Star Formation Newsletter#372 1-10
KASI

To better Sub-mm
study theWavelength
radial polarizationin IRC+10
216, we216
use “radial Stokes parameters” Qr and Ur , asPolarimetryof IRC+10
equation6, where3 the reference frame
is rotated by
the polar angle
at each point with respect
to the star l
1, 2
4
5, 2
6, 7, 28, 9

B-G Andersson,

Janik Karoly, Pierre Bastien, Archana Soam,
Simon Coudé,10Michael S. Gordon, and Sydney Fox-Middleton11, 2

Qr = +Q cos 2⇠ + U sin 2⇠, Ur =Mehrnoosh Tahani,

Q sin 2⇠ + U cos 2⇠,

1 Institute for Scientific Research, Boston College, 140 Commonwealth Avenue, Chestnut Hill, MA 02467, USA

20
where ⇠ = arctan
angle of a given(Lazarian'20)
pixel coordinate position (x, y) (corresponding toy y0 is the polar
94035, USA•(2thek-RAT)
3 Jeremiah Horrocks
coordinates)
andthe locationofstar.
Becauseof themoderate
Declination of IRC+10 216 (⇠Anderssonet (xal.
0 , y0 ) isUniversity
Institute,of Central
Lancashire,
Preston PR1
2HE,
UK
4 Institut haveomittedcos( ) factor
for& theRight
Ascension
distance induthe
numerator.
de Recherche
sur theles Exoplanètes(iREx)
Centrede Rechercheen AstrophysiqueQuébec(CRAQ),
Université de Montréal,DépartementdePhysique,1375, AvenuewhileThérèse-Lavoie-Roux,
Montréal,
QC,
H2V
0B3,polarization.
Canada•𝒗×𝑩(E-RAT)B
Qr shows
radialpolarization,negative Qr indicates
tangentialpTo
betterstudy the Uradialpolarizr represents
3.1.
Radial Positive
coordinate
polarization
5 Indian Institute of Astrophysics, II Block, Koramangala, Bengaluru 560034, India
AGBC) E-RAT
with an angle of ±45 from( the radial direction.
Therefore, zero Urequation
indicates 6,
purelyradialtangentialpo
where
theorreferencefram
6 Department of Earth, Environment, and Physics, Worcester State University, Worcester, MA
01602, USA0000
ial polarization
216,
we thinuse annuli“radial
Stokesparameters”
Ur , asdefined inaround the star and find th
Wefor
take
(⇠
2.2 pcin HAWC+and ⇠ Q
14r andin JCMTobservations)
IRC+10216in CIRC+10
AGB
d=123
7 CenterAstrophysics | Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138, USA
erence frame8 Banting
is rotated
byFIR
polar
angle
at
eachtoAstrophysics
pointrespect
to thelocation:
Qthe
and
Ur in
each forannulusidentifywith
theradialprofileof Stanford
Qrstarand
Ur . Following
we determine Qr =(θ=2"-5")
JCMT/POL-2(θ=14")
r SOFIA/HAWC+
and KIPAC
Fellow:
Kavli
Institute
Particle& Cosmology(KIPAC),
University,
Stanford,that
CA 94305,866v1 [astro-ph.SR] 22 Dec 2023

2 SOFIA Science Center, Universities Spacex Researchx
Association, NASA Ames Research Center, M.S. N232-12, Mo↵ett Field, CA

I>20δI, P>2.5δP9δθ=11.5°

USA< UrResearch>
Covington Fellow: Dominion Radio Astrophysical Observatory, Herzberg Astronomy and Astrophysics
Centre, National x x0
✓
=
0.5
⇥
arctan,where⇠ = arctan y y0 is the polarr Council Canada, P. O. Box 248, Penticton, BC V2A 6J9 Canada
Research<Q>
r
10 Ball Aerospace, 1600 Commerce St., Boulder, CO 80301
coordinates) and (x0 , y0 ) is the loca
Qr>0
Qr<0
Andersson 11
et al.
Physics Department, Santa Clara University, 500 El Camino Real, Santa Clara, CA 95053, USA

Qr = +Q cos 2⇠ + U sin 2⇠, U =
12

Ur=0

Q sin 2⇠ + U cos 2⇠,(6)

s the polar angle of a given
pixelbycoordinatey) (corresponding
equatorial
as defined
Tahani et al.position(2023) and(x,shown
in Figure 3 for theto
HAWC+
53 µm (upper
left )panel),haveomittedthe cos(
factorHAWC
for t
rightofpanel)and the JCMT
POL-2 850
observations(lowerpanel).
dataradial
have thesameis the location of the star. (upper
Becausethe moderate
Declinationofµm
IRC+10216 (⇠13.25) weQThe
Positivepolarizatr shows
Abstract
154 µm withµm
of SNR(I)>
20 inandthe
SNR(P )> 2.5. Allowing for 5% uncertainty,
a point
cos
>850
0.95
(including
an withangleof✓r±45fromthe radactor for the Right Ascension
distance
We present SCUBA-2/POL-2
850 numerator.
µm polarimetricobservationsofthecircumstellar
envelope
(CSE)
53 µm
bar)
represents
radialpolarization
atthatradius.
This
choiceisclearlysomewhat
arbitrary,but
asthe carbon-richbranch (AGB)
star IRC+10 216.
Both FIR and polarization
optical
Wepolarization
take thin annuli (⇠ 2.200canin beHl polarization, whileof negative
Qr asymptotic
indicatesgiant
tangential
polarization.
Ur represents
Figure3
providesareasonable
separation
betweensystematicallyradialandnon-radialpolarization.
Th
data indicate grains aligned with their long axis in the radial direction relative to theQcentral
star. The00
00 r and Ur in each annulus to ident
m the radial direction.
Therefore,zeroU
indicates
purelyradialortangential
polarization.
r
53µm
observations
show
clear
radialpolarization
between
6
and
45
,
while
the JCMT
observations do not
850 µm polarization does not show this simple structure. The 850 µm data are indicative, albeit
not
00
00
00
00
2.2 in HAWC+ and
⇠ 14
JCMT
observations)around
the
star
and
find
the
averagedclear
polarization.
The HAWC+
154suchµm aobservations
show
radialpolarization
conclusive,of inaradialmagnetic
dipolegeometry.
Assuming
simpledipolegeometry,theresulting only from 5 to 28 .
850 µmprofile
polarizationboth
Zeemanobservations
structure
Theof
blue
markers
Figurewith
3 show
theof pixels andwithsmall-scalepolarization
measurements included for
2numberk-RAT
us to identify the radial
Qgeometry
Uisrconsistent.inFIR
Followingthat
wedeterminerx andFigure 7. Left panel shows the SOFIA/HAWC+ 53 µm polarization vectors in cyan in the envelope of IRC+10 216 with
JCMT/POL-2 850 µm polarization vectors overlaid in black. Background image is the 53 µm emission. The right-hand panel
shows the JCMT/POL-2 850 µm data, in black, overlaid on SOFIA/HAWC+ 154 µm emission with polarization vectors (incyan). Because of the large beam sizes, relative to the o↵set from the CSE center, the 850 µm data may be prone to significant
beam-averaging and not show the true polarization. In this figure, we show the over-sampled maps of the HAWC+ data toemphasize the di↵erences in polarization geometry. Beam sizes are shown in the lower left corner.

in the CSE.
there is thesignificant
line polarization
within with
the SCUBA-2
850 in the number of poi
bin.While
Comparing
uncertainties
for thecontainedcos(✓r ) values
the variation
850spectralµm indicatedµm pass-band
the thesource,is unlikely
polarizationis results
are dominatedshowsforthat
sourcethat
for ourthe broadband
larger uncertainties
dispersion
withinsample,thaa<dominantUrit >
asdefinedby eachTahaniet al.rather(2023)✓r line=larger
0.5
⇥
,
(7)
by
polarization.
To
explaingrainalignment,
grain
mineralogye↵ects,duetoeitherat 154 and 850 µm are comparable, they are significantly
than thatforarctan
53 µm, so thecomparison
is not fullythe required
higher measurement errors.
straight-forward.

<Q >ization with SNR(I)> 20 and SNR(P )> 2.5. The x and y axes represent the radial profile of cos ✓r as
and the radius from the center of the star. The dashed horizontal line shows cos ✓r = 0.95, with points
g their error bars) representing radial polarization (allowing for 5% uncertainty; see Tahani et al. (2023)
blue dots illustrate the number of pixels (satisfying the SNR cut) in each annulus. Upper left panel:
1,POL-2
2 observations.
tions. Upper right panel: HAWC+ 154 µm observations. Lower left panel: JCMT
rtoon illustrating the radial polarization frame (see Eq. 6).

Sub-mm Wavelength Polarimetry of IRC+10 216

Janik Karoly,3 Pierre Bastien,4 Archana Soam,5, 2 Simon Coudé,6, 7, 2 Mehrnoosh Tahani,8, 9
11, 2
Michael S. Gordon,10 and Sydney Fox-Middleton
Sub-mm wave polarimetry of IRC+10 216
11

B-G Andersson,

1 Institute for Scientific Research, Boston College, 140 Commonwealth Avenue, Chestnut Hill, MA 02467, USA
2 SOFIA Science Center, Universities Space Research Association, NASA Ames Research Center, M.S. N232-12, Mo↵ett Field, CA

850 µm66v1 [astro-ph.SR] 22 Dec 2023

94035, USA

3 Jeremiah Horrocks Institute, University of Central Lancashire, Preston PR1 2HE, UKrr

1 sur3les Exoplanètes (iREx) & Centre de Recherche en Astrophysique du Québec (CRAQ),
4 Institut de Recherche

Sub-mm wave polarimetry of IRC+10 216

15balanced by the electrostatic potential of the grain, and hence be dependent on the opacity to the interstellar radiation
field, but not involve the 1/n(e) factor, as implied by the semi-empirical correlation seen in Figure 10. Detailed
modeling, applicable to the conditions of the CSE (beyond the scope of this paper), will be needed to fully address
this issue.
While for small grains the electric moment can originate as part of grain structure (Draine & Lazarian 1998), for thelarge grains indicated in the IRC+10 216 CSE (e.g. Groenewegen 1997) grain charging is likely required (A. Lazarian,
2022, private communications). Since the electric dipole moment of a grain depends on the total charge on the grain
Figure 5. Left: The 850 µm dust
emission
map is shown
the POL-2
850we
µmuse
polarization(I >I and p >p ) proxy for grain charging and(cf.
Weingartner
2006; with
Lazarian2020),
the spacevectors
densityof20electronsas2.5ourplotted in black over the best fit dipole morphology shown by the cyan stream-plot (the orientation of the field-lines represent
electric alignment. The blue dashed line in the outer envelope corresponds
toelectrons
released by photo-ionization,
the polarization “E-vectors”). The image is zoomed in to show just the envelope. Right: A plot of the reduced 2red value which
whilethethe
red dashedcurve corresponds
to electrons
duearoundto cosmic
is found using Eq. 9 as it varies withdi↵erent
field rotations⇥. A minimum
can be seen
⇥ =ray125 ionization.
(E-vectors)Ivlev
with et al. (2015) have argued thatgrain-charging by cosmic rays in the inner envelope, which is similar in gas parameters to their region “I”, should be
an uncertainty of ⇠15
inefficient.

