2019/11/08

The Star Formation Newsletter #322 6-15 竹村英晃（総研大M2）
6.

Inﬂuence of Wolf‒Rayet stars on surrounding star-forming molecular clouds

7.

A Search for Spatially Resolved Infrared Ro-Vibrational Molecular Hydrogen Emission from theDisks of Young Stars

8.

ALMA resolves the hourglass magnetic ﬁeld in G31.41+0.31

9.

Kinematics around the B335 protostar down to au scales

10. Probing planet formation and disk substructures in the inner disk of Herbig Ae stars with CO
rovibrational emission
11. Signatures of an eccentric disc cavity: Dust and gas in IRS 48
12. The ALMA-PILS survey: propyne (CH3CCH) in IRAS 16293­2422
13. The mass of dusty clumps with temperature and density structure
14. Dust accretion in binary systems: implications for planets and transition discs
15. VLA cm-wave survey of young stellar objects in the Oph A cluster: constraining extreme UV- andX-ray-driven disk photo-evaporation ‒ A pathﬁnder for Square Kilometre Array studies

7

A Search for Spatially Resolved Infrared Ro-Vibrational Molecular Hydrogen Emission
from the Disks of Young Stars
Tracy L. Beck1 and Jeffrey S. Bary2
1

Space Telescope Science Institute; 2 Colgate University

E-mail contact: tbeck at stsci.edu
We present results from a survey searching for spatially resolved nTable 1
UV, Near-IR, and Mid-IR H2 Emissions in CTTS Environments
H2 Emission
Diagnostic

WavelengthRange

Gas Density(cm−3)

Temperature(K)

Excitation
Mechanism

Emission
Location

UV electronic
dipoletransitions

1100–1600 A<103

2000–3000(1) Nonthermal pumping
by stellar Lyα(2) Nonthermal pumping
by LyαR<∼10 au,
Disk Surface
Extended Outﬂows
and Winds

IR rovibrational
quadrupoletransitions

1–6 μm(1) Collisional excitation inshock-heated material(2) Collisional excitation throughstellar X-ray ionization+heating(3) Collisional excitation throughstellar UV heating(4) IR cascade from nonthermal
pumping by Lyα(5) Shock excitation frommass accretion infall in
multiple-star systems

Extended outﬂows andwinds to ?100 auR<∼50 au,
disk surfaceR<∼50 au,
disk surfaceR<∼30 au,
disk surface
Regions thatshould be
dynamically cleared(1) Collisional excitation
through stellar heatingR<∼30 au,
closer to thedisk midplane

103–106

1500–3000<2000

Mid-IR rotational
6–28 μm>∼106<1000 K
quadrupoletransitions
The Astrophysical Journal, 884:159 (27pp), 2019 October 20

References
(1)
(2)
(3)
(4)
(5)
(6)
(7)

(9)
Beck & Bary

References. (1) Black & van Dishoeck 1987; Ardila et al. 2002; Herczeg et al. 2002, 2004; France et al. 2012; (2) Ardila et al. 2002; Saucedo et al. 2003; Walter et al.
2003; France et al. 2012; (3) Burton et al. 1989b; Eislöffel 2000; Eislöffel et al. 2000; Takami et al. 2004, 2007; Beck et al. 2008; (4) Tiné et al. 1997; Maloney et al.
1996; Bary et al. 2003; Nomura & Millar 2005; Nomura et al. 2007; Bary et al. 2008; (5) Bary et al. 2003; Nomura & Millar 2005; Nomura et al. 2007; (6) Black &van Dishoeck 1987; Bary et al. 2003; Nomura & Millar 2005; Nomura et al. 2007; Bary et al. 2008; (7) Beck et al. 2008; Dutrey et al. 2016; (8) this study; (9) Thi
et al. 1999; Thi et al. 2001; Sheret et al. 2003; Bitner et al. 2007; Bitner et al. 2008.

excitation mechanism over collisional excitation. Near-IR H2
S(0) lines at 12.28, 17.03, and 28.0 μm are used to quantify
measures denser warm gas in LTE in the upper disk layers
the molecular hydrogen component in dense extended disks.
excited by central stellar ﬂux, and in the shock-excited inner
The Spitzer Space Telescope IRS instrument with the R∼600
outﬂows. The mid-IR H2 traces cooler, denser gas closer to thehigh-resolution mode was not quite sensitive enough to detect
these very weak quadrupolar rotational H2 transitions above
disk midplane within ∼30 au of the central star. Figure 1(b) is a
representation of the H2 emission from an equal-mass 100 au
bright mid-IR continuum emission in most of the systems
studied in the CTTS surveys (Baldovin-Saavedra et al. 2011).
separation binary star. The disk emissions shown in Figure 1(a)From our present survey sample, only AA Tau, UY Aur, andare also present here, though each circumstellar disk is
AB Aur have measured rotational H2 transitions from Spitzer ordynamically truncated at ∼30 au (Artymowicz & Lubow 1994).
The system is encompassed by a circumbinary ring with 300 au
high spectral resolution ground-based measurements (BitnerFigure 1. Cartoon depictions of the possible locations of UV (blue), near-IR (red), and mid-IR (violet) molecular hydrogen emitting gas from the disks and outﬂows inわかったこと（計１０個）
5. ν=1-0 Q(3) / ν=1-0 S(1)の輝線比は、AA TauとUY Aurのknotでは、視線方向にextinctionが（ほとんど）ないものとconsistent

