Star Formation Newsletter#336 1-8
Yusuke Aso (KASI)

Resolving the outer ring of HD 38206 using ALMA and constraining limits
on planets in the system
Mark Booth ,1‹ Michael Schulz,1 Alexander V. Krivov,1 Sebastián Marino ,2,3 Tim D. Pearceand Ralf Launhardt2

1

1 Astrophysikalisches Institut und Universitätssternwarte, Friedrich-Schiller-Universität Jena, Schillergäßchen 2-3, D-07745 Jena, Germany
2 Max Planck Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg, Germany

3 Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK

Accepted 2020 October 23. Received 2020 October 21; in original form 2020 September 1

ABSTRACTHD 38206 is an A0V star in the Columba association, hosting a debris disc first discovered by IRAS. Further observations by
Spitzer and Herschel showed that the disc has two components, likely analogous to the asteroid and Kuiper belts of the Solarsystem. The young age of this star makes it a prime target for direct imaging planet searches. Possible planets in the system
can be constrained using the debris disc. Here, we present the first ALMA observations of the system’s Kuiper belt and fit themusing a forward modelling MCMC approach. We detect an extended disc of dust peaking at around 180 au with a width of
140 au. The disc is close to edge on and shows tentative signs of an asymmetry best fit by an eccentricity of 0.25+0.10−0.09 . We use
the fitted parameters to determine limits on the masses of planets interior to the cold belt. We determine that a minimum of four
planets are required, each with a minimum mass of 0.64 MJ , in order to clear the gap between the asteroid and Kuiper belts ofthe system. If we make the assumption that the outermost planet is responsible for the stirring of the disc, the location of its
inner edge and the eccentricity of the disc, then we can more tightly predict its eccentricity, mass, and semimajor axis to be+0.5+12
ep = 0.34+0.20−0.13 , mp = 0.7−0.3 M J , and ap = 76−13 au.
Key words: planet–disc interactions – circumstellar matter – stars: individual: HD 38206 – planetary systems – submillimetre:planetary systems.

1 I N T RO D U C T I O N
As one of the key components of a planetary system, studying debris
discs enables us to understand the current make-up of a planetarysystem and its formation and evolution. In recent years, the Atacama
Large Millimeter/submillimeter Array (ALMA) has made it possible
to image these discs at long wavelengths in much finer detail than
was previously possible (for a recent review, see Hughes, Duchêne &Matthews 2018). Of particular interest are systems where both debris
discs and at least one planet have been observed. Analysis of such
systems is of prime importance for understanding the interaction
between planets and the disc. Examples of such systems include

by Spitzer/MIPS (Rieke et al. 2005), Spitzer/IRS (Morales et al.
2009), Gemini/T-ReCS (Moerchen, Telesco & Packham 2010), andHerschel/PACS (Morales et al. 2016). By analysing both the resolved
Herschel images and the full SED, Morales et al. (2016) demonstratethat the system is seen close to edge on and has two belts at 11 and
160 au. The system is thought to be a member of the Columba
association (Torres et al. 2008), giving it an age of 42+6
−4 Myr (Bell,
Mamajek & Naylor 2015). The young age of this system means that
it is a prime candidate for direct imaging surveys, although no planets
have been detected so far. Shannon et al. (2016) developed a modelfor the minimum mass of planets required to clear a gap in a two belt
debris disc system. They use HD 38206 as an example case and show

Resolving the outer ring of HD 38206 using ALMA and constraining limits
on planets in the system
1‹

1

1

2,3

Mark Booth , Michael Schulz, Alexander V. Krivov, Sebastián Marino ,and Ralf Launhardt2

Tim D. Pearceの続き

1

1 Astrophysikalisches Institut und Universitätssternwarte, Friedrich-Schiller-Universität Jena, Schillergäßchen 2-3, D-07745 Jena, Germany
2 Max Planck Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg, Germany

Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK
次がわかっている。惑星は必要か？
(i)カスケードでダストができるほど微惑星が撹拌。
Accepted 2020 October 23. Received 2020 October 21; in original form 2020 September 1(ii)内側と外側のリングのギャップ。
(iii)⾮対称は動的相互作⽤。
ABSTRACT3

Ø 200 kmの微惑星がいくつかあったなら13 Myrで⼗分撹拌（Krivov&Booth18）。
Ø ⼩惑星帯とカイパーベルトのようにギャップは惑星を⽰唆。
Ø 同じ平⾯、同じ質量、円、log uniform spacingのとき必要な個数。
⻄に⻑い
ギリギリ安定な最⼤個数。その2倍の間隔でもギリギリ掃ける（最⼩個数）。
Ø 20 or 16ヒル半径離れた惑星が42 Myr以内に間の微惑星を散らす。
Key words: planet–disc interactions – circumstellar matter – stars: individual: HD 38206 – planetary systems – submillimetre:planetary systems.

1 I N T RO D U C T I O N
As one of the key components of a planetary system, studying debris
discs enables us to understand the current make-up of a planetarysystem and its formation and evolution. In recent years, the Atacama
Large Millimeter/submillimeter Array (ALMA) has made it possible
to image these discs at long wavelengths in much finer detail than
was previously possible (for a recent review, see Hughes, Duchêne &Matthews 2018). Of particular interest are systems where both debris
discs and at least one planet have been observed. Analysis of such
systems is of prime importance for understanding the interaction
between planets and the disc. Examples of such systems include

by Spitzer/MIPS (Rieke et al. 2005), Spitzer/IRS (Morales et al.
2009), Gemini/T-ReCS (Moerchen, Telesco & Packham 2010), andHerschel/PACS (Morales et al. 2016). By analysing both the resolved
Herschel images and the full SED, Morales et al. (2016) demonstratethat the system is seen close to edge on and has two belts at 11 and
160 au. The system is thought to be a member of the Columba
association (Torres et al. 2008), giving it an age of 42+6
−4 Myr (Bell,
Mamajek & Naylor 2015). The young age of this system means that
it is a prime candidate for direct imaging surveys, although no planets
have been detected so far. Shannon et al. (2016) developed a modelfor the minimum mass of planets required to clear a gap in a two belt
debris disc system. They use HD 38206 as an example case and show

Downloaded from https://academic.oup.com/mnras/article/500/2/1604/5942883 by KASI user on 12 February 2021

HD 38206 is an A0V star in the Columba association, hosting a debris disc first discovered by IRAS. Further observations by
Spitzer and Herschel showed that the disc has two components, likely analogous to the asteroid and Kuiper belts of the Solarsystem. The young age of this star makes it a prime target for direct imaging planet searches. Possible planets in the system
can be constrained using the debris disc. Here, we present the first ALMA observations of the system’s Kuiper belt and fit themusing a forward modelling MCMC approach. We detect an extended disc of dust peaking at around 180 au with a width of
140 au. The disc is close to edge on and shows tentative signs of an asymmetry best fit by an eccentricity of 0.25+0.10−0.09 . We use
the fitted parameters to determine limits on the masses of planets interior to the cold belt. We determine that a minimum of four
planets are required, each with a minimum mass of 0.64 MJ , in order to clear the gap between the asteroid and Kuiper belts ofthe system. If we make the assumption that the outermost planet is responsible for the stirring of the disc, the location of its
inner edge and the eccentricity of the disc, then we can more tightly predict its eccentricity, mass, and semimajor axis to be+0.5+12
ep = 0.34+0.20−0.13 , mp = 0.7−0.3 M J , and ap = 76−13 au.

