星形成ゼミ
The Star Formation Newsletter 335
1~7

徳田一起 (大阪府立大学/NAOJ)

1

A case of simultaneous star and planet formation2

Probing episodic accretion with chemistry: CALYPSO observations ofIRAM04191+1522 Results from the CALYPSO IRAM-PdBI survey

3

The role of the magnetic field in the fragmentation process: the case of
G14.225-0.506

4

Testing Disk Identification Methods Through Numerical Simulations ofProtostellar Evolution

5

Formation of the Musca filament: Evidence for asymmetries in the accretion
flow due to a cloud-cloud collision

6

ALMA chemical survey of disk-outflow sources in Taurus (ALMA-DOT). IV. Thioformaldehyde (H2CS) in protoplanetary disks: spatial distributions and bindingenergies

7

Testing the star formation scaling relations in the clumps of the North Americanand Pelican cloud complexes

1Abstracts
A case of simultaneous star and planet formation

Felipe O. Alves, L. Ilsedore Cleeves, Josep M. Girart, Zhaohuan Zhu, Gabriel A. P. Franco, Alice Zurlo, Paola
Caselli While it is widely accepted that planets are formed in protoplanetary disks, there is still much debate on when thisprocess happens. In a few cases protoplanets have been directly imaged, but for the vast majority of systems, disk gaps
and cavities – seen especially in dust continuum observations – have been the strongest evidence of recent or on-going planet
formation. We present ALMA observations of a nearly edge-on (i = 75 ) disk containing a giant gap seen in dust but not in
12
CO gas. Inside the gap, the molecular gas has a warm (100 K) component coinciding in position with a tentative free-freeemission excess observed with the VLA. Using 1D hydrodynamic models, we find the structure of the gap is consistent withbeing carved by a planet with 4-70 MJup . The coincidence of free-free emission inside the planet-carved gap points to the planet
being very young and/or still accreting. In addition, the 12 CO observations reveal low-velocity large scale filaments alignedwith the disk major axis and velocity coherent with the disk gas that we interpret as ongoing gas infall from the local ISM.
This system appears to be an interesting case where both a star (from the environment and the disk) and a planet (from thedisk) are growing in tandem.

Probing episodic accretion with chemistry: CALYPSO observations of IRAM04191+1522
Results from the CALYPSO IRAM-PdBI survey
S. Anderl, S. Maret, S. Cabrit, A. J. Maury, A. Belloche, Ph. André, A. Bacmann, C. Codella, L. Podio,
F. Gueth Context. The process of mass accretion in the earliest phases of star formation is still not fully understood: Does
the accretion rate smoothly decline with the age of the protostar or are there short, intermittent accretion bursts? Aims. We
aim to explore whether or not the observed C18 O and N2 H+ emission pattern towards the VeLLO IRAM 04191+1522 can beunderstood in the framework of a scenario where the emission is chemically tracing a past accretion burst. Methods.We usedhigh-angular-resolution Plateau de Bure Interferometer (PdBI) observations of C18 O and N2 H+ towards IRAM 04191+1522
that were obtained as part of the CALYPSO IRAM Large Program. We model these observations using a chemical code with atime-dependent physical structure coupled with a radiative transfer module, where we allow for variations in the source luminosity. Results. We find that the N2 H+ line emission shows a central hole, while the C18 O emission is compact. The morphology ofthese two lines cannot be reproduced with a constant luminosity model based on the present-day internal luminosity (0.08 Lsun ).
However, the N2 H+ peaks are consistent with a constant-luminosity model of 12 Lsun . Using a model with time-dependent
temperature and density profiles, we show that the observed N2 H+ peak emission could indeed be caused by a past accretion

22牡牛座にあるClass 0 超低光度天体VeLLO (L<0.08 Lo) のPdBIの観測
温度が上がるとN2H+が壊されて逆にCOは昇華する=>過去のaccretion burst を反映？(ALMAの先行研究, Hsieh+18)
Outflowの向き

強度
プロファイルの向き

2の続き

L = 0.08Lo (一定)の時

L = 12Lo まで上げたモデル

・Accretion burst はいつ起こったか？: 1000年より前ではない・明るさから予想される- 現在のaccretion rate : 3e-5 Mo/yr- burst 時のaccretion rate : 2e-7 Mo/yr
VeLLOのタイムスケールが1万年くらいで(Hsieh+18)、その1%がburst だとClass 0の終わりまでに最終的に0.2-0.25 Mo の星になる(褐色矮星ではない)3
Kock+12で開発された手法を適用