V773 Tau shows the second-strongest kinematic structure in
the H2 emission proﬁle, behind only the anomalously strong
redshifted jet seen in RW Aur.
UY Aur has a known Herbig–Haro ﬂow (HH 386; Hirthet al. 1997), with spatially resolved inner jets from both the A
and B stars and a wide-angle wind from UY Aur A (Pyo et al.
2014). The collimated blueshifted jet from UY Aur B extends
to the northeast toward UY Aur A, and the redshifted ﬂow fromUY Aur A extends to the southwest toward UY Aur B. The
apparent outﬂows nearly align with the binary orientation. We
clearly detect strong H2 emission in several knots that can betraced to these known [Fe II] jets (Pyo et al. 2014). In
Figures 12(b)–(d) and Figure 14, three positions A, B, and C
are designated. Position A is the location of the strongest
measured blueshifted H2 in the environment of UY Aur.
Comparison with the [Fe II] maps of Pyo et al. (2014) showsthat this emission traces the inner blueshifted jet from UY Aur
B. Position B traces a strong knot of slightly redshifted outﬂow
emission, and Position C shown in Figures 12 and 14 traces
strongly redshifted emission from the southwestern jet fromUY Aur A. The bright arc of H2 emission that we detect to thesoutheast of UY Aur A has a counterpart in the low-velocity[Fe II] blueshifted maps presented by Pyo et al. (2014).
The UY Aur A+B binary exhibits extensive H2 emissionthat fully encompasses this young system (Figure 14(a)). Threearc starts at the northern side of UY Aur A and wraps aroundthe east to the south−southeast of the star. This particular arc
does not seem to have a direct counterpart in [Fe II] emission
measured by Pyo et al. (2014), but the overall morphology issimilar to the geometry that they propose for the corresponding
redshifted wide-angle outﬂow from UY Aur A. However, inner
redshifted outﬂows are usually very difﬁcult to measure
because the optically thick central dust disk blocks clear
detection of the emission on the far side of the disk. UY Aur A
has a dense inner dust disk measured by ALMA (Tang et al.
2014). If the line traced in yellow is an arc from the redshifted
wind, the fact that we see this arc initiate within 0 15 fromthe north of UY Aur A and wrap around to the east−southeast
necessitates a special viewing geometry and a sparse amount ofobscuring dust in the inner ∼20 au of the circumstellar disk.
The third line overplotted in cyan in Figure 14(a) traces asimilar arc of emission from UY Aur B.
The UY Aur system geometries presented in Figure 5 of Pyo
et al. (2014) are updated and shown here in Figures 14(b) and(c). Figure 14(b) presents our observed view, and Figure 14(c)shows an expanded view of the geometry as viewed from theright side (consistent with Pyo et al. 2014). The location of themeasured collimated jets, wide-angle wind components, andregions with strong H2 emission are highlighted. The strongly
redshifted knot C is associated with the outskirts of the jet from

The Astrophysical Journal, 884:159 (27pp), 2019 October 20

Beck & Bary

わかったこと（計１０個）
7. X線のluminosityとH2の回転振動励起の輝線のluminosityの

The Astrophysical Journal, 884:159 (27pp), 2019 October 20間に逆相関がある

Beck & Bary

• Classical T Tauri星がweak-lined T Tauri星に進化する• X線の解離・加熱はClassical T Tauri星のinner diskのいける、近赤外線のH2の放射の主要な励起機構ではない
8. 連星系の周りでは、輝線の強度と輝線が観測された領域が単独星に比べて大きい• 系の運動によるショック、質量降着、傾いた系における
outﬂowの相互作用という励起機構が考えられる
9. GM Aur, AB Aur, LkHα 264の観測結果は、innner diskからの放射のものとconsistent

Figure 18. Rovibrational v=1–0 S(1) ﬂux plotted vs. distance from the central star for GM Aur and LkHα 264. Overplotted is the disk model from Nomura & Millar
Figure
13.
(a)
(Log)
X-ray
luminosity,(b)stellarages,(c)stellarmasses,and(d)(log) massaccretion
rates plottedvs. theμm rovibrational
2 linel Journal, 884:159 (27pp), 2019 October 20
Beck& Bary(2005),
scaledtothe observed
systemﬂux(log)
at 202.12
au distancesfrom theHstars.
luminosity. Measurement of the H2 luminosity in AB Aur is a lower limit because of the occulting spot used for the observation. The H2 luminosity plotted for LkCa
15 is the 3σ detection limit.

10.GM Aur, AB Aur, LkHα 264の観測結果とNomura &similar to the measured singles rather than the multiple
systems.
The young star multiple systems surveyed thus far havestronger H2 emission line luminosity over a greater overall
spatial area than the single-star systems. This is naturally
expected for spatially resolved binaries or higher-order multiples because the two (or more) disk+outﬂows have greater
combined ﬂux and span a larger overall area on the sky
compared to single-star systems (e.g., Figure 1). Interpretationof results for GG Tau A and UY Aur suggests that at least two
additional H2 gas excitation mechanisms may exist solely inyoung multiple systems: shock excitation from system
dynamics and mass accretion infall (GG Tau A), and shocked
arcs from interacting jets and wide-angle outﬂows in slightly
misaligned systems (UY Aur).

