2022/10/14

星形成ゼミ
The Star Formation Newsletter 354
徳田一起 (九州大学/国立天文台)
36~4236

The Role of Magnetic Fields in the Stability and Fragmentation of Filamentary
Molecular Clouds: Two Case Studies at OMC-3 and OMC-4

37

A massive Keplerian protostellar disk with flyby-induced spirals in the Central
Molecular Zone

38

Gaia EDR3 comparative study of protoplanetary disk fractions in young stellar
clusters39

Gas Column Density Distribution of Molecular Clouds in the Third Quadrant ofthe Milky Way

40

Modeling snowline locations in protostars: The impact of the structure ofprotostellar cloud cores

41

ALMA Images the Eccentric HD 53143 Debris Disk

42

Unraveling the observational signatures of cloud-cloud collision and hubfilament sys- tems in W31

caused it, disfavoring this scenario in the formation of this apparent shell.

Role of Magnetic Fields in the Stability and Fragmentation of Filamentary Molec36 Theular Clouds: Two Case Studies at OMC-3 and OMC-4

Pak Shing Li, Enrique Lopez-Rodriguez, Archana Soam, Richard I. Klein F We present the stability analysis of tworegions, OMC-3 and OMC-4, in the massive and long molecular cloud complex of Orion A. We obtained 214 µm HAWC+/SOFIA
polarization data, and we make use of archival data for the column density and C18 O (1-0) emission line. We find clear depolarization in both observed regions and that the polarization fraction is anti-correlated with the column density and thepolarization-angle dispersion function. We find that the filamentary cloud and dense clumps in OMC-3 are magnetically supercritical and strongly subvirial. This region should be in the gravitational collapse phase and is consistent with many youngstellar objects (YSOs) forming in the region. Our histogram of relative orientations (HROs) analysis shows that the magnetic
field is dynamically sub-dominant in the dense gas structures of OMC-3. We present the first polarization map of OMC-4. We
find that the observed region is generally magnetically subcritical except for an elongated dense core, which could be a resultof projection eﬀect of a filamentary structure aligned close to the line-of-sight. The relative large velocity dispersion and theunusual positive shape parameters at high column densities in the HROs analysis suggest that our viewing angle may be close toaxes of filamentary substructures in OMC-4. The dominating strong magnetic field in OMC-4 is unfavorable for star formationand is consistent with much fewer YSOs than in OMC-3.

磁場(の相対的な働き)がOMC-3とOMC-4で違う

massive Keplerian protostellar disk with flyby-induced spirals in the Central Molec37 Aular Zone

Xing Lu, Guang-Xing Li, Qizhou Zhang, Yuxin Lin F Accretion disks are an essential component in the paradigm of theformation of low-mass stars. Recent observations further identify disks surrounding low-mass pre-main-sequence stars perturbed
by flybys. Whether disks around more massive stars evolve in a similar manner becomes an urgent question. We report thediscovery of a Keplerian disk of a few solar masses surrounding a 32 solar-mass protostar in the Sagittarius C cloud around theGalactic Center. The disk is gravitationally stable with two embedded spirals. A combined analysis of analytical solutions andnumerical simulations demonstrates that the most likely scenario to form the spirals is through external perturbations induced
by a close flyby, and one such perturber with the expected parameters is identified. The massive, early O-type star embeddedin this disk forms in a similar manner with respect to low-mass stars, in the sense of not only disk-mediated accretion, but also
flyby-impacted disk evolution.

・銀河中心部のALMAの観測(大質量星周り)
Gaia EDR3 comparative study of protoplanetary disk fractions in young stellar clusters・小質量星と同様なと同様に形成されるが、flybyによってスパイラルが誘起されるか？
I. Mendigutía, E. Solano, M. Vioque, L. Balaguer-Nuñez, A. Ribas, N. Huélamo, C. Rodrigo F (Abridged) The
lifetime of protoplanetary disks around young stars limits the timescale when planets form. A disk dissipation timescale < 10=>ALMAのwebサイトでプレスリリース記事
Myr was inferred from surveys providing the fraction of stars with disks in young stellar clusters with diﬀerent ages. However,most previous surveys focused on the compact region within 2 pc from the clusters’ centers, for which the disk fraction
https://alma-telescope.jp/news/accretiondisk-202206
information considering the outer part is practically absent. We aim to test if disk fraction estimates change when inferredサジタリウスC分子雲(銀河中心)に本当にあるのか？
-速度が同じ(-50 km/s)で分子輝線の線幅も円盤領域より大きい(>2km/s)
ギ酸メチル
1.3mm連続波
4.7 MoQパラメータ
1.3 Mo