M17領域のダストコアに対してCSOの350μm 連続波偏波観測コントア:NH3
背景: Spitzer

APEX 870μm

大橋et al. 2016より
・偏波のデータからすぐにわかること- Hub-Nの方はフィラメントに対して垂直- Hub-Sの方はbimodal な分布をしている
偏波率に関しては数%から20%程度,
StokesIが上がれば上がるほど偏波率が下がる

3の続き

強度勾配のマップ白コントア: SMA 1.3mm
・(色々解析をやった上で)
Hub-Nはsingle core
どうやらHub-Nでは磁場よりも重力の方が強そう,
Hub-Sはfragmentation?
中心のhub中心に向かってとhubにaccretion ?
・Hub-Nの方がSより磁場が強そう<=これがfragmentation の違いの原因？
でも大きくは変わらないので環境要因も考えられるrather than from diﬀerent intensity of the G-field.

4

Testing Disk Identification Methods Through Numerical Simulations of Protostellar
EvolutionYusuke Aso, Masahiro N. Machida We test whether the radii of circumstellar disks can be reliably determined in observations applying the results of a numerical simulation. Firstly, we execute a core collapse simulation which starts from a rotating
magnetized spherical core, and continue the calculation until the protostellar mass reaches 0.5 Msun. Then, for each set ofsimulation data, we calculate the radiative transfer to generate the data cube for the synthetic observation. The spatial andvelocity resolutions of the synthetic observation are 0.15 arcsec (20 au) and 0.1 km/s, respectively. We define seven diﬀerent disk
radii. Four radii are estimated from the synthetic observation, using the continuum image, continuum visibility, C18O channel
map, and C18O position velocity (PV) diagram. The other three radii are taken from the simulation and use the disk rotation,
infall motion, and density contrast around the protostar to identify the disk. Finally, we compare the disk radii estimatedfrom the systemic observation with those from the simulation. We find that the disk radius defined using the PV diagram canreliably trace the Keplerian disk when the protostellar mass is larger than M⇤ >⇠ 0.2 Msun independent of the inclination
angle to the line of sight. In addition, the PV diagram provides an accurate estimate of the central stellar mass through thewhole protostellar evolution. The simulation also indicates that the circumstellar disk is massive enough to be gravitationallyunstable through the evolution. Such an unstable disk can show either a circular or spiral morphology on a similar timescale.

町田さんの分子雲コアコラプスのsimulation
をFormationof the Musca filament: Evidence for asymmetries
in the accretion flow due
to a cloud-cloudcollision
擬似観測して観測から中心星の質量や半径を計測できるか？

L. Bonne, S. Bontemps, N. Schneider, S. D. Clarke, D. Arzoumanian, Y. Fukui, K. Tachihara, T. Csengeri,
R. Guesten, A. Ohama, R. Okamoto, R. Simon, H. Yahia, H. Yamamoto Context. Dense molecular filaments areubiquituous in the interstellar medium, yet their internal physical conditions and formation mechanism remain debated. Aims.
We study the kinematics and physical conditions in the Musca filament and the Chamaeleon-Musca complex to constrain thephysics of filament formation. Methods. We produced CO(2-1) isotopologue maps with the APEX telescope that cut throughthe Musca filament. We further study a NANTEN2 12 CO(1-0) map of the Musca cloud and the HI emission of the ChamaeleonMusca complex. Results. The Musca cloud contains multiple velocity components. Radiative transfer modelling of the COemission indicates that the Musca filament consists of a cold (⇠10 K), dense (nH2 ⇠104 cm 3 ) crest, which is best describedwith a cylindrical geometry. Connected to the crest, a separate gas component at T⇠15 K and nH2 ⇠103 cm 3 is found, theso-called strands. The filament crest has a transverse velocity gradient that is linked to the kinematics of the nearby ambient
cloud. Studying the large scale kinematics, we find coherence of the asymmetric kinematics from the 50 pc HI cloud down tothe Musca filament. We also report a strong [C18 O]/[13 CO] abundance drop by an order of magnitude from the filament crestto the strands over a distance < 0.2 pc in a weak far-ultraviolet (FUV) field. Conclusions. The dense Musca filament crestis a long-lived (several crossing times), dynamic structure that can form stars in the near future because of continuous mass

・原始星質量がM∗ >∼ 0.2 Msunよりも大きい場合には、
PV図は半径を見積もるのに有効・原始星進化を通して、中心性質量を測定することが可能
・円盤は不安定でスパイラルアームを生じさせる

