星形成ゼミ
The Star Formation Newsletter 325
1~8

徳田一起 (大阪府立大学/NAOJ)

1

On the mass segregation of cores and stars

2

Exploring the formation pathways of formamide near young O-type stars

3

Are Inner Disc Misalignments Common? ALMA Reveals an Isotropic Outer DiscIn- clination Distribution for Young Dipper Stars

4

The Orion Protostellar Explosion and Runaway Stars Revisited: Stellar Masses,
Disk Retention, and an Outflow from BN

5

ALMA observations reveal no preferred outflow–filament and outflow–magnetic
field orientations

6

The Young Suns Exoplanet Survey: Detection of a wide orbit planetary masscompanion to a solar-type Sco-Cen member

7

USco1621 B and USco1556 B: Two wide companions at the deuterium-burning
mass limit in Upper Scorpius

8Seeds of Life in Space (SOLIS) V. Methanol and acetaldehyde in the protostellar
jet- driven shocks L1157-B0 and B1

1
分子雲コアが中心集中しているが、前主系列星はそうではない=>分子雲コアが分裂してそうなるのではなく、dynamical evolution でそうなる
やったこと：分子雲とその分裂片のトイモデルを作ってdynamical evolutionで観測を再現できるかどうか確かめた(ΛMSRを評価した)
CMF(IMF)を再現するように、300 個のコアを用意して、それが710~1100個に分裂するまで計算を続けた
Random fragmentation: コアがランダムに1~5個(同じ質量)に分裂
Low-mass fragmentation: 軽いコア(<1Mo)が1~5個に分裂High-mass fragmentation: 思いコア(>1Mo)が1~5に分裂

MSR: Mass Segregation Ratio>1: 中心集中している<1: 離散的Migration は最大で0.5 pc
Fragments が移動(dynamicalejectionを再現)

1の続き

コアがsegregate しておらず、random fragmentationでmigration が起こらないモデル◯: コア▲: もっとも重いコア
×: もっとも重いfragments
・: fragments

コアがsegregate してrandom fragmentation/migrationが起こるモデル

1の続き

灰色：ランダムにfragmentationするモデル
赤:fragmentsがランダムにmigrationする

2 https://arxiv.org/pdf/1909.07982
Exploring the formation pathways of formamide near young O-type stars
V. Allen1,2,3 , F.F.S. van der Tak2,3 , A. López-Sepulcre4,5 , Á. Sánchez-Monge6 , V.M. Rivilla7, and R.
Cesaroni7
1NASA Goddard Space Flight Center, 8800 Greenbelt Road, Greenbelt, MD 20771, USA; 2 Kapteyn AstronomicalInstitute, University of Groningen, Landleven 12, 9747 AD Groningen, the Netherlands; 3 SRON, Landleven 12, 9747
AD Groningen, the Netherlands; 4 CNRS, IPAG, Univ. Grenoble Alpes, F-38000 Grenoble, France; 5 IRAM, 300 rue
de la Piscine, 38406 Saint-Martin d’ Hères, France; 6 I. Physikalisches Institut, Universität zu Köln, Zülpicher Straße77, 50937 Köln, Germany; 7 INAF, Osservatorio Astrofisico di Arcetri, Largo Enrico Fermi 5, I-50125 Florence, Italy
E-mail contact: veronica.a.allen at nasa.gov
Context. As a building block for amino acids, formamide (NH2 CHO) is an important molecule in astrobiology andastrochemistry, but its formation path in the interstellar medium is not understood well.
Aims. We aim to find empirical evidence to support the chemical relationships of formamide to HNCO and H2 CO.
Methods. We examine high angular resolution (∼0.′′ 2) Atacama Large Millimeter/submillimeter Array (ALMA) mapsof six sources in three high-mass star-forming regions and compare the spatial extent, integrated emission peak position,and velocity structure of HNCO and H2 CO line emission with that of NH2 CHO by using moment maps. Throughspectral modeling, we compare the abundances of these three species.
Results. In these sources, the emission peak separation and velocity dispersion of formamide emission is most often
similar to HNCO emission, while the velocity structure is generally just as similar to H2 CO and HNCO (within errors).
From the spectral modeling, we see that the abundances between all three of our focus species are correlated, and therelationship between NH2 CHO and HNCO reproduces the previously demonstrated abundance relationship.
Conclusions. In this first interferometric study, which compares two potential parent species to NH2 CHO, we findthat all moment maps for HNCO are more similar to NH2 CHO than H2 CO in one of our six sources (G24 A1). For
the other five sources, the relationship between NH2 CHO, HNCO, and H2 CO is unclear as the diﬀerent moment maps
for each source are not consistently more similar to one species as opposed to the other.
Accepted by A&A
http://arxiv.org/pdf/1912.11883