3.2 Mo32 Mo中心星のケプラーfit
円盤は安定?
中心星の明るさ ~ a few x 10^5 Lo
Bの影響はfly-byに考慮に入っていない(入れていない)

流体計算コード
PHANTOMで計算

32 Mo
3.2 MoCredit: Lu et al.
Fly-byイベントは起こりうるのか？

論文の図
赤点がsink 粒子
疑問: ソースAは3.2で本当に良いのか？

- サジタリウスCでの星の密度5 x 10^4 pc^-3星の間の相対速度1km/s, 近点2000au, 相互作用する合計質量 40 Moの場合タイムスケールは、800年になる=>大質量星の原始星(円盤)が回転する時間及び、進化タイムスケール10^4 yrより十分短いin this disk forms in a similar manner with respect to low-mass stars, in the sense of not only disk-mediated accretion, but also
flyby-impacted disk evolution.

Gaia EDR3 comparative study of protoplanetary disk fractions in young stellar clusters
I. Mendigutía, E. Solano, M. Vioque, L. Balaguer-Nuñez, A. Ribas, N. Huélamo, C. Rodrigo F (Abridged) The
lifetime of protoplanetary disks around young stars limits the timescale when planets form. A disk dissipation timescale < 10Myr was inferred from surveys providing the fraction of stars with disks in young stellar clusters with diﬀerent ages. However,most previous surveys focused on the compact region within 2 pc from the clusters’ centers, for which the disk fraction
information considering the outer part is practically absent. We aim to test if disk fraction estimates change when inferredfrom an extended region around the clusters’ centers. Gaia EDR3 data and a best-suited, Virtual Observatory (VO)-based
tool -Clusterix-, are used to identify member stars for a representative sample of 19 young clusters considering two concentricfields of view (FOV) with radii 20 pc and 2 pc. Our analysis reveals that the inner disk fractions inferred from the compact
and the extended regions are equal within 10%, which does not support a previous hypothesis proposing that disk fractions
should be significantly larger considering extended regions. A list of member and disk stars in each cluster is provided andstored in a VO-compliant archive. Averaged values and plots characterizing the whole clusters are also provided, including HR観測領域全体のマップ

MonOB1領域のマップ
NPDFのフィッティングMach number, M, of molecular clouds. Overall, as predicted by numerical simulations, the N-PDFs of the molecular clouds
with active star formation activity tend to have N-PDFs with power-law high-density tails.

Modeling snowline locations in protostars: The impact of the structure of protostellar

40 cloud cores

Nadia M. Murillo, Tien-Hao Hsieh, Catherine Walsh F Abridged Context: Snowlines during star and disk formation
are responsible for a range of eﬀects during the evolution of protostars, such as setting the chemical composition of the envelopeand disk. This in turn influences the formation of planets by changing the elemental compositions of solids and aﬀecting
the collisional properties and outcomes of dust grains. Snowlines can also reveal accretion bursts, providing insight into theformation process of stars. Methods: A numerical chemical network coupled with a grid of cylindrical-symmetric physicalmodels was used to identify what physical parameters alter the CO and H2 O snowline locations. The investigated parameters
are the initial molecular abundances, binding energies of CO and H2 O, heating source, cloud core density, outflow cavity opening
angle, and disk geometry. Simulated molecular line emission maps were used to quantify the change in the snowline location
with each parameter. Conclusions: The models presented in this work show that the CO and H2 O snowline locations do notoccur at a single, well-defined temperature as is commonly assumed. Instead, the snowline position depends on luminosity,
cloud core density, and whether a disk is present or not. Inclination and spatial resolution aﬀect the observability and successful
measurement of snowline locations. We note that N2 H+ and HCO+ emission serve as good observational tracers of CO andH2 O snowline locations. However, constraints on whether or not a disk is present, the observation of additional molecular
tracers, and estimating envelope density will help in accurately determining the cause of the observed snowline position. Plotsof the N2 H+ and HCO+ peak emission radius versus luminosity are provided to compare the models with observations of deeply
embedded protostars aiming to measure the CO and H2 O snowline locations.