H2のFlux

these systems is characterized by spatially compact andcentrally dominated line ﬂux with no measurable kinematic
structure and no evidence for extended discrete knots or high
LTE gas temperatures suggesting shock excitation or an
outﬂow origin.
Figure 17 shows the log-scaled continuum-subtracted H2
images of GM Aur, AB Aur, and LkHα 264. The cyan ellipse
in the GM Aur view (panel (a)) presents the orientation of
circumstellar disk material sampled by the 0.9 mm dust
continuum emission, shown here in the location of the 50×
rms dust contour from Figure 1(a) of Macías et al. (2018). The
near-IR H2 emission from GM Aur is spatially compact, andthe majority of the ﬂux arises from within 0 2 (∼32 au) of thecentral star. GM Aur has an inner cavity in the dust disk within
35 au (Hughes et al. 2009; Macías et al. 2018), and the H2 gas
onal v=1–0 S(1) ﬂux plotted vs. distance from the central star for GM Aur and LkHα 264. Overplotted is the disk modelfrom 19.
Nomura& MillarFigureLineratio limits
rovibrationalHv=2–1
S(1)/v=1–0 S(1) ﬂux
ﬁlls thisregion.
The oflow-levele observed system ﬂux at 20 au distances from the stars.
2 from GM Aur shows
plotted vs. distance from the central star for GM Aur, AB Aur, and LkHα 264.
4.3. Rovibrational H2 from the Disks of Young Stars
nonaxially symmetric structures with a slight overall north–
Overplotted are the three X-ray+UV “Model A” disk models for 10 μm, 1 mm,

中心星からの距離

and massive circumsystem ring of material that encompasses
the three stars. A distribution of dust has been seen near thenorth of the stars in the scattered light maps of GG Tau A,
revealing that material exists at locations that should be
dynamically cleared in this complex multiple system (Krist
et al. 2002; Duchêne et al. 2004). The GG Tau system also
includes GG Tau Ba and Bb at a ∼10″ projected separation to
the south (White et al. 1999). Thus, GG Tau is a very young
quintuple-star system. The GG Tau Bb component has a verylate spectral type, making it a likely brown dwarf.
The v=1–0 S(1) line emission was measured in GG Tau A
by Bary et al. (2003) with a ﬂux of 6.9×10−15erg cm−2 s−1.
They interpreted the mission as arising from gas in the inner
disks from one or more of the stars. Beck et al. (2012)
presented the H2 maps from Figure 4 of this study and showedthat the extended H2 emission is strongest from the northeastern region ∼40 au away from the stars. Since the time ofthat publication, improved maps of the dust and CO gas from
ALMA have revealed that the region of brightest H isMillar (2005)、Nomura et al. (2007)を比較• emissionを星からの距離の関数で表した結果、GM AurとLkHαでconsistent• ν=2-1 S(1) / ν=1-0 S(1)の輝線比の検出限界を調べると、Nomura et al. (2007)の10cmまでのダストの成長モデルと、LkHα 264の結果が合わない9Kinematics around the B335 protostar down to au scales
Per Bjerkeli1 , Jon P. Ramsey2,4 , Daniel Harsono3 , Hannah Calcutt1 , Lars E. Kristensen4 , Matthijs H.
D. van der Wiel5, Jes K. Jørgensen4 , Sébastien Muller1 and Magnus V. Persson1
1

Department of Space, Earth, and Environment, Chalmers University of Technology, Onsala Space Observatory,
439 92 Onsala, Sweden; 2 Department of Astronomy, University of Virginia, Charlottesville, VA 22904, USA; 3
Leiden Observatory, Leiden University, P.O. Box 9513, NL-2300 RA Leiden, The Netherlands; 4 Niels Bohr Instituteand Centre for Star and Planet Formation, University of Copenhagen, Øster Voldgade 57, DK-1350 Copenhagen K,
Denmark; 5 ASTRON, the Netherlands Institute for Radio Astronomy, Oude Hoogeveensedijk 4, 7991 PD Dwingeloo,
The Netherlands
E-mail contact: per.bjerkeli at chalmers.se
The relationship between outflow launching and the formation of accretion disks around young stellar objects isstill not entirely understood, which is why spectrally and spatially resolved observations are needed. Recently, theAtacama Large Millimetre/sub-millimetre Array (ALMA) carried out long-baseline observations towards a handfulof young sources, revealing connections between outflows and the inner regions of disks. Here we aim to determine
15
the small-scale kinematical and morphological properties of the outflow from the isolated protostar B335 for which no
Keplerian disk has, so far, been observed on scales down to 10 au. We used ALMA in its longest-baseline configuration
to observe emission from CO isotopologues, SiO, SO2 , and CH3 OH. The proximity of B335 provides a resolution of∼3 au (0.03!! ). We also combined our long-baseline data with archival observations to produce a high-fidelity image
covering scales up to 700 au (7!! ). 12 CO has an X-shaped morphology with arms ∼50 au in width that we associatewith the walls of an outflow cavity, similar to what is observed on larger scales. Long-baseline continuum emission is
confined to <7 au from the protostar, while short-baseline continuum emission follows the 12 CO outflow and cavity
walls. Methanol is detected within ∼30 au of the protostar. SiO is also detected in the vicinity of the protostar, but
extended along the outflow. The 12 CO outflow does not show any clear signs of rotation at distances >∼30 au fromthe protostar. SiO traces the protostellar jet on small scales, but without obvious rotation. CH3 OH and SO2 trace aregion <16 au in diameter, centred on the continuum peak, which is clearly rotating. Using episodic, high-velocity,
12
CO features, we estimate the launching radius of the outflow to be <0.1 au and dynamical timescales of the orderof a few years.
Accepted by Astronomy & Astrophysics
https://arxiv.org/pdf/1909.05178