Université de Montréal, Département de Physique, 1375, Avenue Thérèse-Lavoie-Roux, Montréal, QC, H2V 0B3, Canada
5 Indian Institute of Astrophysics, II Block, Koramangala, Bengaluru 560034, India
6 Department
Sub-mm wave polarimetry of
IRC+10 216
13
of Earth, Environment,
and Physics, Worcester State University, Worcester, MA 01602, USA
sight magnetic field strength, based on the CN (J=1-0) Zeeman observations of Duthu et al. (2017),
ial distance from the central star using an r scaling (blue open symbols7and curves, right axis) andfordashed
Astrophysics | Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138, USAack, filled, symbols and curves, left axis). The weighted (W; solid lines) andCenterunweighted (UW;
nt results, both in amplitude and phase
(see
text
for
details).
( Particle) Astrophysics
850µm
8 Banting and KIPAC Fellow: Kavli Institute for& Cosmology (KIPAC), Stanford University, Stanford, CA 94305,
USA ß(<12.5")
9 Covington Fellow: Dominion Radio Astrophysical Observatory, Herzberg Astronomy and Astrophysics Research Centre, National
Research Council Canada, P. O. Box 248, Penticton, BC V2A 6J9 Canada
10 Ball Aerospace, 1600 Commerce St., Boulder, CO 80301
E-RAT
11 Physics Department, Santa Clara University, 500 El Camino Real, Santa Clara, CA 95053, USA
3

Abstract

E-RAT of the circumstellar envelope (CSE)
We present SCUBA-2/POL-2 850 µm polarimetric observationsof the carbon-rich asymptotic giant branch (AGB) star IRC+10 216. Both FIR and optical polarization
data indicate grains aligned with their long axis in the radial directionFigure
relative
toamountthecentralstar.
Thewith the electron density by photo-ionization due to
10. (Left) The
of 850µm polarization
is well correlateddi↵use radiation(UV)thefield(blue dashedcalculated
by we
Li et
al. (2014)
inet
theFigure 6. To test the validity of thethe external
minimization,noting that
reducedneverline)
approaches
zero,followAndraeal.IRC+10 216 envelope (the scalingof
twofitvertical
axes
have
been arbitrarily
set to(Right)
show
thecorrelation).
dashed curve represents modeled electron
850µm
polarization
does
not
show
this
simplestructure.
The
µm
data
are
indicative,
albeitnot(2010). (Left)
The 850residuals forthethebest
solutionyieldsa peaked
distribution.
Recalculating
theThe red
minimizationof CO (J=3–2) at ⌫=345.796 GHz, SiS (J=19–18) at ⌫=344.779 GHz, and CS 7–6 at ⌫=342.883 GHz. These lines
densitygeneratedcosmicrays in the denser
inner shell.
As shownshows
by Ivleval. (2015)data
grain-charging by cosmic rays in thewhile eliminating each of the data
points,in turn,byshows
a consistent
minimum.
The ordinate
the eteliminatedare all located at wavelengths with transmissions above 95% of the peak transmission of the SCUBA-2 850 µm filter
their region µm“I”) is inefficient.
(Right) A direct comparison between polarization and electron density(arbitrarily numbered). inner envelope (similar to 850
⾒(MET) k-RATAssumingpointsuch
⾒conclusive,a magnetic
a simple
dipolegeometry,theresulting(Cookson et al. 2018). The SMA primary beam (6m antennae)
at 850 µm is about 36 of
and Girart
et al. (2012) achieved dipole geometry.
for distances beyond 20 (where the latter is dominated by photo-ionization in the Li et al. (2014) models) yields a formallya synthesized beam of 2.6 ⇥1.6 . Also, as shown by Girart et al. (2006), the SMA filters out emission that arises
significant correlation.
aZeemanradial geometry alone.
Even so, the over-all andreduced small-scale
for the fit with only a structuremono-pole component is lower thanfrom structures larger 850
than about 10
,
so
the
two
data
sets
are
not
trivialtocompareinaquantitativeway.
However,
850µmpolarizationgeometryisconsistent
with
both
observationsµm
for the combined fit.
if we use the CO data from Girart et al. (2012) and the conversion factors given in Drabek et al. (2012), we canestimate the possible Goldreich-Kylafis contamination in our observations. Using the Girart et al. (2012) measurement
4. RESULTS
intemperature
theWhile there is significant spectral line polarization contained
the inSCUBA-2
3.4. Comparison of withinpolarization properties
di↵erent wavelengths 850of the Stokes Q parameter, we find a peak line brightness
2 K and a width of 20 km/s. If the JCMT(FeC)ofCSE.
Our FIR, especially the 53 µm, and optical polarization data (Andersson et al. 2022, Andersson et al., 2023b, inconversion factor is valid also for the Stokes Q parameter, we find3a polarized intensity on the order of 30 mJy/beam
The clear di↵erences in the polarization geometry between the 53 and 850 µm data, makes it is worthwhile to directly
preparation) indicate grainalignment withthe long
axis in the radial direction away from the central star, supporting aµm
pass-bandfor doesthesource, it is unlikely that our compare
broadband
polarization
resultsaredominatedwhich would contribute a significant signal in our polarized
intensity,
assuming the spatial filtering
not strongly
the polarization at several wavelengths. Figure 7 compares the polarization geometry for the 53, 154 and 850
second-order radiative grain alignment mechanism (Hoang & Lazarian 2009). We stress that, as we argued in the formera↵ect the comparison.
µm data. The 154 µm does show a somewhat intermediary geometry, possibly indicating a transition from the radial(Andersson et al. 2022),
the radial dependenceof theeither
FIR polarization does not support a mechanical (gas-dust
However, if we compare the polarization geometry between
observations(SOFIA/HAWC+ and JCMT/POL-2)
byourline
polarization.
To explain the required grain alignment,
grain paper
mineralogye↵ects,due topolarization seen at 53 µm to the “dipole-like” structure seen at 850 µm. We note, however, that while the beam sizes
with those of Girart et al. (2012) the picture becomes more complicated. As Figure 9 shows, the latter only detect
drift) alignment mechanism (e.g. Gold 1952) as the primary driver. The JCMT/POL-2 850 µm data, presented here,
Figure 8. The polarization fraction for the 53, 154, and 850 µm polarization is plotted against the Stokes I intensities at
each wavelength. For the 850 µm data, a single well-defined power-law is apparent. The 53 µm is well fit by a two-component
distribution with a steeper slope at small fluxes (similar to the 850 µm one) followed by a shallower slope, o↵set to somewhat
higher values at the intersection. The 154 µm falls in between the two, with a hint of an o↵set, seen in the 53 µm data, at thehigh end of the 154 µm intensity distribution. If the 154 µm data are fit to only intensities less than 0.1 Jy/arcsec2 an exponent
consistent with that for the steep part of the 53 µm and the 850 µm data is found. See text for details. All data have been
debiased.

00

2

2

2

2

00

00

00

00

2

ded from https://academic.oup.com/mnras/article/527/4/10279/7478015 by KASI user on 02 February 2024

Dynamics in Star-forming Cores (DiSCo): project overview and the firstlookgion (left) and a multipeak starless core NGC 1333-3 (right). towards the B1 and NGC 1333 regions in Perseus

ed

−1

ge
es
ly

eon
ry
te
es
es
in
ec

Downloaded from https://academic.oup.com/mnras/article/527/4/10279/7478015 by

pe
a
&
fy
de
in
ch
05

Downloaded from https://academic.oup.com/mnras/article/527/4/10279/7478015 by KASI user on 02 February 2024

er
nt
el
le
we
all
se
ep

Che-Yu,1,2 ‹ Rachel
Friesen,3 Jialu Li,4 Anika Schmiedeke ,5,6 David Frayer,6 Zhi-Yun Li,2
is basically no N2 H+ emission associatedwith Chen
protostellar
core
78John Tobin,
W. Looney,
Stella Offner ,9 Lee G. Mundy,4 Andrew I. Harris,4 Sarah Church,10Per-emb-24 (Fig. 7, left), which could suggestthat thisLeslie
protostaris11
5
5
Dynamics2 in Star-forming Cores (DiSCo)
10289
Eve
Ostriker,
Jaime
actually at a later evolutionary stage insteadofC.
a Class0 source(seeE. Pineda, Tien-Hao Hsieh and Ka Ho Lam
1 Lawrence Livermore National Laboratory, Livermore, CA 94550, USA
2 Departmente.g. Tobin et al. 2016a). On the other hand,
while being
previouslyof Astronomy,
University of Virginia, Charlottesville, VA 22904, USA
3 Department of Astronomy & Astrophysics, University of Toronto, Toronto, ON M5S 3H4, Canada
Dynamics in Star-forming Cores (DiSCo)
identified as a core using GAS data with 304arcsec resolution, starless
Department of Astronomy, University of Maryland, College Park 20742 MD, USA‘core’ N1333-2 is actually a ring-like structure(Fig. 7, right).
These he Physik, Giessenbachstrasse 1, D-85748 Garching, Germany
5 Max-Planck-Institutfür extraterrestrisc
6 Green Bank Observatory, Green Bank, WV 24944, USA
two targets were thus removed from the analysis.
7 National Radio Astronomy Observatory, Charlottesville, VA 22904, USA
pc protostars and/or
In0.01-0.05
some cases, multiple
local maxima
ofUniversity
N2 H+ of Illinois, Urbana, IL 61801, USA
8 Departmentof Astronomy,ofAstronomy,
UniversityUSAemission
are too close
to oneanother, 9 Department
and there
is no planeclosed of Texas, Austin, TX 78712,DiSCoàGreenBank
Telescope
focal
10
Department, Stanford University, Stanford, CA 94305, USA
contour (either NH column density+or N2 H11+Physics
emission)withasingleDepartment of Astrophysical Sciences, Princeton University, Princeton, NJ 08544, USA
45 B1-bN/B1-bS
Class 0 63
2Htarget. This is the case forNPer-emb-6/Per-emb-10,(see Fig.
4), Per-emb-27/N1333-8,
Per-bolo-45/N1333-21,-emb- dv=0.023 km/s, σ~0.05 K~9",4x4
array, 30.4"
N2H+Per
J=1-0,
Accepted 2023 December
15. Received 2023 December 12; in original form 2023 September 25
12/Per-emb-13/IRAS4B’ (see Fig. 5), and the SVS 13 region (seeFig. 6). Also, when the second local maximum around the coreN2size,
H+ we
mom0
STR
ACT
area Herschelis weak or small inloosenA Bour
criterion
to include
Na2crucial
H+ mom01
The internal
velocity
structurerole in providing the initial conditions for star formationsuch sub-tructures inside the identified coreboundary.
This
is thewithin dense gaseous cores playsinmolecular
clouds.
Ho
we
ver,
the
kinematic
properties
of
dense
gas
at
core scales (∼0.01−0.1 pc) has not been extensively
case for N1333-1, N1333-13, N1333-17, N1333-22, and N1333characterized
becauseof
instrument
limitations
until
the
uniquecapabilities
of GBT-Argus became available. The ongoing
23 (see Figs 5 and 6; the ⾒larger core area
are marked
with
dark
7. Program,Two previously-definedcores[left: Class 0 protostar
Per-24,markedby aaims
green star;right: a starlessmarkedby distribution
a green circle) with
GBT-ArgusFigure
Large
DynamicsinStar-forming
Cores(DiSCo)thus
to investigate
thecore,originandof no core-likestructure in integrated
N2 H+ emission (in K km s−1 , colourmap and black contours in the level of 1 K km s−1 ] from DiSCo. Column density [NH in cm−2 , inpurple ellipses). All these coresB1
are categorizedas’multiples’inourangular momentumof star-forming
cores. DiSCo will survey all starless cores and Class 0 protostellar cores in the Perseus
NGC1333
the level of !log (66NH /cm2 ) = 0.1] contours from Herschel are plotted as light grey contours. The beam is shown in the bottom left corner in each panel, andanalysis.
molecular othercomplex
down
to
∼0.01
pc
scales<0.05 km s−1 velocity
resolution
using the dense gas tracer N2 H+ . Here,DiSCo targets in the fields of view
are withalso marked.
Class
0
2 if we define the normalizedweintensitypresent thefirst dataacrosssets from DiSCo towards the B1 and NGC 1333 regions in Perseus. Our results suggest that a denseInterestingly,
variation), which indicating
can then be these
combined
the fitted
core’sinternal
velocity
structure
has little correlation with other core-scale1993
properties,
gas withmotions
maycorebe radius R to
the core to be
derivethespecific
angularmomentumJ≡
L/M∼
R 2 ω = R 2 ∇v .
originated externally from cloud-scale turbulence. These first data sets also reaffirm the ability of GBT-Argus for studying dense!I
log Npeak − log
Ipeak − Iboundary
Weaddress
then compare
the J−Rmomentum
relation fromproblem
our DiSCowith
data awith previous
boundarystructure and provided an empirical basis for future studies that
coreNvelocity
the angular
≡
or
,
(1)
observations(Goodman
et
al.
1993
;
Casellietal.
2002; Pirogov et al.
broad sample.
Ipeak
Ipeak
log Nstatisticallypeak
2003; Chen, Launhardt & Henning 2007; Tobin et al. 2011; Yen et al.