アストロバイオロジー/ケミストリーにおいて重要な分子種の9ALMAを用いた観測3Are Inner Disc Misalignments Common? ALMA Reveals an Isotropic Outer Disc Inclination Distribution for Young Dipper Stars
M. Ansdell1,2,3, E. Gaidos4 , C. Hedges5 , M. Tazzari6 , A.L. Kraus7 et al.
1Center for Integrative Planetary Science, University of California at Berkeley, Berkeley, CA 94720, USA; 2 Department of Astronomy, University of California at Berkeley, Berkeley, CA 94720, USA; 3 Flatiron Institute, SimonsFoundation, 162 Fifth Ave, New York, NY 10010, USA; 4 Department of Earth Sciences, University of Hawai’i atMan̄oa, Honolulu, HI, USA; 5 NASA Ames Research Center, Moﬀett Blvd, Mountain View, CA 94035, USA; 6 Institute of Astronomy, University of Cambridge, Madingley Road, CB3 0HA, Cambridge, UK; 7 Department of Astronomy,
The University of Texas at Austin, Austin, TX 78712, USA
E-mail contact: mansdell at flatironinstitute.org
Dippers are a common class of young variable star exhibiting day-long dimmings with depths of up to several tensof percent. A standard explanation is that dippers host nearly edge-on (70◦ ) protoplanetary discs that allow close-in(<1 au) dust lifted slightly out of the midplane to partially occult the star. The identification of a face-on dipper discand growing evidence of inner disc misalignments brings this scenario into question. Thus we uniformly (re)derive
the inclinations of 24 dipper discs resolved with (sub-)mm interferometry from ALMA. We find that dipper disc
inclinations are consistent with an isotropic distribution over 0◦ –75◦ , above which the occurrence rate declines (likely
an observational selection eﬀect due to optically thick disc midplanes blocking their host stars). These findings
indicate that the dipper phenomenon is unrelated to the outer (>10 au) disc resolved by ALMA and that inner discmisalignments may be common during the protoplanetary phase. More than one mechanism may contribute to thedipper phenomenon, including accretion-driven warps and "broken" discs caused by inclined (sub-)stellar or planetarycompanions.
Accepted by MNRAS
http://arxiv.org/pdf/1912.01610

ALMA を用いたギャップのある円盤の観測

The Orion Protostellar Explosion and Runaway Stars Revisited:
内側のdiskと外側のdiskとミスアライメントは割とcommon
Stellar Masses,Disk Retention, and an Outflow from BN
1
3
John Ballyいくつかのメカニズム, Adam Ginsburg2 , Jan Forbrich, and Jaime Vargas-González3(質量降着によるwarpやコンパニオンの影響？)

4

The Orion Protostellar Explosion and Runaway Stars Revisited:
Stellar Masses, Disk Retention, and an Outflow from BN
John Bally1 , Adam Ginsburg2 , Jan Forbrich3 , and Jaime Vargas-González3
1

Center for Astrophysics and Space Astronomy, Astrophysical and Planetary Sciences Department, University ofColorado, UCB 389 Boulder, Colorado 80309, USA; 2 Department of Astronomy, University of Florida, Bryant Space
Science Center, Stadium Road, Gainesville, FL 32611; 3 Centre for Astrophysics Research, School of Physics, Astronomy and Mathematics, Hertfordshire University, College Lane, Hatfield, AL10 9AB, UK
E-mail contact: john.bally@colorado.edu

The proper motions of the three stars ejected from Orion’s OMC1 cloud core are combined with the requirement that
their center of mass is gravitationally bound to OMC1 to show that radio source I (Src I) is likely to have a massaround 15 M⊙ consistent with recent measurements. Src I, the star with the smallest proper motion, is suspected tobe either an AU-scale binary or a protostellar merger remnant produced by a dynamic interaction ∼550 years ago.
Near-infrared 2.2 µm images spanning ∼21 years confirm the ∼55 km/s motion of ‘source x’ (Src x) away from thesite of stellar ejection and point of origin of the explosive OMC1 protostellar outflow. The radial velocities and massesof the Becklin-Neugebauer (BN) object and Src I constrain the radial velocity of Src x to be VLSR = −28 ± 10 km/s.
Several high proper-motion radio sources near BN, including Zapata 11 ([ZRK2004] 11) and a diﬀuse source nearIRc 23, may trace a slow bipolar outflow from BN. The massive disk around Src I is likely the surviving portion ofa disk that existed prior to the stellar ejection. Though highly perturbed, shocked, and re-oriented by the N-bodyinteraction, enough time has elapsed to allow the disk to relax with its spin axis roughly orthogonal to the propermotion.
Accepted by The Astrophysical Journal
http://arxiv.org/pdf/2001.00899