Dynamical stellar masses of pre-main sequence stars in Lupus and Taurus obtained with ALMA
surveys in comparison with stellar evolutionary models
Teresa A. M. Braun,1 Hsi-Wei Yen,1 Patrick M. Koch,1 Carlo F. Manara,2 Anna Miotello,2 andLeonardo Testi2, 3
1 Academia Sinica Institute of Astronomy and Astrophysics, 11F of Astro-Math Bldg, 1, Sec. 4, Roosevelt Rd, Taipei 10617, Taiwan
2 European Southern Observatory (ESO), Karl-Schwarzschild-Str. 2, D-85748 Garching, Germany

mixのjarXiv:2012.07441v1 [astro-ph.SR] 14 Dec 2020

11
INAF/Osservatorio Astrofisico di Arcetri, Largo Enrico
Fermi 5, I-50125 Florence, ItalyØ 正確なIMFのためにMspec（PMSでばらつく）をM
dynで校正。
Table 5. Measured parameters
face-on disks
in the Lupus region
Ø ALMA, 0.12"-0.25",
1-3forMyr,
Lupus& Taurus(~150 pc)。
ABSTRACT
Name
RA
Dec
A
dist line data of pre-main sequence (PMS) stars in the Lupus and Taurus
We
analysed iarchivalPmolecularØ ダスト円盤からi,PAを決められるもの30(Lupus) + 37 (Taurus)。
star-forming regions
obtainedwith ALMA surveys with an integration time of a few minutes per
[ ]
[ ]
[pc]
13stacked
We
the
data
CO and C3-2（あればCNも）をスタック。
O (J = 2–1 & 3–2) and CN (N = 3–2, J = 7/2–5/2)
Ø 輝線の感度が不⼗分でもCO, 120.0±15.0
C18
Oof160J=2-1,
Sz83
15:56:42.29 source.
-37:49:15.82
16.0
to enhance
ratios, and measured the stellar masses of 45 out of 67 PMS stars
Sz113 16:08:57.78 lines-39:02:23.21· · · the signal-to-noise···163Ø 薄いケプラー円盤を基準としたラインプロファイルをスタックして最⾼のS/NになるM
Sz114 16:09:01.83 from
-39:05:12.79
16.0
160.0
the Keplerianrotation
in162
their circumstellar disks. The measured dynamical stellar masses were*とvsys。
comparedtothestellarmassesestimatedfromthespectroscopic
measurements
with
seven
di↵erent
Note—We measured the inclination and position angles with theØ プロファイルをガウシアンフィットしてガウシアンの重みで±1σを積分して信号とする。
molecular-line data forface-onevolutionary
disks whose inclination
angleswerestellarmodels.
Wefound that the magnetic model of Feiden (2016) provides the best
measured to be  30 with the continuum data.
2で50%まで。
estimateof the stellar masses in the mass range of 0.6 M  M  1.3 M with a deviation of <0.7
Ø ピーク<4σや線幅<3chansは不採⽤。空間は95%フラックス半径。エラーバーはχfrom the dynamical masses, while all the other models underestimate the stellar masses in this mass
range by 20% to 40%. In the mass rangeof <0.6 M , the stellar masses estimated with the magnetic
Ø 3DモデルDALIでチェック。i>70°ではM*を30%過⼤評価。
3

13

+6.0
4.0
+6.0
4.0

18

+25.0
10.0

?

13

model of Feiden (2016) have a larger deviation (> 2 ) from the dynamical masses, and other, nonmagnetic stellar evolutionary models of Siess et al. (2000), Bara↵e et al. (2015) and Feiden (2016) show
better agreements with the dynamical masses with the deviations of 1.4 to 1.6 . Our results show
the mass dependence of the accuracy of these stellar evolutionary models.
Keywords: Pre-main sequence stars (1290), Circumstellar disks (235), Stellar masses (1614), Stellar
evolutionary models (2046)
1. INTRODUCTION

The mass is an important characteristic of a star. It
determines not only the luminosity and temperature of
the star, but also its evolution and feedback to the interstellar medium (Burkert 2004; Ceverino & Klypin 2009).
Furthermore, mass determination of a large sample ofyoung stars is essential to constrain the initial massfunction (IMF). The IMF is a key to understand thephysics of star formation and is also important to understand the evolution of stellar clusters and galaxies(Je↵ries 2012; Hopkins 2018).
One method widely adopted to determine stellar
masses uses the information of the luminosity and e↵ective temperature of a star. By incorporating the physical

Diagram) is compared to the theoretical evolutionary
tracks from the stellar evolutionary models to constrain
the mass and age of the star. The advantage of this approach is the large number of stars that it can be applied
to. With existing facilities it is possible to perform surveys on large samples of stars and provide data for the
spectroscopic method to determine stellar masses (e.g.,
Rigliaco et al. 2012; Herczeg & Hillenbrand 2014; Alcaláet al. 2017; Manara et al. 2017).
eff evolutionary models are in gooddyn
The di↵erent stellar
agreement for main sequence (MS) stars and have been
compared with various precise direct measurements ofstellar mass (e.g., from orbital motion of binaries).
Therefore, this method is considered reliable for MS

M*とi, R, Mgas, Σに相関はないのでバイアス無し。
全密度

分⼦密度

分⼦種による差も無し。

Ø ⾼感度観測とも合う（Dとiをスケール後）。
Ø T を５つに分けてM が中央値より3倍外れるものは連星候補。

Dynamical stellar masses of pre-main sequence stars in Lupus and Taurus obtained with ALMA
surveys in comparison with stellar evolutionary models
Teresa A. M. Braun,1 Hsi-Wei Yen,1 Patrick M. Koch,1 Carlo F. Manara,2 Anna Miotello,2 andLeonardo Testi2, 3の続き

1 Academia Sinica Institute of Astronomy and Astrophysics, 11F of Astro-Math Bldg, 1, Sec. 4, Roosevelt Rd, Taipei 10617, Taiwan

mixのjarXiv:2012.07441v1 [astro-ph.SR] 14 Dec 2020

2 European Southern Observatory
17(ESO), Karl-Schwarzschild-Str. 2, D-85748 Garching, Germany
3 INAF/Osservatorio Astrofisico di Arcetri, Largo Enrico Fermi 5, I-50125 Florence, Italy

ABSTRACTØ M <0.6 M ではBHAC15, F16, SFD00が1.6σで合う。
Ø 0.6 ‒ 1.3 M はmagnetic F16のみ合う。他は2040%過⼩評価。
Ø magnetic F16が正しい場合、磁場でゆっくり収縮
するのでT Tauri期が⻑い可能性。
Ø しかし、magnetic F16は<0.6 Msunを説明できな
いので、星進化の物理がM に依ることを⽰唆。

We analysed archival molecular line data of pre-main sequence (PMS) stars in the Lupus and Taurus*
sunstar-forming regions obtained with ALMA surveys with an integration time of a few minutes per
source. We stacked the data of 13 CO and C18 O (J = 2–1 & 3–2) and CN (N = 3–2, J = 7/2–5/2)
lines to enhance the signal-to-noise ratios, and measured the stellar masses of 45 out of 67 PMS stars
sun dynamical stellar masses werefrom the Keplerian rotation in their circumstellar disks. The measured
compared to the stellar masses estimated from the spectroscopic measurements with seven di↵erent
stellar evolutionary models. We found that the magnetic model of Feiden (2016) provides the best
estimate of the stellar masses in the mass range of 0.6 M  M?  1.3 M with a deviation of <0.7
from the dynamical masses, while all the other models underestimate the stellar masses in this mass
range by 20% to 40%. In the mass range of <0.6 M , the stellar masses estimated with the magnetic
model of Feiden (2016) have a larger deviation (> 2 ) from the dynamical masses, and other, nonmagnetic stellar evolutionary models of Siess et al. (2000), Bara↵e et al. (2015) and Feiden (2016) show
better agreements with the dynamical masses with the deviations of 1.4 to 1.6 . Our results show*
the mass dependence of the accuracy of these stellar evolutionary models.
Keywords: Pre-main sequence stars (1290), Circumstellar disks (235), Stellar masses (1614), Stellar
evolutionary models (2046)

