2022/06/24

星形成ゼミ
The Star Formation Newsletter 352
徳田一起 (九州大学/国立天文台)
13~18
13

Images of Embedded Jovian Planet Formation At A Wide Separation Around ABAurigae

14

Dusty circumbinary discs: inner cavity structures and stopping locations ofmigrating planets

15

The Many-Faceted Light Curves of Young Disk-bearing Stars in Taurus as Seen byK2

16

New evidences in IRDC G333.73+0.37: colliding filamentary clouds, hubfilament sys- tem, and embedded cores

17

ALMA Survey of Orion Planck Galactic Cold Clumps (ALMASOP): Evidence for a
Molecular Jet Launched at an Unprecedented Early Phase of Protostellar
evolution

18

Different molecular filament widths as tracers of accretion onto filaments

(13)

概要
重力不安定で形成されたと思われる惑星形成の兆候を捉えました。
背景・コア集積v.s.円盤不安定~100 auの軌道にあって木星よりも5倍くらい重い惑星をどうやって作るのか？
=>円盤分裂説か？
・これまでの惑星のダイレクトイメージングの例
PDS 70bc- そこそこ進化進んだ系- 20-30 auの軌道
この天体の新しい点- Embedded phase で- 軌道大きいところ (430-580 au)で惑星形成の兆候を捉えた使った装置: Subaru Coronagraphic Extreme Adaptive Optics

project (SCExAO), Coronagraphic High-Resolution Imager
and Spectrograph (CHARIS) 2016~2020年の観測
Hubble Space Telescope (HST) 2007年と2021年

(13続き)Orbits. (中略)This modellingsuggests that AB Aur b’s orbit isviewed ~27-58deg from face-on
with an eccentricity of e ~ 0.190.60, and a semi-major axis of~45-143 au. Nearly all of theseorbits do not cross the millimeterresolved dust ring; a subset ofthem imply that AB Aur b is
coplanar with the disk.

散乱光ではない: (1) diskに繋がっていない&偏波率が低い(2) Hαでちゃんと光っているevidence for a jovian protoplanet around AB Aurigae orbiting at a wide projected separation (93 au), likely responsible for multiple planet-induced features in the disk. Its emission is reproducible as reprocessed radiation from an embedded protoplanet.
We also identify two structures located at 430-580 au that are candidate sites of planet formation. These data reveal planet
formation in the embedded phase and a protoplanet discovery at wide, > 50 au separations characteristic of most imaged exoplanets. With at least one clump-like protoplanet and multiple spiral arms, the AB Aur system may also provide the evidence
for a long-considered alternative to the canonical model for Jupiter’s formation: disk (gravitational) instability.

(14)

Dusty circumbinary discs: inner cavity structures and stopping locations of migratingplanets

Gavin A. L. Coleman, Richard P. Nelson, Amaury H. M. J. Triaud F We present the results of two-fluid hydrodynamical simulations of circumbinary discs consisting of gas and dust, with and without embedded planets, to examine theinfluence of the dust on the structure of the tidally truncated inner cavity and on the parking locations of migrating planets.
In this proof-of-concept study, we consider Kepler-16 and -34 analogues, and examine dust fluids with Stokes numbers in therange 10 4  St  10 1 and dust-to-gas ratios of 0.01 and 1. For the canonical dust-to-gas ratio of 0.01, we find the inclusionof the dust has only a minor eﬀect on the cavity and stopping locations of embedded planets compared to dust-free simulations.
However, for the enhanced dust-to-gas ratio of unity, assumed to arise because of significant dust drift and accumulation, wefind that the dust can have a dramatic eﬀect by shrinking and circularising the inner cavity, which brings the parking locationsof planets closer to the central binary. This work demonstrates the importance of considering both gas and dust in studies ofcircumbinary discs and planets, and provides a potential means of explaining the orbital properties of circumbinary planets
such as Kepler-34b, which have hitherto been diﬃcult to explain using gas-only hydrodynamical simulations.