105

ALMA OBSERVATIONS REVEAL NO PREFERRED OUTFLOW–FILAMENT AND OUTFLOW–MAGNETIC
FIELD ORIENTATIONS
T. Baug1 , Ke Wang1 , Tie Liu2 , Mengyao Tang3 , Qizhou Zhang4 , Di Li5, 6 , Eswaraiah Chakali7 , Sheng-Yuan Liu8 ,Anandmayee Tej9 , Paul F. Goldsmith10 , Leonardo Bronfman11 , Sheng-Li Qin3 , Viktor L. Toth12 , Pak-Shing Li13 ,and Kee-Tae Kim14

iv:1912.13240v1 [astro-ph.GA] 31 Dec 2019

大質量星形成領域(IRDC)のoutflowが磁場やフィラメントの向きと相関があるかどうか調べた=>なかったフィラメントの向きはABSTRACT
単一鏡のデータで決定
We present a statistical study on the orientation of outflows with respect to large-scale filaments andthe magnetic fields. Although filaments are widely observed toward Galactic star-forming regions,the exact role of filaments in star formation is unclear. Studies toward low-mass star-forming regions
revealed both preferred and random orientation of outflows respective to the filament long-axes, while
outflows in massive star-forming regions mostly oriented perpendicular to the host filaments, andparallel to the magnetic fields at similar physical scales. Here, we explore outflows in a sample of
11 protoclusters in H ii regions, a more evolved stage compared to IRDCs, using ALMA CO (3–2)
line observations. We identify a total of 105 outflow lobes in these protoclusters. Among the 11targets, 7 are embedded within parsec-scale filamentary structures detected in 13 CO line and 870 µmcontinuum emissions. The angles between outflow axes and corresponding filaments (γFil ) do not show
any hint of preferred orientations (i.e., orthogonal or parallel as inferred in numerical models) withrespect to the position angle of the filaments. Identified outflow lobes are also not correlated with themagnetic fields and Galactic plane position angles. Outflows associated with filaments aligned along
the large-scale magnetic fields are also randomly orientated. Our study presents the first statisticalresults of outflow orientation respective to large-scale filaments and magnetic fields in evolved massive
star-forming regions. The random distribution suggests a lack of alignment of outflows with filaments,
which may be a result of the evolutionary stage of the clusters.
Keywords: stars: formation – ISM: clouds – ISM: jets and outflows

ターゲット選定
ASTEでHCN(4-3)の観測でblueemission profile

Dense star-forming cores may form within these filamentary structures (André et al. 2010; Arzoumanian et al.
Herschel observations revealed ubiquitous filamentary
2011; Lee et al. 2014). Filaments are even capable to leadstructures in Galactic star-forming clouds. Filaments are
the formation of massive stars (m∗ ! 8M⊙ ) at their comobservationally characterized as overdense elongated feamon junction (“hub”; Myers 2009; Dale & Bonnell 2011).
tures of molecular clouds having an aspect ratio of more
Two types of gas flows are typically expected in a starthan ∼5–10 (André et al. 2014). These filaments areforming filament. These could be large scale flows fromconsidered to play an important role in star formation.
the surrounding cloud onto the short-axis of the filamentor flow of gas from the parent cloud along the long-axis
Corresponding author: Ke Wang (kwang.astro@pku.edu.cn)of the filament (Kirk et al. 2013; Fernández-López et al.
1 Kavli Institute for Astronomy and Astrophysics, Peking Uni2014). Generally, flow of gas along the long-axis of a filaversity, 5 Yiheyuan Road, Haidian District, Beijing 100871,
ment is implied by velocity gradients of the gas within filChina
2 Shanghai Astronomical Observatory, Chinese Academy ofグレー: 870μm aments (Liu et al. 2016a; Wang 2018; Yuan et al. 2018).
ALMA観測:黄色がdriving
sourceの位置
Sciences,
80 Nandan Road,
Shanghai200030, China
Observationally such phenomena is indeed noted in sev3 Department of Astronomy, Yunnan University,
Blue/Red:
CO outflow
Kunming,
1. INTRODUCTION

磁場の向きPlanck衛星の偏光観測

5の続き

なぜ相関がないのか：HII領域が発達しており、進化した領域を見ているから- Outflowよりも恒星風からの勢いの方が強くなる- 多重星の相互作用により回転の向きがランダムになるからAccepted by MNRAS

7

http://arxiv.org/pdf/1912.04284

USco1621 B and USco1556 B: Two wide companions at the deuterium-burning mass
limit in Upper Scorpius
Patricia Chinchilla1,2 , Víctor J.S. Béjar1,2 , Nicolas Lodieu1,2 , Bartosz Gauza3,4 , Maria Rosa Zapatero
Osorio5 et al.
1

