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Spectroastrometric Study of Ro-vibrational CO Emission from the Herbig Ae star HD 179218 with
iSHELL on the NASA Infrared Telescope Facility
Sean D. Brittain,1 John S. Carr,2 and Joan R. Najita30v1 [astro-ph.SR] 7 May 2018

1

Department of Physics & Astronomy, 118 Kinard Laboratory, Clemson University, Clemson, SC 29634-0978, USA
2
Naval Research Laboratory, Code 7211, Washington, DC 20375, USA
3
National Optical Astronomy Observatory, 950 N. Cherry Ave., Tucson, AZ 85719, USA

ABSTRACT
We present analysis of commissioning M band data acquired with the infrared echelle
spectrograph (iSHELL) on NASA’s Infrared Telescope Facility. In this paper we describe the delivered performance of the instrument for these M band observations andthe data reduction process. The feasibility of using iSHELL for spectro-astrometry
is tested on the Herbig Ae/Be star HD 179218 and we show that sub-milliarcsecond
fidelity is achievable.
1. INTRODUCTION
used to study phenomena such as binaries (Baiet al. 2004; Porter et al. 2004),
High-resolution
observations of H leyD1998; Baines
S spectroscopic
1
A M
D
outflows(Whelan&
Garcia2008; Davies et al.
CO in /2disks
1 around/ / young stars have
E been8 usedBLN
792010), and disks (e.g. Acke & van den Ancker
to elucidate the evolutionary status of warm gas
2006; Brittain et al. 2009; Pontoppidan et al.
in disks around young stars (Najita et al. 2000,
2011). While the spatial resolution of a PSF is
2003, 2007; Carr et al. 2001; Carr 2007; Britlimited to ⇠1.2D/ , the relative centroid of theMin-Kai Lin†

Dusty disc-planet interaction with dust-free simulations

strophysics, Academia Sinica, Taipei 10617, Taiwan

Jhih-Wei Chen? , Min-Kai Lin†
Institute of Astronomy and Astrophysics, Academia Sinica, Taipei 10617, Taiwan

ABSTRACT

arXiv:1805.00940v1 [astro-ph.EP] 2 May 2018

4 May 2018

ABSTRACT

Protoplanets may be born into dust-rich environments if planetesimals formed through,Protoplanets may be born into dust-rich environments
iforplanetesimals
formedstreaming
gravitational instabilities,
or if thethroughprotoplanetary disc is undergoing massloss due to disc windsdiscor photoevaporation.
Motivatedby this possibility, we explore
streaming or gravitational instabilities, or if the protoplanetaryis undergoing
mass
1 0
1
the interaction between low mass planets and dusty protoplanetary discs with focus
on disc-planet
We implement Linwe& Youdin’s
newly developed, purely hydroloss due to disc winds or photoevaporation. Motivatedbytorques.
this possibility,
exploreddynamic model of dusty gas into the Pluto code to simulate dusty protoplanetary
the interaction between low mass planets and dusty
protoplanetary
discs
with
focus
discs with an embedded planet. We find that for imperfectly coupled=dust and highmetallicity,e.g. Stokes
number 10 3purely
and dust-to-gas
ratio ⌃d /⌃g = 0.5, a ‘bubble’
on disc-planet torques. We implement Lin & Youdin’s
newly
developed,hydrodevelops inside the planet’s co-orbital region, which introduces unsteadiness
0in the0.
dynamic model of dusty gas into the Pluto code
dusty
protoplanetaryflow. toThe simulate
resulting disc-planet
torquessustain large amplitude oscillations that perwell beyond that in simulations with perfectly coupled dust or low dust-loading,/,
discs with an embedded planet. We find that forsists
imperfectly
coupled dust and highwhere co-rotation torques are always damped. We show that the desaturation of the
co-rotation
torques⌃
byd finite-sized
related to potential vorticity
metallicity, e.g. Stokes number 10 3 and dust-to-gas
ratio/⌃g = particles
0.5, ais ‘bubble’
1generation,tg5from the misalignment of dust and gas densities. We briefly discuss possible implicadevelops inside the planet’s co-orbital region, which
unsteadinessin thediscs. We also demonstratetions for introduces
the orbital evolutionof protoplanets in dust-rich
1
Lin & amplitude
Youdin’s dust-freeoscillations
framework reproduces
previous
results pertaining to dusty
flow. The resulting disc-planet torques sustain largethat
perprotoplanetary discs, including dust-trapping by pressure bumps, dust settling,
0 andsists well beyond that in simulations with perfectly
coupleddust or low dust-loading,the streaming
instability.
5
where co-rotation torques are always damped. We
theaccretion
desaturationof themethods: numerical, proto- S
Keyshowwords: that
accretion,
discs, hydrodynamics,
planetary discs
1
co-rotation torques by finite-sized particles is related
to potential vorticity generationfrom the misalignment of dust and gas densities. We briefly discuss possible implica5 3
5tions for the orbital evolution 1of INTRODUCTION
protoplanets in dust-rich discs. We andalso
demonstrate
non-isothermal discs (e.g. Paardekooper & Mellema
2006, 2008; Baruteau& Masset 2008a; Paardekooper et al.
Lin & Youdin’s dust-free framework
reproduces previous results pertaining
to dusty
The gravitational interaction between protoplanets and2010; Masset & Casoli 2010; Benı́tez-Llambay et al. 2015),
theirdust-trapping
protoplanetary disc, whichto the planet’sbumps,
orbitalprotoplanetary discs, including
byleadspressure
dust
andto name settling,a few. While thesestudies present important genevolution, likely plays a key role in shaping the architecture
eralizations,
they
have
been
limitedto purely gaseous discs.
the streaming instability.
of planetary systems (Baruteau et al. 2014, 2016). It is thus
necessary to understand how realistic disc conditions a↵ect
planet-disc interaction.
Since the pioneering study of Goldreich & Tremaine(1980) almost four decades ago, the disc-planet problem
has been extended to include many physical e↵ects expectedin protoplanetary discs. These include turbulence (e.g. Nel-

However, protoplanetary discs are dusty (Testi et al.
Key words: accretion, accretion discs, hydrodynamics, methods: 2014).
numerical,
protoIt is thus natural
to consider dusty disc-planet interaction(e.g.
Paardekooper& Mellema 2004; Fouchet et al.
planetary discs
2007; Zhu et al. 2012; Ayli↵e et al. 2012; Dipierro et al.
2016; Dipierro & Laibe 2017). Recent e↵orts in this direc-

Ø ocylyLkkp
Ø .34. 0G
4

rXiv:1805.01802v1 [astro-ph.GA] 4 May 2018INFALL SIGNATURES IN A PRESTELLAR CORE EMBEDDED IN THE HIGH-MASS 70 µM DARK IRDC
G331.372-00.116
Yanett Contreras,1 Patricio Sanhueza,2 James M. Jackson,3 Andrés E. Guzmán,2, 4 Steven Longmore,5Guido Garay,4 Qizhou Zhang,6 Quang Nguyπn-Lu’o’ng,7 Ken’ichi Tatematsu,2 Fumitaka Nakamura,2Takeshi Sakai,8 Satoshi Ohashi,9 Tie Liu,10, 11 Masao Saito,2 Laura Gomez,12 Jill Rathborne,13 andScott Whitaker14

g

6

n

m a
o Md
ri oc
a School of Mathematical
Tand Physicald Sciences,-(University
4 ofA Newcastle,
LUniversity
2(((, Socy
Drive, Callaghan NSW 2308, Australia

Contr

1 Leiden Observatory, Leiden University, PO Box 9513, NL-2300 RA Leiden, the Netherlands

2 National Astronomical Observatory of Japan, National Institutes of Natural Sciences, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan3

Departamento de Astronomía, Universidad de Chile, Camino el Observatorio 1515, Las Condes, Santiago, Chileu
Astrophysics Research Institute, Liverpool John Moores University, 146 Brownlow Hill, Liverpool L3 5RF, UK( .0.
75 4B Center for Astrophysics,)( 60 GardenCStreet, Cambridge,) >C MA 02138,AUSA+
Harvard-Smithsonian
4
5
6

.34 .
A DB B
2A

7 The Canadian Institute for Theoretical Astrophysics (CITA), University of Toronto, 60 St. George Street, Toronto, Ontario, M5S 3H8,

Contreras et al.
Canada8 The University of Electro-Communications, Chofu, Tokyo 182-8585, Japan
9 RIKEN, 2-1, Hirosawa, Wako-shi, Saitama 351-0198, Japan
10 Korea Astronomy and Space Science Institute, 776 Daedeokdaero, Yuseong-gu, Daejeon 34055, Republic of Korea
IRDC G331.372-00.116

511 East Asian Observatory, 660 N. A’ohoku Place, Hilo, HI 96720, USA
12 Joint ALMA Observatory, Alonso de Córdova 3107, Vitacura, Santiago, Chile
13 CSIRO Astronomy and Space Science, P.O. Box 76, Epping NSW 1710, Australia
14 Physics Department, Boston University, Boston, MA, USA.73.62.3
.34 .