C14, BHAC15, F16: non-gray boundary、オパシ
ティが周波数で違う。
1. INTRODUCTION
Diagram) is compared to the theoretical evolutionary
tracks fromthe stellar
evolutionary models to constrain
The mass is an important characteristic of aPS99,
star. It Br12:
grayboundary。
the
mass
and
age
of
the
star. The advantage of this apdetermines not only the luminosity and temperature ofproachisthelarge
numberof stars that it can be applied
SFD00:
non-grayの解析的フィット。
the star, but also its evolution and feedback to the interto.
With
existing
facilities
it is possible to perform surstellar medium (Burkert 2004; Ceverino & Klypin 2009).
ü
対流のmixing
lengthもそれぞれ違う。
veys
on
large
samplesofstars
and provide data for the
Furthermore, mass determination of a large sample ofspectroscopic
methodtodeterminestellar masses (e.g.,young stars is essential to constrain the initialü massmagnetic
F16以外non-magnetic。
Rigliaco et al. 2012; Herczeg & Hillenbrand 2014; Alcaláfunction (IMF). The IMF is a key to understand thephysics of star formation and is also important to understand the evolution of stellar clusters and galaxies(Je↵ries 2012; Hopkins 2018).
One method widely adopted to determine stellar
Figure 6. Deviation between the spectroscopic and dynamical stellar
masses.uses
The namethe model is labelled
the upper
massestheofinformation
ofintheluminosity and e↵ecright corner of each diagram. Red crosses mark the mean deviations of the measurements in the respective mass ranges, andofinaTable
star.
incorporating
the physicaldashed vertical lines denote the three mass ranges. The calculatedtive
meantemperaturedeviations are shown
10. ByThe stars,
marked全密度

分⼦密度

et al. 2017; Manara et al. 2017).
The di↵erent stellar evolutionary models are in good
agreement for main sequence (MS) stars and have been
compared with various precise direct measurements ofstellar mass (e.g., from orbital motion of binaries).
Therefore, this method is considered reliable for MS

H2 mass–velocity relationship from 3D numerical simulationsof jet-driven molecular outflows
A. H. Cerqueira1 , B. Lefloch2 , A. Esquivel3 , P. R. Rivera-Ortiz2 , C. Codella4,2 , C. Ceccarelli2 , and L. Podio4
1

LATO/DCET, Universidade Estadual de Santa Cruz, Rod. Jorge Amado, km 16, Ilhéus, BA, CEP 45662-900, Brazil
e-mail: hoth@uesc.br
2
CNRS, Univ. Grenoble Alpes, IPAG, BP 53, 38000 Grenoble, France
e-mail: bertrand.lefloch@obs.ujf-grenoble.fr
3
Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, Apartado Postal 70-543, 04510 Ciudad de México,
Mexico4
INAF, Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy
Received 26 August 2020 / Accepted 1 December 2020
ABSTRACT
Context. Previous numerical studies have shown that in protostellar outflows, the outflowing gas mass per unit velocity, or mass–

velocity distribution m(v), can be well described by a broken power law / v . On the other hand, recent observations of a sample ofoutflows at various stages of evolution show that the CO intensity–velocity distribution, closely related to m(v), follows an exponential
law / exp( v/v0 ).
Aims. In the present work, we revisit the physical origin of the mass–velocity relationship m(v) in jet-driven protostellar outflows. We
investigate the respective contributions of the different regions of the outflow, from the swept-up ambient gas to the jet.
Methods. We performed 3D numerical simulations of a protostellar jet propagating into a molecular cloud using the hydrodynamicalcode Yguazú-a. The code takes into account the most abundant atomic and ionic species and was modified to include the H2 gas heating
and cooling.
Results. We find that by excluding the jet contribution, m(v) is satisfyingly fitted with a single exponential law, with v0 well in therange of observational values. The jet contribution results in additional components in the mass–velocity relationship. This empiricalmass–velocity relationship is found to be valid locally in the outflow. The exponent v0 is almost constant in time and for a given level ofmixing between the ambient medium and the jet material. In general, v0 displays only a weak spatial dependence. A simple modeling of
the L1157 outflow successfully reproduces the various components of the observed CO intensity–velocity relationship. Our simulations
indicate that these components trace the outflow cavity of swept-up gas and the material entrained along the jet, respectively.
Conclusions. The CO intensity–velocity exponential law is naturally explained by the jet-driven outflow model. The entrained material
plays an important role in shaping the mass–velocity profile.
Key words. stars: formation – ISM: jets and outflows

1. Introduction
Outflows from young stellar objects (YSOs) can exhibit agreat variety of morphological and physical characteristics. In
the youngest (104 yr) and deeply embedded Class 0 protostars (André et al. 2000), outflows are easily traced using the
CO molecule and their presence is ubiquitous in star forming
regions, indicating that they are a common manifestation of bothlow- and high-mass star formation processes (Wu et al. 2004;
Lee 2020). On the other hand, protostellar jets were first associ-H2 mass–velocity relationship from 3D numerical simulationsof jet-driven molecular outflows
A. H. Cerqueira1 , B. Lefloch2 , A. Esquivel3 , P. R. Rivera-Ortiz2 , C. Codella4,2 , C. Ceccarelli2 , and L. Podio4

ira et al.: Jet-cavity kinematical relationship1

LATO/DCET, Universidade Estadual de Santa Cruz, Rod. Jorge Amado, km 16, Ilhéus, BA, CEP 45662-900, Brazil
e-mail: hoth@uesc.br
2
CNRS, Univ. Grenoble Alpes, IPAG, BP 53, 38000 Grenoble, France
e-mail: bertrand.lefloch@obs.ujf-grenoble.fr
3
Fig. 8. ModelUniversidad
DR_SS at t = 400,
1200 andAutónoma
2000 yr (fromto bottom)Apartado
and for an inclination
angle i = 04510
30 . Left:
distribution
molecular
Instituto de Ciencias Nucleares,
Nacional
detopMéxico,
Postal 70-543,
Ciudadde of
México,mixdensity. Right: mass–velocity
gas column
relationship is depicted in black for each value of the jmix parameter, from jmix = 0.0 (first column) to
Mexicojmix = 1.0 (fourth column). The profiles were calculated considering the whole computational domain. The exponential best fit is drawn in red and
4
INAF, Osservatorio Astrofisico
Fermi 5, 50125 Firenze, Italy
the exponentdi
v0 Arcetri,is given forLargoeach jmixE.value.

Ø j が⼤きいと⾼速度成分増加àjet由来の分⼦ガスの寄与。
Ø 全質量と分⼦の差は先頭でのH2の乖離。

A. H. Cerqueira et al.: Jet-cavity kinemati

Received 26 August 2020 / Accepted 1 December 2020
ABSTRACT
Context. Previous numerical studies have shown that in protostellar outflows, the outflowing gas mass per unit velocity, or mass–

velocity distribution m(v), can be well described by a broken power law / v . On the other hand, recent observations of a sample ofoutflows at various stages of evolution show that the CO intensity–velocity distribution, closely related to m(v), follows an exponential
law / exp( v/v0 ).
Aims. In the present work, we revisit the physical origin of the mass–velocity relationship m(v) in jet-driven protostellar outflows. We
investigate the respective contributions of the different regions of the outflow, from the swept-up ambient gas to the jet.
Methods. We performed 3D numerical simulations of a protostellar jet propagating into a molecular cloud using the hydrodynamicalcode Yguazú-a. The code takes into account the most abundant atomic and ionic species and was modified to include the H2 gas heating
and cooling.
Results. We find that by excluding the jet contribution, m(v) is satisfyingly fitted with a single exponential law, with v0 well in therange of observational values. The jet contribution results in additional components in the mass–velocity relationship. This empiricalmass–velocity relationship is found to be valid locally in the outflow. The exponent v0 is almost constant in time and for a given level ofmixing between the ambient medium and the jet material. In general, v0 displays only a weak spatial dependence. A simple modeling ofFig. 9. Model
DR_P atthet = various
400, 1200,components
and 2000 yr andofforthe
an observed
inclination angle
i = 30 . The results arepresented for four
values of
the L1157 outflow successfully
reproduces
CO ofintensity–velocity
relationship.
Ourdifferent
simulations
the jet–ambient gas mixing degree jmix (from top to bottom): 0.0, 0.3, 0.6, 1.0. Left: maps of H2 column density obtained by integration over the
1 swept-up gas and the material entrained along the jet, respectively.
indicate that these components
trace
the
outflow
cavityofvelocity range between 1 and +150 km s . Right: mass–velocity relationship obtained for the molecular gas (black) and the fitted curve (red). The
0 The entrained material
exponent v0 is given foreach jmix value.
Conclusions. The CO intensity–velocity
exponential
law is naturally explained by the jet-driven outflow model.
plays an important role in shaping the mass–velocity profile.

