Star Formation News Letter:No.309 #28-37
2018.10.26 寺澤祥子
28. Multiplicity of disc-bearing stars in Upper Scorpius and Upper Centaurus-Lupus
29. A large-scale survey of CO and its isotopologues toward the Rosette molecular cloud
30. The formation of peptide-like molecules on interstellar dust grains
31. A Submillimeter Burst of S255IR SMA1 - The Rise And Fall Of Its Luminosity
32. The HH30 edge-on T Tauri star. A rotating and precessing monopolar outflow
scrutinized by ALMA
33. Multiple rings in the transitional disk of GM Aurigae revealed by VLA and ALMA
34. Pyroclastic Blowout: Dust Survival in Isolated versus Clustered Supernovae
35. First Results of an ALMA Band 10 Spectral Line Survey of NGC 6334I: Detections of
Glycolaldehyde (HC(O)CH2OH) and a New Compact Bipolar Outflow in HDO and CS
36. A global correlation linking young stars, clouds, and galaxies. Towards a unified view ofstar formation.
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37. Protostellar classification using supervised machine learning algorithms

#32 The HH30 edge-on T Tauri star.
A rotating and precessing monopolar outflow scrutinized by ALMA
F. Louvet, C. Dougados, S. Cabrit, D. Mardones, F. M´enard, B. Tabone4 C. Pinte, and W.R.F. Dent
導入・目的

➢ 原始星の質量は原始惑星系円盤のガスの降着によって増え、更なる星の成長を促す➢ 原始惑星系円盤のジェットの角運動量はClass 0 /1 , T Tauri星の間の様々な進化段階において、測定なされている-しかし、過去にHSTで検出した際の円盤の回転方向と、逆のT Tauri星も発見された➢ 今回はCOのエンベロープを示す主系列星を詳しく調べ、円盤のジェットの研究を推し進める

観測天体
・観測天体：HH30(T tauri型の前主系列星、~140pc)
・観測日時：ALMA cycle 2 period（2015年7月19日、2015年7月21日）
・帯域幅：Band6(211-275GHz）・基線長：13-1570m
2

結果・ 12𝐶𝑂 emission➢ 高速度と中間速度では、 12𝐶𝑂 emission lineの由来が異なる• 高速度では円盤の成分から、中間速度では円盤とアウトフローから由来している➢ システム速度は6.8km/s±0.1km/s• システム速度に対して対称であり、エンベロープをほぼ平面に見れる

中央は高速度部分(11.3km/s < V < 14km/s)、
右は中間速度（2.6km/s < V < 11.3km/s）部分のモーメント0マップ

チャンネルマップ3

・ 12𝐶𝑂 emission

ディスクの表面(y = -1.2’’)からy=3”までの横軸で切断➢ y = 0’’ケプラー回転円盤の特徴である、対称性をもつ➢ 0.36’’ < y < 2’’
全体として楕円形の要素を示す。
中央部分に位置する円錐形の空洞の周囲にemissionが発生すると考えられる➢ y > 2”
円盤が片側のみとなり、これは主に青方偏移。内側部分の楕円形の放射が見られる。

円盤を横方向に切断したPV図4

考察➢ 円錐状になっている空洞部分の質量を推定
水素分子の柱密度(𝑁𝐻2 )を求めたところ、2.25 × 1020𝑐𝑚−2となった。
従って、平均ガス質量μ、柱密度𝑁𝐻2 を用いると、30Kの時➢ エンベロープの軸に沿って、30au毎に分割
分割した部分の質量を上記と同様の手順で行った結果、半径-質量の関係は250auまでほぼ一定

30au毎に切ったエンベロープの個々の質量5➢ ディスク面上の距離zに対し、0.1” < z < 1.75”の範囲かつ半径250auまで楕円モデルをフィッティング
【結果】
• 半径
z=0.1”の範囲まで半径の変化が、中心角が35°±0.7°の円錐と完全に一致
z=0.1”の時は22auなので、これが円錐の半径上限• 投影された速度：VcentとVr×sin i は
いずれも一定に見えるが、
Vcent：0.1km/sよりも遥かに小さい
Vr×sin i ：5.3×10^-4km/s➢ 円盤の内側に位置する空洞
この空洞からは光蒸発 or 磁気の遠心分離のいずれかのシナリオに起因する円盤のジェットが期待されるフィッティング結果

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#33

Multiple rings in the transitional disk of GM Aurigae revealed by VLA
and ALMA
Enrique Macias, Catherine C. Espaillat, Alvaro Ribas, Kamber R. Schwarz, Guillem Anglada,
Mayra Osorio, Carlos Carrasco-Gonzalez, Jose F. Gomez and Connor Robinson