10283

2015–) ISM:
and simulations& lines:
Ostriker2018), which is shown inKeylevelwords:
stars: formationto– stars: protostars – ISM: kinematics and dynamics
molecules(Chen– radio
ISM.
where Iboundary is the intensity of the contour
corresponding
Fig. 9 (left panel).
the core boundary, we find that the normalized intensity difference
Clearly, DiSCo cores blend nicely in with the existing trend thatroughly follows a power-law correlation J ∝ R1.5 (see e.g. Chen et al.
!I/Ipeak tends to have a power-law correlation with size, as shown inBonner-Elbert+
The
fitNascentof DiSCodata
J ∝ Rα with α =(protostellar2019adiscs;).e.g.
theleast-square
VLA/ALMA
Disk
andgives
MultiplicFig. 8. While both the log of NH column density
emission
1 I N T andRO DN
U2CHT I O
N
1.55 Surv± 0.15,and αet=al.1.59± 0.04all data (fromity (VANDAM)
ey, Tobin
2016b; the when
Mass combining
Assembly of
were used as I here,2 we see that they follow
a similar power-law
bothandobservations
andwithsimulations)shown in Fig.
In molecular clouds (MCs), multiscale supersonic flows compress
Stellar Systems
their Evolution
the SMA (MASSES)
surve9y,(left panel).
4.
DiSCo
N Hwhile
maps forin theassembly
B1 region. Identified
core boundaries
ver,Figure
note
that
thecorescore
roughly
follows(dashedthe ellipses) with mean velocity gradient direction (arrows) overplottedcorrelation to the core size, roughly as !material
I/Ipeak ∝r. While
neitherof overdense regions, which may
to initiate
the creation
Stephens et Ho
al.we
2018
] we
scales.
These
observations
revealedfeatureson normalized line-of-sight velocity maps (!v ≡ v − v |in km s ) and integrated N H intensity (grey contours; in the level of 1 K·km s ). Green+same
power-law,thescatter
in
J
for
a
given
radiusisprettylarge,
represent fitting
using Herschelcolumn density
to becomecores and then collapse gravitationally tothat generally agree ellipses/arrows
with the picture
thatresults
multiscale
turbulence
is contours, while purple ellipses/arrows showing cores identified using N H emission.
N2 H emission intensity nor H2 columnshrink
density
canprestellar
be directly
Yellow stars mark the location of Class 0 protostars, while green circles represent dense cores (as N H peaks) identified in previous literature (see Section
2

+

los

form protostellar systems (Shu, Adams & Lizano 1987). Turbulenceloslos core−1than oneorder
Considering
the definition of
dynamicallymore
significant
duringthe ofstarmagnitude.
formation process,including

2

+

−1

2

+

2

+

ps://academic.oup.com/mnras/article/527/4/10279/7478015 by KASI user

arked by a green circle) with no core-like
Dynamics
in Star-forming Cores (DiSCo): project overview and the first−2
DiSCo. Column density [NH in cmlook, intowards the B1 and NGC 1333 regions in Perseus
he bottom left corner in each panel, and

Che-Yu Chen ,1,2 ‹ Rachel Friesen,3 Jialu Li,4 Anika Schmiedeke ,5,6 David Frayer,6 Zhi-Yun Li,2
John Tobin,7 Leslie W. Looney,8 Stella Offner ,9 Lee G. Mundy,4 Andrew I. Harris,4 Sarah Church,10552
Eve C. Ostriker,11 Jaime E. Pineda,10290
Tien-Hao
C.-Y.Hsieh
Chen etand
al. Ka Ho Lam
1 Lawrence Livermore National Laboratory, Livermore, CA 94550, USA
2
4
6
7
8
9

10
11

lid circles) and simulations (open circles). DiSCo objects for B1 andombining DiSCo data and previous observations (solid circles) and simulations (open circles). DiSCo objects for B1 ande categories: protostellar cores (stars), starless cores (triangles
A),B andS T R A C T cores (stars), starless cores (triangles), anderent
various symbols represent the three categories:
protostellar
1.59 ± colours,
0.04 withandχ 2 = 0.14), which is very close to the1.59
fit±using
DiSCo
0.04
The
internal
velocity
structure
withintodense
cores plays a crucial role in providing the initial conditions for star formation
the least-square fit using all data on the plot (J ∝ R
with
χ 2 = 0.14),
which
is very close
the fitgaseoususing DiSCo
and the dispersion of the velocity
gradient direction (bottominpanel)
1.5
molecular
clouds.
Hogradient
wever, thekinematic
properties
0.09). Right: The mean velocity gradient (top panel) and the dispersionof thevelocity
direction(bottom
panel) of dense gas at core scales (∼0.01−0.1 pc) has not been extensively
characterized because of instrument
limitations until
the unique capabilities
of GBTArgus became
available. The ongoinge size.
DynamicsinStar-forming
Cores(DiSCo)10291
Dynamics
in Star-forming
Cores(DiSCo)10291
αFigure 9. Left
: The J−R correlation combining DiSCo data and previous observations (solid circles) and simulations (open circles). DiSCo objects for B1 and
GBTArgus
Large
Program,DynamicsinStar-forming
Cores(DiSCo)
thus
aims
to
investigate
theoriginand distribution of∡(∇$,∇$)
NGC 1333 regions are marked by different colours, and various symbols represent the three categories: protostellar cores (stars), starless cores (triangles), and1.59± 0.04in
angular momentum of star-forming cores.
DiSCo
will
surv
e
y
all
starless
cores
and
Class
0
protostellar
corestheχ 2Perseus
multiples (squares). Dotted line shows the least-square fit using all data on the plot (J ∝ R
with= 0.14), which is very close to the fit using DiSCo± 0.15 with−1
data only
(J ∝<
R1.55
= 0.09). Right: The mean velocity(top panel)and the dispersion
the velocity gradient direction (bottom panel)molecular complex down to ∼0.01 pc scales
with
0.05
km s χ 2 velocity
resolution
using gradientthe densegas tracer
N2 H+ . ofHere,
the core, as functions of the core size.
we present the first data sets from DiSCowithin
towards
the B1 and NGC 1333 regions in Perseus. Our results suggest that a dense
core’s internal velocity structure has little correlation with other core-scale properties, indicating these gas motions may beoriginated externally from cloud-scale turbulence. These first data sets also reaffirm the ability of GBT-Argus for studying dense
core velocity structure and provided an empirical basis for future studies that address the angular momentum problem with a'.)statistically broad sample.

Downloaß with the existing trend that
icely inrelation J ∝ R (see e.g. Chen et al.
𝜎 α = ~0°
DiSCo data gives J ∝ R with<30°
ß
.04 when combining all data (fromons) shown in Fig. 9 (left panel).
ße core assembly roughly follows theJ-R∆𝑣(𝑅) ∝ 𝑅
J for a given radius is pretty large,
Larson'w
law
Key words: stars: formation – stars: protostars – ISM: kinematics and dynamics – ISM:
molecules – radiolines: ISM.
tude. Considering the definitionofharp dependence on R, this suggests(protostellar discs; e.g. the VLA/ALMA Nascent Disk and MultiplicI N T RO D U C T I O N
e size is relatively weak and has 1large
ity (VANDAM) Survey, Tobin et al. 2016b; the Mass Assembly of
In molecular clouds (MCs), multiscale supersonic flows compress
Stellar Systems and their Evolution with the SMA (MASSES) survey,
he upper-right panel of Fig. 9, whichmaterial to initiate the creation of overdense regions, which may
Stephens et al. 2018] scales. These observations revealed features
shrink to become prestellar cores and then collapse gravitationally tothat generally agree with the picture that multiscale turbulence isform protostellar systems (Shu, Adams & Lizano 1987). Turbulence
dynamically significant during the star formation process, including
v . This shows that the mean velocity

Downloaded from https://academic.oup.com/mnras/article/527/4/10279/7478015 by KASI use

Downloaded from https://academic.oup.com/mnras/article/527/4/10279/7478015 by KASI u

5

Downloaded from https://academic.oup.com/mnras/article/527/4/10279/7478015 by KASI user on 02 February 2024

3

Downloa
Downloaded from https://academic.oup.com/mnras/article/527/4/10279/7478015 by KASI u

ined with the fitted core radius Department
R to of Astronomy, University of Virginia, Charlottesville, VA 22904, USA
Department of Astronomy & Astrophysics, University of Toronto, Toronto, ON M5S 3H4, Canada
mentum J ≡ L/M ∼ R 2 ω = R 2Department∇v . of Astronomy, University of Maryland, College Park 20742 MD, USA
Max-Planck-Institut für extraterrestrische Physik, Giessenbachstrasse 1, D-85748 Garching, Germany
Green Bank Observatory, Green Bank, WV 24944, USAn from our DiSCo data with previous
National Radio Astronomy Observatory, Charlottesville, VA 22904, USA
Department of Astronomy, University of Illinois, Urbana, IL 61801, USA
Department
Texas, Austin, TX 78712, USA
93; Caselli et al. 2002; Pirogov etal. of Astronomy, University of 1
Physics Department, Stanford University, Stanford, CA 94305, USA
Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544, USA
ng 2007; Tobin et al. 2011; Yen etal.
𝜎∡(∇$,∇$)
Ostriker2018), which is shownin
Accepted 2023 December 15. Received 2023 December 12; in original form 2023 September 25

JWST Observations of JOYS+: Mid-infrared detection of gas-phase SO2 emission
in a low-mass protostar
Young protoStars
The case of NGC 1333 IRAS 2A: Hot core or accretion shock?

SO2

S
sub-mmSO2
θ=0.2"-0.4"

M. L. van Gelder1 , M. E. Ressler2 , E. F. van Dishoeck1,3 , P. Nazari1 , B. Tabone4 , J. H. Black5 ,Ł. Tychoniec6 , L. Francis1 , M. Barsony7 , H. Beuther8 , A. Caratti o Garatti9 , Y. Chen1 , C. Gieser3 ,V. J. M. le Gouellec10, ? , P. J. Kavanagh11 , P. D. Klaassen12 , B. W. P. Lew13 , H. Linnartz14 , L. Majumdar15,16 ,G. Perotti8 , and W. R. M. Rocha1,14<1%(Affiliations can be found after the references)
Received 29 September 2023 / Accepted 24 November 2023
ABSTRACTNGC 1333 IRAS 2A,