B335をALMA (Band 6)で観測し、近傍での力学状態を調べる （分解能 ~3 au）• Protostar
Probing planet formation and disk substructures in the inner disk of Herbig Ae stars
CO0、
rovibrationalemissionauスケールの観測でKeplerian diskは観測されていないClass
d~100 pc、10
•with
4
1
Arthur D. Bosman1 , Andrea Banzatti2,3 , Simon 13
Bruderer,
Alexander
G.G.M.
Tielens, Geoffrey
A.
12CO（他の短基線のデータとcombine）,
18
CO,
C
O,
SiO,
SO
,
CH
OH,
continuum(1.3 mm)
2
3• Blake5, and Ewine F. van Dishoeck1,4
1

2

12COとdustの観測• 12COは”X”のような形の分布• ダストもそのcavity wallに沿って分布している• ”X”の回転を示す結果がほぼない（後述）• ダストはprotostar付近で作られて遠くへ運ばれたのではなく、局所的に取り除かれた／運ばれていったと考えられる

背景：continuum (1.3 mm)、カラー：12CO (mom-0)

SiOとCH3OH
SiO

continuum emission (greyscale). Contours are from 3 in steps of 1 ,where = 2.1 mJy beam 1 km s 1 . The synthesized beam is shown in
the lower left corner of the map.

B335のCH3OHのスペクトルとLTEモデル

LTEを仮定すると、Fig. 7. The CH
3 OH 5 1,4 –4 2,3 E (vt =0) and CH3 OH 61,5 –72,5 A (vt =1)
lines of CH3 OH
detected towards220K
B335 (black
ガスの温度は20Kline) with an LTE spectral model overlaid in blue.
柱密度は 6.8 0.1 1018 cm-2

(Yen et al. 2015; Chandler & Sargent 1993). This value is similar to tabulated values for MRN grains (Mathis et al. 1977)
with thin ice mantles at high densities and a standard gas-to2
dust mass ratio(Ossenkopf& Henning 1994), but is slightly
S
d
1.3
mm
∵ Mlower= what is generally, assumed
Tdust = 200
K I and II disks
B335の周り半径7 auにあるダストの質量 Mdust = 3 × 10−4 M⊙
for Class
1.3 mm thandust)Harsono et al. 2018). Assuming that(e.g. Ricciκ1.3
etmm
al. B(T2010;
the gas temperature in the methanol emitting region is a goodproxy for the dust temperature in the continuum emitting region−4
半径25 auにあるダストの質量 7.5 × 10 M⊙ (Evans et al. 2015)とcomparable(200 K; see Sec. 3.2.1), the resulting circumstellar mass within
7 au is Mdust = 3 ⇥ 10 4 M . This mass is comparable to the
7.5 ⇥ 10 4 M inferred within a 25 au radius by Evans et al.
(2015), and in the case of spherical symmetry, therefore, consistent with a power-law density distribution with index, p = 2(Yen et al. 2015). The circumstellar mass is two orders of mag-

質量emission.
at 22 au, i
The P
distinctly
The FWHand 13 aucantly sm
locities ob
the protos
inferred fr
signature,
ever, the ehigher vel
strain thefore not ru(red dashe
That sate vicinittion of theto the flux
to reprodu
the coeffic
1 indicate
present on
0.3 and thsitions (athat the so
the estima
ters in thevelocity gvalues of 1
transitions
pared to th
from theet al. (201
nitude coa

PV図0.05M◉の星への自由落下
0.05M◉の星の周りのケプラー回転
emissionのピーク

12COの観測より
mom-1マップ

高い分解能で観測をしても、Keplerian diskは観測されなかった（回転があったとしても、とても遅い）→B335がとても若い and/or magnetic breakingによって円盤の形成・成長が抑制されている

6

Influence of Wolf–Rayet stars on surrounding star-forming molecular clouds

T. Baug1 , Richard de Grijs2,3,4 , L. K. Dewangan5 , Gregory J. Herczeg1 , D. K. Ojha6 , Ke Wang1 , Licai
Deng7 and B. C. Bhatt8
1
Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871, People’s Republic of China;
2
Department of Physics and Astronomy, Macquarie University, Balaclava Road, Sydney, NSW 2109, Australia; 313Research Centre for Astronomy, Astrophysics and Astrophotonics,
Macquarie University, Balaclava Road, Sydney,
NSW 2109, Australia; 4 International Space Science Institute–Beijing, 1 Nanertiao10-80021T(,).5(2)-64339.4(a)-5.9(t)2.61.7(p)--316.7(r)-6--316.cm-3(d)8ALMA resolves the hourglass magnetic field in G31.41+0.31