Ø ⼤域的にも局所的にもexp(‒v/v )。
ß L1157のCO観測でも同じ傾向。
Close inspection of the mass–velocity relationships reveals profiles (case j = 0.0) and the presence of the jet as a bump
Key words. stars: formation–
ISM:
jets andoutflows
that the exponential
fitting(red curves) provides excellent solu- at v ' 40 km s for j= 1.0. Between these two extremes
mixのjØ
他の観測のv0(1.6-12.5)もage,
で説明
tions
over thewhole velocity range for jvaluesof 0.3. For we find great variability. Wei,
notejthatsomeresidual emission ismixhigher values of j , the high-velocity range of the distribution found in the low-velocity (1 < v < 20 km s ) range of the disv 10 km s is still accurately fitted, with a higher value of v , tribution, which can be fitted by two exponential functions. This
可能。
Nevertheless,the originof detailthe inmolecular
as can be seen in Fig. 9 (e.g., panels j = 0.6). This expresses
point is addressedin morethe followingoutflows
paragraph. associ1. Introduction
the fact that the jet contribution tends to make the mass–velocity
ated with YSOs is still debated (see Lee 2020, for a recent
distribution
shallower,
as discussed
above. On thetheØ
若いほど、説明に必要なj
Outflows from young stellar
objects(YSOs)
can exhibita otherthehand,mix（ジェットの寄
slopes in the intermediate velocity range depend onreview).
mixingThey are believed to be the by-product of an interacgreat
physicalcharacteristics.
In explain
Fig. 5. Model DR at t = 400 yr and an inclination
anglevariety
i = 30 . of
Themorphologicaltionthis:
betweenmorethatcollimatedjet and/or
wind,
level, andand weidentify two
mechanisms that may
the Thea results
we have discussed
so far referto theproduced
global mass–in or
400
yr,for fouri=30°与）が⼤きい。
results arepresented
different values of thethe jetand ambientof material
for v & 10Classkm s 0in thecase of swept-up
Hvelocity
relationship computed
over the whole computational
youngest(10 yr) and lackdeeplyembedded
protoby the star–diskinteraction,and its surrounding
medium (Ballygas mixing degree j (from top to bottom): 0.0,
0.3, (André
0.6, 1.0. Left:stars
et al. 2000), outflows are easily traced using the 2016). As the wind and/or jet bow shock propagate into the ambiH column density obtained by integration over the velocity
e of i = 60 . maps of全質量、分⼦COmolecule
and their presence is ubiquitous in star forming ent medium, the gas of the excavated cavity walls advances andrange,
between
+1
and
+150
km
s
.
Right:
mass–velocity
relationshiphe 0 km s <regions,
indicatingthat they are a common manifestation of both excites a profusion of molecular emission lines. For low mass
obtainedforthemoleculargas(black)
and
the
total
gas
(blue).
Bottom⽮印: パルスによるbump
g power law
分⼦密度
H swept-up
mass–
lowand high-massstar formation processes (Wu et al. 2004; YSOs in particular, this can take place via one of three mainn inside each panel: ( j = 1.0), the green dots correspond to the
mix
1

mix

mix

1

1

mix

0

mix

4.4. From large- to small-scale

4

1

mix

2

1

d 10 km s 1 <mix

A135, page 10 of 15

12

velocity relationship obtained by DC03 (see their Lee
Fig. 2).
We show2020).
On thethe other hand, protostellar jets were first associbest-fitting power laws m(v) / v to the velocity intervals v  10 km s 1

2

Fig. 10. Model DR_P at t = 1200 yr under an inclination of 30 . Top:map of H2 column density for jmix = 1.0. The location of the apertures
A1-A4 used to extract the mass–velocity relationships are drawn withblack circles. Bottom: mass–velocity relationship averaged over the circular apertures A1 to A4. The best exponential fits are drawn in dashedred. The value of v0 is given for each value of jet–ambient material
mixing ratio jmix = 0, 0.3, 0.6, 1.0.

縦が場所に対応。

mechanisms (see Arce et al. 2007, for a comprehensive review):
domain. However, the possibility of a local exponential fitting

positions.
bottom pa
We ve
consider athe mass–
the apertu
compariso
Our fivelocity di
fit m(v) /exponentia
flow is asomewhatrial ( jmix =between th
vides a ver
at all posi
for positio
These valmass–velo
A highposition A
appears th
velocity doutflow ca(intermitte
A clovelocity dtowards po
v = 25 km
tion is obs
In order t
the geommass–velo
times in th2000 yr, ato the plan
the mass–

5. Discu

5.1. Molec

Lefloch etH2 mass–velocity relationship from 3D numerical simulationsの続き
of jet-driven molecular outflows
A. H. Cerqueira1 , B. Lefloch2 , A. Esquivel3 , P. R. Rivera-Ortiz2 , C. Codella4,2 , C. Ceccarelli2 , and L. Podio4
A. H. Cerqueira et al.: Jet-cavity kinematical relationship1

LATO/DCET, Universidade Estadual de Santa Cruz, Rod. Jorge Amado, km 16, Ilhéus, BA, CEP 45662-900, Brazil
e-mail: hoth@uesc.br
2
CNRS, Univ. Grenoble Alpes, IPAG, BP 53, 38000 Grenoble, France
e-mail: bertrand.lefloch@obs.ujf-grenoble.fr
3
Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, Apartado Postal 70-543, 04510 Ciudad de México,
Mexico4
INAF, Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy
Received 26 August 2020 / Accepted 1 December 2020

低速
ABSTRACT
⾼速
L1157の観測
Context. Previous numerical studies have shown that in protostellar outflows, the outflowing gas mass perunit velocity, or mass–
velocity distribution m(v), can be well described by a broken power law / v . On the other hand, recent observations of a sample ofIRAM
30 m, CO 2-1
outflows at various stages of evolution show that the CO intensity–velocity distribution, closely related to m(v),follows an exponential
law / exp( v/v0 ).
Aims. In the present work, we revisit the physical origin of the mass–velocity relationship m(v) in jet-driven protostellar outflows. We
investigate the respective contributions of the different regions of the outflow, from the swept-up ambient gas to the jet.
Methods. We performed 3D numerical simulations of a protostellar jet propagating into a molecular cloud using the hydrodynamicalcode Yguazú-a. The code takes into account the most abundant atomic and ionic species and was modified to include the H2 gas heating
and cooling.
Results. We find that by excluding the jet contribution, m(v) is satisfyingly fitted with a single exponential law, with v0 well in therange of observational values. The jet contribution results in additional components in the mass–velocity relationship. This empiricalmass–velocity relationship is found to be valid locally in the outflow. The exponent v0 is almost constant in time and for a given level ofmixing between the ambient
mixmedium and the jet material. In general, v0 displays only a weak spatial dependence. A simple modeling of
the L1157 outflow successfully reproduces the various components of the observed CO intensity–velocity relationship. Our simulations
indicate that these components trace the outflow cavity of swept-up gas and the material entrained along the jet, respectively.
Conclusions. The CO intensity–velocity exponential law is naturally explained by the jet-driven outflow model. The entrained material
plays an important role in shaping the mass–velocity profile.