導入・目的➢ 電波望遠鏡の技術の発達は、原始惑星系円盤の詳細な構造の解明と深く関与している➢ 円盤の下部構造、ダストの進化、惑星形成のプロセス等の役割との関連性を知りたい➢ 先行研究で円盤の内部に空洞があるとされる、同一のT Tauri型星をVLAとALMAで観測を行う。
２つの観測結果を比較し、解析モデルを用いて原始惑星系円盤の構造の理解を深める
観測天体
・観測天体：GM Aurigae (T tauri型星、160±2pc)
VLA

観測機器

ALMA

2016年6月17日、7月20日

観測日時

Cycle 4(2016年11月11日)

150m-10000m

基線長15m-890m

Qband (40-50GHz)

Band域

Band 7(273-373GHz)

7mm

spw

𝐶18 𝑂 （J = 3-2）、 13𝐶𝑂 （J = 3-2）、 0.9mm

0.18”×0.15"

角度分解能

0. 29”×0. 20”
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結果
傾斜角：52.8°
位置角：56.5°➢ 中央に空洞と見られる箇所が検出
SEDより空洞部分の半径は~35au➢ エンベロープが方位角に対して非対称
西側のピーク強度が東側より約5σ明るい➢ ALMA側でのみ広範囲でのemissionが見られる

1,ALMA（上）とVLA（下）の連続波画像2, ALMA(左)とVLA(右)のSED

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考察

モデルのフィッティング

SEDに沿った解析モデルをそれぞれ作成。

➢ 2つのリングから構成される••

それぞれ半径~40au、~80au
第2のリングの外側を第3のリングとみなすまでにはならない➢ 内側のリングが円盤の空洞と繋がっている•

単一の惑星ではなく、複数の惑星が関与している可能性の示唆➢ 外側のリングの起源は不明➢ それぞれのモデルの内側のリングの半径が一致していない•ALMAでは42.5±0.2au、VLAでは39±1auと異なる
1. 今回のTarget天体は非対称な構造をしているために、空洞部分のダストの縁のガス圧力はサブmm粒子よりmm/cm粒子でより強くなる。よって、7mmで検出されるラストが空洞部分の縁に蓄積している可能性
2. 円盤の空洞内部のイオン化ガスの存在している可能性。
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#36 A global correlation linking young stars, clouds, and galaxies.
Towards a unified view of star formation.
I. Mendigutia, C.J. Lada and R.D. Oudmaijer
導入・目的

1. 星形成速度(SFR)は、星形成領域の総ガス質量（𝑀𝑑𝑔 ）と線形に相関している➢ 60年前に提唱された「Schmidt-Kennicuttの法則」に基づく観測より、様々な種類の星系銀河で成立している

2. Class IIの原始星の質量増加率(𝑀ሶ 𝑎𝑐𝑐 )と原始惑星系円盤のガス質量（ 𝑀𝑑𝑖𝑠𝑘 ）も直線的に相関している➢ この二つの相関を包括できる条件を考え、その検証を目標とする
手法➢ 文献の値を用いて、39個の星形成雲（数百pc~数kpc）と、62個のClass IIの原始星の「SFR- 𝑀𝑑𝑔 の対数グラフ」を作成➢ 原始星への質量降着率と、Class IIのみならず、Class 0/Iの原始星の周囲の総ガス質量がこの対数グラフにどのような影響を及ぼしているかを検証する
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Class II原始星と分子雲のSFR−𝑀𝑑𝑔 の対数グラフ

考察

1. 分子雲のSFRは、分子雲内の原始星の質量降着速度の和Class IIの原始星の質量降着率は、1.7×、−1Class 0/Iの原始星では、
𝑦𝑟 となり、１つの分子雲につき20の原始星を有すると仮定した結果、後者の場合ではという数値になった。
➢ この数値はグラフ内の分子雲の平均SFRの観測値と一致。

2. 個々の原始星のガス質量の和は、分子雲内の密度の高いガス質量の割合
SFR- 𝑀𝑑𝑔 の相関関係を原始星以外にも、分子雲や銀河の𝑀𝑑𝑖𝑠𝑘 に用いる。

その後にΣ𝑀𝐶𝑆 /𝑀𝑑𝑔 を計算し、各々のガスの割合を計算。
Class 0/Iの原始星の場合、0.012 <ΣMcs/ Mdg <0.34銀河の場合、初めに時間スケールによる補正を行い、平均値を用いる。
補正後では
とより、
0.01<Σ𝑀𝐶𝑆 /𝑀𝑑𝑔 <0.35。
原始星と銀河の両方の場合において、同等の割合を示した。