M. T. Beltrán et al.: Polarization in G31.41+0.31

1
M. T. Beltrán1 , M. Padovani1 , J. M. Girart2,3 , D. 3.
Galli, R. Cesaroni1 , R. Paladino4 , G. Anglada5 , R.
Results
Estalella6 , M. Osorio5 , R. Rao7 , Á. Sánchez-Monge8 , Q. Zhang9
3.1. Continuum emission 2
1
INAF-Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, I-50125 Firenze, Italy; Institut de Ciències de l’Espai
3shows the mapof theStokes I,
namely, thetotal inten(ICE, CSIC), Can Magrans s/n, E-08193 Cerdanyola delFigure
Vallès,1 Catalonia,
Spain;
Institutd’Estudis
Espacials
desity at 41.3mm, in G31. The
intensity map is consistent
with thede Catalunya (IEEC), E-08034 Barcelona, Catalonia, Spain;
INAF-Istituto
di Radioastronomia,
via P. Gobetti
mm dustCSIC,
continuum
emissionobtained s/n,
by BEL18
with
101, I-40129 Bologna, Italy; 5 Instituto de Astrofı́sica de 1.4
Andalucı́a,
Glorietade la map
Astronomı́a,
E-18008,
similar angularresolution.
The twocores detectedby BEL18
Granada, Spain; 6 Departament de Fı́sica Quàntica i Astrofı́sica,
Institutde Ciènciesdel Cosmos,
Universitat
deand named
NE7 andMain ofareAstronomy
clearly visible.
Thanks to theBarcelona, IEEC-UB, Martı́ i Franquès 1, E-08028 Barcelona,
Spain;
Instituteand Astrophysics,
8
higherUSA;
sensitivityof our polarized
observations,
we could
image
Academia Sinica 645 North Aohoku Place, Hilo, Hawaii 96720,
I. Physikalisches
Institut,
Universitätzu Köln,surrounding
both coresandZülpicher Str. 77, D-50937 Köln, Germany; 9 Center for low-intensity
Astrophysics extended| Harvardemission& Smithsonian,60
GardenStreet,00
additionalcores,
such
as
the
one
located⇠3
to the southeast ofCambridge, MA 02138, USA
the Main core. The morphology of the low-intensity (5 ) emisE-mail contact: mbeltran at arcetri.astro.itsion resembles that observed with the SMA at 870 µm and 100
resolution.
noticedBEL18, the revealed
Main coreContext. Submillimeter Array (SMA) 870 µm polarization angularobservationsof theAs
hotalreadymolecular
corebyG31.41+0.31
appears
rather uniform
and compact,
no hints
of fragmenone of the clearest examples up to date of an hourglass-shaped
magnetic
field morphology
in a withhigh-mass
star-forming
tation despite the fact that the synthesized beam is at least ten
region.
timesinless
the corediameter. However,as suggestedby these
Aims. To better establish the role that the magnetic field plays
thethancollapseof G31.41+0.31,
we carriedout Atacama
authors,
homogeneousand monolithic
appearanceof thecore
Large Millimeter/submillimeter Array (ALMA) observationsof thethepolarized
dust continuum
emission
at 1.3 mmwithis probably
due to a combinationof large
dust continuum
opacan angular resolution four times higher than that of the previous(sub)millimeter
observations
to achieve
an unpreceity and insufficient angular resolution to resolve the small-scaledented image of the magnetic field morphology.
structure of the extended component. In fact, new ALMA obserMethods. We used ALMA to perform full polarization observations at00 233 GHz (Band 6). The resulting synthesizedvations at ⇠0. 08 have resolved the core in at least four embedded
beam is 0.28” × 0.20” which, at the distance of the source, corresponds to a spatial resolution of ∼875 au.
sources, confirming that fragmentation has already taken place
Results. The observations resolve the structure of the magnetic
field in G31.41+0.31
and allow us to study the fieldin G31 (Beltrán
et al., in prep.).
in detail. The polarized emission in the Main core of G31.41+0.41
successfully
with thea semi-analyticalmagneThe totalis flux
measuredfitinside
5 contour level,
which
tostatic model of a toroid supported by magnetic fields. has
Thea best
that
field
well
size fitof model⇠400 orsuggests
15 000 au
at thethe magnetic
distance of
theissource,
1
represented by a poloidal field with a possible contributionofa toroidal
component
ofpeak∼10%
ofisthe369
poloidalcompois
6.86
±
0.06
Jy,
while
the
flux
±
1
mJy
beam
.
◦
◦
nent, oriented southeast to northwest at ∼ −44 and withan inclinationof ∼mode−45 of. The
magnetic fieldis oriented
Becauseof the TDM
the observations,which
provides341
perpendicular to the northeast to southwest velocity gradient
this core (⇠40
on scales
10 –10au. This
limiteddetected
spectralinresolution
km sfrom), andthe intenseline
supports the hypothesis that the velocity gradient is due torotationofofG31
the(e.g.,core andsuggestsa rotationhasemission
Beltrán
et al. that
2005;such
Rivillaet al. 2017),
little effect on the magnetic field. The strength of the magnetic
thethecentralof thewiththe totalfield
fluxestimatedmeasuredinfor
Stokesregion
I should
be coreconsidered
the Davis-Chandrasekhar-Fermi method is ∼8–13 mG andanimplies
ratiocontamination,in this region weis slightly
upper that
limit.theTo mass-to-flux
estimate the line
used thesupercritical (λ=1.4–2.2).
dust continuum emission flux obtained by BEL18, who carriedConclusions. The magnetic field in G31.41+0.31 maintains
an hourglass-shaped
down
to scalesofout observations
at 217 GHz morphology
with a similar
angularresolution
00(⇠0.
22) but muchithigher(2.7
km s 1 ) which<1000 au. Despite the magnetic field being important in
G31.41+0.31,
is notspectral
enoughresolution
to prevent
fragmentation
them
to sources
properlyembedded
determineinthe
level.
The
and collapse of the core, as demonstrated by the presenceallowedof at least
four
thecontinuum
center of thecore.
dust continuum emission inside the 5 contour level at 217 GHz
Accepted by A&A
is 3.75 Jy. We estimated the continuum dust emission flux athttps://www.aanda.org/articles/aa/pdf/2019/10/aa35701-19.pdf
233 GHz from that at 217 GHz adopting the scaling S ⌫ / ⌫↵ ,where the spectral index ↵ = 2 + and is the dust emissiv-