0.6",(293 pc), dv=85 km/s,

Context. Thanks to the Mid-InfraRed Instrument (MIRI) on the James Webb Space Telescope (JWST), our ability to observe vantheGelder,star M. L., et al.: A&A, 682, A78 (2024)

formation process in the infrared has greatly improved. Due to its unprecedented spatial and spectral resolution and sensitivity in the
2.3. LTEmodelinner
fitting regions. An abundant
mid-infrared,
JWST/MIRI
theslabwarm
van Gelder, M. L.,
et al.: A&A, 682,
A78 (2024)can see through highly extincted protostellar envelopes and probe
molecule in these warm inner regions is SO2 , which is a common tracer of both outflow
accretion
shocksas inwell
as hot core
Theandmolecularemissionfeaturesthe continuum-subtracted
spectra were fitted with simple slab models assuming LTE. Thischemistry.
is a similar approach to what is applied to other low- and highAims. This paper presents the first mid-infrared detection of gaseous SO2 emission in an embedded
low-mass protostellar system richmass sources (Carr & Najita 2008; Salyk et al. 2011; Tabone et al.
in complex molecules and aims to determine the physical origin of the SO2 emission.
2023; Grant et al. 2023; Perotti et al. 2023; Francis et al. 2024). It
is important
notelow-mass
here that the protostellar
assumption of LTE
is likely not
Methods. JWST/MIRI observations taken with the Medium Resolution Spectrometer (MRS)of tothebinaryvalid for the MIR ro-vibrational transitions of SO2 detected in
NGC 1333 IRAS 2A in the JWST Observations of Young protoStars (JOYS+) program are presented.
The
observations
revealemission
IRAS 2A. Nevertheless, LTE models can still constrain physicalfrom the SO2 ⌫3 asymmetric stretching mode at 7.35 µm. Using simple slab models and assuming
local
thermodynamic
equilibrium
quantities suchas therotational temperature
within a vibraexcitedthe
state.results
The implications
the assumption(LTE), we derived the rotational temperature and total number of SO2 molecules. We thentionallycomparedto thoseofderived
fromof LTE
will be further discussed in Sect. 4.1.
high-angular-resolution SO2 data on the same scales (⇠50 100 au) obtained with the Atacama
Large
Millimeter/submillimeterArray
In the slab models, the emission is assumed to arise from
(ALMA).
a slab of gas with an excitation temperature T ex (which in thecase aroundof LTE istheapproximately
equal continuum
to the kinetic temperature),
Results. The SO2 emission from the ⌫3 band is predominantly located on ⇠50 100 au scales
mid-infraredpeakdensity N, and an emitting area equal to ⇡R2 . The latof the main component of the binary, IRAS 2A1. A rotational temperature of 92 ± 8 K isatercolumn
derivedfromthe⌫lines.
This
is
in
good
3
was parameterized as a circular emitting area with a radius
agreement with the rotational temperature derived from pure rotational lines in the vibrational
groundstateoriginate(i.e., ⌫ from
= 0)any
with
ALMA
R, but could
in reality
shapedregion with
an
area
equal
to ⇡R2 . The intrinsic
velocitybroadening
V was(104 ± 5 K), which are extended over similar scales. However, the emission of the ⌫3 lines in the
MIRI-MRS
spectrum
is
not
in
LTE
fixed to 3.5 km
4 s 1 based on ALMA data covering SO2 (see
given
that
the
total
numberofmolecules
predicted
by
a
LTE
model
is
found
to
be
a
factorof2⇥
10higherthanwhatisderivedforvan Gelder, M. L., et al.: A&A, 682, A78 (2024)
Sect. 3.2). It is important to note that in case of optically thinthe ⌫ = 0 state from the ALMA data. This difference can be explained by a vibrational temperaturethat is⇠100
K higherthan theof V,
emission, the derived
columndensities
are independent
whereasin case oftemperature
optically thick emission
columnderived rotational temperature of the ⌫ = 0 state: T vib ⇠ 200 K versus T rot = 104 ± 5 K. The
brightness
derivedthefrom
thedensitywith 1/ V (Tabone et al. 2023). Given that SO2 has many
continuum around the ⌫3 band (⇠7.35 µm) of SO2 is ⇠180 K, which confirms that the ⌫3 scales
=
1
level
is
not
collisionally
populatedbutro-vibrational lines close to each other in wavelength in the MIR,
rather infrared-pumped by scattered radiation. This is also consistent with the non-detectionit of⌫2 bendingat 18into20accountµm. Thewastheimportant
to take modeline overlap
in order todensityexcitation
temperature.
similar rotational temperature derived from the MIRI-MRS and ALMA data implies that derive
they anareaccurate
in factcolumn
tracing
the andsame
molecular
Moreover, the spectral resolving power of MIRI-MRS aroundgas. The inferred abundance of SO2 , determined using the LTE fit to the lines of the vibrational
ground state in (Labiano
the ALMA
data, is7.35 µm is about / ⇠ 3500
et al. 2021; Jones et al.
881.0 ± 0.3 ⇥ 10 with respect to H2 , which is on the lower side compared to interstellar and2023),
cometaryices (1010 7 ).resolution of ⇠ 85 km s 1 ,corresponding
to a velocity
meansandthat thethe lines
are notline
spectrally
resolved
and could
Conclusions. Given the rotational temperature, the extent of the emission (⇠100 au inwhichradius),narrowwidthsin thebe blended withex
other lines (of, e.g., SO2 itself, H2 O) in the MIRI
ALMA data (⇠3.5 km s 1 ), the SO2 in IRAS 2A likely originates from ice sublimation inthecentralhot
core
aroundtheprotostardata.
rather than from an accretion shock at the disk–envelope boundary. Furthermore, this paper shows
the importanceof radiative
The spectroscopic
information(i.e., line pumping
wavelengths, EinAij , upper
energythelevelphysics
Eup , degeneracy) of the MIR
and of combining JWST observations with those from millimeter interferometers such as stein
ALMA
to probe
on diskgupscalesro-vibrational transitions of SO2 was taken from the HITRAN
and to infer molecular abundances.
2
database (Gordon et al. 2022) and converted to the Leiden

ν1:
ν2:
ν3:
ν3

, 9 µm, 20 µm

P-branch 7.4 µm
LTE
R Q
Q
ALMA
LTE

T

, 7 µm4

non-

Atomic and Molecular Database (LAMDA) format (van der Tak

Key words.
stars:– to make it compatible with the slab modelFig. 1. Spectrum (top panel) and continuum images at various wavelengths(bottom astrochemistryrow) of IRAS 2A. –Instars:
the topformation
panel, four –insets
arelow-masspresented: – stars: protostars – ISM:etmoleculesal. 2020) in orderFig. 3. Integrated intensity map of SO2 observed with MIRI-MRS
in color. The image is integrated over the Q-branch of the ⌫3 band:[7.34,7.35] µm and shown using a sqrt stretch to enhance fainter emission. The continuum around 7.35 µm is overlaid in white contours
and peaks on the primary component, IRAS 2A1, extending somewhat
toward the south in the direction of the scattered light. The positions of
IRAS 2A1 and IRAS 2A2 are depicted with the white stars. A whitescale bar is displayed in the bottom left, and the size of the PSF is presented as the filled white circle in the bottom right. The directions of thetwo outflows originating from IRAS 2A1 and IRAS 2A2 are indicatedwith the colored arrows (Tobin et al. 2015).

Q-branch
150 x 90 au
H2differential extinction caused by the 7.25 µm and 7.4 µm

with the non-detection of the ⌫2 band, predominantly due to the
JOYS+:
Mid-infrared
detectionof gas-phaseSOtolarger extinction
at MIR
wavelengths
comparedmillimeter2 emission
wavelengths (e.g.,inMcClure2009;protostar
Chapman et al. 2009).
a low-mass
Onecasesolutionfor1333
theIRASlack 2A:of emission
inaccretionthe ⌫2 band
could beTheof NGCHot core orshock?
that the line-to-continuum ratio is too low in this region, since
M. L. van Gelder1 , M. E. Ressler2 , E. F. van Dishoeck1,3 , P. Nazari1 , B. Tabone4 , J. H. Black5 ,6783continuum
levelon the⇠19, Y.JyChen
at1 1820 µm
Ł.theTychoniec, L. Francis1 ,flux
M. Barsony, H.isBeuther, A.order
Caratti oof
Garatti, C. Gieser
,
10,
11
12
13
14
15,16
V. J. compared
M. le Gouellec to, P.⇠20
J. Kavanagh,
P.
D.
Klaassen
,
B.
W.
P.
Lew
,
H.
Linnartz,
L.
MajumdarmJy around7.35 µm. The predicted line emis- ,G. Perotti8 , and W. R. M. Rocha1,14
sion peaks at ⇠1 Jy
for the strongest peaks of the ⌫3 model,(Affiliations can be found after the references)
corresponding to a line-to-continuum
ratio of 1. This suggests
ALMA
29 September 2023 / Accepted 24 November 2023
that this cannotReceived
explainthe absence of the ⌫2 band since a lineto-continuum ratio down
0.01 shouldstill be
LTE toABSTRACT
Trot=104
K detectable onContext.
to the continuum.
Mid-InfraRed Instrument(MIRI) on the James
Webb Space
Telescope(JWST),
our ability
to observe thethe stara Thanks
strongMoreover,
this
would
also
not
explainformation process in the infrared has greatly improved. Due to its unprecedented(τ~0.1)
spatial and spectral resolution and sensitivity in the
mid-infrared,
JWST/MIRI can see
through highlythe
extincted
protostellar envelopes
and probe the warmneeded
inner regions. inAn abundant
discrepancy
betweennumberof moleculesthemolecule in these warm inner regions is SO 34, whichis a common tracer of both outflow and accretion shocks as well as hot coreSO2chemistry.
LTE slab models to explain
the emission in ⌫ = 0 state with
Aims. This paper presents the first mid-infrared detection of gaseous SO emission in an embedded low-mass protostellar system richin complex
molecules andand aimsthe
to determine
the physicalwith
origin ofMIRI.
the SO emission.
ALMA⌫3 band
Scattered continuum radiMethods. JWST/MIRI observations taken with the Medium Resolution Spectrometer (MRS) of the low-mass protostellar binary
ation
out toof ⇠8butnotprogram
to longer
wavelengths
NGC 1333
IRAS is
2A inpresent
the JWST Observations
Youngµm
protoStars(JOYS+)
are presented.
The observations reveal(seeemission
ν2 ν3
8 µm.
µm
from the SO ⌫ν3asymmetric stretching mode at 7.35
Using simple slab models and assuming local thermodynamic equilibrium1),the rotationalsuggestingthatthe ⌫of3SOband
could
be infrared-pumped(LTE),Fig.
we derived
temperature andtotal number
molecules.
We then compared
the results to those derived fromhigh-angular-resolution SO data on the same scales (⇠50 100 au) obtained with the Atacama Large Millimeter/submillimeter Arrayν1
on ⇠100 au scales whereas this does not occur for the ⌫2 band
(ALMA).
Results. The SO emission from the ⌫ bandis predominantlyon ⇠50 100 au
around the mid-infrared continuum peak
Trotlocated
JWST
TKscalesexHowever, the data can only be accurately fitted for a very large complex organics suchasmethanol(CH OH)and methyl
for- ALMA
at
19
µm.
The
infraredradiationaround19µm
originates
of
the
main
componentofthebinary,IRAS
2A1.
A
rotationaltemperature
of
92
±
8
is
derivedfromthe ⌫ lines. Thisfrom
is in goodemitting area of &5000 au, which is in strong contrast with the mate (CH OCHO; see Fig. A.3) and with the compact emissionagreementwiththerotationaltemperature
derivedfrompurerotational
lines
in
the
vibrational
groundstate(i.e., ⌫ = 0) with ALMA
extent of the emission in Fig. 3 (<150 au).
inT
the MIRI-MRS data (i.e., 0.5 ⇥ 0.3 in diameter; see Fig. 3).
T
T
~200
K
rot
vib (104vib
thatis thenotextended
Fig. 1).
±thermal
5 K),lines
which
aredustextendedoversimilarHowever,emissionof the ⌫ lines(seein the MIRI-MRS
spectrum is not in LTE
This is a clear indication that the assumption of LTE is not
The purerotationalof SO
and SOemission
detectedby scales.
valid and thus that derived physical quantities, most notably the ALMA werefittedthat
usingthethetotalsamenumber
LTE slabof
model
fitting progiven
molecules
predicted by a LTE model is found to be a factor of 2 ⇥ 10 higher than what is derived for
T
T
~180
K
T
~200
K
number of molecules, should be analyzed in more detail. Since cedure as forthedata(Sect.
The submillimeter
Similarlyto⌫2 bendingmode,
the ⌫vib
symmetricalb⌫MIRI-MRS
IRbe explainedthe= 0 statefromthe2.3).
ALMA
data.theThis difference
canby a vibrationalthat is ⇠100 K stretchhigher than the
1temperature
the rotational distribution within the ⌫ band is well-fitted by line lists of both SO and SO were taken from the Cologne
derivedrotationaltemperature
of
the
⌫
=
0
state:
T⇠
200
K
versus
T
=
104
±
5
K.
The
brightness
temperature derived from thea single temperature, this temperature accurately describes the Database for Molecular
Spectroscopy(CDMS;
Mülleretal.
ingaroundmode
between
8.5 and 9 µm is overproduced by the best-fit
⌫ the
band
(⇠7.35rotational temperature within this vibrationally excited state, but 2001, 2005;continuum
Endres et al.
2016), the
where
entry
of SOµm)
wasof SO is ⇠180 K, which confirms that the ⌫ = 1 level is not collisionally populated but
ratherby scatteredat 18 20 µm. The
from infrared-pumped
Müller & Brünken (2005)
and theradiation.
entry of This is also consistent with the non-detection of the ⌫ bending
it does not necessarily represent the kinetic temperature. On the mostly taken
8 modefrom⌫rotational
model
(see
Fig.
B.4).
The
absenceofthattheemission
the
ALMA
H
SO
~10
other hand, the values
derived for Bandthe total number7of molecules
SO is basedonseveralworks(e.g.,
Lovas
1985; the3 spectroscopic
similartemperature
derivedfrom
MIRI-MRS
and ALMA
data implies
theyarein fact tracing thesame molecular22
and the size of the emitting area are not valid, both because of Belov et al.gas.
1998,Thefor transitions
ALMA Bandfrequencies).
inferred atabundanceof 7SO, determined using the LTE fit to the lines of the vibrational ground state in the ALMA data, isthe conflict with the measured size of the emitting
well The ALMAin total five pure rotational (i.e., ⌫ = 0)
7 data± cover
10 fivewithrespectoftotheH, whichis on
cosmic10derived5,forareatheasvibra10
SO
Sthe lower side compared to interstellar and cometary ices (10 10 ).
as the large discrepancy
with the values
transitions 1.0
of SO 0.3
and⇥also
transitions
SO 2isoConclusions.
Given
the8rotationaltemperature, the extent of the emission (⇠100 au in radius), and the narrow line widths in thetional ground state in the ALMA data (see Sect. 3.2). This will topologue (seeTable
A.1). However,
severalofthesetransitions
A78,
page
of
19
be further discussed in Sect. 4.1. SO
are blendedALMA
with strongof complex
organics
such
as 2A likely originates fromàdataemission(⇠3.5 kms ), theSO in
IRAS
ice sublimation in the central hot core around the protostar
HO
2
2
CH OCHOrather
and CH
CHO.
Fortunately,
two transitions
of SO
than
from
an accretion
shock at thedisk–envelope boundary. Furthermore, this paper shows the importance of radiative pumping
and one transition of SO are (relatively) unblended. This isand of combining JWST
observations
with those frominterferometers such as ALMA to probe the physics on disk scales
SO2
ALMA
3.5millimeter
km/s
important to determine the column densityand excitation temand to infer molecular abundances.
?