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Class II原始星,分子雲,銀河のSFR−𝑀 の対数グラフ

#28 Multiplicity of disc-bearing stars in Upper Scorpius and Upper
Centaurus-Lupus
Rajika L Kuruwita, Michael Ireland, Aaron Rizzuto, Joao Bento and Christoph Federrath
ABSTRACT
We present observations of disc-bearing stars in Upper Scorpius (US) and Upper Centaurus-Lupus (UCL) with moderate
resolution spectroscopy in order to determine the influence of multiplicity on disc persistence after ∼ 5−20Myr.
Discs were identified using infra-red (IR) excess from the Wide-field Infra-red Survey Explorer (WISE) survey.
Our survey consists of 55 US members and 28 UCL members, using spatial and kinematic information to assign a probability ofmembership.
Spectra are gathered from the ANU 2.3m telescope using the Wide Field Spectrograph (WiFeS) to detect radial velocity
variations that indicate the presence of a companion.
We identify 2 double-lined spectroscopic binaries, both of which have strong IR excess.
We find the binary fraction of disc bearing stars in US and UCL for periods up to 20 years to be 0.06+0.07−0.02 and
0.13+0.06−0.03 respectively.
Based on the multiplicity of field stars, we obtain an expected binary fraction of ∼ 0.12+0.02−0.01 .

The determined binary fractions for disc-bearing stars does not vary significantly from the field, suggesting that the overall
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lifetime of discs may not differ between single and binary star systems.

#29 A large-scale survey of CO and its isotopologues toward the Rosettemolecular cloud
Rajika L Kuruwita, Michael Ireland, Aaron Rizzuto, Joao Bento and Christoph Federrath
ABSTRACT
Using the PMO-13.7m millimeter telescope at Delingha in China, we have conducted a large-scale simultaneous survey of 12CO, 13CO, and C18O
J=1-0 emission toward the Rosette molecular cloud (RMC) region with a sky coverage of 3.5 × 2.5 deg 2 .
The majority of the emission in the region comes from the RMC complex with velocities lying in the range from -2 km/s to 20.5 km/s.
Beyond this velocity range, 73 molecular clumps are identified with kinematic distances from 2.4 kpc to 11 kpc.
Based on the spatial and velocity distribution, nine individual clouds, C1-C9, have been identified for the RMC complex.
It appears that the C3 cloud is different from other clouds in the RMC complex in view of its characteristic velocity, excitation temperature, andvelocity dispersion.
Most of the young stellar clusters in the region are located in positions of both high column density and high excitation temperature.

Seven new molecular filaments are discovered in the RMC complex.
Evidence for cloud-cloud collision is found in the region of young stellar clusters REFL9 and PouF, showing that these young stellar clusters
probably result from a cloud-cloud collision.
The abundance ratios of 13CO to C18O in the region have a mean value of 13.7 which is 2.5 times larger than the solar system value, showing that13
UV photons from the nearby OB clusters have strong influence on the chemistry of clouds in the RMC complex.

#30 The formation of peptide-like molecules on interstellar dust grains
N.F.W. Ligterink, J. Terwisscha van Scheltinga, V. Taquet, J.K. Jørgensen, S. Cazaux,
E.F.van Dishoeck and H. Linnartz
ABSTRACT
Molecules with an amide functional group resemble peptide bonds, the molecular bridges that connect amino acids, and may thus be relevant inprocesses that lead to the formation of life.
In this study, the solid state formation of some of the smallest amides is investigated in the laboratory.
To this end, CH4:HNCO ice mixtures at 20 K are irradiated with far-UV photons, where the radiation is used as a tool to produce the radicals
required for the formation of the amides.
Products are identified and investigated with infrared spectroscopy and temperature programmed desorption mass spectrometry.
The laboratory data show that NH2CHO, CH3NCO, NH2C(O)NH2, CH3C(O)NH2 and CH3NH2 can simultaneously be formed. The NH2CO radical
is found to be key in the formation of larger amides.
In parallel, ALMA observations towards the low-mass protostar IRAS 16293−2422B are analysed in search of CH3NHCHO (N-methylformamide)
and CH3C(O)NH2 (acetamide).
CH3C(O)NH2 is tentatively detected towards IRAS 16293−2422B at an abundance comparable with those found towards high-mass sources.
The combined laboratory and observational data indicates that NH2CHO and CH3C(O)NH2 are chemically linked and form in the ice mantles ofinterstellar dust grains.
A solid-state reaction network for the formation of these amides is proposed.