10

Probing planet formation and disk substructures in the inner disk of Herbig Ae stars
with CO rovibrational emission
Arthur D. Bosman1 , Andrea Banzatti2,3 , Simon Bruderer4 , Alexander G.G.M. Tielens1 , Geoffrey A.
Blake5 , and Ewine F. van Dishoeck1,4
1

Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands; 2 Department of Physics,
Texas State University, 749 N Comanche Street, San Marcos, TX 78666, USA; 3 Department of Planetary Sciences,
University of Arizona, 1629 East University Boulevard, Tucson, AZ 85721, USA; 4 Max-Planck-Institut für Extraterrestrische Physik, Gießenbachstrasse 1, 85748 Garching, Germany; 5 Division of Geological & Planetary Sciences,
California Institute of Technology, 1200 E California Blvd, Pasadena, CA 91125
E-mail contact: bosman at strw.leidenuniv.nl
CO rovibrational lines are efficient probes of warm molecular gas and can give unique insights into the inner 10 AU of
proto-planetary disks. Recent studies have found a relation between the ratio of lines originating from the second andfirst vibrationally excited state, denoted as ν2/ν1, and the emitting radius of CO. In disks around Herbig Ae stars thevibrational excitation is low when CO lines come from close to the star, and high when lines only probe gas at large
radii (more than 5 AU). We aim to find explanations for the observed trends between CO vibrational ratio, emitting
radii, and NIR excess, and identify their implications in terms of the physical and chemical structure of inner disks
around Herbig stars. Slab models and full disk thermo chemical models are calculated. Simulated observations fromthe models are directly compared to the data. Broad CO lines with low vibrational ratios are best explained by awarm (400–1300 K) inner disk surface with gas-to-dust ratios below 1000; no CO is detected within/at the inner dust
rim, due to dissociation at high temperatures. In contrast, explaining the narrow lines with high vibrational ratios
requires an inner cavity of a least 5 AU in both dust and gas, followed by a cool (100–300 K) molecular gas reservoir
with gas-to-dust ratios greater than 10000 at the cavity wall. In all cases the CO gas must be close to thermalization
with the dust. The high gas-to-dust ratios needed to explain high ν2/ν1 in narrow CO lines for a subset of group I
disks can naturally be interpreted as due to the dust traps that have been proposed to explain millimeter dust cavities.
The broad lines seen in most group II objects indicate a very flat disk in addition to inner disk substructures within
10 AU that can be related to the substructures recently observed with ALMA.
Accepted by A&A
http://arxiv.org/pdf/1909.02031

Signatures of an eccentric disc cavity: Dust and gas in IRS 48
Josh Calcino1 , Daniel J. Price2 , Christophe Pinte2,3 , Nienke van der Marel 4 , Enrico Ragusa5 , Giovanni
Dipierro5 , Nicolás Cuello6,7, Valentin Christiaens2

11

Signatures of an eccentric disc cavity: Dust and gas in IRS 48
Josh Calcino1 , Daniel J. Price2 , Christophe Pinte2,3 , Nienke van der Marel 4 , Enrico Ragusa5 , Giovanni
Dipierro5 , Nicolás Cuello6,7, Valentin Christiaens2
1
School of Mathematics and Physics, The University of Queensland, QLD 4072, Australia; 2 Monash Centre for Astrophysics (MoCA) and School of Physics and Astronomy, Monash University, Clayton Vic 3800, Australia; 3 Univ.
164
Grenoble Alpes, CNRS, IPAG, F-38000 Grenoble, France; Herzberg Astronomy & Astrophysics Programs, National
Research Council of Canada, 5071 West Saanich Road, Victoria BC V9E 2E7, Canada; 5 Department of Physics
and Astronomy, University of Leicester, Leicester, United Kingdom; 6 Instituto de Astrofı́sica, Pontificia Universidad
Católica de Chile, Santiago, Chile; 7 Núcleo Milenio de Formación Planetaria (NPF), Chile
E-mail contact: j.calcino at uq.edu.au
We test the hypothesis that the disc cavity in the ‘transition disc’ Oph IRS 48 is carved by an unseen binary companion.
We use 3D dust-gas smoothed-particle hydrodynamics simulations to demonstrate that marginally coupled dust grains
concentrate in the gas over-density that forms in the cavity around a low binary mass ratio binary. This produceshigh contrast ratio dust asymmetries at the cavity edge similar to those observed in the disc around IRS 48 and othertransition discs. This structure was previously assumed to be a vortex. However, we show that the observed velocity
map of IRS 48 displays a peculiar asymmetry that is not predicted by the vortex hypothesis. We show the unusual
kinematics are naturally explained by the non-Keplerian flow of gas in an eccentric circumbinary cavity. We further
show that perturbations observed in the isovelocity curves of IRS 48 may be explained as the product of the dynamicalinteraction between the companion and the disc. The presence of a ∼0.4 M! companion at a ∼10 au separation canqualitatively explain these observations. High spatial resolution line and continuum imaging should be able to confirm
this hypothesis.
Accepted by MNRAS
http://arxiv.org/pdf/1910.00161