合うモデル
i=10°, j =0.9

mixのj

Key words. stars: formation – ISM: jets and outflows

1. Introduction

Nevertheless, the origin of the molecular outflows associ-Fig. 11. Left: model DR_P at t = 1200 yr under an inclination of 10 (towards
the YSOs
observer).
Top: debatedmap of H(see= 0.9, inated withis still
Lee density
2020, forfor jmixa recent
2 column
the velocity
intervals
25 km
s 1 ] (top)and [30km s 1 ]a (bottom).
TheThey
5000 areau apertureused
the mass–velocity
distribution
Outflows
fromyoung [1stellarobjects(YSOs)
can 45
exhibitreview).
believed
to tobeextract
the by-productof an interacis drawn
by ofa circle.
Bottom: molecularmass–velocity
distribution
at position
A4. Wehave superposed
the best
exponential
greatvarietymorphologicaland physicalcharacteristics.
Inextractedtion between
a morecollimatedjet and/or
wind,
producedfitsinm(v)or /4components associated with velocity intervals [1 25 km s 1 ] (red) and [30 45 km s 1 ] (blue). The exponent value vi is given
exp(
v/v
)
to
the
i
the youngest (10 yr) and deeply embedded Class 0 proto- by the star–disk interaction, and its surrounding medium (Bally
for both velocity intervals. Right: ASAI observations of L1157-B1. Top : intensity–velocity distribution obtained in the CO J = 2–1 towards shockstars(André et al. 2000), outflows are easily traced using the 2016). As the wind and/or jet bow shock propagate into the ambiposition B1 in an aperture of about 4000 au (1100 at the distance to the source). The line profile is fitted by a linear combination of two exponential
COfunctions
molecule
theirpresence
in star forming ent medium, the gas of the excavated cavity walls advances andg1 and/ exp(
v/12.5)(blue),isgubiquitous
2 / exp( v/4.4) (red) (from Lefloch et al. 2012). Bottom: associated mass–velocity distribution, adopting a
excitesa profusionof molecularemissionlines.g1For
regions,
indicating
that
they
are
a
commonmanifestationof bothstandard CO-to-H2 abundance ratio and the excitation conditions
derivedby Leflochet al. (2012)
for the velocity
components
andlow
g2 . mass

Ø モデルの⾼速成分はjet shock impact region (Mach disk)だけではなく、フィラメント状。
Ø ⾼速分⼦流（L1157など）全体を⼲渉計で観測すればわかる。
全密度
分⼦密度
low- and high-mass star formation processes (Wu et al. 2004;
Lee 2020). On the other hand, protostellar jets were first associ-YSOs in particular, this can take place via one of three main
mechanisms (see Arce et al. 2007, for a comprehensive review):

Instituto Nacional de Astrofı́sica, Optica y Electrónica, Luis Enrique Erro 1, Sta. Ma. Tonantzintla, Puebla, CP 72840, Mexico

3 Instituto de Astrofı́sica de Canarias, Calle Vı́a Láctea S/N, E-38205 La Laguna, Tenerife, SpainMNRAS 500, 5552–5560 (2021)

doi:10.1093/mnras/staa3631

4 Byurakan Astrophysical Observatory,
Advance Accesspublication
2020Aragatzotn,
November 21 Armenia
Byurakan
0213,

The age of the carina young association and potential membership
Accepted 2020 November 13. Received
November 13; in original form 2020 July 17
of HD 2020
95086
Mark Booth ,1‹ Carlos del Burgo2,3 and Valeri V. Hambaryan

ABSTRACT

1,4

1 Astrophysikalisches Institut und Universitätssternwarte, Friedrich-Schiller-Universität Jena, Schillergäßchen 2–3, D-07745 Jena, Germany
2 Instituto Nacional de Astrofı́sica, Óptica y Electrónica, Luis Enrique Erro 1, Sta. Ma. Tonantzintla, Puebla, CP 72840, Mexico
3

Downloaded from https://academic.oup.com/mnras/article/500/4/5552/5998234 by KASI user on 12 Februde Astrofı́sica de Canarias, Calle Vı́a Láctea S/N, E-38205 La Laguna, Tenerife, Spain
Carina is a nearby young4 Instituto
stellarassociation.
far,0213,only
a small
Byurakan
AstrophysicalObservatory, So
Byurakan
Aragatzotn,
Armenianumber of stars have been clearly identified as members of
this association. In this paper, we reanalyse the membership of the association in light of Gaia DR2 data, in particular finding
Accepted
2020 November
13. Received 2020 November
form2020 July
17 is noteworthy as one of the few stars that hosts boththat HD 95086 is a potential
member(probabilityof 71 13;perin originalcent).
Thisstar
a detected debris disc and a directly imaged planet. It has previously only been considered as a potential member of the Lower
B S T RofA CtheT Scorpius–Centaurus association. We also reanalyse the age of the Carina association. Using
Centaurus Crux (LCC) –Apart
Carina is a nearby young stellar association. So far, only a small number of stars have been clearly identified as members ofa Bayesian inference codethisapplied
to infer a solution from stellar evolution models for the most probable (>99 per cent) members
association. In this paper, we reanalyse the membership of the association in light of Gaia DR2 data, in particular finding+1.1
that HDa potential member(probability
71 permuchcent). This
star is noteworthy
as one of the studies.
few stars thathosts bothwe have revised
Myr,youngerthan previous
Whilstof Carina, we infer an age
for95086
the isassociationof 13.3−0.6 ofa detected debris disc and a directly imaged planet. It has previously only been considered as a potential member of the Lower
HD 95086’s association membershipfrom LCC to Carina, the fact that we also find Carina to have a younger age, similar to that
Centaurus Crux (LCC) – part of the Scorpius–Centaurus association. We also reanalyse the age of the Carina association. Usingof LCC, means that the estimatesof HDcode
95086b’s
mass
remainHowever,
theprobableyoungerof Carina
a Bayesian inference
applied to infera solution
fromunchanged.
stellar evolution models
for the most(>99ageper cent)
members does mean that
+1.1
Myr, amuch
youngerpreviousclearlystudies. Whilst
we planet
have revised
Carina, wemember,infer an ageHDfor theassociationof 13.3−0.6hasthe companion to anotherof Carina
44627
(AB
Pic),
mass
thatthanis morein therather than brown
HD 95086’s association membership from LCC to Carina, the fact that we also find Carina to have a younger age, similar to thatdwarf range.
of LCC, means that the estimates of HD 95086b’s mass remain unchanged. However, the younger age of Carina does mean thatthe companion to another Carina member, HD 44627 (AB Pic), has a mass that is more clearly in the planet rather than brown
dwarf
range. – stars: evolution – stars: individual: HD 95086 – stars: kinematics and dynamics – planetarycircumstellar
matter

Key words:
Key associations:words: circumstellar
matter – stars: evolution – stars: individual: HD 95086 – stars: kinematics and dynamics – planetarysystems – open clusters andgeneral.
systems – open clusters and associations: general.