van Gelder, M. L., et al.: A&A, 682, A78 (2024)

2

2

2

34

Fig. 6. Integrated intensity maps of the SO2 82,6 71,7 (left, Eup = 43 K), SO2 164,12 163,13 (middle, Eup = 164 K), and SO2 174,14 173,15 (right,
Eup = 178 K) transitions in color. The images are integrated over [ 2,2] km s 1 with respect to the Vlsr of 6.7 km s 1 . The white vertical bar in
2 contours.
3
the colorbar on top of each image indicates the 3 threshold. The 0.875 mm continuum is overlaid as black
The main continuum peak is
associated with IRAS 2A1 and the secondary peak toward the south with IRAS 2A2. The directions of the two outflows originating from IRAS 2A1
and IRAS 2A2 are indicated with the colored arrows in the middle panel (Tobin et al. 2015). The size of the beam is shown in the bottom right, and2
in the bottom left a scale bar is displayed.
2

3

00

34

2

2

3

34

2

3

3

3

00

3

2

vib

3

3

rot

3

2

2

8

2 34

2

1

3

Integrated intensity maps of the SO2 82,6 71,7 (Eup = 43 K), SO2
164,12 163,13 (Eup = 164 K), and 34 SO2 174,14 173,15 (Eup =

2

2

4

2

34

3.2. Comparison to ALMA data

2

3

34

8

2

2

2

2

perature. All lines of SO2 and 34 SO2 are spectrally resolved witha FWHM of 3.5 km s 1 , which is similar to the FWHM of theKeyastrochemistry– stars:formation – stars: low-mass – stars: protostars – ISM: molecules –lines of HDO
33,1 words.
42,2 and thecomplex organics.
No vibrational

7

alone (e.g., Bruderer et al. 20
ing the infrared radiative pumprotational levels within the vib
tained since only J = 0, ±1 t
pumping thus leads to a more hwithout significantly changing
rotational temperature), supportemperatures measured in the ⌫3
The importance of infraredtified by comparing the results
band and the ⌫ = 0 state. As
level is radiatively pumped fromlevel population is set following
a vibrational temperature T vib
tional temperature, T vib , T rot .
number of molecules predicted
ALMA data can then be approx
NSO2 ,MIRIe h⌫/(kB Tvib )/ h⌫/(k T ) ,B rot
NSO2 ,ALMAewhere NALMA and NMIRI are
needed in the LTE models of thetively, T rot the derived rotationa

ences, Seoul National University, Seoul 08826, Republic of Korea
and Astrophysics, Peking University, Yiheyuan 5, Haidian Qu, 100871 Beĳing, People’s Republic of China
king University, No.5 Yiheyuan Road, Haidian District, Beĳing 100871, People’s Republic of Chinad Astrophysics, 5071 West Saanich Road, Victoria, BC, V9E 2E7, Canada
tronomy, University of Victoria, Victoria, BC, V8P 5C2, Canadater, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea
Mizna Ashraf,1¢ Jessy Jose1 †, Ho-Gyu Lee2 , Carlos Contreras Peña3,4 , Gregory J Herczeg5,6 ,An outburst and FU Ori-type disk of a former low luminosity
protostar
Hanpu Liu5,6 , Doug Johnstone7,8 and Jeong-Eun Lee3,91 Indian Instituteeceived 2023 December 12; in original form 2023 September
30of Science Education and Research (IISER) Tirupati, Rami Reddy Nagar, Karakambadi Road, Mangalam (P.O.), Tirupati 517 507, India

ABSTRACTrXiv:2312.10827v2 [astro-ph.SR] 14 Jan 2024

2 Korea Astronomy and Space Science Institute, 776, Daedeok daero, Yuseong-gu, Daejeon, 34055, Republic of Korea

3 Department of Physics and Astronomy, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea
4 Research Institute of Basic Sciences, Seoul National University, Seoul 08826, Republic of Korea

5 Kavli Institute for Astronomy and Astrophysics, Peking University, Yiheyuan 5, Haidian Qu, 100871 Beĳing, People’s Republic of China
6 Department of Astronomy, Peking University, No.5 Yiheyuan Road, Haidian District, Beĳing 100871, People’s Republic of China
7 NRC Herzberg Astronomy and Astrophysics, 5071 West Saanich Road, Victoria, BC, V9E 2E7, Canada

8 Department of Physics and Astronomy, University of Victoria, Victoria, BC, V8P 5C2, Canada
Strong accretion outbursts onto
protostars are associated with emission dominated by a
10
9 SNU Astronomy Research Center, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea
viscously heated disk, which is characterized by high luminosities. We report the discovery
SSTgbsJ214706
and characterization of a strong mid-IR (3.4, 4.6 `m) outburst in the embedded protostar SSTgbs J21470601+4739394 (hereafter SSTgbsJ214706). SSTgbsJ214706 has steadily brightened
Accepted 2023 December 13. Received 2023 December 12; in original form 2023 September 30
in the mid-infrared by ⇠ 2 magnitudes
over the past decade, as observed by NEOWISE.
Follow-up investigations with the Gemini near-IR spectrograph reveal that SSTgbsJ214706 is
ABSTRACTa binary system with a spatially extended outflow. The outburst
is occurring on the more embedded southeast (SE) component, which dominates the mid-Strong
and accretion
far-infraredemissionfrom are associated with emission dominated by aoutbursts
onto protostars
the source. The outbursting component exhibits a spectrum
consistentwith
an isFU
Ori-typeby high luminosities. We report the discovery
viscously
heated disk,whichcharacterizedandcharacterizationofastrongmid-IR(3.4, of
4.6 `m) outburst in the embedded protostar SSToutburst, including the presence of enhanced absorption observed in the molecular bands
gbs J21470601+4739394 (hereafter SSTgbsJ214706). SSTgbsJ214706 has steadily brightened
CO. The luminosity of the SE component is estimated to bein ⇠the0.23
L beforeoutburstoverandthe past decade, as observed by NEOWISE.
mid-infraredby ⇠ the2 magnitudes
0.95 reveal that SSTgbsJ214706 is⇠ 0.95 L during the outburst, which is 1 to 2 orders of magnitude
fainter thanbonafideFU spectrographFollow-up investigations
with theGemini near-IR
binary systemwith a spatiallyextended outflow.
Ori outbursts. We interpret this eruption as an FU Ori-typeaoutburst,
althoughthe possibilityof The outburst is occurring on the more embedded southeast (SE) component, which dominates the mid- and far-infrared emission frombrightening following an extinction episode cannot be ruledout. We discuss the implications
the source. The outbursting component exhibits a spectrum consistent with an FU Ori-type
and potential explanations for such a low-luminosity eruption.
outburst, including the presence of enhanced absorption observed in the molecular bands of

CO. The luminosity of the SE component is estimated to be ⇠ 0.23 L before the outburst and⇠ 0.95 L during the outburst, which is 1 to 2 orders of magnitude fainter than bonafide FU
Key words: stars: formation – stars: protostars – stars: variables

wth in young stellar objects (YSOs) is
ar is deeply embedded in its natal enve-

Ori outbursts. We interpret this eruption as an FU Ori-type outburst, although the possibility ofbrightening following an extinction episode cannot be ruled out. We discuss the implications
and potential explanations for such a low-luminosity eruption.
Key words: stars: formation – stars: protostars – stars: variables

some protostars are underluminous when compared to these expectations. Such low luminosity objects, characterized by internal
luminosities Lint . 0.2 L , represent an extreme casesomein theob1 INTRODUCTION
protostars are underluminous when compared to these ex-

2

0.23

FU Ori

8 I. Physikalisches Institut, Universität zu Köln, Zülpicher Straße 77, D-50937 Köln, Germany

α-enhanced astrochemistry: the carbon cycle in extreme galactic
conditions

9 CAS Key Laboratory of FAST, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100101, China
10 NAOC-UKZN Computational Astrophysics Centre, University of KwaZulu-Natal, Durban 4000, South Africa

1‹

2,3 ‹

2,3

Ying-He Zhao ,4,5 Gan Luo ,6,2
Donghui Quan ,1,7 Xue-Jian Jiang ,1 Yichen Sun ,2,3 Theodoros Topkaras,8 Di Li 9,1,10 and Ziyi Guo2,3

Thomas
G. Bisbas, Zhi-Yu, 2023
EdaSeptember
Gjergo 21,
Accepted 2023 December
5. Received
2023 December
5; inZhang
original form

1 Research Center for Intelligent Computing Platforms, Zhejiang Lab, Hangzhou 311100, China

ABSTRACT

2 School of Astronomy and Space Science, Nanjing University, Nanjing 210093, China

3 Key Laboratory of Modern Astronomy and Astrophysics, Nanjing University, Ministry of Education, Nanjing 210093, China
4dwarfs. We perform astrochemical modelling to simulate the impact of an α-enhanced ISM gas cloud on the abundances of
Key words: radiative transfer – methods:+ numerical – ISM: abundances – photodissociation region (PDR) – galaxies: ISM.