The ALMA-PILS survey: propyne (CH3CCH) in IRAS 16293−2422
H. Calcutt1 , E. R. Willis2, J. K. Jørgensen3 , P. Bjerkeli1 , N. F. W. Ligterink4 , A. Coutens5 , H. S. P.
Müller6, R. T. Garrod2 , S. F. Wampfler4 and M. N. Drozdovskaya4
1

Department of Space, Earth and Environment, Chalmers University of Technology, 41296, Gothenburg, Sweden;
2
Departments of Chemistry and Astronomy, University of Virginia, Charlottesville, VA 22904, USA; 3 Niels Bohr
Institute, University of Copenhagen, Øster Voldgade 5−7, DK-1350 Copenhagen K., Denmark; 4 Center for Space andHabitability, University of Bern, Gesellschaftsstrasse 6, CH-3012 Bern, Switzerland; 5 Laboratoire d’Astrophysiquede Bordeaux, Univ. Bordeaux, CNRS, B18N, allée Geoffroy Saint-Hilaire, 33615 Pessac, France; 6 I. Physikalisches

12

The ALMA-PILS survey: propyne (CH3

13

The mass of dusty clumps with temperature and density structure
Riccardo Cesaroni1
1

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

E-mail contact: cesa at arcetri.inaf.it
We consider a dusty clump in the two cases of spherical and cylindrical symmetry to investigate the effect of temperature and density gradients on the observed flux density. Conversely, we evaluate how the presence of such gradientsaffects the calculation of the clump mass from the observed flux. We provide the reader with approximate expressions
relating flux density and mass in the optically thick and thin limits, in the Rayleigh-Jeans regime, and discuss thereliability of these expressions by comparing them to the outcome of a numerical code. Finally, we present an application of our calculations to three examples taken from the literature, which shows how the correction introduced after
taking into account temperature and density gradients may affect our conclusions on the stability of the clumps.
Accepted by Astronomy and Astrophysics
http://arxiv.org/pdf/1909.07259

Dust accretion in binary systems: implications for planets and transition discs
Yayaati Chachan1,2,3 , Richard A. Booth2 , Amaury H. M. J. Triaud4 and Cathie Clarke2
1

Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA; 2
Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK; 3 St John’s College,
University of Cambridge, Cambridge, CB2 1TP, UK; 4 School of Physics and Astronomy, University of Birmingham,
Edgbaston, Birmingham B15 2TT, UK
E-mail contact: ychachan at caltech.edu

The presence of planets in binary systems poses interesting problems for planet formation theories, both in cases
where planets must have formed in very compact discs around the individual stars and where they are located near
the edge of the stable circumbinary region, where in situ formation is challenging. Dust dynamics is expected toplay an important role in such systems, since dust trapping at the inner edge of circumbinary discs could aid in situ
formation, but would simultaneously starve the circumstellar discs of the solid material needed to form planets. Here
we investigate the dynamics of dust in binary systems using Smooth Particle Hydrodynamics. We find that all our
simulations tend towards dust trapping in the circumbinary disc, but the timescale on which trapping begins depends
on binary mass ratio (q) and eccentricity as well as the angular momentum of the infalling material. For q >∼ 0.1, wefind that dust can initially accrete onto the circumstellar discs, but as the circumbinary cavity grows in radius, dust
eventually becomes trapped in the circumbinary disc. For q = 0.01, we find that increasing the binary eccentricity

14

Dust accretion in binary systems: implications for planets and transition discs
Yayaati Chachan1,2,3 , Richard A. Booth2 , Amaury H. M. J. Triaud4 and Cathie Clarke2
1

Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA; 2
Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK; 3 St John’s College,
University of Cambridge, Cambridge, CB2 1TP, UK; 4 School of Physics and Astronomy, University of Birmingham,
Edgbaston, Birmingham B15 2TT, UK
E-mail contact: ychachan at caltech.edu