Images the Eccentric HD 53143 Debris Disk
41 ALMA
Meredith A. MacGregor, Spencer A. Hurt, Christopher C. Stark, Ward S. Howard, Alycia J. Weinberger, BinRen, Glenn Schneider, Elodie Choquet, Dmitri Mawet F We present ALMA 1.3 mm observations of the HD 53143
debris disk - the first infrared or millimeter image produced of this 1 Gyr-old solar-analogue. Previous HST STIS coronagraphic
imaging did not detect flux along the minor axis of the disk which could suggest a face-on geometry with two ’clumps’ of dust.
These ALMA observations reveal a disk with a strikingly diﬀerent structure. In order to fit models to the millimeter visibilities
and constrain the uncertainties on the disk parameters, we adopt an MCMC approach. This is the most eccentric debris disk
observed to date with a forced eccentricity of 0.21 ± 0.02, nearly twice that of the Fomalhaut debris disk, and also displays
apocenter glow. Although this eccentric model fits the outer debris disk well, there are significant interior residuals remainingthat may suggest a possible edge-on inner disk, which remains unresolved in these observations. Combined with the observed
structure diﬀerence between HST and ALMA, these results suggest a potential previous scattering event or dynamical instability
in this system. We also note that the stellar flux changes considerably over the course of our observations, suggesting flaring at
millimeter wavelengths. Using simultaneous TESS observations, we determine the stellar rotation period to be 9.6 ± 0.1 days.

Unraveling the observational signatures 1Gyr(10億歳)のデブリディスクのALMA観測of cloud-cloud collision and hub-filament systems in W31

距離18.3 pc (GAIA)A. K. Maity, L. K. Dewangan, H. Sano, K. Tachihara, Y. Fukui, N. K. Bhadari F To understand the formation

Eccentric modelがよくfitできる・Forced eccentricity 0.21

・Proper eccentricity 0.11=>フォーマルハウトで大観銀働りトき中銀働もフき違銀う測大きフthe observational signatures of cloud-cloud collision and hub-filament sys42 Unravelingtems in W31

A. K. Maity, L. K. Dewangan, H. Sano, K. Tachihara, Y. Fukui, N. K. Bhadari F To understand the formation
process of massive stars, we present a multi-scale and multi-wavelength study of the W31 complex hosting two extended HII
regions (i.e., G10.30-0.15 (hereafter, W31-N) and G10.15-0.34 (hereafter, W31-S)) powered by a cluster of O-type stars. Several
Class I protostars and a total of 49 ATLASGAL 870 µm dust clumps (at d = 3.55 kpc) are found toward the HII regions wheresome of the clumps are associated with the molecular outflow activity. These results confirm the existence of a single physicalsystem hosting the early phases of star formation. The Herschel 250 µm continuum map shows the presence of hub-filamentsystem (HFS) toward both W31-N and W31-S. The central hubs harbour HII regions and they are depicted with extendedstructures (with Td ⇠ 25-32 K) in the Herschel temperature map. In the direction of W31-S, an analysis of the NANTEN212CO(J = 1-0) and SEDIGISM 13 CO(J = 2-1) line data supports the presence of two cloud components around 8 and 16 km
s 1 , and their connection in velocity space. A spatial complementary distribution between the two cloud components is also
investigated toward W31-S, where the signposts of star formation, including massive O-type stars, are concentrated. Thesefindings favor the applicability of cloud-cloud collision (CCC) around ⇠2 Myr ago in W31-S. Overall, our observational findings
support the theoretical scenario of CCC in W31, which explains the formation of massive stars and the existence of HFSs.

13◯: Class I ソース

*フィラメントの同定はgetsf(Men’shchikov 2021)というアルゴリズムを使用

相補的な分布

PV図上のV-型構造

表示の画像30Dor in the LMC

The bright red-yellow streaks superimposed on the background NIR image come from CO observations taken by ALMA,
revealing complex filamentary networks stretching away approximately, from the central cluster, not unlike anupscaled version of the Orion Nebula Cluster. Credit: ESO, ALMA (ESO/NAOJ/NRAO)/Wong et al. 2022, ESO/M.-R.
Cioni/VISTA Magellanic Cloud survey.

共同研究者(Tony Wong+22)と自身の貢献の宣伝
大型の扇型フィラメント構造がLMCで見つかりつつある(Tokuda+22及び、Fukui+19: Tokuda+19も参照)