Downloaded from https://academic.oup.com/mnras/article/527/3/8886/7464047 by guest on 29 February 2024

Yunnan Observatories, Chinese Academy of Sciences, Kunming 650011, China
Astrochemistry 5has
been widely developed as a power tool to probe the physical properties of the interstellar medium (ISM)
Key Laboratory of Radio Astronomy and Technology, Chinese Academy of Sciences, A20 Datun Road, Chaoyang District, Beijing 100101, P. R. China
6 Institut de Radioastronomie Millimetrique, 300 rue de la Piscine, Domaine Universitaire de Grenoble, F-38406 Saint-Martin d’Héres, France
in various conditionsof the Milky Way (MW) Galaxy, and in near and distant galaxies. Most current studies conventionally
7 Xinjiang Astronomical Observatory, Chinese Academy of Sciences, No. 150 Science 1-Street, Urumqi 830011, P. R. China
apply linear scaling
to all elemental
abundances based on the gas-phase metallicity. However, these elements, including carbon
8 I. Physikalisches
Institut, Universität zu Köln, Zülpicher Straße 77, D-50937 Köln, Germany
9 CAS Key Laboratory of FAST, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100101, China
and oxygen, are enriched differentially by stellar nucleosynthesis and the overall galactic chemical evolution, evident from
10 NAOC-UKZN Computational Astrophysics Centre, University of KwaZulu-Natal, Durban 4000, South Africa
α-enhancement in
multiple galactic observations such as starbursts, high-redshift star-forming galaxies, and low-metallicity
dwarfs. We perform astrochemical modelling to simulate the impact of an α-enhanced ISM gas cloud on the abundances of2023 December
5. Received
2023 December
5; in original
formcycle’.
2023 September
21
the three phasesAcceptedof carbon(C+ , C,CO) dubbed
as ‘thecarbonThe ISM
environmental parameters considered include−17−15 −1two cosmic-ray ionization rates (ζ CR = 10
and 10 s ), two isotropic FUV radiation field strengths (χ /χ 0 = 1 and 102 ),and (sub-)linearAdust-to-gas
B S T R A C T relations against metallicity, mimicking the ISM conditions of different galaxy types. In galaxies+
with [C/O] < 0,Astrochemistry
CO, C, and C,been
all decreasein bothasabundancesandemission,thoughwith ofdifferential
biases.
The(ISM)
low-J COhas
widely developed
a power tool toprobe
the physicalproperties
the interstellar
medium+in various
conditionsof the tracer
Milky Way(MW)
Galaxy, andnear anddistant
current studies conventionallyemission is foundto be themost stable
for themolecular
gas,inwhile
C and
C galaxies.
trace HMost
2 gas only under limited conditions,apply linear scaling to all elemental abundances based on the gas-phase metallicity. However, these elements, including carbon
in line with recent discoveries of [C I]-dark galaxies. We call for caution when using [C II] 158 µm and [C I](1–0) as alternativeand oxygen, are enriched differentially by stellar nucleosynthesis and the overall galactic chemical evolution, evident fromH2 -gas tracers forboth diffuseinanddense
gas with
non-zero[C/O]ratios.
α-enhancement
multiplegalactic
observations
such
as starb
ursts, high-redshift star-forming galaxies, and low-metallicity

the three phases of carbon (C , C, CO) dubbed as ‘the carbon cycle’. The ISM environmental parameters considered include
two cosmic-ray ionization rates (ζ CR = 10−17 and 10−15 s−1 ), two isotropic FUV radiation field strengths (χ /χ 0 = 1 and 102 ),and (sub-)linear dust-to-gas relations against metallicity, mimicking the ISM conditions of different galaxy types. In galaxies
with [C/O] < 0, CO, C, and C+ , all decrease in both abundances and emission, though with differential biases. The low-J CO
Seifried et al. 2020+; Hu, Sternberg & van Dishoeck 2021). These
1 I N T RO D U Cemission
T I O Nis found to be the most stable tracer for the molecular gas, while C and C trace H2 gas only under limited conditions,to understandthe[Cphysicalproperties
and theline emission of
in line with recent discoveries of [C I]-dark galaxies. We callhelp
for caution
when using
II] 158 µm
and [C I](1–0)
as alternative
To study the evolution
the multiphaseinterstellar
medium(ISM)
the ISM
both in Galactic local clouds and distant galaxies, especially
H2 -gasoftracers
for both diffuse
and densegas with
non-zero [C/O]
ratios.

[C/O] < 0

ISM

CO, C, C+CO[CII]158μm
and the star-formation process in galaxies through cosmic time, [C/O]
nowadays0since the JWST in combination with
the Atacama Large CI
Key words: radiative transfer – methods: numerical – ISM: abundances – photodissociation region (PDR) – galaxies: ISM.
it is required to understand the astrochemistry that occurs under
Millimeter/sub-millimeter Array (ALMA) offer an unprecedented
the different environmental conditions. These conditions act as an
view of our Universe.
energy source that powers the ISM, which in turn compensates with
Metallicity is one of the most important environmental parameters
2020; Hu,
Sternberg &role
van inDishoeck2021).its
These
a number of cooling
functions,leading
toits
thermalbalance.
VariousoftheSeifried
ISM, etasal.
it plays
a significant
controllingchemistry
1 I N T RO D U C T I O N
helptounderstandthephysicalproperties
and
the
line
emissioncomputational works model these processes, either in static but(see Maiolino & Mannucci 2019, for a review). Metals areofthe key
To study the evolution of the multiphase interstellar medium (ISM)
the ISM both in Galactic local clouds and4distant galaxies, especiallychemically evolved(e.g. Le Petitprocess
et al. 2006
; Röllig
et al. 2007
; time,coolants
in thecold(Tcombination
ISM, Largesuch as thekin < 10 K)
andclouds
the star-formationin galaxies
throughcosmicnowadayssince
the phase
JWST inwithofthethe
AtacamaölligBisbas et al. 2012it; isFerland
et
al.
2017
;
R
&
Ossenkopf-Okada
[C
II
]
158
µm
and
[O
I
]
63
µm
fine-structurelines,
molecularrequired to understand the astrochemistry that occurs under
Millimeter/sub-millimeter Array (ALMA) offer an unprecedented lines

wnloaded from https://academic.oup.com/mnras/article/527/3/8886/7464047 by guest on 29 February 2024

Advance Access publication 2023 December 8

7 Xinjiang Astronomical Observatory, Chinese Academy of Sciences, No. 150 Science 1-Street, Urumqi 830011, P. R. China

H2

München, Scheinerstr. 1, 81679 Munich, Germany;
Exzellenzcluster ORIGINS, Boltzmannstr. 2, D-85748 Garching, Germany;
email: til.birnstiel@lmu.de

Dust growth and evolution in
protoplanetary disks

Keywords

4 by the author(s).

planet formation, protoplanetary disks, circumstellar
matter,Birnstiel
dust,
TilmanSolar System, accretion disks
University Observatory, Faculty of Physics, Ludwig-Maximilians-Universität

arXiv:2312.13287v1 [astro-ph.EP] 20 Dec 2023

n. Astrophys. 2024. (62Abstract

München, Scheinerstr. 1, 81679 Munich, Germany;
Exzellenzcluster ORIGINS, Boltzmannstr. 2, D-85748 Garching, Germany;
email: til.birnstiel@lmu.de

Over the past decade, advancement of observational capabilities, specifically the Atacama Large Millimeter/submillimeter Array (ALMA) and
SPHERE instrument, alongside theoretical innovations like pebble acKeywords
Annu.
Rev. Astron.
Astrophys. 2024. (62cretion, have
reshaped
our understandingof planet
formation and the/ page):1–48
planetformation,
protoplanetary disks, circumstellar matter, dust,
physics of protoplanetarydisks.
Despitethisprogress,
mysteries
persistCopyright © 2024 by the author(s).
Solar
System,accretionAllrightsreserved
along the winded path of micrometer-sized dust, from the interstellar disks
medium, through transport and growth in the protoplanetary disk, to
Abstract
becoming gravitationally bound bodies. This review outlines our current knowledge of dust evolution in circumstellarOver
disks,
yielding
theadvancement of observational capabilities, specifthe past
decade,following insights:
ically the Atacama Large Millimeter/submillimeter Array (ALMA) and
SPHERE
instrument,• Theoretical and laboratory studies have accurately
predicted
thealongside theoretical innovations like pebble accretion,
have
reshaped
growth of dust particles to sizes that are susceptible to accumu- our understanding of planet formation and thephysics
protoplanetarydisks. Despite this progress, mysteries persist
lation through transport processes like radial
drift ofandsettling.
along the winded path of micrometer-sized dust, from the interstellar• Critical uncertainties in that process remain the level of turmedium, through transport and growth in the protoplanetary disk, tobulence, the threshold collision velocities at which dust growth
becoming gravitationally bound bodies. This review outlines our curstalls, and the evolution of dust porosity. rent knowledge of dust evolution in circumstellar disks, yielding the• Symmetric and asymmetric substructure arewidespread.
following
insights:Dust
traps appear to be solving several long-standing• issues
in planet
Theoreticaland laboratory studies have accurately predicted theformation models, and they are observationally consistent
withparticles to sizes that are susceptible to accumugrowth of dust
being sites of active planetesimal formation.
lation through transport processes like radial drift and settling.
• In some instances, planets have been identified •asCriticalthe causes
beuncertainties
in that process remain the level of turbulence,thethresholdcollision velocities at which dust growthhind substructures. This underlines the need to study earlier
stalls,andtheevolutionof dust porosity.
stages of disks to understand how planets can form so rapidly.
• Symmetric and asymmetric substructure are widespread. Dust

In the future, better probes of the physical conditions in optically thicktraps appear to be solving several long-standing issues in planet
regions, including densities, turbulence strength, kinematics, and parformation models, and they are observationally consistent withticle properties will be essential for unraveling the physicalprocesses
atbeing
sites of active
planetesimal formation.
play.
• In some instances, planets have been identified as the causes be-hind substructures. This underlines the need to study earlier
stages of disks to understand how planets can form so rapidly.

2a Results: Galaxy to cloud scales
Clare Dobbs 1,⇤

2a Results: Galaxy to cloud scales

4QL, UK

Clare Dobbs 1,⇤

Correspondence*:
Corresponding Author
c.l.dobbs@exeter.ac.uk

1 School of Physics and Astronomy, University of Exeter, Stocker Road, Exeter, EX4

4QL, UK
Correspondence*:
Corresponding Author
c.l.dobbs@exeter.ac.uk

ABSTRACT

Simulations from the scales of isolated galaxies to clouds have been instrumental in informing
ABSTRACTus about molecular cloud formation and evolution.
Simulations are able to investigate the rolesof gravity, feedback, turbulence, heating and cooling, and magnetic fields on the physics of the
Simulations from the scales of isolated galaxies to clouds have been instrumental in informinginterstellar medium, and star formation. Compared to simulations of individual clouds, galactic
us about molecular cloud formation and evolution. Simulations are able to investigate the roles
and sub-galactic scale simulations can include larger galactic scale processes such as spiralof gravity, feedback, turbulence, heating and cooling, and magnetic fields on the physics of thearms, bars, and larger supernovae bubbles, which may influence star formation. Simulations
interstellar medium, and star formation. Compared to simulations of individual clouds, galactic
show cloud properties and lifetimes in broad agreement with observations. Gravity and spiraland sub-galactic scale simulations can include larger galactic scale processes such as spiralarms are required to produce more massive GMCs, whilst stellar feedback, likely photoionisation,
arms, bars, and larger supernovae bubbles, which may influence star formation. Simulations
leads to relatively short cloud lifetimes. On larger scales, supernovae may be more dominantshow cloud properties and lifetimes in broad agreement with observations. Gravity and spiralin driving the structure and dynamics, but photoionisation may still have a role. In terms ofarms are required to produce more massive GMCs, whilst stellar feedback, likely photoionisation,
the dynamics, feedback is probably the main driver of velocity dispersions, but large scaleleads to relatively short cloud lifetimes. On larger scales, supernovae may be more dominant
processes such as gravity and spiral arms may also be significant. Magnetic fields are generally
in driving the structure and dynamics, but photoionisation may still have a role. In terms offound to decrease star formation on galaxy or cloud scales, and simulations are ongoing to study
the dynamics, feedback is probably the main driver of velocity dispersions, but large scale
whether clouds are sub or supercritical on different scales in galaxy scale simulations. Simulations
processes such as gravity and spiral arms may also be significant. Magnetic fields are generally
on subgalactic scales, or zoom in simulations, allow better resolution of feedback processes,
found to decrease star formation on galaxy or cloud scales, and simulations are ongoing to study
filamentary structure within clouds, and the study of stellar clusters.
whether clouds are sub or supercritical on different scales in galaxy scale simulations. Simulations
on subgalactic scales, or zoom in simulations, allow better resolution of feedback processes,
Keywords: keyword, keyword, keyword, keyword, keyword, keyword, keyword, keyword
filamentary structure within clouds, and the study of stellar clusters.