(2018a) compared to 20 and 45 bona fide members for Columba and(2018a)compared
Tuc-Hor,
respectively.to 20 and 45 bona fide members for Columba and1 I N T RO D U C T I O N There are a number of methods for determining the age of aIn
thispaper, we reconsider the membership of the Carina
Tuc-Hor, respectively.
star. These include using gyrochronology, X-ray emission, lithium
association in Section 2 based on the Gaia DR2 data. In doing so,
There are a number of methods
for determining
the ageofmodels.
a Not Inwethis
paper,
we isreconsider
themembermembershipof the Carina
depletion, chromosphericactivity, and stellar
evolution
proposethat HD 95086
a potential Carina
for the firstallmethods
workequally
well
for
all
spectraltypes
andevolution
time.
The
age
of
this
star
is
of
particularinterest
as
it
hosts
both
a
star. These include using gyrochronology, X-ray emission, lithium
phases, and the accuracy for an individual star is usually not highdirectly imaged planet and a resolved debris disc. In Section 3, wedepletion, chromospheric activity,and 2012).
stellarevolutionmodels.
Not(see e.g. Vican
However,most stars
are thought
to form inthen reconsider the age of the association, first by comparing stellar
clustersfor
that allslowlydisperse into
associations(e.g. Ambartsumianevolution models to the Gaia photometry and then by considering
all methods work equally wellspectraltypes
and evolution
1 I N T RO D U C T I O N

1947; Blaauw 1964) before dispersing completely into the Galactic

the kinematic evolution of the association. We conclude in Section 4

Institut d’Estudis Espacials de Catalunya, E-08030 Barcelona, Catalonia, Spain
Universidad de Chile, Camino el Observatorio 1515, Las Condes, Santiago de Chile, Chile
9
The Graduate
University
for Advanced Studies, SOKENDAI, Osawa 2-21-1, Mitaka, Tokyo 181-8588, JapanThe Explosion
10 in Orion-KL as Seen by Mosaicking the Magnetic Field with ALMANRAO Array Operations Center, P.O. Box O, Socorro, NM, USA
11Paulo C. Cortes1,2 , Valentin J. M. Le Gouellec3,4, Charles L. H. Hull2,5,12 , Josep M. Girart6,7 , Fabien Louvet4,8,
National Astronomical
Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan
Edward B. Fomalont1,2 , Seiji Kameno2,5,9 , George A. Moellenbrock10 , Hiroshi Nagai9,11 , Kouichiro Nakanishi9,11 , andReceived 2020 October 1; revised 2020 NovemberEric
3; Villard
accepted
2020 November 15; published 2021 February 2
2,3© 2021. The American Astronomical Society. All rights reserved.

8

1

National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903, USA; paulo.cortes@alma.cl
2
Joint ALMA Observatory, Alonso de Córdova 3107, Vitacura, Santiago, Chile
3
European Southern Observatory, Alonso de Córdova 3107, Vitacura, Santiago, Chile
4
Université Paris-Saclay, CNRS, CEA, Astrophysique, Instrumentation et Modélisation de Paris-Saclay, F-91191, Gif-sur-Yvette, France
5
National Astronomical Observatory of Japan, NAOJ Chile, Alonso de Córdova 3788, Ofﬁce 61B, 7630422, Vitacura, Santiago, Chile
6
Institut de Ciències de l’Espai (ICE-CSIC), Campus UAB, Carrer de Can Magrans S/N, E-08193 Cerdanyola del Vallès, Catalonia, Spain
7
Institut d’Estudis Espacials de Catalunya, E-08030 Barcelona, Catalonia, Spain
8
Universidad de Chile, Camino el Observatorio 1515, Las Condes, Santiago de Chile, Chile
9
The Graduate University for Advanced Studies, SOKENDAI, Osawa 2-21-1, Mitaka, Tokyo 181-8588, Japan
10
NRAO Array Operations Center, P.O. Box O, Socorro, NM, USA
11
National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan
Received 2020 October 1; revised 2020 November 3; accepted 2020 November 15; published 2021 February 2

Abstract
We present the ﬁrst linear-polarization mosaicked observations performed by the Atacama Large Millimeter/
submillimeter Array (ALMA). We mapped the Orion-KLeinmann-Low (Orion-KL) nebula using super-sampled
mosaics at 3.1 and 1.3 mm as part of the ALMA Extension and Optimization of Capabilities program. We derive themagnetic ﬁeld morphology in the plane of the sky by assuming that dust grains are aligned with respect to the ambient
magnetic ﬁeld. At the center of the nebula, we ﬁnd a quasi-radial
Abstract magnetic ﬁeld pattern that is aligned with the explosive
We present
the ﬁrst linear-polarization
mosaicked au),observations
performedby thethe Atacama
Millimeter/transitions into a quasiCO outﬂow up to a radiusof approximately
12″ (∼5000
beyondwhichpatternLargesmoothlysubmillimeter Array (ALMA). We mapped the Orion-KLeinmann-Low (Orion-KL) nebula using super-sampled
hourglass shape resembling
morphology
in larger-scaleobservations
byprogram.
the James-Clerk-Maxwell
Telescopemosaics atthe
3.1 and
1.3 mm as part ofseen
the ALMA
Extension and Optimizationof Capabilities
We derive themagneticﬁeldmorphology
in
the
plane
of
the
sky
by
assumingthat
dust
grainsarealignedwithrespecttotheambient(JCMT). We estimate an average magnetic ﬁeld strength  B§  9.4 mG and a total magnetic energy of 2×1045 erg,
magnetic ﬁeld. At the center of the nebula, we ﬁnd a quasi-radial magnetic ﬁeld pattern that is aligned with the explosive
which is three orders oflessof approximately
than the 12″energythe explosiveCO
outﬂow.
that the ﬁeld has
CO magnitude
outﬂow up to a radius(∼5000 inau), beyond
which the patternsmoothlytransitionsWe
into aconclude
quasihourglass shape resembling the morphology seen in larger-scale observations by the James-Clerk-Maxwell Telescope
been overwhelmed by theoutﬂow and that a shock is propagating from the center of the nebula, where the shock front is(JCMT). We estimate an average magnetic ﬁeld strength  B§  9.4 mG and a total magnetic energy of 2×1045 erg,
which isthree orders
magnitude lessthe energy
the explosive
outﬂow. We center.
conclude that the ﬁeld has
seen in the magnetic ﬁeld
lines
at aofdistanceofthan∼5000
auin fromthe CO
explosion
been overwhelmed by the outﬂow and that a shock is propagating from the center of the nebula, where the shock front isseen in the magnetic ﬁeld lines at a distance of ∼5000 au from the explosion center.

Uniﬁed Astronomy Thesaurus concepts: Astrochemistry (75); Polarimetry (1278); Dust continuum( )Uniﬁed Astronomy Thesaurus concepts: Astrochemistry (75); Polarimetry (1278); Dust continuum emission (412);
Star formation (1569); Protostars (1302); Shocks (2086); Interstellar dust (836); Young stellar objects (1834);
Interstellar magnetic ﬁelds (845)
1. Introduction
The Orion nebula has been a subject of intense research since its
discovery by Fabri de Peiresc in 1610 (Miller 2016). Home to theTrapezium, a star cluster containing massive stars, the Orion
nebula also hosts the closest high-mass star-forming region to theSun: the Orion integral-shaped ﬁlament (Johnstone & Bally 1999).
This one-degree-long, 2200 Me ﬁlament is embedded in the
50,000 Me Orion A cloud (Bally et al. 1987). The ∼100 Me Orion
Molecular Core 1 (OMC1), located behind the Orion nebula(Genzel & Stutzki 1989) at a distance of ∼414 pc (Menten et al.
2007), is the densest and most molecule-rich part of the Orion A
cloud. OMC1 contains the Orion-KL nebula, which has beenmassive stars in the nebula, as suggested by the high-velocity
proper motions of BN, source I, and source x (Bally et al.
2017, 2020). This explosion affected the surrounding gas, as
shown by vibrationally excited H2 and [Fe II] emission thatreveals a spectacular network of collimated outﬂows known as the“Orion ﬁngers,” which extend for 0.1 pc in a wide-angle, conicalconﬁguration (Allen & Burton 1993; Colgan et al. 2007; Ballyet al. 2015). A plethora of observations of additional outﬂow
tracers conﬁrm this link between the outﬂow and the explosive
event. In the millimeter, the ﬁngers were detected in high-velocity
CO emission by the Submillimeter Array (SMA; Zapata et al.