IRDC

Table 3. Summary of physical parameter derived for ALMA1
Figure 3. Dust continuum emission at 1.1 mm toward
ALMA1. Overlaid in contours is shown the 40% to 90%
Submitted to ApJParameter
Valueof the dust continuum
emission.
The red contour shows thearea of the leaf
definedby
thedendrogram.
The dashed red
Flux (267 GHz) 26 mJy
ABSTRACTellipse shows the area representing the first and second moref f
0.041±0.004 pc
mentsof the structure
determined by the dendrogram. The
Using Galactic Plane surveys, we have selected a massive (1200 M ), cold (14 K) 3.6-70 µm dark IRDC
G331.372M
17.6±8.8 M
black ellipse shows
00.116. This IRDC has the potential to form high-mass stars and, given the absence of current starformation the 2-D Gaussian fit obtained with CASA.
The beam is M
shown
in the lower
left cornerof the image.
2.4±0.6M
virsignatures, it seems to represent the earliest stages of high-mass star formation. We have mapped the whole IRDC with↵
0.14±0.08
the Atacama Large Millimeter/submillimeter Array (ALMA) at 1.1 and 1.3 mm in dust continuum and line emission.vir
at thesystemic 5vcmn(H2 profile)(8.5±2.7)⇥10
lsr 3(-87.7 km.34. a self-absorbed
The dust continuum reveals 22 cores distributed across the IRDC. In this work, we analyze thephysical
1properties2s ) of the core,
which is determinedthe central ve⌃
0.65 gr cm by
Figure 1. Infrared emission
appearsasa darkfeatureup toconfirming+
most massive core,
ALMA1,
which
hasevenno molecular
outflows
detected in the CO (2-1), SiO (5-4),
andofHthe
1 A toward
DB DG331.372-00.116.
P of theG331.372-00.116
eM.34.
s70 µm,2 COlocitydeuterated
molecules(N
D
and DCO+ ).
2
M
1.19
the early stage of evolution of this clump. Left panel
the Spitzermassive
GLIMPSE(Blue:µm, green: (virial parameter ↵vir = MvirThe+(3-2): Threelines. color
This image
core isof relatively(M bands= 17.6M ),3.6subvirialized/M HCO= 0.14),spectra show a blue-red asymmetrywithṀ(1.96±0.10)⇥10 3 M yr 1
4.5 µm, and red: 8 µm). Middle panel : Spitzer
MIPSGALµm infraredemission. (transonic
Right panelMach: HerschelPACS
70 µmUsing the HCO+ (3-2) line, we theandis barely24
aﬀectedby turbulence
numberof 1.2).
findblue-shifted
the first peak brighter than4 the red-shifted peak.
t
3.3⇥10 yr
emission. In all the panels the 70% to 90% of the peak dust continuum emission from ATLASGAL is overlaid in white contours.
profile isf ftypically explained as a sign of infall, asdetection of infall signatures in a relatively massive, prestellar core (ALMA1) with the potential to formThis
a high-mass
Figure 2. Dust continuum emission at 1.1 mm (267 GHz) toward G331.372-00.116. Overlaid in contours is the ATLASGAL dust
continuum emission (60% to 90% of the peak emission). The ALMA beam is shown in the lower left corner of the images. The
cross shows the position of ALMA1 and the rest of the cores identified are marked by blue circles with their respective number.
This images shows that the overall emission recovered by ALMA follows well the shape and elongation of the ATLASGAL
emission. However, although there are several cores at the center of the map, the most massive core is located in the lower partof the IRDC, not being coincident with the peaks observed in the ATLASGAL images. We recovered the same core distribution
on our ALMA observations carried out during 2013 and 2015. These observations were conducted independently, confirmingthat there is no error on the coordinates of the ALMA images.

e
e
y
t
e
el
e
t

d

+

e
&

rXiv:1805.01802v1 [astro-ph.GA] 4 May 2018

treras et al.

depends on the density profile of the core as func
INFALL SIGNATURES IN A PRESTELLAR CORE EMBEDDED IN THE HIGH-MASSµM DARKIRDC ⇢(r) / r n (MacLaren et al.
the70radial
distance,
G331.372-00.116
Here we adopt a value of n = 1.8, which has been
to be representative for high-mass star-forming
1
2
3
2, 4
Yanett Contreras, Patricio Sanhueza, James M. Jackson, Andrés E. Guzmán,
Steven Longmore,5(Mueller
et al. 2002; Garay et al. 2007). The viria
4672
Guido Garay, Qizhou Zhang, Quang Nguyπn-Lu’o’ng, Ken’ichi Tatematsu, Fumitaka Nakamura,2ofRathborne,
ALMA1 13is andderived to be Mvir = 2.4 ± 0.6 M ,Takeshi Sakai,8 Satoshi Ohashi,9 Tie Liu,10, 11 Masao Saito,2 Laura Gomez,12 Jill
14
Scott Whitakervirial parameter is ↵vir = 0.14 ± 0.08, assuming
uncertainty
in the mass value. The low value+
18
Figure 4. Left:ØHCO
(3-2) (black)aand CSO (2-1)(red)
2ntospectra overlaid to the dust c
1 Leiden Observatory, Leiden University, PO Box 9513, NL-2300 RA Leiden, the Netherlands++
virialparameterforsuggeststhatturbu
ALMA1. Right upper panel: Mean spectra across ALMA1ALMA1of the HCO(3-2),DCO
2 National Astronomical Observatory of Japan, National Institutes of NaturalØSciences,
19O
9 Mitaka,
VTokyo 181-8588,
S the stability of ALMA1(
2-21-1 Osawa,Japan
insuﬃcienttomaintainemission.
Here both optically thin tracers shows a single peak at the position of the vLSR
3 School of Mathematical and Physical Sciences, Universityof Newcastle, University Drive, Callaghan NSW 2308, Australia
Ø 1515, Las Condes,
f Santiago,
e+ shows
S etclearly
4 Departamento de Astronomía, Universidad de Chile,et Chile
al.
2011;
Tan
al. 2013;
Lu et al.
2015; Zhan
shows
red-peaked
profile,while
HCO
the typicalblue-peakedinCaminoael small
Observatorio
5 Astrophysics Research Institute, Liverpool John Moores University, 146 Brownlow
Hill, lines
Liverpool
UK
Ø 481
d
tmy
spectra of the samefour
asL3in5RF,
the
upper
panel.
the r
infallprofileetis al.
also2017).
eviden
2015;
Ohashiet Hereal. 2016;
Sanhueza
6 Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA
HNC there is no evidence
of infall.
It is possible
2 V
v thats magnetic )fields
5 play a role
7 The Canadian Institute for Theoretical Astrophysics (CITA), University ofØ
Toronto, 60 St. George Street, Toronto, Ontario, M5S 3H8,
1stability of this core (Zhang et al. 2014; Frau et al
Canadais then 1.19 ( thØ H2 /= 0.22 km), indicating
7 sK G/) 7 H thatK Gthe/
) where B is the magn
8 The University of Electro-Communications, Chofu, Tokyo 182-8585, JapanThe virial mass taking into theaccount
gas in the core is transonic.
core themasscontribu
density
9 RIKEN, 2-1, Hirosawa, Wako-shi, Saitama 351-0198, Japan
Ø ‒
ia
D3
10 Korea Astronomy and Space Science Institute, 776 Daedeokdaero,
aofmagnetic
field support wouldInbe
given
The virial
mass of
ALMA1
is calculated
using
order
toby:
reach v
Yuseong-gu,
Daejeon34055, RepublicKorea
11 East Asian Observatory, 660 N. A’ohoku Place, Hilo, HI 96720, USA✓✓ magnetic◆fiel✓◆ 21), ◆the12 Joint ALMA Observatory, Alonso de Córdova 3107, Vitacura, Santiago, Chile
R
5
2n
1 2
5 2n
R
v
to be of v2the+ order, MB,vir = 3(2)Mvir = 3
13 CSIRO Astronomy and Space Science, P.O. Box 76, Epping NSW 1710, Australia
A ,of
G
3
n
6
3
n
G
14 Physics Department, Boston University, Boston, MA, USA
certainty in the core’
neticand
field
have
b
where
n=
1.8notas in
R isu
the eﬀective
radiusofthe core,
G isAlfven
the velocity,
A is theØx
4 CC where
419
tln
k
Submitted to ApJ
fieldbystrengths
2. TheAlfvenvelocity Suchis given
constant
whose
value
A = B/N( is7aHtionØ/) gravitational
D H 7 = constant,/ .+Land n
MGO
lar cores (Zhang et adepends
on the density profile of the core as function of
ABSTRACTnward prestellar core cthearadial/ K)
r 3.6-70(MacLaren
et al.
1988).
Using Galactic Plane surveys, we have selectedmassive distance,(1200 M ), ⇢(r)cold (14µm dark IRDC
G331.372Ø 3((, +high-mass
7
0670
V
+7
A
H
ial. 2018)00.116. This IRDC
has the (,potential to form
stars
given
absenceof current
formation(Beuther etHere
weHadopt
aand,
value
ofthe
n=
1.8, which
hasstarbeen
foundsignatures, it seems torepresent the earliest stages of high-mass star formation. We have mapped the whole IRDC withVe
to be representative for high-mass star-forming regions
the Atacama Large Millimeter/submillimeter Array (ALMA) at 1.1 and 1.3 mm in dust continuum and line emission.
5.1.2. A Relatively M
et IRDC.
al.
Garay2007).
The virialmassØ reveals 22 cores distributedO(Mueller
e 2002;f et
The dust continuum
across the
In thiswork,
we al.
analyzethe S
physicalpropertiesof the most massive core, ALMA1, which hasof
molecular outflows
detectedbe
in thevirCO=(2-1), SiO(5-4),H2 CO
is Hderived
± 0.6
M and
, and
its
) MG noALMA1(L massived M ),7
a to
i M
O 2.4
i j
(3-2) lines. ThisØcore is/(relatively(M = 17.6
subvirialized(virialparameter↵vir = Mvire/M = 0.14),
virialparameter
is
↵
=
0.14
±
We estimated the cvir+ 0.08, assuming a 50%
and is barely aﬀected by turbulence (transonic Mach number of 1.2). Using the HCO (3-2) line, we find the first
uncertainty
masswith
value.
The lowvalueof the(3-2) molecular line e
detection of infall signatures in a relatively massive,
prestellar incorethe(ALMA1)the potential
to forma high-massophysik, Karl-Schwarzschild-Str. 1, 85748 Garching, Germany
onomie, Königstuhl 17, 69117 Heidelberg, Germany, TN9 1SP, UK
Ionised gas kinematics in bipolar H II regions
Planetary Science, University of Kent, Canterbury, CT2 7NH, UK