(15)

The Many-Faceted Light Curves of Young Disk-bearing Stars in Taurus as Seen by K2

Ann Marie Cody, Lynne A. Hillenbrand, Luisa M. Rebull F We present a comprehensive study of the variabilityproperties of young disk-bearing stars in the Taurus star-forming region, paralleling our previous investigation in rho Oph andUpper Sco. A sample of 99 confirmed Taurus association members is placed in the diagnostic Q-M plane of flux asymmetry (M)and quasi-periodicity (Q), which guides our assignment of variability classes. We find a similar proportion of flux-symmetricvariables in Taurus, but more bursters and fewer dippers relative to Upper Sco. The regions also diﬀer in that the amplitudes
for periodic and quasi-periodic sources are larger in Taurus relative to the more evolved Upper Sco star/disk systems. The
relationship between photometric variability patterns at optical wavelengths, which arise in the inner disk and at the stellar
surface, are assessed relative to available disk inclination measurements.

New evidences in IRDC G333.73+0.37: colliding filamentary clouds, hub-filament system, and embedded cores

L. K. Dewangan F To unravel the star formation process, we present a multi-scale and multi-wavelength study of the fila-(16)分子雲衝突からのhub-filament 形成G333.73+0.37- absorption features against the Galactic background in
the Spitzer images, and- has a filamentary appearance- the sub-mm and mm images => filamentary- total mass of the IRDC to be ∼4700 M⊙- assuming a distance of 2.6 kpc- dust clumps: ∼87 – 1530 M⊙- Two bright infrared sources S1 and S2 H ii regions

使ったデータ- SEDIGISM 13CO(J =2−1) and C18O(J =2−1) line data
- ALMA ほかいっぱい

六角形はATLASGAL 870μmのダストクランプの位置

(16続き)yxpx

Contour: 13COz

(16続き)ALMAの1.38mm マップ
ALMAの1.38mm で導出したコア?の物理量

the presence of low-mass cores toward the HFS associated with S2 gives
an impression that the cores producing massive stars may not gain theentire mass prior to core collapse, but instead, these entities gain masssimultaneously=>小質量のコアがいるということは、大質量星の形成の前段階で全ての質量を獲得しているわけではない。

(17)G208.89–20.04Walma : a very young source having an upper limit of Tbol ∼ 31 K and Lbol ∼ 0.8 Lo
ファーストコアとセカンドコアの間くらい？
ジェットを持つ天体の中では最も若い原始星か？

黒:12CO
赤:SiO

(17続き)Outflow の長さと重水素化合物peakとの差
N2D+はOnly two channels, atvelocity 5.6–7.0 km/s

MC35-mmは(Fujishiro, Tokuda+20)

元の図はMaureira et al. (2020)

(18)・フィラメント幅の測定が時間に依存する分子種(広めの幅)
C2H, CO, CN, CS, and C3H2
・時間にあまり依存しなさそう(細い幅をトレース)
N2H+, NH3, H2CO, HNC and CH3OH=>いろんな分子種で観測することによってフィラメントへのaccretion をトレースできる物理モデル(18続き)
ガス流入モデルIn this picture, proposed by Gómez & Vázquez-Semadeni (2014, GV14 from here on),
川の流れのように(ガスの長軸方向の流入)=>Longitudinal ﬂows consistent with the scenario de- scribed above have been widely
observed in a number of ﬁlamentary molecular cloud (一応観測で正当化されている)・SPH code gadget-2 で計算: warm neutral medium に温度と密度を似せた2つの衝突流
GV14 フィラメントの長さ∼ 15 pc, 質量 of ∼ 103 M⊙- a ﬂaWened density proﬁle with a core size of ∼ 0.3 pc and a power-law envelope with anapproximately −2.5 logarithmic slope.
- accre[on rate toward the ﬁlament is 10 M⊙ pc−1 Myr−1
ガス流入しない 静的なモデル (あまり詳しく書いてなかった)

化学反応とは完全にデカップルしているとする (ポストプロセッシング)
化学進化の計算 (Walsh+12; 14)=>元々は原始惑星系円盤のために開発2分子(e.g., CO)からH2CO, CH3OHなどの有機分子まで- Gas phase chemistry, Rate12 version of the UMIST(McElroy+2013)
初期条件の- Gas grain chemistry, OSU 2008
アバンダンス(Garrod+2008; Laas+2011)(原子から始める)

(18続き)Late-type

幅の比

シンボルの順: (左から)定常状態=>降着率を半分=>普通の降着=>降着率を2倍

early-type
横軸: 降着率
分子種同士で比を取ったら、accretion トー
レサーとして感度が上がるのでは