1

Yuji Ebisawa, Nami, KarlM.
The AstrophysicalJournal, Sakai
904:136 (13pp), 2020
December
1 Menten, Yoko Oya https://doi.org/10.3847/1538-4357/abc16f, and Satoshi Yamamoto© 2020. The American Astronomical Society. All rights reserved.
Department of Physics
and Research Center for the Early Universe, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
2
RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
3
Max-Planck-Institut
Auf
dem Hügel
69, Intensity
D-53121 Bonn,
Germany
Temperature Structurefürof Radioastronome,
the Pipe NebulaStudiedby theAnomalyof the OH
Received 2020 March 12; revised 2020 September
29;
accepted
2020
October
13;
published
2020
November 27
18 cm Transition1

Yuji Ebisawa1, Nami Sakai2, Karl M. Menten3

Abstract, Yoko Oya1

, and Satoshi Yamamoto1

Department of Physics and Research Center for the Early Universe, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
2
RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
3
Max-Planck-Institut für Radioastronome, Auf dem Hügel 69, D-53121 Bonn, Germany
Received 2020 March 12; revised 2020 September 29; accepted 2020 October 13; published 2020 November 27

We present observations of the four hyperﬁne structure components of the OH 18 cm transition (1612, 1665, 1667,
and 1720 MHz) toward a ﬁlamentary dark cloud, the Pipenebula, with the Green Bank Telescope. A statistical
Abstract
present observationsof the four hyperﬁne
structurecomponentsof the OH 18 cmoftransition(1612, 1665,
1667,
equilibrium analysis is We
appliedto the spectra,
and thekinetic
temperaturea diffusemolecular
gas surrounding
and 1720 MHz) toward a ﬁlamentary dark cloud, the Pipe nebula, with the Green Bank Telescope. A statisticaldense cores is determinedaccurately;
the derived
temperature
ranges offrom
40molecular
to 75 gas
K.surrounding
From this result, we assess
equilibrium
analysis is applied
to the spectra,
and the kinetic temperaturea diffuse
dense
cores
is
determinedaccurately;thederivedtemperature
ranges
from
40
to
75
K.
From
this
result,we assess from a nearby star
the heating effect on theﬁlamentary structure of the nebula’s “stem” region due to UV photons
the heating effect on the ﬁlamentary structure of the nebula’s “stem” region due to UV photons from a nearby starθ-Ophiuchi and a possible
ﬁlament–ﬁlamentcollisionin thetheand“stem”
and “bowl”
θ-Ophiuchi
and a possible ﬁlament–ﬁlamentcollisionin the interface
interface of theof“stem”“bowl” regions.
In the stem regions. In the stem
region, the gas kinetic temperature is found to be almost independent of the apparent distance from θ-Ophiuchi: theregion, the gas kinetic temperatureis thefound
to visible.
be almostindependentof theapparent
distance
UV-heating effect bystar is not
On the other
hand, the gas kinetic
temperatureis raised,as high asfrom θ-Ophiuchi: the∼75 K,
at theof the two ﬁlamentaryThis resultthe
provideswith additional
support for the is raised, as high as
UV-heating effect by thestarisinterface
not visible.
On the structures.
other hand,gasuskinetic
temperatureﬁlament–ﬁlament collision scenario in the Pipe nebula.
∼75 K, at the interfaceUniﬁedof thetwo ﬁlamentary structures. This result provides us with additional support for the
Astronomy Thesaurus concepts: Molecular clouds (1072); Interstellar molecules (849)
ﬁlament–ﬁlament collision scenario in the Pipe nebula.
the bowl region
exhibiting an extended
structure(849)
in the eastern
1. IntroductionMolecular clouds (1072);
Uniﬁed Astronomy Thesaurus concepts:
Interstellar
molecules
part. Since the Pipe nebula is a nearby (∼145 pc) object (Alves
The 18 cm transition of the hydroxyl radical (OH) has
extensively been observed toward molecular clouds, late-typestars and external galaxies (e.g., Harju et al. 2000; Darling &Giovanelli 2002; Caswell 2004; Hoffman et al. 2005; Wolak
al. 2012; Ebisawa et al. 2015, 2019; Xu et al. 2016; Li et al.
k etk2018). It is the Λ-type doubling transition in the groundrotational state, and consists of four hyperﬁne structure (hfs) lines
at 1612, 1665, 1667, and 1720 MHz. It is well known that theobserved intensity ratio of the four hfs lines is often different
from the ratio expected in the local thermodynamic equilibrium(LTE) condition; I1612: I1665: I1667: I1720  1: 5: 9: 1 (e.g., Harju
et al. 2000; Ebisawa et al. 2015). Such intensity anomalies can becaused by collisional and/or radiative processes among therotational states (Elitzur et al. 1976; van Langevelde et al. 1995;
Ebisawa et al. 2019). Ebisawa et al. (2015), on the basis of theirstatistical equilibrium calculations, reported that the intensity
ratio is sensitive to the gas kinetic temperature. They demonstrated that the gas kinetic temperature of warm (Tk  30 K)
molecular clouds can be determined accurately from theobserved intensities. Furthermore, the critical density of the& Franco 2007) with little star formation activity except for the
B59 region (Onishi et al. 1999), it has been a good target to
study molecular-cloud formation (Lada et al. 2008; RománZúñiga et al. 2010). Its magnetic-ﬁeld structure has been
investigated by polarimetry (Alves et al. 2008, 2014; Franco
et al. 2010). A bright B2 IV star, θ Ophiuchi (HD 157056), is
located about 3 pc away from the Pipe nebula (Figure 1), andfeedback with this star has been invoked for shaping thestructure and the formation process of the nebula (Onishi et al.
1999; Gritschneder & Lin 2012).
The velocity structure of the Pipe nebula was studied in the12
CO along with its isotopologue lines. Figure 2 shows theintegrated intensity maps of the 13CO (J  1–0) (cyan contours)
and 12CO (J  1–0 ) (red contours) lines by Onishi et al. (1999)
overlaid on the visual extinction (AK) map of Figure 1. The 12CO
map is prepared by integrating over the velocity range from 6 to
10 km s−1 (Onishi et al. 1999). As shown in Figure 2, the 13CO
line traces a ﬁlamentary structure elongated along the west toeast direction, which is seen in the visual extinction map. We
hereafter call this structure the W-E ﬁlament. On the other hand,

Green Bank Telescope, OH 18 cm, Pipe nebula。
the bowl region exhibiting an extended structure in the eastern
Introduction
正確なT1. =40-75
K。幹ではT がθ-Ophiuchiからの距離に依らないのでUV-heating無し。
part. Since the Pipe nebula is a nearby (∼145 pc) object (Alves
The 18 cm ⼆つのフィラメントの交差点に向かってT
transition of the hydroxyl radical (OH) has kが増加。フィラメント衝突。
& Franco 2007) with little star formation activity except for theextensively been observed toward molecular clouds, late-typestars and external galaxies (e.g., Harju et al. 2000; Darling &Giovanelli 2002; Caswell 2004; Hoffman et al. 2005; Wolak
et al. 2012; Ebisawa et al. 2015, 2019; Xu et al. 2016; Li et al.
2018). It is the Λ-type doubling transition in the groundrotational state, and consists of four hyperﬁne structure (hfs) lines
at 1612, 1665, 1667, and 1720 MHz. It is well known that theobserved intensity ratio of the four hfs lines is often
different
2−3

B59 region (Onishi et al. 1999), it has been a good target to
study molecular-cloud formation (Lada et al. 2008; RománZúñiga et al. 2010). Its magnetic-ﬁeld structure has been
investigated by polarimetry (Alves et al. 2008, 2014; Franco
et al. 2010). A bright B2 IV star, θ Ophiuchi (HD 157056), is
located about 3 pc away from the Pipe nebula (Figure 1), andfeedback with this star has been invoked for shaping thestructureand the formation process of the nebula (Onishi et al.
12