Hannah S. Dalgleish1? , Steven N. Longmore1 , Thomas Peters2 ,Jonathan
D. Henshaw1,3 , Joshua L. Veitch-Michaelis4 , and James S. Urquhart5
1

Y; in original form ZZZAstrophysics Research Institute, Liverpool John Moores University, Liverpool, L3 5RF, UK

2 Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Str. 1, 85748 Garching, Germany
3 Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany

ABSTRACT

arXiv:1805.00479v1 [astro-ph.SR] 1 May 2018

4 I3D Robotics Ltd, Tonbridge, TN9 1SP, UK

5 Centre for Astrophysics and Planetary Science, University of Kent, Canterbury, CT2 7NH, UK

3
I
Stellar feedback plays a fundamentalrole
in YYY;shaping
evolution of galaxies. HereAccepted XXX.
Received
in originalthe
form ZZZ
84 2c
we explore the use of ionised gas kinematics in young, bipolar H ii regions as a probe
G H
ABSTRACTof early feedback in these star-forming environments.
We have undertaken a multiStellar feedback plays a fundamental role in shaping the evolution of galaxies. Herem as a probe2/
wavelength study of a young, bipolar H ii region in
the Galactic
disc,
we explore
the use of ionised
gas G316.81–0.06,
kinematics in young, bipolar H ii regions
3
of
early
feedbackinthesestar-forming
environments.
We
have
undertakenamultiwhich lies at the centre of a massive (⇠ 10 M ) wavelength
infrared-darkcloud filament. It is-. 0 /
6
study of a young, bipolar H ii region in the Galactic disc, G316.81–0.06,
3
the centre gasof a massive(⇠ 10perpenM ) infrared-dark cloud filament.
isstill accreting molecular gas as well as driving a ⇠ which
0.2 lies
pc ationised
outflow
2 Itp84
1still accreting molecular gas as well as driving a ⇠ 0.2 pc ionised gas outflow perpendicular to the filament. Intriguingly, we observe a large
velocity
gradient(47.81±
3.21
dicular to the filament. Intriguingly, we observe a large velocity gradient (47.81 ± 3.21
2k c
1
1km s 1 pc 1 ) across the toionisedgasoutflow.
in a directionThis
perpendicular to the outflow. This
km s pc ) across the ionised gas in a direction perpendicularthekinematic signature of the ionised gas shows a reasonable correspondence with the8skinematic signature of the ionised gas shows a reasonable
correspondencewiththe comparison between our obsimulations of young
H ii regions. Based ona qualitative
servations and these simulations, we put forward a possible explanation
for the velocity
4 2
simulations of young H ii regions. Based on a qualitative
comparison between our obgradients observed in G316.81–0.06. If the velocity gradient perpendicular to the outflow is causedexplanation
by rotation of the forionisedgas,velocity
then we infer that this rotation is a direct
servations and these simulations, we put forward a possible
theresult of the initial net angular momentum in the natal molecular cloud. If this explagradients observed in G316.81–0.06. If the velocity nation
gradient
perpendicular
to should
the beoutis correct,
this kinematic signaturecommon in other young (bipolar)Hiiregions.
Wesuggestthat
furtherquantitative
analysis
flow is caused by rotation of the ionised gas, then we
infer that this rotation is a direct of the ionised gas kinematics of young H ii regions, combined with additional simulations, should improve ourunderstandingof feedback
at these If
earlystages.
result of the initial net angular momentum in the natal
molecular
cloud.
this
explawords: ISM:
ii regions;young
kinematics
and dynamics - stars: massive; protostars
nation is correct, this kinematic signature should beKey
commoninHother(bipolar)
H ii regions. We suggest that further quantitative analysis of the ionised gas kinematics of young H ii regions, combined with additional simulations, should improve our
1 INTRODUCTION
photoionising radiation, and supernovae); and thermal feedunderstanding of feedback at theseearly stages.
back (e.g. non-ionising radiation).
Feedback from high-mass stars (i.e. OB stars with M? 8
M ) is fundamental to the shaping of the visible Universe.
From the moment star formation begins, stellar feedback
commences, injecting energy and momentum into the natal
environment. This feedback can both hinder and facilitate

Key words: ISM: H ii regions; kinematics and dynamics - stars: massive;
protostars
Stellar feedback encompasses many astrophysical processes, moderating star formation from stellar scales (⌧ 1pc) to cosmological kpc-scales (e.g. driving Galactic out-

CLOUD-CLOUD COLLISION INDUCED STAR FORMATION IN IRAS 18223-1243
CLOUD-CLOUD COLLISION INDUCED STAR FORMATION IN IRAS 18223-1243

ABSTRACTABSTRACTIn theofdirectionof.6l =
17
.6, –the19 star-forming, the star-forming
sites
Sh2-53
2-53 andand IRAS
18223-1243
are promiIn the direction
l
=
17
–
19
sites
Sh
IRAS
18223-1243
are prominently observed, and seem to be physically detached from each other. Sh 2-53 has been investigated at
nently observed,
and seembe physicallydetached
from eachenvironment
other. Sh of
2-53
has
been investigatedatthe junctionof thetomolecularfilaments,
while a larger-scale
IRAS
18223-1243
remains
the junctionunexplored.
of the moleculara larger-scaleof IRASremains
The goalfilaments,of this paperwhile
is to investigate
the starenvironment
formation processes
in the18223-1243
IRAS site (area13
unexplored. ⇠0Theof thispaper
is GRS
to investigate
the starformation
processes
IRAS ofsite.4 goal⇥ 0 .4).
Basedon theCO line data,
two molecular
clouds,peakinginatthe
velocities
45 (area1
13
and 51km s on, areplots,
a relatively
weak peaking
CO emission
is detected of 45⇠0 .4 ⇥ 0 .4).
Basedthefound.
GRSIn13theCOposition-velocity
line data,1 two
molecular
clouds,at velocities
a link between
1intermediate velocities (i.e. 47.5–49.5 km s ) between these two clouds, illustrating13
and 51 km sat,
arefound.
Intheposition-velocity
plots,arelatively
weakCOemissionis detected
two parallel elongated velocity structures.1 These clouds are physically connected in both space andat intermediate
velocities(i.e. 47.5–49.5s )free-free
betweenthese two
clouds,illustrating
a link between
velocity.
The MAGPIS
data at 20 km
cm trace
continuum
emission
towardthe IRAS 18223-1243
two parallel source.
elongatedstructures.
These
clouds data,
are physicallyconnected
in both young
space andUsingvelocity
the Spitzer
and UKIDSS
photometric
we have identified
infrared-excess
objectsdata(YSOs),
andcm
have
observed
their continuum
groups toward
the intersectionof the clouds.
velocity. Thestellar
MAGPISat 20
trace
free-free
emission
towardzones
the IRAS
18223-1243
IRAS
is alsoUKIDSS
spatially seenat an interfaceof thethese observationalyoung
source. Using
the18223-1243
Spitzer andphotometricdata,
weclouds.
have Considering
identified infrared-excess
findings, we propose the onset of the collision of two clouds in the IRAS site about 1 Myr ago, whichstellar objects(YSOs), and have observed their groups toward the intersection zones of the clouds.
triggered the birth of massive star(s) and the YSO groups. A non-uniform distribution of the GPIPS
IRAS 18223-1243
also spatiallyseen at angles
an interfaceof the toward
clouds.theConsidering
these indicating
observational
H-bandisstarlightmean polarizationis also observed
colliding interfaces,
findings, we theproposeonsetof thecollisionof field
twomorphology.
clouds in the IRAS site about 1 Myr ago, which
impacttheof thecollisionon themagnetic
triggered theSubject
birthheadings:
of massive
and– HII
the regions
YSO groups.
A non-uniform
distributionof 18223the GPIPS
dust,star(s)extinction– ISM: clouds– ISM: individual
object (IRAS1243)–
stars:
formation–stars:
pre-mainsequence
H-band starlight mean polarization angles is also observed toward the colliding interfaces, indicating
the impact of the collision on the magnetic field morphology.
Subject headings: dust,
extinction – HII regions – ISM: clouds– ISM:
individual
object(IRAS
18223-et1. INTRODUCTION
have beenreported(e.g. Furukawa
et al.
2009; Ohama
I Massive
I OB-stars
z 1243)y7
UFukui M
RG/67
al. 2010,
2017a,b;et al. 2014,2016, 2018;-4
Baug etformationstars: pre-main
sequence( 8–Mstars:) are themajor16
and–7
ultimateal.
2016;
Dewangan
2017;
Dewangan
&
Ojha
2017;
sourcesYof mechanical
and=radiative energyHp= in galaxies,
l KSRG Y Yt-4 k DeM
wangan et al. 2017; Fujita et al. 2017; Torii et al. 2017a,b;
which are produced from their birth until their death.
Y p Yh of therOG7
C A 821.77 HayashimRG
Y
et al.Y974
2018; Kohno et al. 2018; Sanoet al. 2018).
The understanding
formation processes of such have
1. INTRODUCTION
been
reported(e.g.
Furukawa
et
al.
2009;
Ohama etInfrared-darkclouds (IRDCs) are often investigated asstars3DA
is still one of the outstanding
star forma- al. 2010,ps topics
z in974
MPRG/5157
2017a,b;
Fukui
et al.
2016, the2018;
elongatedfilamentary
clouds,and2014,also harbor
earlyBaug etMassive OB-stars( 8M) Zinnecker
are the major
and2007;
ultimatetion
research
(e.g.
&
Yorke
Tan
et
al.
Y of mechanicalYei andrOG
al. phases
2016; of
Dewangan
2017; Dewangan
Demassive OB-stars(see reviews &by OjhaBergin2017;&sourcesradiative
energygalaxies,2014). In recent
years, to explain
thein
originof massive
Tafalla2007;
André
et
al.
2014,
and
references
therein).
stars andfrom
youngtheirclusters,
a cloud-cloud
collision(CCC) wangan et al. 2017; Fujita et al. 2017; Torii et al. 2017a,b;
which are produced
birthuntil their
death.
It implies
that2018;
such elongatedcan beSano
considered
Hayashi
et al.
Kohno etclouds
al. 2018;
et al. 2018).
process has
been formation
proposed as processes
an interesting
The understandingof theof alternativesuchas the potential sites to probe the formation mechanisms