5Musca filament (d~140 pc)の分子輝線等の観測
Sheetかfilament か？

これPlanck dust emission
2MASS
内側がHerschel

使ったデータ・Gaia DR2=>距離決定 140pc
・APEX/PI230: 12CO, 13CO, C18O(2-1)
真ん中の小さい四角: APEX・APEX/FLASH+: 12CO(3-2), 13CO(3-2), 12CO(4-3)
一番外側の四角: NANTEN2・NANTEN2: 12CO(1-0)
マルチラインの解析:filament crest
・Planck: dust emissionと偏波密度10^4 cm^-3, 温度10K=>円柱・HI

5の続き

青プロファイル: 平均HIスペクトル赤プロファイル: その場所のローカルなHIスペクトル黒点線：CO の中心速度観測から推定される
Musca filamentの形成
シナリオ(Inoue+18の理論計算とconsistent)

6 ALMA chemical survey of disk-outflow sources in Taurus (ALMA-DOT). IV. Thioformaldehyde (H2 CS) in protoplanetary disks: spatial distributions and binding energies

C. Codella, L. Podio, A. Garufi, J. Perrero, P. Ugliengo, D. Fedele, C. Favre, E. Bianchi, C. Ceccarelli, S.
Mercimek, F. Bacciotti, K. L. J. Rygl, L. Testi Aims: To trace the radial and vertical spatial distribution of H2CS, a key
species of the S-bearing chemistry, in protoplanetary disks. To analyse the observed distributions in light of the H2CS binding
energy, in order to discuss the role of thermal desorption in enriching the gas disk component. Methods: In the context ofthe ALMA chemical survey of Disk-Outflow sources in the Taurus star forming region (ALMA-DOT), we observed five ClassI or early Class II sources with the o-H2CS(71 ,6-61 ,5) line on a 40 au scale. We estimated the binding energy (BEs) of H2CS
using quantum mechanical calculations, for the first time, for an extended, periodic, crystalline ice. Results: We imaged H2CS
in two rotating molecular rings in the HL Tau and IRAS04302+2247 disks. The outer radii are about 140 au (HL Tau), and115 au (IRAS 04302+2247). The edge-on geometry of IRAS 04302+2247 reveals that H2CS emission peaks, at radii of 60-115
au, at z = ±50 au from the equatorial plane. The column densities are about 1014 cm 2 . For HL Tau, we derive, for the firsttime, the [H2CS]/[H] abundance in a protoplanetary disk (about 10 14 ). The BEs of H2CS computed for extended crystalline
ice and amorphous ices is 4258 K and 3000-4600 K, respectively, implying a thermal evaporation where dust temperature islarger than 50-80 K. Conclusions: H2CS traces the so-called warm molecular layer, a region previously sampled using CS, andH2CO. Thioformaldehyde peaks closer to the protostar than H2CO and CS, plausibly due to the relatively high-excitation levelof observed 71 ,6-61 ,5 line (60 K). The H2CS BEs implies that thermal desorption dominates in thin, au-sized, inner and/or
upper disk layers, indicating that the observed H2CS emitting up to radii larger than 100 au is likely injected in the gas due tonon-thermal processes.

7 Testing the star formation scaling relations in the clumps of the North American andPelican cloud complexes

Swagat R. Das, Jessy Jose, Manash R Samal, Shaobo Zhang, Neelam Panwar The processes which regulate the starformation within molecular clouds are still not well understood. Various star-formation scaling relations have been proposed toexplain this issue by formulating a relation between star-formation rate surface density (⌃SFR ) and the underlying gas surface
density (⌃gas ). In this work, we test various star formation scaling relations, such as Kennicutt-Schmidt relation, volumetricstar-formation relation, orbital time model, crossing time model, and multi free-fall time scale model towards the North Americanand Pelican Nebulae complexes and in cold clumps associated with them. Measuring stellar-mass from young stellar objects
and gaseous mass from CO measurements, we estimated mean ⌃SFR , star formation rate per free-fall time, and star formationeﬃciency (SFE) for clumps to be 1.5 M yr 1 kpc 2 , 0.009, 2.0%, respectively, while for the entire NAN complex the values
are 0.6 M yr 1 kpc 2 , 0.0003, and 1.6%, respectively. For clumps, we notice that the observed properties are in line with thecorrelation obtained between ⌃SFR and ⌃gas , and between ⌃SFR and ⌃gas per free-fall time and orbital time for Galactic clouds.
At the same time, we do not observe any correlation with ⌃gas per crossing time and multi free-fall time. Even though we see
correlations in former cases, however, all models agree with each other within a factor of 0.5 dex, and discriminating between
these models is not possible due to the current uncertainties in the input observables. We also test the variation of ⌃SFR versus
the dense gas, but due to low statistics, a weak correlation is seen in our analysis.