1 INTRODUCTION:2312.01854v1 [astro-ph.GA] 4 Dec 2023

rXiv:2312.01854v1 [astro-ph.GA] 4 Dec 2023

1 School of Physics and Astronomy, University of Exeter, Stocker Road, Exeter, EX4

Keywords: keyword, keyword, keyword, keyword, keyword, keyword, keyword, keyword

Simulations on the scales of isolated galaxies and on kiloparsec scales have allowed us to resolve the
1 INTRODUCTION
multiphase interstellar medium (ISM), molecular clouds,
and larger scale feedback processes such as
supernovae whilst also including larger scale galactic structure such as spiral arms, bars or galaxy centres.
Simulations on the scales of isolated galaxies and on kiloparsec scales have allowed us to resolve thePreprint typeset using L TEX style openjournal v. 09/06/15

DOES GOD PLAY DICE WITH STAR CLUSTERS?
Y. Grudić1,† , Stella
R. Offner2 , Dávid Guszejnov3,†
DOES GOD Michael
PLAY DICEWITHSTAR S.CLUSTERS?
5, Claude-André Faucher-Giguère4, andPhilip F. Hopkins

Michael Y. Grudić1,†, Stella S. R. Offner2

1

3,†
Carnegie
Observatories, 813 Santa Barbara St, Pasadena, CA
USA, Dávid Guszejnové Faucher-Giguère4 91101,, and
2 Department,ofClaude-Andr
Astronomy, The University of Texas at Austin, TX 78712, USA
5
3
Philip F. Hopkins
Center for Astrophysics | Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138, USA

4 CIERA and Department of Physics and Astronomy, Northwestern University, 1800 Sherman Ave, Evanston, IL 60201, USA and
1 Carnegie Observatories,
813 Santa Barbara
St, Pasadena, CA 91101, USA
5 TAPIR, Mailcode 350-17, California Institute of Technology, Pasadena, CA 91125, USA
2 Department of Astronomy, The Universityof Texas at Austin, TX 78712, USA

arXiv:2307.00052v3 [astro-ph.GA] 7 Dec 2023

3 Center for Astrophysics | Harvard & Smithsonian, 60 Garden Street, Cambridge,
VersionMA
December
2023
02138,11,USA

4 CIERA and Department of Physics and Astronomy, Northwestern University, 1800 Sherman Ave, Evanston, IL 60201, USA andABSTRACT
5 TAPIR, Mailcode 350-17, California Institute of Technology, Pasadena, CA 91125,
USA

When
a detailed
VersionDecember
11, model
2023 of a stellar population is unavailable, it is most common to assume that stellar
masses are independently and identically distributed according to some distribution: the universal
initial mass function (IMF). However, stellar masses resulting from causal, long-ranged physics cannot
beABSTRACT
truly random and independent, and the IMF may vary with environment. To compare stochastic
samplingwith a physicalrun a suitetoofassume
100 STARFORGE
radiation magnetohydrodynamics
When a detailed model of a stellar populationis unavailable,
it model,is mostwecommon
that stellar
simulationsof
low-massstarclusterformationin
2000M
cloudsthat form ⇠ 200 stars each on
masses are independently and identically distributed according to some distribution: the universal
average. The stacked IMF from the simulated clouds has a sharp truncation at ⇠ 28M , well below
initial mass function (IMF). However, stellar
resulting maximum
from causal,
long-ranged
cannotthemasses
typically-assumed
stellarmass Mup ⇠physics
100 150M
and the total cluster mass. The
be truly random and independent, and thesequence
IMF mayvary
with environment.
To compareof starformation
is not totally random:
massivestochasticstars tend to start accreting sooner andfinish oflater
the average star.
However,
final cluster properties such as maximum stellar mass
sampling with a physical model, we run a suite
100than
STARFORGE
radiation
magnetohydrodynamics
and totala similar
scatteronto random sampling. Therefore
simulations of low-mass star cluster formation
inluminosity
2000M havecloudsthatamountform of⇠cloud-to-cloud
200 stars eachstochastic sampling does not generally model the stellar demographics of a star cluster as it is forming,
average. The stacked IMF from the simulated
clouds has a sharp truncation at ⇠ 28M , well below
but may describe the end result fairly well, if the correct IMF – and its environment-dependent upper
the typically-assumed maximum stellar massM
100 150M and the total cluster mass. The
cuto↵ –upare⇠known.
sequence of star formation is not totally random:
massivestars
to start
accretingsoonergeneraland – stars: formation
Subject headings:
stars:
masstend
function– galaxies:
star clusters:

⾒

(IMF)

100

finish later than the average star. However, final cluster properties such as maximum stellar massand total luminosity have a similar amount of cloud-to-cloud
scatter to random sampling.
Therefore
28 in
1. INTRODUCTION
one starcan a↵ect another via gravity and feedback
stochastic sampling does not generally model the stellar demographics of a star cluster as
itformis forming,
theofprotostellar
outflows,
winds,
radiation,
superAstrophysicists aim to interpret light from galaxies andnovae,
andcosmicrays.
Sostochastic
sampling
cannotbut may describe the end result fairly
well,
if
the
correct
IMF
–
and
its
environment-dependent
upper
star clusters in terms of their stellar populations and thebe the ground-truth star formation process, and if starcuto↵ – are known.
physical processes that a↵ect them. More often than not,clusters deviate from it significantly then so will any redetailed
knowledgestarof theindividualgeneralstars is notavailable,
Subject headings: stars: mass function– galaxies:
clusters:– stars:formationsulting inferences from the integrated light of galaxies
so inferences about the system rely on a model of their(Weidner & Kroupa 2006; Kroupa et al. 2013; Kroupa &stellar demographics. The cornerstone of such models is
Jerabkova 2021).
the stellar initial massone
function
the distribution
1. INTRODUCTION
star(IMF):
can a↵ectanotherofvia gravity
and allfeedback
Of course,
models inare wrong at some level, but
stellar birth masses (Salpeter 1955; Hopkins 2018). The
the
form
of
protostellar
outflows,
winds,
radiation,
super- sampling from an invarisomeareuseful.
Stochastic
to modeling a galaxy or star clusAstrophysicists aim to interpret light from standard
galaxies approachand
ant IMFsampling
has enjoyedwide application due to its simnovae,
So stochastic
cannotter is andto sample
massesandfromcosmic
the IMFrays.
and evolvetar clusters in terms of their stellar populations
the stellar
plicityand theandlack ifof staran alternative model with comthe
stars
forwardintime
accordingtoastellarevolubetheground-truth
star
formation
process,
hysical processes that a↵ect them. More often
than
not,
pelling
physicalmotivation.
It has been used to chartion model (e.g. Leitherer
et al. deviate
1999; Bruzual
clusters
from&itCharlot
significantly
thenstarso clusters
will anyreacterize
and
their
demographics from phoetailed knowledge of the individual stars is notavailable,
2003).
sulting inferences from the integratedof galaxies
tometrylight(Fumagalli
et al. 2011; da Silva et al. 2012),
o inferences about the system rely on a modelof their
A commonmodel assumption is that stellar masses are
gives aKroupa
marginally-better
fit to the data than
(Weidner& Kroupa
Kroupawhere
et al.it 2013;&
sampledindependently
and identicallyfrom an2006;
invarianttellar demographics. The cornerstone of suchmodelsis
IMF-averaged
photometricmodelswithout
stochasticity
Jerabkova
2021).
IMF (“stochastic
he stellar initial mass function (IMF): the distributionof sampling”), i.e., the probability of a
(Krumholz
et al.level,2015) butand can enable inferences aboutstar forming with mass m
does
notdepend
on
the
mass
Of
course,allmodels
are
wrong
at
some
1
tellar birth masses (Salpeter 1955; Hopkinsof2018).
Thethe highly-incomplete low-mass cluster population, if acanother star m2 , some
nor theare
macroscopic
of sampling
useful. properties
Stochastic
frometaninvari-Stochastic sampling has also
curate (Tangal. 2023).
tandard approach to modeling a galaxy or
starclusthe system the star is forming in. Or, in other words,

IMF

STARFORGE

IMF

European Southern Observatory (ESO), Karl-Schwarzschild-Straße 2, D-85748 Garching, Germany© 2023. The Author(s). Published by the American Astronomical Society.

3
University of Connecticut, Department of Physics, 196A Auditorium Road, Unit 3046, Storrs, CT 06269, USA
4
Astrophysics Research Institute, Liverpool John Moores University, 146 Brownlow Hill, Liverpool L3 5RF, UK
5
JWST Reveals
Widespread CO Ice and Gas Absorption in the Galactic Center Cloud

Max-Planck-Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg, Germany
Shanghai Astronomical Observatory, Chinese Academy ofG0.253+0.016
Sciences, 80 Nandan Road, Shanghai 200030, Peopleʼs Republic of China
7
DepartmentAdamof Physics
andAstronomy,
Universityof Kansas, 1251 Wescoe Hall Dr., Lawrence, KS 66045, USA
1
2
Ginsburg , Ashley T. Barnes , Cara D. Battersby3 , Alyssa Bulatek1 , Savannah Gramze1 ,
8
4,5
1
8
UK ALMA RegionalJonathanCentre D.
Node,Jodrell Bank
CentreofDaniel
Manchester,Manchester
M13 9PL, UK
Henshaw, Desmond
Jefffor , Astrophysics,
Xing Lu6 , E. The
A. C.University
Mills7 , andL. Walker
1
Department2023
of Astronomy,
University
Florida, P.O. Box
112055,Gainesville,14;
FL, USA
Received 2023 August 22; revised
September
14;of accepted2023
Septemberpublished 2023 December 4

6

European Southern Observatory (ESO), Karl-Schwarzschild-Straße 2, D-85748 Garching, Germany

3
University of Connecticut, Department of Physics, 196A Auditorium Road, Unit 3046, Storrs, CT 06269, USA
4
Astrophysics Research Institute, Liverpool John Moores University, 146 Brownlow Hill, Liverpool L3 5RF, UK
5

Abstract

Max-Planck-Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg, Germany
Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030, Peopleʼs Republic of China
7
Department of Physics and Astronomy, University of Kansas, 1251 Wescoe Hall Dr., Lawrence, KS 66045, USA
8
UK ALMA Regional Centre Node, Jodrell Bank Centre for Astrophysics, The University of Manchester, Manchester M13 9PL, UK
Received 2023 August 2; revised 2023 September 14; accepted 2023 September 14; published 2023 December 4