305v1 [astro-ph.GA] 18 May 2018[astro-ph.GA] 18 May 2018

1
2
3
4
1
4
L. K. Dewangan, D. K.
Ojha, I.2 ,Zinchenko
T.BaugBaug
L. K. Dewangan, D.
K. OjhaI. Zinchenko3,, andand T.

The Eccentric Cavity, Triple Rings, Two-Armed Spirals, andDouble Clumps of the MWC 758 Disk
1,2

Ø
Ø

805.12141v1 [astro-ph.SR] 30 May 2018

– 28 –

2

2 4RCI3– 30 –

4

Ruobing Dong , Sheng-yuan Liu , Josh Eisner , –SeanAndrews , Je↵rey Fung , Zhaohuan
29 –
5
4
6
Zhu , Eugene Chiang , Jun Hashimoto , Hauyu Baobab Liu7 , Simon Casassus8 , Thomas
Deprojected 0.87 mm Continuum Emission Map
Esposito4 , Yasuhiro Hasegawa9 , Takayuki Muto10 , Yaroslav Pavlyuchenkov11 , David
Wilner3 , Eiji Akiyama12 , Motohide Tamura5,13 , and John Wisniewski14

g
c
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RM 6 MB 2, LC
JJ CJotus <7
r Wu

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ABSTRACT

<7
pstW

m l
b (

Spatially resolved structures in protoplanetary disks hint at unseen planets.
Previous imaging observations of the transitional disk around MWC 758 revealed.- JJ ) )/ JAN , . , ( AP ( T8R%B AJ
an inner cavity, a ring-like outer disk, emission clumps, and spiral arms, all possibly generated by companions. We present ALMA dust continuum observationsof MWC 758 at 0.87 millimeter (mm) wavelength with 43⇥39 mas angular resØolution (6.9⇥6.2 AU) and 20 µJy beam 1 rms. The central sub-mm emission

d0, T8R
Ø
g
c l
A1 )(
1
=21/
Ø ==5bga ( )( APe1

Steward Observatory, University of Arizona, AZ 85721, USA

2

Institute of Astronomy and Astrophysics, Academia Sinica, Taipei 10617, Taiwan

3

Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138,Ø
USA
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Fig. 3.— Azimuthally-averaged radial profiles in four select4Department of Astronomy, University of California at Berkeley, Campbell Hall, Berkeley, CA 94720-3411,
radially-averaged azimuthal profiles in three circular rings ((b)
USAthe rings are 0.00 03 (Arm 1), 0.00 04(north clump), and 0.00 13 (soutALMA image (Figure 2). The four regions in (a) and (c) are d
2.— Deprojected image of MWC 758 assuming i=21 and PA=62 in Cartesian and polar (radial5
g. 1.— Panels (a) and (b): ALMA 0.87 mm continuum emission
from MWC 758
a beam andsize Fig.
Departmentof withPhysics
Astronomy,
Universityof
Nevada,Las
Vegas,
4505
South
MarylandinParkway,
Figure⇥39 mas (6.9⇥6.2 AU; labeled at the lower left corner). North is up and east is to the left. In panel (b), azimuthal) coordinates. The top and bottom rows are identical, apart from the annotations. In panel (c),3 2c, and the three rings in (b) and (d) are centered on
the
three
curvesarethreeellipses1⇥,
1.35⇥,
and
1.7⇥
the
size
of
the
ellipse
fit
to
the
inner
ring
at
the
Vegas,
89154,
USA arethetwoclumps. See §3.2 and §4.1 for discussions.
ructures are labeled; the green dotted contours are at theLas
3 noiselevel; theNV
two greensolid contours
00

Ø
g<7 i
Ø <7

y
NPBJJ

5 LMKH C

D

cavity edge (a=0. 32, e=0.1, and one focus on the star), and the four shaded regions are selected azimuthal

half peak intensity at each clump; the solid, dotted, and dashed white arcs trace out the inner, middle,
directions (their radial profiles are plotted in Figure 3a and 3c). In panel (d), the three curves are the threed outer rings, respectively; and the inset is a 0.00 2 zoom of the6central region (stellar location marked by ellipses in panel (c) (line-types are consistent). They roughly trace out (inside to outside) the inner ring2

Astrobiology Center of NINS, 2-21-1, Osawa, Mitaka, Tokyo 181-8588, Japan

805.12141v1 [astro-ph.SR] 30 May 2018

32 –The Eccentric Cavity, Triple Rings, Two-Armed Spirals, andDouble Clumps of the MWC 758 Disk
Ruobing Dong1,2 , Sheng-yuan Liu2 , Josh Eisner1 , Sean Andrews3 , Je↵rey Fung4 , Zhaohuan
Zhu5 , Eugene Chiang4 , Jun Hashimoto6 , Hauyu Baobab Liu7 , Simon Casassus8 , Thomas
Esposito4 , Yasuhiro Hasegawa9 , Takayuki Muto10 , Yaroslav Pavlyuchenkov11 , David
Wilner3 , Eiji Akiyama12 , Motohide Tamura5,13 , and John Wisniewski14

P

ABSTRACTØ nti y mn ( +aʼaSpatially resolved
protoplanetary
Ø structures.23. in406
L disks
P hint at
Lunseen planets.
Previous imaging observationstransitionalM
disk LaroundØ . < of the.23.
aMWC 758 revealed
an inner cavity, a ring-like outer disk,Nemission
N clumps, and spiral arms, all posM
sibly generated by companions. We present ALMA dust continuum observations
Øa) n Iy iàof MWC 758 at 0.87 millimeter (mm) wavelength with 43⇥39 mas angular resb rxu 1
L– 33 –

olution (6.9⇥6.2 AU) and 20 µJy beam
1

<<on
LN
A,

rms. The central sub-mm emission

Steward Observatory, University of Arizona, AZ 85721, USA

2

Institute of Astronomy and Astrophysics, Academia Sinica, Taipei 10617, Taiwan
Ø31
g3
Harvard-Smithsonian Center for
Astrophysics, 60 Garden Street,
Cambridge,
406
5.-+
J -MA 02138,
J USA=
Department of Astronomy,ØUniversityof California at Berkeley,94720-3411,<<<aon
p Campbell Hall,gBerkeley, CARga
USA
4

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Department of Physics and Astronomy, University of Nevada, Las Vegas, 4505 South Maryland Parkway,
Las Vegas, NV 89154, USA
6

Astrobiology Center of NINS, 2-21-1, Osawa, Mitaka, Tokyo 181-8588, Japan

IoI

p
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aris, PSL, CNRS, UPMC, Université Paris Diderot, 5 place Jules Janssen, 92195 Meudon, Franced Astronomy, University of Sheffield, Hounsfield Road, Sheffield S3 7RH, UK

Is stellar multiplicity universal? Tight stellar binaries in
the Orion Nebula Cluster
Gaspard Duchêne,1,2? † S. Lacour3 , E. Moraux2 , S. Goodwin4 , J. Bouvier2

YY; in original form ZZZ

1 Astronomy Department, University of California Berkeley, CA 94720, USA
2 Université Grenoble Alpes, CNRS, IPAG, 38000 Grenoble, France