Instituto de Astrofísica de Canarias (IAC), Calle Vía Láctea s/n, 38200 La Laguna, Tenerife, Spain; 2 Departamentode Astrofísica, Universidad de La Laguna (ULL), 38205 La Laguna, Tenerife, Spain; 3 Departamento de Astronomía,Universidad de Chile, Camino El Observatorio 1515, Las Condes, Santiago, Chile; 4 Janusz Gil Institute of Astronomy,
University of Zielona Góra, Lubuska 2, 65-265 Zielona Góra, Poland; 5 Centro de Astrobiología (CSIC-INTA), Ctra.
de Ajalvir km 4, 28850 Torrejón de Ardoz, Madrid, Spain
E-mail contact: pcg at iac.esOur aim is to identify analogues of gas giant planets, as companions at wide separations of very young stars. To identify
these objects, we cross correlated the Visible and Infrared Survey Telescope for Astronomy (VISTA) Hemisphere Survey(VHS) and the United Kingdom Infrared Telescope Infrared Deep Sky Survey Galactic Clusters Survey (UKIDSS GCS)
catalogues to search for common proper motion companions to 1195 already known members of Upper Scorpius (USco;age ∼5–10 Myr, distance ∼145 pc). We present the discovery and spectroscopic characterisation of two very wide
substellar companions of two early-M stars in Upper Scorpius: USco1621 B and USco1556 B. We obtained opticaland near-infrared low-resolution spectroscopy of the candidates to characterise their spectral energy distribution andconfirm their membership to the association. We also acquired adaptive optics images of the primaries and secondaries
to search for signs of binarity and close companions. We determined a spectral type of M8.5 in the optical for bothcompanions, along with L0 and L0.5 in the near-infrared for USco1621 B and USco1556 B, respectively. The spectraof the two companions show evident markers of youth. The comparison with theoretical evolutionary models gives
estimated masses of 0.015±0.002 and 0.014±0.002 M⊙ , with temperatures of 2270±90 and 2240±100 K, respectively.
The physical separations between the components of both systems are 2880±20 and 3500±40 AU for USco1621 andUSco1556 systems, respectively. We did not find any additional close companion in the adaptive optics images. The
probability that the two secondaries are physically bound to their respective primaries, and not chance alignments ofUSco members, is 86%, and the probability that none of them are physically related is 1.0%.
Accepted by A&A
http://arxiv.org/pdf/1912.04150Seeds of Life in Space (SOLIS) V. Methanol and acetaldehyde in the protostellar jet-8

Seeds of Life in Space (SOLIS) V. Methanol and acetaldehyde in the protostellar jetdriven shocks L1157-B0 and B1
C. Codella1,2 , C. Ceccarelli2,1 , E. Bianchi2 , N. Balucani3,2,1 , L. Podio1 , P. Caselli4, S. Feng5,6,7 , B.
Lefloch2 , A. López-Sepulcre2,8 , R. Neri8 , S. Spezzano4 and M. De Simone2
1INAF, Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy; 2 Univ. Grenoble Alpes, CNRS,
Institut de Planétologie et d’Astrophysique de Grenoble (IPAG), 38000 Grenoble, France; 3 Dipartimento di Chimica,Biologia e Biotecnologie, Via Elce di Sotto 8, 06123 Perugia, Italy; 4 Max-Planck-Institut für extraterrestrische Physik(MPE), Giessenbachstrasse 1, 85748 Garching, Germany; 5 National Astronomical Observatory of China, Datun Road
20, Chaoyang, Beijing, 100012, P. R. China; 6 CAS Key Laboratory of FAST, NAOC, Chinese Academy of Sciences,P. R. China; 7 National Astronomical Observatory of Japan, 2 Chome-21-1 Osawa, Mitaka-shi, Tokyo-to 181-0015,

L1157のアウトフロー ショック領域のIRAM-NOEMA観測 (Large programの一環)- アセトアルデヒド(CH3CHO)がどのように形成されたかが知りたい
複雑な有機分子の起源に迫る gas phase v.s. dust grain どちらか
*先行研究ではNH2CHO(ホルムアミド)はgas phase らしいことがわかった
12

ここらへん
Wikipediaより

利点
1. 原始星からのエミッションを除外できる(~0.11 pc離れている) など

メタノール

アセトアルデヒド

コントア: 12CO blueshifted outflow

8の続き

B1bクランプ
N(CH3OH): 1.3e16 cm^-2
N(CH3CHO):7e13 cm^-2
他のprotostellar envelope 領域(100 au以内)とオーダーで変わらないモデルとの比較
Gas かgrain か切り分けできない

Future work (gas vs grainを切り分けるためには)・ショックが起こった100年以内の領域を見つける
・エチルラジカル (CH3CH2) と酸素原子の観測が重要
エチルラジカルは現在観測できる知られている周波数帯にない
酸素(63μm) はSOFIAが可能