A. Eckart , F. Eisenhauer , M. Filho, F. Gao , E. Gendron , R. Genzel , S. Gillessen , R. Grellmann ,9119
M. Habibi , X. Haubois , F. Haussmann , T. Henning1 , S. Hippler1 , Z. Hubert16 , M. Horrobin6 , A. Jimenez Rosales9 ,The GRAVITY young stellar object survey
L. Jocou16 , P. Kervella10 , J. Kolb11 , S. Lacour10 , J.-B. Le Bouquin16 , P. Léna10 , H. Linz1 , T. Ott9 , T. Paumard10 ,1
IV. The1 ,CO
Oph at sub-au
G. Perrin10 , O. Pfuhl4 , M. C. Ramírez-Tannus
C. overtone
Rau9 , G. emission
Rousset10in, S.51Scheithauer, J.scales
Shangguan9 , J. Stadler9 ,9,15
10
9 2,3,59
O. Straub9 , C. Straubmeier6 , E.GRAVITY
Sturm9 ,Collaboration:
E. van Dishoeck, F. ?Vincent, S.1,2,3
von, F. Widmann,
M. Koutoulaki1,2,3,4,, R. Garcia Lopez, A.Fellenberg
Natta2 , R. Fedriani,
16
9 Garatti1,2,3 , T. P.6 Ray2 , D. Coffey2,1 , W.
9 Brandner1 , C. 9,6
11 7,8,11 , L. Klarmann1 ,A.
CarattioDougados,
P.
J.
V.
GarciaE. Wieprecht, M. Wiest , E. Wiezorrek , S. Yazici , and G. Zins
L. Labadie6 , K. Perraut16 , J. Sanchez-Bermudez1,18 , C.-C. Lin1,19 , A. Amorim8,17 , M. Bauböck9 , M. Benisty16,14 ,9J. P. Berger16 , A.(Affiliations
Buron9 , P. Caselli
Y. foundClénet10after, V. Coudé
du Foresto10 , P. T. de Zeeuw15,9 , G. Duvert16 , W. de Wit11 ,can ,bethereferences)
6,12
9
7,8,11
9
A. Eckart , F. Eisenhauer , M. Filho, F. Gao , E. Gendron10 , R. Genzel9,13 , S. Gillessen9 , R. Grellmann6 ,911
9
M. Habibi , X. Haubois , F. Haussmann , T. Henning1 , S. Hippler1 , Z. Hubert16 , M. Horrobin6 , A. Jimenez Rosales9 ,
16
10
11
10
L. JocouReceived, P. Kervella, J. Kolb2020, S. Lacour, J.-B.
LeOctober
Bouquin16, P. Léna10 , H. Linz1 , T. Ott9 , T. Paumard10 ,
22
March
/
Accepted
20
2020
G. Perrin10 , O. Pfuhl4 , M. C. Ramírez-Tannus1 , C. Rau9 , G. Rousset10 , S. Scheithauer1 , J. Shangguan9 , J. Stadler9 ,O. Straub9 , C. Straubmeier6 , E. Sturm9 , E. van Dishoeck9,15 , F. Vincent10 , S. von Fellenberg9 , F. Widmann9 ,9E. Wieprecht, M. Wiest6 , E. Wiezorrek9 , S. Yazici9,6 , and G. Zins11
ABSTRACT(Affiliations can be found after the references)

Context. 51 Oph is a Herbig Ae/Be star that exhibits strong near-infrared CO ro-vibrational emission at 2.3 µm, most likely originating

Received 22 March 2020 / Accepted 20 October 2020in the innermost regions of a circumstellar disc.
Aims. We aim to obtain the physical and geometrical properties of the system by spatially resolving the circumstellar environment of
ABSTRACTthe inner gaseous disc.
Context. 51 Oph
is aLarge
Herbig Ae/Be
star that exhibits
strong near-infrared
CO ro-vibrationalemission atto2.3spatiallyµm, most likely
originating
Methods. We used the second-generation
Very
TelescopeInterferometer
instrument
GRAVITY
resolvethe continin the innermost regions of a circumstellar disc.
uum and the CO overtone emission.
We
obtained
data
over
12
baselineswiththeauxiliary
telescopes
andderivevisibilities,
and theAims. We aim to obtain the physical and geometrical properties of the system by spatially resolving the circumstellar environment of
inner gaseous
differential and closure phases as athefunctionof disc.
wavelength. We used a simple local thermal equilibrium ring model of the CO emission
Methods. We used the second-generation Very Large Telescope Interferometer instrument GRAVITY to spatially resolve the continto reproduce the spectrum and COuum
lineanddisplacements.
the CO overtone emission. We obtained data over 12 baselines with the auxiliary telescopes and derive visibilities, and theResults. Our interferometric data differential
show thatstar
is marginallyresolvedWeat usedouraspatial
resolution,with ringa radius± 2.65 R .
and theclosurephasesas a function of wavelength.
simple local
thermal equilibrium
model ofof
the⇠10.58
CO emission
toreproducethespectrum
and
CO
line
displacements.
The K-band continuum emission fromthe disc is inclined by 63 ± 1 , with a position angle of 116 ± 1 , and 4 ± 0.8 mas (0.5 ± 0.1 au)
Results. Our interferometric data show that the star is marginally resolved at our spatial resolution, with a radius of ⇠10.58 ± 2.65 R .
across. The visibilities increase within
thecontinuum
CO lineemission,
indicatingthat
COa position
is emitted
The K-band
emissionfrom the discis inclined by
63 ±the1 , with
angle ofwithin
116 ± 1 , theand 4dust-sublimation± 0.8 mas (0.5 ± 0.1 au) radius.
across.
The
visibilities
increase
withintheCOlineemission,
indicating
that
the
CO
is
emittedwithinthedust-sublimation
radius. (NBy modelling the CO bandhead Byspectrum,
wederivethatthe weCOis thatemittedfroma fromhot a(Thot=(T1900–2800
K)andanddense
CO =modellingtheCObandhead
spectrum,
derivetheCOisemitted=
1900–2800
K)
dense
(N
CO =
21
2
21
2
(0.9–9) ⇥ 10 cm ) gas. The analysis
displacement
withrespectwith
to respect
the continuum
allowsustotoinfer
infer
that
(0.9–9) of⇥ 10thecm CO) gas.line
The analysisof the CO line
displacement
to the continuum
allows usthat theCOthe
is CO isemittedfrom awell
region within
0.10 ± 0.02theau across,well within the dust-sublimation
radius.
The inclination
andposition
position angleof theofCOtheline CO line
emitted from a region 0.10 ± 0.02 au
across,dust-sublimation
radius. The
inclination
and
angle
emitting region is consistent with that of the dusty disc.
emitting region is consistent with thatof theOur
dusty
disc.
Conclusions.
spatially
resolved interferometric observations confirm the CO ro-vibrational emission within the dust-free region
of
the
inner
disc.
Conventional
disc models exclude
the presenceof CO
in the dust-depleted
regions of Herbig
AeBe
Ad hoc region
Conclusions. Our spatially resolved interferometric observations
confirm
the COro-vibrationalemission
withinthestars.
dust-freemodels of the innermost disc regions, that can compute the properties of the dust-free inner disc, are therefore required.
of the inner disc. Conventional disc models exclude the presence of CO in the dust-depleted regions of Herbig AeBe stars. Ad hoc
Key words. accretion, accretion disks – stars: formation – techniques: interferometric – stars: pre-main sequence –models of the innermost disc regions,that can compute the properties of the dust-free inner disc, are therefore required.
stars: individual: 51 Oph

Key words. accretion, accretion disks – stars: formation – techniques: interferometric – stars: pre-main sequence –stars: individual: 51 Oph

1. Introduction

Circumstellar discs are crucial for understanding how stars andplanets form. In spite of the enormous wealth of data provided

regions, and this has only been possible for a few objects (Kraus
et al. 2008; Eisner et al. 2007; Lazareff et al. 2017; GRAVITY
Collaboration 2019). Still, this is a region of great importance,

VLTI, GRAVITY
CO ro-vibrational
2.3 µm
Herbig disk
連続波で10.6 Rsunの星と0.5 auの円盤。
COが0.1 au,
1900-2800 K, 0.99x1021 cm-2から。
dust-sublimationより内側。