3 LESIA/Observatoire de Paris, PSL, CNRS, UPMC, Université Paris Diderot, 5 place Jules Janssen, 92195 Meudon, France

ABSTRACT

arXiv:1805.00965v1 [astro-ph.SR] 2 May 2018

4 Department of Physics and Astronomy, University of Sheffield, Hounsfield Road, Sheffield S3 7RH, UK%. n
We present a survey for the tightest visual binaries among 0.3–2 M members the
XXX. Received YYY; in original form ZZZ
1%Orion Nebula Cluster (ONC).AcceptedAmong
42 targets, we discovered 13 new 0.00025–0.0015
61
companions. Accounting for the Branch bias, we find a companion star fraction (CSF)
ABSTRACT+8in the 10–60 au range of 21 5 %, consistent withWethat
observed
star-forming
0upresent
a survey for in
the other
tightest visualbinaries among 0.3–2 M members theOrion Nebula Cluster (ONC). Among 42 targets, we discovered 13 new 0.00025–0.0015
regions (SFRs) and twice as high as among fieldstars;Accounting
this excess
is foundwitha3
N
companions.
for the Branchbias, we finda companion
star fraction (CSF)+8
in the 10–60 auof 21 5 %, consistent
with thatthis
observed in other star-forming
high level of confidence. Since our sample is dominatedbyrangedisk-bearing
targets,61
60
regions (SFRs) and twice as high as among field stars; this excess is found with aindicates that disk disruption by close binaries is inefficient,
or
has
not
yet
taken
place,
high level of confidence. Since our sample is dominated by disk-bearing targets, thisC6 61
indicatesthat disk
disruption
by closebinaries isoutside
inefficient, or has not yet 4
taken place,in the ONC. The resulting separation distribution
in theONC
drops
sharplyin the ONC. The resulting separation distribution in the ONC drops sharply outside
O1
60 au. These findings are consistent with a scenario
in whichtheinitial
60 au. Thesefindings are
consistent
withmultiplicity
a scenario in which the initial multiplicity
properties, set by the star formation process itself, are identical in the ONC andproperties, set by the star formation process itself,
are identical in the ONC and2
in other SFRs and subsequently altered by the cluster’s dynamical evolution. Thisthat the dynamicalfragmentation process
does not dependon the global properties of ain other SFRs and subsequently altered by theimplies
cluster’s
evolution.
Thisslatter areOmolecular cloud, but on the local properties of prestellar cores, and that the
implies that the fragmentation process does not self-regulated
depend ontheglobalpropertiesofato be nearly identical in a wide range of environments.
These results,
O1
N
however,
raise
anew
the
questionoftheorigin
of
field
stars
as
the
tight
binaries wemolecular cloud, but on the local properties of prestellar
cores,
andthat
thelatterarehave discovered will not be destroyed as the ONC dissolves into the galactic field. O1
O3
self-regulated to be nearly identical in a wide range
of environments.
It thus appears
that most field starsThese
formed inresults,
regions that di↵er from well-studied
SFRs in the Solar neighborhood, possibly due to changes in core fragmentation on
M Ouhowever, raise anew the question of the origin ofstars as the tight binaries we
Gyrfield
timescales.
ahave discovered will not be destroyed as the ONC
dissolves
field.– open cluster and associaKey words:
binaries:intovisual –thestars:galactic
pre-main-sequence
individual:
Orion
Nebulafrom
Cluster well-studied
It thus appears that most field stars formed in tions:regions
that
di↵er
O1
SFRs in the Solar neighborhood, possibly due to changes in core fragmentation on
Gyr timescales.
1

INTRODUCTION

cus has been on the hunt for significant di↵erences between
the multiplicity properties of di↵erent stellar populations.
From the earliest studies of populations of T Tauri stars, it
was clear that visual binaries are twice as common in nearby
SFRs as they are among field stars of similar masses at sepa-

stellar multiplicity in the youngest
stellar cluster and associaKey words: binaries: visualThe– ubiquity
stars:ofpre-main-sequence– openpopulations has been long established, proving that thistions: individual: Orion Nebula
Cluster
is aninherent feature of the star formation process itself

DEEP, HIGH-RESOLUTION ALMA OBSERVATIONS
1
3
4
1
J. A. Eisner1 , PROTOPLANETARY
H. G. Arce2 , N. P.
Ballering, J.INBally, S. M.
Andrews, R. INITIAL
D. Boyden, J. FROMDi Francesco5 , M.
DISKPROPERTIESTHE ORIONNEBULA
CLUSTER:RESULTS5
Fang1 , D. Johnstone5 , J. S. Kim1 , DEEP,R. K.HIGH-RESOLUTION
Mann5 , B. Matthews, I. Pascucci6 , L. Ricci7 , P. D. Sheehan8 , J. P.
ALMA OBSERVATIONS
9Williams
1
2
1
3
J. A. Eisner , H. G. Arce , N. P. Ballering , J. Bally , S. M. Andrews4 , R. D. Boyden1 , J. Di Francesco5 , M.

Fang1 , D. Johnstone5 , J. S. Kim1 , R.Accepted
K. Mann5 for, B. Publication
Matthews5 , I.
inPascucci
ApJ 6 , L. Ricci7 , P. D. Sheehan8 , J. P.
9Williams
Accepted for Publication in ApJ

3669v1 [astro-ph.SR] 9 May 2018

ABSTRACTABSTRACTof the Orion Nebula Cluster that provide the
We present ALMA 850 µm continuum observations
Weresolution
present ALMA
8500.00µm
continuum
observations of the Orion Nebula Cluster that provide thehighest angular(⇠
1⇡00 40 AU) and deepest sensitivity (⇠ 0.1 mJy) of the region tohighest angular resolution (⇠ 0. 1 ⇡ 40 AU) and deepest sensitivity (⇠ 0.1 mJy) of the region todate. We mosaickeda field containing⇠ 225
ornear-IR-identified
near-IR-identified
young⇠ 60 of whichdate. We mosaickeda field containing⇠ 225optical
optical or
young stars,⇠ 60stars,of which
are also optically-identified“proplyds”.
detect continuum
emission
at 850 µm
towards
80%
are also optically-identified“proplyds”.
WeWedetect
continuum
emission
at 850µm⇠ towards
⇠ 80%
of
the
proplydsample,
and
⇠
50%
of
the
largersampleofpreviously-identified
clustermembers.
of the proplyd
sample, and ⇠ 50% of the larger sample of previously-identified cluster members.
Detected objects have fluxes of ⇠ 0.5–80 mJy. We remove sub-mm flux due to free-free emission in
Detected objects
have fluxes⇠ 0.5–80
mJy.
Weinremove
sub-mmdue assumptions
to free-freesome objects,
leaving aofsample
of sources
detected
dust emission.
Underflux
standardof emission inthin ofdisks,
sub-mmdetected
fluxes correspondto dustmasses of ⇠0.5 to 80
Earth masses.
some objects,isothermal,
leaving opticallya samplesourcesin dustemission.
Under
standard
assumptions ofWemeasurethe
distributionofdisk
sizes,
and
find
that
disks
in
this
regionareparticularlycompact.
isothermal, opticallythin disks, sub-mm fluxes correspond to dust masses of ⇠ 0.5 to 80 Earth masses.
Such compact disks are likely to be significantly optically thick. The distributions of sub-mm flux
We measure andtheinferred
distribution
disk smaller,
sizes, andfinddisks
thatthandisks
in this region
are particularlycompact.
disk size ofindicate
lower-flux
in lower-density
star-forming
regions ofsimilarage.areMeasuredcorrelated weaklyopticallywith stellarthick.
mass, contrary
studies in other ofstarsub-mm flux
Such compact
diskslikelydisk
tofluxbeissignificantly
The todistributions
regions
that foundsteeper correlations. We find a correlation between disk flux and distanceand inferred forming
disk
size
indicate
1smaller, lower-flux disks than in lower-density star-forming regions offrom the massive star ✓ Ori C, suggesting that disk properties in this region are influenced strongly
similar age. Measured
disk environment.
flux is correlated weakly with stellar mass, contrary to studies in other starby the rich cluster
forming regions
thatfoundGalaxy:Open
steeper correlations.
We find a correlation
betweendisk flux
Subject
headings:
Clusters and Associations:Individual:
Orion,
Stars:Planetary
Sys-and distance
1 tems:Protoplanetary Disks, Stars: Pre-Main-Sequence
from the massive star ✓ Ori C, suggesting that disk properties in this region are influenced strongly
by the rich cluster environment.
1. INTRODUCTION
core of Jupiter likely formed on a much shorter timescale,
Subject headings: Galaxy:Open
Clusters and Associations:Individual:
Orion, etStars:Planetary
Sys< 1E
Myr (Kruijer et
al. 2017; Deschal. 2017).210
Proto06 tems:Protoplanetary
a birth-sites
AofDisks,-.
%sA
6
Protoplanetarydisks are theplanetaryStars: planetary
Pre-Main-Sequencedisks with cleared gaps or holes around stars
systems, and the properties of disks relate directly to
L8 85 46lthe planets that may potentially form. In particular,Jo constrains
Mpy theNmass budget
C for planet formaEO
disk masstion, 1.
andINTRODUCTION
hence the mass distribution of planets. The
minimum-mass solar nebula (MMSN) needed to form the

uLSY
aged.
. 1 Myr alsoy
suggest rapid
formation of giant plan-rm
ets (e.g.,
ALMAL
Partnership et al. JC
2015; Dong etJodal. 2015;
SheehanEisner 2017).
disk onmassesacceleratecore of&JupiterlikelyHigher
formeda muchshorter timescale,planet formation timescales (since collision rate scales< 1surface
Myr (Kruijer
et al.
2017; rapid
Deschet al.
withdensity). The
apparently
growthof 2017). Proto-