The presence of planets in binary systems poses interesting problems for planet formation theories, both in cases
where planets must have formed in very compact discs around the individual stars and where they are located near
the edge of the stable circumbinary region, where in situ formation is challenging. Dust dynamics is expected toplay an important role in such systems, since dust trapping at the inner edge of circumbinary discs could aid in situ
formation, but would simultaneously starve the circumstellar discs of the solid material needed to form planets. Here
we investigate the dynamics of dust in binary systems using Smooth Particle Hydrodynamics. We find that all our
simulations tend towards dust trapping in the circumbinary disc, but the timescale on which trapping begins depends
on binary mass ratio (q) and eccentricity as well as the angular momentum of the infalling material. For q >∼ 0.1, wefind that dust can initially accrete onto the circumstellar discs, but as the circumbinary cavity grows in radius, dust
eventually becomes trapped in the circumbinary disc. For q = 0.01, we find that increasing the binary eccentricity
increases the time required for dust trapping to begin. However, even this longer timescale is likely to be shorter thanthe planet formation timescale in the inner disc and is insufficient to explain the observed pre-transitional discs. This
indicates that increase in companion eccentricity alone is not enough to allow significant transfer of solids from theouter to the inner disc.
Accepted by MNRAS
https://arxiv.org/pdf/1908.11377

VLA cm-wave survey of young stellar objects in the Oph A cluster: constraining extreme
UV- and X-ray-driven disk photo-evaporation – A pathfinder for Square Kilometre
Array studies
A. Coutens1 , H. B. Liu2 , I. Jiménez-Serra3 , T. L. Bourke4 , J. Forbrich5 , M. Hoare6 , L. Loinard7,8 ,18

15

VLA cm-wave survey of young stellar objects in the Oph A cluster: constraining extreme
UV- and X-ray-driven disk photo-evaporation – A pathfinder for Square Kilometre
Array studies
A. Coutens1 , H. B. Liu2 , I. Jiménez-Serra3 , T. L. Bourke4 , J. Forbrich5 , M. Hoare6 , L. Loinard7,8 ,L. Testi2,9 , M. Audard10,11 , P. Caselli12 , A. Chacón-Tanarro13 , C. Codella9,14 , J. Di Francesco15,16 ,F. Fontani9 , M. Hogerheijde17,18, A. Johansen19 , 18
D. Johnstone15,16 , S. Maddison20 , O. Panić6 , L. M.
Pérez21 , L. Podio9 , A. Punanova22 , J. M. C. Rawlings23 , D. Semenov24,25 , M. Tazzari26 , J. J. Tobin27 ,M. H. D. van der Wiel28 , H. J. van Langevelde29,16 , W. Vlemmings30, C. Walsh6 and D. Wilner31
1

LAB, France; 2 ESO, Germany; 3 QMUL, UK; 4 SKA, UK; 5 University of Hertfordshire, UK; 6 University of Leeds,
UK; 7 IRyA, UNAM, México; 8 IA, UNAM, México; 9 INAF, Italy; 10 University of Geneva, Switzerland; 11 Universityof Geneva, Switzerland; 12 MPE, Germany; 13 OAN, Spain; 14 IPAG, France; 15 NRS-HAA, Canada; 16 Universityof Victoria, Canada; 17 Leiden University, The Netherlands; 18 API, The Netherlands; 19 Lund Observatory, Sweden;
20
CAS, Australia; 21 Universidad de Chile; 22 Ural Federal University, Russia; 23 UCL, UK; 24 Ludwig Maximilian
University, Germany; 25 MPIA, Germany; 26 University of Cambridge, UK; 27 NRAO, USA; 28 ASTRON, The
Netherlands; 29 JIVE, The Netherlands; 30 Chalmers University of Technology, Sweden; 31 CfA, USA
E-mail contact: acoutens at gmail.com
Observations of young stellar objects (YSOs) in centimeter bands can probe the continuum emission from growing dust
grains, ionized winds, and magnetospheric activity, which are intimately connected to the evolution of protoplanetarydisks and the formation of planets. We have carried out sensitive continuum observations toward the Ophiuchus A
star-forming region using the Karl G. Jansky Very Large Array (VLA) at 10 GHz over a field-of-view of 6! with aspatial resolution of θmaj × θmin ∼ 0.4!! × 0.2!! . We achieved a 5 µJy beam−1 root-mean-square noise level at thecenter of our mosaic field of view. Among the eighteen sources we detected, sixteen are YSOs (three Class 0, five
Class I, six Class II, and two Class III) and two are extragalactic candidates. We find that thermal dust emission
generally contributes less that 30% of the emission at 10 GHz. The radio emission is dominated by other types ofemission such as gyro-synchrotron radiation from active magnetospheres, free-free emission from thermal jets, free-freeemission from the outflowing photo-evaporated disk material, and/or synchrotron emission from accelerated cosmicrays in jet or protostellar surface shocks. These different types of emission could not be clearly disentangled. Our
non-detections towards Class II/III disks suggest that extreme UV-driven photoevaporation is insufficient to explain
the disk dispersal, assuming that the contribution of UV photoevaporating stellar winds to radio flux does not evolvewith time. The sensitivity of our data cannot exclude photoevaporation due to X-ray photons as an efficient mechanism
for disk dispersal. Deeper surveys with the Square Kilometre Array will be able to provide strong constraints on disk
photoevaporation.
Accepted by Astronomy & Astrophysics
http://arxiv.org/pdf/1909.03515

Sub-stellar companions of the young weak-line TTauri Star DoAr21
Salvador Curiel1 , Gisela N. Ortiz-León2 , Amy J. Mioduszewski3, and Rosa M. Torres4
1