6

We report JWST NIRCam observations of G0.253+0.016, the molecular cloud in the Central Molecular Zone
known as “The Brick,” with the F182M, F187N, F212N, F410M, F405N, and F466N ﬁlters. We catalog 56,146
stars detected in all six ﬁlters using the crowdsource
package. Stars within and behind The Brick exhibit
Abstract
prodigious absorption
in the F466N ﬁlter that is produced by a combination of CO ice and gas. In support of thisWe report JWST NIRCam observations of G0.253+0.016, the molecular cloud in the Central Molecular Zone
in theF466N, F470N, andconclusion, and asknowna generalpresent
modelsCO gasandandﬁlters.
CO2Weice
as “Theresource,
Brick,” with wethe F182M,
F187N,
F212N,ofF410M,
F405N,
andiceF466N
catalog
56,146stars
detectedinallsix
ﬁltersusing
thecrowdsource
package.
Stars
withinandbehindThe
Brickexhibit
F410M ﬁlters. BothCO gas and ice contribute to the observed stellar colors. We show, however, that CO gas does
prodigious absorption in the F466N ﬁlter that is produced by a combination of CO ice and gas. In support of thisnot absorb the Pfβconclusion,and Huò
in F466N,
but
thatmodels
theseof CO
lines
show
excessindicatingthat CO ice isin the F466N, F470N,
andandlines
as a general
resource, we
present
gas and
ice and
CO2 iceabsorption,
F410M
ﬁlters.
Both
CO
gas
and
ice
contributetotheobserved
stellarcolors.
We
show,however,
that
CO
gas
does
present and contributes
to observed F466N absorption. The most strongly absorbed stars in F466N are extincted by
not absorb the Pfβ and Huò lines in F466N, but that these lines show excess absorption, indicating that CO ice is∼2 mag, corresponding
tocontributes>80% toﬂux
loss.F466N
Thisabsorption.
high observed
absorption
requireshigh bycolumn densities ofpresent andobserved
The most strongly
absorbed stars
in F466Nvery
are extincted∼2
mag,
corresponding
to
>80%
ﬂux
loss.
This
high
observed
absorption
requiresvery
highcolumndensities
ofCO, and thus a total
CO column that is in tension with standard CO abundance and/or gas-to-dust
ratios. ThisCO, and thus a total CO column that is in tension with standard CO abundance and/or gas-to-dust ratios. Thisand2dust-to-gas
ratio
are
in Galactic
the Galactic
Centerthan disk.
in theresult suggests the result
CO/Hratio and dust-to-gas
ratio
are greater
greater in theCenter thanin the Galactic
Ice Galactic disk. Ice
suggests
the CO/H
2 ratioand/orgas
absorption
isobserved
even
in
the
cloud
outskirts,
implying
that
additional
cautionisneededwhen
and/or gas absorption is observed even in the cloud outskirts, implying that additional caution is needed wheninterpreting stellar photometry in ﬁlters that overlap with ice bands throughout galactic centers.
interpreting stellarUniﬁed
photometry
in ﬁlters that overlap with ice bands throughout galactic centers.
Astronomy Thesaurus concepts: Infrared dark clouds (787); Ice composition (2272)
Uniﬁed Astronomy Thesaurus concepts: Infrared dark clouds (787); Ice composition (2272)

JWST NIRCam
F466N

1. Introduction

G0.253+0.016, also known as “The Brick,” is among theCObest-studied infrared dark clouds in the Galaxy (Lis et al. 1991;

1. Introduction

Lis & Carlstrom 1994; Lis et al. 1994, 2001; Lis &Menten1998; asLongmoreal. 2012; isClark
et al. the2013;
G0.253+0.016, also
known
“The etBrick,”among
Kauffmann et al. 2013; Rodríguez & Zapata 2013; Rathborne
best-studied infrared darkcloudsin the(Lis
et Johnston
al. 1991;
et al. 2014a,
2014b,
2015;Galaxy
Bally et al.
2014;
et al.
2014; Pillai
2016; Marsh
Lis & Carlstrom 1994;
Liset al.et2015;
al.Federrath
1994,et al.
2001;
Lis et&al.
2016; Walker et al. 2016; Henshaw et al. 2019, 2022; Petkova
Menten 1998; Longmore
et It al.
2012;
et al. 2023).
is well
known Clark
for being etdenseal.
and 2013;
turbulent(Clarketal.
2013;
Rathborne
et
al.
2015;
Federrathetal. 2016;
Kauffmann et al. 2013; Rodríguez & Zapata 2013; Rathborne
Mills et al. 2018; Henshaw et al. 2019, 2020) while exhibiting
et al. 2014a, 2014b, few
2015;
et al.much
2014;
Johnstonet suchal. asigns ofBally
star formation,less thanis typical for
massiveFederrath
cloud (Longmore
al. 2012;
Rodríguez
2014; Pillai et al. 2015;
et al. et2016;
Marshet al.&

6

56,146CO

Gas in the Galactic Center is notably different from gas seenelsewhere in our Galaxy. It is richer in complex molecules(Jones et al. 2012) and warmer (Ao et al. 2013; Ginsburg et al.
in ettheGalactic
Centernotably thedifferent from gas seen
2016;Gas
Kriegeral. 2017).
Despitehigh gasistemperatures,
dust
in
the
Central
Molecular
Zone
(CMZ)
is
not
terriblywarm
elsewhere in our Galaxy. It is richer in complex molecules(Tang et al. 2021), so ice can accumulate on dust grains. Ice has(Joneset al.
2012) andwarmeral. 2013; Ginsburg et al.
longbeen seenin mid-infrared
spectraof sources(Aoin the et
Galactic
Center
(Lutz
et
al.
1996;
Chiar
et
al.
2000;
Monetietal.
2001),
2016; Krieger et al. 2017). Despite high gas temperatures, theas has CO gas. Toward Sgr A*, ice comprises a minority
dust inCentralZoneby(CMZ)(<10%)of thethe CO,
which Molecular
is dominated insteadgas, as is not terribly warm
expectedthe2021),high gas temperatures
extreme velocity(Tanggiven
et al.
so ice canandaccumulate
on dust grains. Ice has
dispersion of gas in the inner parsec (Moneti et al. 2001;
long been
seenBeyondin mid-infrared
spectraoficesources in the Galactic
Moultaka
et al. 2009).
the inner parsec,
though, theproperties
the Galactic
Centerare little
explored.
of Moneti et al. 2001),
Centerof(Lutzet al.
1996;
Chiar
et Aal.handful
2000;*
Infrared Space Observatory spectra were taken towardvarious

CO/H2

/

CO2
CO

2, Ireland
Ural Federal University, 19 Mira Str., 620002 Ekaterinburg, Russia

The influence of accretion bursts on methanol and water inmassive young stellar objects

December 13, 2023

3, 4 , M. Güdel1, 5 , A. Caratti o Garatti6, 7 , A. M. Sobolev8
R. Guadarrama1 , E. I. Vorobyov1, 2 , Ch. Rab
ABSTRACT1of Astrophysics, University of Vienna, Türkenschanzstrasse 17, A-1180 Vienna, Austria
Context. The e↵ect ofDepartment
accretion
bursts on massive young stellar objects (MYSOs) represents a new research field in the study ofe-mail: rodrigo.guadarrama@univie.ac.atyoung stars and their2 environment.
impactsuchUniversity,
bursts Rostov-on-Don,on the disc344090
and envelope
has been observed and plays the role of a
Research Institute ofThe
Physics,
SouthernofFederal
Russia3
Max-Planck-Institut
fürabout
extraterrestrische
Physik, Giessenbachstrasse
1,85748 Garching, Germany"smoking gun" providing
information
theproperties
of
the
burst
itself.
4
University Observatory, Faculty of Physics, Ludwig-Maximilians-Universität München, Scheinerstr. 1, 81679 Munich, Germany
5
Aims. We aim to investigate
the impact
an accretionburst
on massivewith di↵erent types of envelopes and to study the e↵ects
Max-Planck-Institut
für ofAstronomie,
Königstuhl
17, 691176
Heidelberg,disks
Germany
6
NAF-Osservatorio
Astronomico
diCapodimonte,
via
Moiariello16,
I-80131
Napoli,
Italyfocus on water and methanol as chemical speciesof an accretion burst on
the temperature structure and the chemistry of the disk. We
7Dublin Institute for Advanced Studies, School of Cosmic Physics, Astronomy & Astrophysics Section, 31 Fitzwilliam Place, Dublin
for this paper.
2, Ireland
8
Ural Federal code
University,
MiraDStr.,
Ekaterinburg, Russia DIsk MOdel) is used to perform simulation of high mass protoMethods. The thermochemical
of 19
PRO
IM620002
O (PROtoplanetary13, 2023
planetary disk modelsDecember
with di↵erent
types of envelopes under the presence of an accretion burst. The models in question represent
di↵erent evolutionary stages of protostellar objects. We calculate and show the chemical abundances in three phases of the simulation
ABSTRACT(pre-burst, burst, and post-burst).
Results. More heavily
embeddedshow
highertemperatures.
The (MYSOs)
impactrepresentsof the accretion
Context.
The e↵ectdisksof accretion
burstson massive
young stellar objects
a new researchburst
field inisthemainly
study of characterized by theyoungstars and
their environment.
The impact
of such bursts
on thethediscdust
and envelope
hasbeen
observed
and plays
the roleadesorption of chemical
speciespresent
in
the
disk
and
envelopefromgrainstothegasphase.
When
theofpost-burst
phase starts,"smoking gun" providing information about the properties of the burst itself.
the sublimated species
freezeout
again. The
degreeof sublimation
depends
strongly
on ofthetype andof toenvelopethe disk is embedded in.
Aims.
We aimto investigate
the impactof an accretion
burst on massive
disks withdi↵erent types
envelopes
study the e↵ectsofanaccretion
burst
on
the
temperature
structureandthechemistry
of
the
disk.
We
focus
on
water
and
methanolaschemicalspecies
An accretion burst in more massive envelopes produces stronger desorption of the chemical species. However, our models show thatfor this paper.
the timescale for the chemistry
to reach thecodepre-burst
state
is independentof thetypeof envelope.
Methods. The thermochemicalof PRODIM
O (PROtoplanetary
DIsk MOdel)
is usedto perform
simulation of high mass protoplanetarydisk
modelswithdi↵erent
types
ofenvelopes
underthepresenceofanaccretion
burst.
models in question
represent
Conclusions. The study shows that the disk’s temperature increases with a more massiveTheenvelope
enclosingit. Thus, the chemistrydi↵erent evolutionary stages of protostellar objects. We calculate and show the chemical abundances in three phases of the simulationof MYSOs in earlier stagesoftheirevolution
reactsstrongertoanaccretion
burst
than
at
later
stageswheretheenvelope has lost most(pre-burst, burst, and post-burst).
Results.
More heavily
embeddedtemperatures.
The impactof the could
accretionalso
burst isprovide
mainly characterized
theof its mass or has beendissipated.
The
studydisksof show
the higher
impactof accretion
burstshelpful by
theoreticalcontext to thedesorption of chemical species present in the disk and envelope from the dust grains to the gas phase. When the post-burst phase starts,
observation of methanol
masersspecies
in massive
the sublimatedfreeze outdisks.
again. The degree of sublimation depends strongly on the type of envelope the disk is embedded in.

iv:2312.07184v1 [astro-ph.SR] 12 Dec 2023

rXiv:2312.07184v1 [astro-ph.SR] 12 Dec 2

8

An accretion burst in more massive envelopes produces stronger desorption of the chemical species. However, our models show thatthe timescale for the chemistry
to reachthe pre-burst state isdisks-methods:
independent of the typeof envelope.
Key words. stars:protostars-stars:
high mass
protoplanetary
numerical

PRODIMO

1. Introduction

Conclusions. The study shows that the disk’s temperature increases with a more massive envelope enclosing it. Thus, the chemistryof MYSOs in earlier stages of their evolution reacts stronger to an accretion burst than at later stages where the envelope has lost mostof its mass or has been dissipated. The study of the impact of accretion bursts could also provide helpful theoretical context to theobservation of methanol masers in massive disks.

Cieza et al. (2016). Another example is the work of Tobin et al.
(2023). Here they report the direct detection of gas-phase waterfrom the disk of V883 Ori and measure the water snowline raCieza et al. (2016). Another example is the work of Tobin et al.
dius at
the
Other
works
that have(2023).
Here
theymidplane.
report the direct
detectionof gas-phasewater studied the e↵ect of
from
the
disk
of
V883
Ori
and
measurethewatersnowline
raaccretion bursts on the chemistry of low-mass
objects are Taquet
dius at the midplane. Other works that have studied the e↵ect ofet al. (2016)
andMolyarovaal. (2018).
accretion
bursts on thechemistryof low-massetobjects
are Taquet In the first one, theKey words. stars:protostars-stars: high mass protoplanetary disks-methods: numerical

Accretion is a fundamental
process in star formation and disk
1. Introduction
evolution. It provides the growing protostar with mass and anguAccretion
fundamental
process instar formationand disk
lar momentum. On theotheris ahand,accretion
feeds
the gravitaevolution. It provides the growing protostar with mass and angutional energy of accreted
matterOnback
tohand,theaccretion
disk andlar momentum.
the otherfeeds circumthe gravita-