1, 2

1

1, 2

1

3

4

5

1

R. Fedriani , A. Caratti o Garatti , D. Co↵ey , R. Garcia Lopez , S. Kraus , G. Weigelt , B. Stecklum , T.P. Ray ,Received 27 October 2017 / Accepted
23 May 2018
and C. M. Walmsley,??
1Dublin Institute for Advanced Studies, School of Cosmic Physics, Astronomy & Astrophysics Section, 31 Fitzwilliam Place, Dublin
2, Irelande-mail: fedriani@cp.dias.ie
2
University College Dublin, School of Physics, Belfield, Dublin 4, Ireland
3
School of Physics, Astrophysics Group, University of Exeter, Stocker Road, Exeter EX4 4WL, UK
4
Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn, Germany
5
Thüringer Landessternwarte Tautenburg, Sternwarte 5, 07778 Tautenburg, Germany

ABSTRACT

Xiv:1805.11512v1 [astro-ph.SR] 29 May 2018

11512v1 [astro-ph.SR] 29 May 201

University College Dublin, School of Physics, Belfield, Dublin 4, Ireland
School of Physics, Astrophysics Group, University of Exeter, Stocker Road, Exeter EX4 4WL, UK
4
Parsec-scale
byD-53121
high-massstellar objects.
Max-Planck-Institut für Radioastronomie,
Aufjets
demdriven
Hügel 69,
Bonn,young
Germany
5
Thüringer Landessternwarte Tautenburg,
Sternwarte
07778
Connecting
the au-5,and
the Tautenburg,
parsec-scaleGermany
jet in IRAS 13481-6124?
3

Context. Protostellar jets in high-mass young stellar objects (HMYSOs) play a key role in the understanding of star formation andprovide us with an excellent tool to study fundamental properties of HMYSOs.
Received 27 October/ Accepted 23 May
2018
Aims. We aim at studying the physicaland2017kinematic
propertiesof the near-IR (NIR) jet of IRAS 13481-6124 from au to parsec
scales.
ABSTRACT
Methods. Our study includes NIR
data
from
the
Very
Large
Telescope
instruments SINFONI, CRIRES, and ISAAC. Information
Context. Protostellar jets in high-mass young stellar objects (HMYSOs) play a key role in the understanding of star formation andprovideenvironment
us with an excellent tool
study fundamental
properties
of HMYSOs. The technique of spectro-astrometry is performed with
about the source and its immediate
istoretrieved
with
SINFONI.
Aims. We aim at studying the physical and kinematic properties of the near-IR (NIR) jet of IRAS 13481-6124 from au to parsec
CRIRES to study the jet on au scales.
The parsec-scale jet and its kinematic and dynamic properties are investigated using ISAAC.
scales.
Methods. Our study includes NIR data from the Very Large Telescope instruments SINFONI, CRIRES, and ISAAC. Information
Results. The SINFONI spectraabout
in thethesource
H andandK bandare richin emission
lines
thatof spectro-astrometry
are mainly isassociatedits immediate
environmentis retrieved
with SINFONI. The
techniqueperformed with with ejection and accreCRIRES to study the jet on au scales. The parsec-scale jet and its kinematic and dynamic properties are investigated using ISAAC.
tion processes. Spectro-astrometry
is applied to the Br line, and for the first time, to the Br↵ line, revealing their jet origin with
Results. The SINFONI spectra in the H and K band are rich in emission lines that are mainly associated with ejection and accretion displacements
processes. Spectro-astrometry
the BrThisline, andfor the first
the Br↵ line, revealing
jet origin with of the au-scale jet and to
milliarcsecond-scale photocentre(11is applied
15 toau).
allowsustime,toto constrain
the their
kinematics
milliarcsecond-scale photocentre displacements (11 15 au). This allows us to constrain the kinematics of the au-scale jet and toits position angle(⇠ 216 ). ISAAC spectroscopy
H emission along
the parsec-scalejet, which allows us jet,to inferwhichkinederive its position angle (⇠ 216 derive). ISAAC
spectroscopy
reveals reveals
H2 emission
along
the parsec-scale
allows us to infer kinematic and dynamic properties of the NIR parsec-scale jet. The mass-loss rate inferred for the NIR jet is Ṁ
⇠ 10 M yr andmatic and dynamic properties ofjet.is roughly
The constantmass-loss
rate history
inferred
forstar.
the
NIR estimate
jet isof Ṁejec ⇠ 10 4 M yr 1 andthe thethrust isNIRṖ ⇠ 10parsec-scale
M yr km s , which
for the formationof the young
A tentative
the ionisation
fraction is derived for the massive jet by comparing the radio and NIR mass-loss rates. An ionisation fraction . 8% is
the thrust is Ṗ ⇠ 10 2 M yr 1 km
s 1 which, whichistheroughly
constant
theformation
historyof atheobtained,means thatbulk of the ejecta
is traced byfor
the NIRjet andthat the radio jet
only delineatessmall young
portion of it.star. A tentative estimate of
the ionisation fraction is derivedKeyfortheISM:massive
jet bycomparing
the radio
and NIR
mass-loss
An ionisation fraction . 8% iswords.
jets and outflows– ISM:
kinematics and dynamics– stars: pre-main
sequence– stars: massive rates.
– stars: individual:
IRAS 13481-6124 – technique: spectroscopic
obtained, which means that the bulk of the ejecta is traced by the NIR jet and that the radio jet only delineates a small portion of it.
2

2

1

ejec

1

4

1

/631 ISM:
2 3jets and outflows
R0
2 kinematics
a and5dynamics
4R tions
HY
8sequenceOT – stars: individual:c
Key words.
– ISM:–uO
stars:
pre-main–throughstars:
massive
1. Introductionof HMYSO
discs in Keplerianrotatione
modellingof CO band-head emission (Ilee et al. 2013), iii) direct detecIRAS– technique:spectroscopic
O13481-6124
p
a in Rn
Injs
recentyears, significant progressO
has been madeun- tion ofI
HMYSO discs in molecular tracers (BeltránYH& de Wit MN
derstanding the formation of high-mass young stellar objects 2016), iv) detection of several parsec-scale collimated infraredeS O/ 8A B (HMYSOs)/ (i.e. M⇤ K8 M , LSr
po Garatti
Set al. V02 Varricattaet al. 2010;Oy
5 ⇥ 103 L ). The latest jets (Carattibol2008, 2015a;
observational and theoretical studies present evidence that tips Cesaroni et al. 2013), and v) discovery of the first disc-mediatedLthe balance of favour in a key debate over how high-mass stars accretion burst in a 20 M YSO (Caratti o Garatti et al. 2017).

1. Introduction

8aSIf, as now
likely, HMYSOs
the accretiontionsof appears
HMYSO
discsform
inthroughKeplerianrotation through modelling
ejection process, then studies of the jet and outflow have the po-form. It now seems likely that HMYSOs are born in the same
way as their low-mass counterparts, via disc accretion, rather

