raysconvective
are not related
About 56%fromof HAeBestarsarchive
without any
for 62 HAeBe stars, among which 44 sources (detection fraction ⇠71%) were detected in X-rays, with 7 being new detections.
known sub-arcsec
companions
have
lower
plasmatemperatures
(kT

2
keV).
We
observeflaring/variabilityin
HAeBestars with
We use this sample as a test bed to conduct a comparative analysis of the X-ray properties of HAeBe stars and their low-massconfirmed low-masscompanions.
ThesestarsFurther,show weplasmatemperatures> 2 keV,to TTSs.
Guidedby thisandinformation
counterparts,
T Tauri Stars(TTSs).
comparethe X-ray propertiesof similar
HAeBe stars
and TTSs
with opticalIRthe X-ray emission
mechanism
in HAeBe
Wesamplefound noof
correlation
X-ray emission
and obtained
disk
we discuss the properties
role of atoTconstrain
Tauri companion
for X-rayemissionseen stars.
in our
HAeBebetween
stars. From
the resultsinproperties
of
HAeBe
stars,
confirmingthat
X-raysarenotrelatedtoaccretion
shocks.
About
56%
of
HAeBe
stars
without
anythis paper, we suggest that X-ray emission from HAeBe stars may not be related to accretion shocks or hidden TTS, but rather
known sub-arcsec companions have lower plasma temperatures (kT  2 keV). We observe flaring/variability in HAeBe stars withcan be due to magneticallydriven coronal emission.

arXiv:2404.03403v1 [astro-ph.SR] 4 Apr 2024

arXiv:2404.03403v1 [astro-ph.SR] 4 Apr 2024

Chandra X-ray Analysis of Herbig Ae/Be Stars

confirmed low-mass companions. These stars show plasma temperatures > 2 keV, similar to TTSs. Guided by this information
we discuss
the roleof a T Tauri
for X-ray emissionin our sample
of HAeBestars. From the results
obtained inimaging
Key words: stars:
coronae– stars:
flarecompanion– stars: low-mass– stars:seen
massive– stars:
pre-main-sequence– techniques:
this paper, we suggest that X-ray emission from HAeBe stars may not be related to accretion shocks or hidden TTS, but rather
spectroscopy
can be due to magnetically driven coronal emission.
Key words: stars: coronae – stars: flare – stars: low-mass – stars: massive – stars: pre-main-sequence – techniques: imaging
spectroscopy

1 INTRODUCTION

62

HAeBe

44

provide a proper explanation for the origin of X-rays in HAeBe stars
due to the limited resolution of the telescope. The advent of the
Herbig Ae/Be (HAeBe) stars are intermediate mass (2 M  M¢ 
ChandraObservatory
in of1999
openeda new
1 INTRODUCTION
provideX-ray
a properexplanation for(CXO)
the origin
X-raysin HAeBestars window
8 M ) young stellar objects. They are the higher mass counterparts ofdue totothe
limitedresolutionof the telescope.
The adventof the(thanksits
highspatialresolution)forstudying
X-raysfrom stars.
intermediate
mass (2HAeBe
M  M¢ 
the T Tauri stars Herbig(TTS)Ae/Be(e.g., (HAeBe)
Brittain stars
et al.are2023).
Like TTSs,
Chandra
X-ray
Observatory(CXO)
in 1999
openeda newwindow
Stelzeretal.
(2006)
studiedasampleof
17
HAeBe
stars,
ofwhich 13
8 M ) young stellar objects. They are the higher mass counterparts of(thanks to its high spatial resolution) for studying X-rays from stars.
stars also show HUemission and infrared (IR) excess from a dusty
the T Tauri stars (TTS) (e.g., Brittain et al. 2023). Like TTSs, HAeBe of them were X-ray emitters. Based on the high plasma temperature
Stelzer et al. (2006) studied a sample of 17 HAeBe stars, of which 13
circumstellar material.
additionto this,andthey
are also
observedstars alsoInshow
HU emission
infrared(IR) excessfrom toa dusty obtained from the spectral analysis, this study ruled out radiativeof them were X-ray emitters. Based on the high plasma temperatureemit UV and X-rays(Zinnecker&InPreibisch
Damianiet al. tocircumstellar
material.
addition to1994;
this, they
are also observedwinds
as thesole
mechanism
andruledsuggestedthat either aobtainedfromtheemission
spectral analysis,
this study
out radiativeand X-rays(Zinnecker
Preibisch 1994;
Damiani et al.
1994; Malfait etemit
al. UV
1998).
The high
energy& radiation
in low-masswinds
as theofsoleemissionmechanismand suggested
that eitherora most ofhuge
fraction
HAeBe
stars
are
intrinsic
X-rayemitters
1994; Malfait
et al. pre-main-sequence1998). The high energy(PMS)
radiationstars
in low-massmain-sequence (MS)stars andishuge fraction of HAeBe stars are intrinsic X-ray emitters or most of
main-sequence (MS) stars and pre-main-sequence (PMS) stars is the companions to HAeBe stars are yet to be discovered. Hamidouche
the companions to HAeBe stars are yet to be discovered. Hamidouche
produced predominantly
due to the involvement of the magnetic field.
produced predominantly due to the involvement of the magnetic field. et al. (2008) studied a sample of 22 HAeBe stars observed with

TT

kT

7

2 keV

HAeBe

56%
HAeBe

X

X