−8

⊙

−1

Centre for Exoplanets and Habitability,
University
Warwick,
Hill theRoad, centre
Coventry, ofCV4the
7AL,arm
UK will possess E = 3
distributionof materialofin
the disk thatGibbet
extends
particles
near
dynamics
code(sphNG)
includingheatingdue
towork
structure(i.e.
thelocationofmaximum
density),
using
near
the
stellarphotosphereanddecreases
monoerenceØmodel
2HE Nconsists( (- of
7a 0.5M+ star,, 7modNP
C
7QM tonically0H NN
55with distance fromthe star(20, 23).
(3Dafriends-of-friends-likealgorithm,
whichJanuary
yields 1,a 2018)set ofdone
andtheradiative
transferofenergyintheflux(Received
January
1,
2018;
RevisedJanuary
1,collapse).
2018;
Acceptedsinkparticle,bydisc
To estimate theopticaldepth oftheobservedreforeidentify
particles
belongingto the7
EN surrounded** a7
NP whose inicnldust continuum
emission,
weperformed
radi-thereforey) points
for eachindividual
spiral.
Each armis thenparticles belonging to theWecanidentify
limitedlimit (Whitehouse
et al. (x,2005;WhiteratureE(Tvalue,) anddi↵usion
surfacedensity(⌃)
withparSubmitted
toRADMC-3D
ApJ (26)
ative transfer
calculations2using
heir
and discard
thevary
otherfittedseparately
minimisation
to a varietyof spiat 1.3 mm (17),via
previous
surfaceden- theirusing
E value,and discard the other parof thecode using thespiral) as house & Bate 2006). A detailed descriptionsity constraint found for the Elias 2-27 disk (20).
allows us to trace the spine of the spiral ral models
aticles.
constant
uncertainty
of to=trace
0.1 the spine of the spiral
ABSTRACTThis(assuming
model reproducestheazimuthally
averagedThis
allows us
can be found in Meru (2015) and Meru et al. (2017).
radialprofileoftheobserved
ALMA
1.3-mmcon0.75
AU foralltinuum
points).
We
use
Nelder-Mead(amoeba)
optiThe spiral(2)wavesin theprotostellar
disc
Elias
2-27
have
been
suggestedof Rmaximum
density),usingdetectedmyʼWmjFig.the
1. Thermal
dust emission
fromthediskNGEsurrounding
emission (fig. S1)(17).
Atsurroundinga radial distance) ofII
P protoplanetary
ND asML Idensity),
C EliasM 2-27.
R The
S ,disk was
structure(i.e.
locationmaximumusing
Tthe(R)location
=Ø
13.4
K
, and
200 au model2
Our reference
consists
of
a
0.5M
star,
modimagedatawavelength
of
1.3
mm,
with
ALMA
reaching an angular resolution of 0.26″ by 0.22″ (indicated
from
the
star
(hereafterreferredtoasradiusandevidence of the disc being
gravitationallyunstable.
However,previouswork
has shown thata massive,
misationtoobtainsaid
minimum,
implemented
via
iends-likealgorithm,
whichyieldsØ )1= R4 NLD83
7 a set
+ 7of
NP
PO )+
by the ellipse in the bottom
left corner),
whichetcorresponds
to 36 by 31 AU
the distancedenoted by PR) larger2thanaR friends-of-friends-like≈ 10 AU, the emis0.75
algorithm,
whichyieldsa atsetof of the star.
Forganal.
stable disc undergoinganencountera massive
also
consistent
the observa⌃(R) as= ⌃a0 sink
(3)
elled
particle,surrounded
by
a
disc
whose
inifield-of-view
center (atwith0, 0) corresponds
to the disk emission peak located at right ascension (J2000) =sion withis opticallythin and thuscompanion
traces the densityare The
scipy.optimize.minimize.
200au
pine
pointsdi↵erent
fittedfunctions(see
16 hours
26 minindividual
45.024s, declinationmodelling(J2000)= –24Eachdegrees 23arm
min 08.250
and coincidental with
7and
EN fourspiral.
(*
7 NPEachof solid material
down tothe midplaneof thehydrodynamicor eacharm
isdensitythen(x,y)particle
pointsforeachspiral.
is s,thentions.
Wespiralcomparethe spiral morphology
of smoothed
simulations
tialindividual
temperature(T)
andsurface
(⌃)
vary
with
the position of the star Elias 2-27. (A) 1.3-mm dust continuum image from the Elias 2-27 protodisk.
At the location of the spiral structures (from
Logarithmic
spiralsarecommonly
foundin isolated
bothcases.
The
gravitationallyunstable
disc
symmetric,
tightlyarms
withplanetary
disk woundover2a 4″
byspiral4″ area. The
color scale
represents
flux density measured
in units of Jansky
R = 100 to 300AU),produces
thefitted
azimuthally
averaged
Ø2 R
zt
d7
EN
-.au.
7spiNP.7
PLj
separately
via
minimisationtoa varietyof spily, between
=
10
au
and
R
=
350
ely
via
minimisationtoavarietyofinout
radius (R) as
per
beam
(1
Jy
=
10
W
m
Hz
).
(B)
Increased
contrast
image
fromprocessing
theoriginal ALMA
optical
depth
t
of
the
dust
continuum
emissiondiscs anddiscs driven
byencounters
witharea(A)asymmetric,
comconstant pitch angle, asGI
predicted
by theinliterature.
The companion
disc’s arms
withobservations shownin constantwith an unsharpuncertainty
masking filter (17).
is t = 0.1 at R = 100 AU, ral
decreasing
to t = 0.02(assuming
simulationisagravitationallyunstable
discmodels
a
of
=
0.1
M
+
P
ssumingof that= 0.1
pitch
anglesincreasewith radius.
these
are not well-fitted by standard analyticat
AU (fig. S1B),
whicharms
is consistent
re b = ba constantat r = a,uncertainty
and thePURELOGsolution
isR = 300However,panion:h ⌃0 = 6 ⇥0 10 7 M au 2 , givingexpressions,a total
disc
0.75
with themeasured
peakAUbrightness
temperafor
all
We
b✓
R
due
to
the
high
disc
mass
and
relatively
lowcompanion
mass. WenoteusethatNelder-Meaddi↵erences (or (amoeba) optints). We
use
Nelder-Mead(amoeba)
opti-, and=R ae, points).
(5)
T (R)
=also
13.4checkK(2)
ture onthe spirals of 1.2 r
K at= 150 AU.
overed
for
c
=
0.
We
specificallywhether200
au2
24 M , and an initial Toomre
Q<
indeed similarities)
in morphology between
pairs ofare
spiralsa to
crucialdiscriminant
between scenarios
The spiral structureseven moreisevident
misationobtainsaid
minimum, implemented via
2 parameter
0.75
in Fig. 2A, mustin which fit
the data
has been
projected
btainsaid minimum,=
implemented
via
R2-27, and
Elias
hence
futurestudiesspiralarms
individually.
If
Elias
2-27
continues
to
where
r
is
cylindricalradius,
and
✓
is
the
azimuthalan⇠250dependenceau.
nearof ⌃(R)b withrfor
issufficientbyrunning⌃0 200au
into a(3)polar coordinate scipy.optimize.minimize.
grid that accounts forshow symmetrictightly wound spiralarms
in futurethen we posit that it is the firstthe viewing
geometryof the disk.observations,
In polar coordi−26−2−1ize.minimize.
gle. check
The nates,a parameter
determines the initial distance of
econd
simulation(Companion), ⌃Finally,⇥ double0 = 1.96 towithn = 1 (VARLOGN).
a ring with zero eccentricity would haveobserved example
of a gravitationallyunstable
protostellar
disc.
spiralscommonly found in isolated2
a constantradiusforall polarLogarithmic
angles.
However,
Ø a totale disc
s
o
c
hn
l
j
the
spiralfrom
theorigin,andb determines
the arewindingu,givingmass
of0.078M,andrespectively,
between
R
=
10
au
and
R
=
350
au.
in
out
ct thespiralsarecommonly
foundinisolated
shown
in
Fig.
2A
are
two
brightstructures
thatspirals do indeed possess a logarithmic
form,
and
in ofdiscs
driven by encounters with a comgrow
in radius
from~100GIto300 discs
AUpitchas the polar
properties
of
the
arm.
The
angle
a logarithmic
all radii.
Keywords:stars:
individual(Elias2-27)—stars:
pre-mainsequence—hydrodynamics— protoplanThe
firstsimulationisagravitationallyunstable
disc
angle
increases.
The
brightest
of
these
two
strucindiscs
drivenbyencounterswithacomalsofitapower
spiralfunction(POW),
where
panion:spirale that forevolve,tures interactions
lies northwest of the star, labeled “NW”;
7
2 disks kru
etary— planet-disk
Ø the
6 GI
3 case thea disccdoes(GI), with ⌃0 = 6 ⇥ 10

M au

, giving a totalthe discspiral structure southeast of the star is labeled

Downloaded from http://science.sciencemag.org/ on June 27, 2018

1805.08041v1 [astro-ph.SR] 21 May 2018e. (2017),
eigenvalues
encodes information
about with motion in the undisturbed
Particleswith
but for E
completenesswe briefly reiterAnd thendisc.
computethe tensor’s
eigenvalues. The num2.
METHODOLOGY
nalityof the The
flow.
For example,
particles E = 2 indicate 2D filamentary
motions eigenvalues(in this case, E
spi-encodes information aboutalient aspects.
simulations
are performed
berSELF-GRAVITY,of positive
ARE ELIAS 2-27’S SPIRAL ARMS DRIVEN BY
OR BY A COMPANION?
ral structure). If the spiralstructure isSTUDY
strongenough,three-dimensional
Smoothed
Particle
Hydro2.1.
Hydrodynamics
ndicatetheir motion
is planar,
consistentthedimensionalityof theflow. For example, particles
A COMPARATIVE SPIRAL
MORPHOLOGY
particlesnear
thecentre
of
the
arm
will
possessE=3
code(sphNG)
including disc.
heating Particles
due to workwith
1, 2
5in theundisturbed
R ES E Ain
RC HJohn| R E POTS
DuncanH. Forgan,
D.RwithIlee,3 E
and=Farzana
Meru3, 4,
1 indicate
theirmotion is planar, consistentOurhydrodynamic
simulations are
fully
described(3D collapse).
the radiative transfer of energy in1 the fluxmotionin theundisturbed
disc. Particles with
SUPA,case,
School of
Physics
and Astronomy,
University ofwith
St Andrews,
North Haugh,
St Andrews
KY16 9SS, UKe 2D Meru
filamentary
motions
spiet al. (2017),
but(infor thiscompletenesswe briefly
reiterparent
molecular cloud(22), accretesparticles
material
We cantherefore
identify
belongingtothe↵usion limit (Whitehouse et al. 2005; White2 Centre for Exoplanet
Science,
University
ofwithSt aAndrew,
St Andrews, KY16 9SS, UK
from its surrounding
diskE
accretion
=mass
2and
indicate
2Dthefilamentary
motions (in this case, spiate
somesalient
aspects.
The
simulations
areperformed. If 2006).
thespiralstructureisstrongenough,3 Institutespiral
using
their
E
value,
discard
other
rate
of
8
×
10
M
year
(25).
Previous
obof
Astronomy,
UniversityofCambridge,
Cambridge,
CB3 0HA,
USA parBate
Adetailed
description
of
the
code
Ø
cn l
d
g
ai
d
servations at 0.6″ to 1.1″ angularresolution were
4 Department
ral
structure).
If thespiralstructure is strong enough,
using
the
Smoothed
ofticles.
Physics, HydroUniversityof Warwick,
Hill theRoad,spine
Coventry,
7AL,
UK
This
allowstoGibbetof CV4thespiraltheinØcentreof three-dimensionalthewillpossess
E =pnu3Particle
undMeru (2015)
andarmMeru
et al.
(2017).
well describedby a ussmoothandtrace
axisymmetric
5

b✓
r
=
ae
,
(5)
⌃ / R 0.5 . For the Companion simulation we“SE.” In Fig. 2B, we present the surface brightness
1
mass of 0.24b✓M , and ann initial1.Toomre
parametercontrast
Q<
1.
Surfacedensityofthegravitationallyunstable
disc(left)
andthecompanion
encounteroverlaid with theof the NW Figure
and SEarms,
definedasthe
INTRODUCTIONbletonon-axisymmetricperturbations,
which
undergoFig. 2. Polar projection of disk emission and measured contrast over the spirals discin the(right)
Elias 2-27d✓of the tache spiral identification
8MJup companion
au (5) ra✓ at 500
(9)r = aeinitially, r =locatedresultsalgorithm(blackcrosses).
identified
as either ’upper’
ratio between thepeakof emission
at
the
arm
6
3d
~
protoplanetary
disk. (A) Projection
onto polarIndividual
coordinates arms
(polar are
angle
q versus deprojectedradial or ’lower’ in=r=arctanb.
(6)
whereisWecylindricalradius,and ✓ is the azimuthal answingr(17).
amplification
into spiralstructures.
1 beyond ⇠ 250 au. the disc,case.
and the backgroundsurfacebrightness
structuresgenerated by gravitationallyunsta-eachdistance to the central star R) of the dust continuum observations from the Elias 2-27 disk. The emission
drowed to freely interact with Spiralmigratefound that both arms have similar contrasts
has been scaled by R in order to aid visualization, and the polar angle is defined as q = 0° (north) increasinggle.
Thea parameter
determines
theinitialdistanceofNatta et al. 2006), hostble
protostellar
discs playana crucial
the evolutionInthesecond(Companion),⌃0role=in1.96⇥
ing ofwhethera protostellar
disc theseis gravitationallyunsta1 Myr;
Luhman& Rieke 1999;
early
structures
are typicallystrongindricalradius,and✓simulationis theazimuthal
ranging
between values
1.3 and At
2.5.
The
spiral times,
toward east. Curves correspond to the best-fit model spirals for the NW and SE arms (dashed lines) and
At
the
time
when
the
simulationisanalysed
Pure logarithmic
spirals(whereb=b0 is a andconstant)ch also includes a radius-dependent pitch angleofble- measuring
its physicalproperties
determining
ing a Class II circumstellar disc potentially exhibiting a7

2

2

armseventuallyreach their highest contrast
at R = 150
AU,of protostars and the planetary systems they
theirconstraint
at the3s level (solidlines). (B)Surface brightness
contrast of the continuum emission along
globalmodes,
whichcanachieve
rapid
accretionof theForganet al. 2-27’S SPIRAL ARMS DRIVEN BY SELF-GRAVITY, OR BY A COMPANION?
ARE ELIAS
Forgan et al.
A COMPARATIVE SPIRAL MORPHOLOGY STUDY

44The Spiral Morphol
The Spiral Morph

Duncan H. Forgan,1, 2 John D. Ilee,3 and Farzana Meru3, 4, 5
1 SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews KY16 9SS, UK

1805.08041v1 [astro-ph.SR] 21 May 2018

2 Centre for Exoplanet Science, University of St Andrew, St Andrews, KY16 9SS, UKØ laAstronomy,Mrnp7
3 Institute of
Universityof Cambridge, Cambridge, CB3 0HA, USA
4 Department of Physics, University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL, UKØ rm gk M /5 Centre for Exoplanets and Habitability, University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL, UKØ< 7
0 .rmu g(Received
k Januaryi1, 2018; Revised January 1, 2018; Accepted January 1, 2018)
Submitted to ApJØoE
MABSTRACTh c
The spiralprotostellar discØ wavesodetected in theMla surrounding Elias 2-27 have been suggested as
evidence of the disc being gravitationally unstable. However, previous work has shown that a massive,
Ø
*20
M rm
7
stable disc undergoing an encounter with a massive companion are also consistent with the observa< morphology
o of stions. We compareE
the spiralsmoothed <particle hydrodynamic simulations modellingboth cases.ØThe gravitationally unstable disc produces symmetric, tightly wound spiral arms withconstant pitch angle, as predicted by the literature. The companion disc’s arms are asymmetric, withpitch angles that increase with radius. However, these arms are not well-fitted by standard analytic
expressions, due to the high disc mass and relatively low companion mass. We note that di↵erences (orindeed similarities) in morphology between pairs of spirals is a crucial discriminant between scenarios
6
Forgan et al.
for Elias 2-27, and hence future studies must fit spiral arms individually. If Elias 2-27 continues toTable
1. Best fitting
parameters
for both
the arms
G.I. andinCompanion
simulation for thethen
spiral wefunctionsshow
symmetric
tightlywound
spiralfuture observations,
positdescribedthat itin isSection
the 2.2.
first
In each case, ‘up’ and ‘low’ refer to the upper and lower arms identified in Figure 1, respectively.
observed example of a gravitationally unstable protostellar disc.

Gravitational Instability
Companion
PURELOG
VARLOGVARLOGN
POW
PURELOG
VARLOGVARLOGN
POW 3. As Figure 2, but for the Companion simulation. The
Figure 2. The isolated GI disc simulation, overlaidKeywords:
with the tachespine individual
points and fourdi↵erent
fitted—spiralfunctions(see sequence — hydrodynamics
Figurestars:(Elias2-27)stars:
pre-main—
protoplanUp spine
Low
UpfittedLow
Up Low
Low
Up
Low
Up
Low
Up
Lowcircle.
ext).
byFigurea redigure 2. The isolated GI disc simulation, overlaid with the tachepoints Up
and fourLowdi↵erentspiral functions(see Up
3. As Figure 2, but for the Companion simulation. T
etary56.9
disks— planet-disk
a
29.2
111.8
56.2
110.3interactions
56.8
55.3 11.5 64.2
33.0
39.4
73.3
46.5
38.5
8.4by a 1.9
ext).
red
circle. the results of tache’s spiral spine idenFigure 1 shows
pirals are typically found with the following function
where b = b0 at r = a, and the PURELOG solution isb00.208 0.205 0.191 0.244 0.123 0.216
0.288 0.243 0.208
0.225 0.148 0.201
tification
the GI(left)
the Companion
or b (Zhual. 2015),
recoveredc =r 0.
Weandalsothecheck
specificallywhether
Figure 1forshows
thediscresultsof andtache’sspiral spinedisc
idenpirals
are ettypically
found with the following functionwhereb = forb at= a,
PURELOGsolutionis
INTRODUCTION
ble
to non-axisymmetricperturbations, (right).
which
undergo[ ] 1.
11.75
11.59 0
17.0
14.2
Note
fordiscthe(left)
Companion
the spine
a linear dependenceof balso
withcheckr is sufficientbywhetherrunningtification
for that
the GIand the disc,Companion
disc
or b (Zhu et al. 2015), ⇣ r ⌘1+⌘ r↵recoveredfor c = 0. We
specificallyc-0.009 -0.029
0.1-0.0060.0003 into
0.00020.014structures.
0.005
pswing amplification
spiralidentificationslightly
missesthelocationofthecomfitswithn=
1(VARLOGN).
Finally,todoublecheckb(r) = hp⇣ ⌘,(7)(right).
Note
that
for
the
Companion
disc,
the
spine
a
lineardependence
of
b
with
r
is
sufficientbyrunningSpiralstructuresgeneratedbygravitationallyunstarrp 1+⌘ r↵r↵ rp↵n-0.49do indeed
0.35
1.0
0.67 1.26
2.40
1.92
1.0
1.0
1.64
1.14This is due to the fact that the particles impanion.
that
the a
a1.0logarithmic
form,
identificationslightly misses the location of the comfits
withnspirals= 1 (VARLOGN).
Finally,
to double checkb(r) = hp,(7) 2 discs
play
crucialrole
in possesstheevolutionAt
earlytimes,
thesestructuresare 9.91
typicallystrongrr↵ rp↵ble protostellar
1.98
3.98
3.63
3.22
3.02
3.26
3.96
4.13
7.80
4.52
3.54
3.85
4.29
2.39
5.03 surrounding
mediately
the companion have a di↵erent
we also fit a power spiral function (POW), where↵

panion. This is due to the fact that the particles imthat the spirals do indeed possess a logarithmic form,
where rp is the orbital radius of the companion⌦ / r ,and theof protostars
planetary systems they eventually
global modes, which can achieve rapid accretion of the