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#31 A Submillimeter Burst of S255IR SMA1 - The Rise And Fall Of Its
Luminosity
Sheng-Yuan Liu, Yu-Nung Su, Igor Zinchenko, Kuo-Song Wang, and Yuan Wang
ABSTRACT
Temporal photometric variations at near infrared to submillimeter wavelengths have been found in low-mass
young stellar objects.
These phenomena are generally interpreted as accretion events of star-disk systems with varying accretion rates.
There is growing evidence suggesting that similar luminosity flaring also occurs in high-mass star/clusterforming
regions.
We report in this Letter the rise and fall of the 900 μm continuum emission and the newly found 349.1 GHz
methanol maser emission in the massive star forming region S255IR SMA1 observed with the Submillimeter Array
and the Atacama Large Millimeter/submillimeter Array.
The level of flux variation at a factor of ∼2 at the submillimeter band and the relatively short 2-year duration ofthis burst suggest that the event is probably similar to those milder and more frequent minor bursts seen in 3D
15
numerical simulations.

#34 Pyroclastic Blowout : Dust Survival in Isolated versus Clustered Supernovae
Sergio Martinez-Gonzalez, Richard Wunsch, Jan Palous, Casiana Munoz-Tunon, Sergiy Silichand Guillermo Tenorio-Tagle
ABSTRACT
Following the current debate on the fate of SN-condensed dust grains, here we explore by means of three-dimensional hydrodynamical
simulations the interaction of dusty supernova remnants (SNRs) with the shocked winds of neighboring massive stars within young massive
stellar clusters (SSCs).
As a comparison, we have also explored the evolution of supernova remnants in the diffuse ISM with constant density.

Since the hydrodynamics of SNRs is intimately related to the properties of their immediate environment, the lifecycle of dust grains in SNRs within
SSCs is radically different from that in the diffuse ISM.
Moreover, off-centered SNRs evolving in the steep density gradient established due to a star cluster wind experience a blowout phase: shellfragmentation due to protruding Rayleigh-Taylor instabilities and the venting of SN ejecta.
Our main finding is that clustered SN explosions will cause a net increase in the amount of dust in the surroundings of young massive stellar
clusters.
Our analysis considers the multiple dust processing resulting from the passage of the SN reverse shock, including its reflection at the SNR’scenter, the injection of shocked stellar winds within the respective remnant’s volume and the effect of secondary forward shocks produced insequential SN explosions.

In the simulations, we have on-the-fly calculated the rates of thermal sputtering and dust-induced radiative cooling provided an initial distributionof grain sizes and dust content.
Fast-moving elongated dusty SN ejecta resemble mushroom clouds violently ascending in a stratified atmosphere after volcanic super-eruptions,16
where the pyroclasts carried by the clouds are wind-driven and eventually accumulate into the vast surroundings.

#35 First Results of an ALMA Band 10 Spectral Line Survey of NGC 6334I: Detections of
Glycolaldehyde (HC(O)CH2OH) and a New Compact Bipolar Outflow in HDO and CS
Brett A. McGuire, Crystal L. Brogan, Todd R. Hunter, Anthony J. Remijan, Geoffrey A. Blake,Andrew M. Burkhardt, P. Brandon Carroll,
Ewine F. van Dishoeck, Robin T. Garrod, Harold Linnartz, Christopher N. Shingledecker and Eric R. Willis

ABSTRACT
We present the first results of a pilot program to conduct an ALMA Band 10 spectral line survey of the high-mass star-forming region
NGC6334I.
The observations were taken in exceptional weather conditions (0.19 mm precipitable water) with typical system temperatures Tsys
<950 K at ~890 GHz.
A bright, bipolar north-south outflow is seen in HDO and CS emission, driven by the embedded massive protostar MM1B.
This has allowed, for the first time, a direct comparison of the thermal water in this outflow to the location of water maser emission fromprior 22 GHz VLA observations.
The maser locations are shown to correspond to the sites along the outflow cavity walls where high velocity gas impacts the surrounding
material.
We also compare our new observations to prior Herschel HIFI spectral line survey data of this field, detecting an order of magnitude
more spectral lines (695 vs 65) in the ALMA data.
We focus on the strong detections of the complex organic molecule glycolaldehyde (HC(O)CH2OH) in the ALMA data that is notdetected in the heavily beam-diluted HIFI spectra. Finally, we stress the need for dedicated THz laboratory spectroscopy to support and17
exploit future high-frequency molecular line observations with ALMA.

#37 Protostellar classification using supervised machine learning algorithms
Oskari Miettinen
ABSTRACTClassification of young stellar objects (YSOs) into different evolutionary stages helps us to understand the formation process of new stars and planetary systems.
Such classification has traditionally been based on spectral energy distribution (SED) analysis. An alternative approach is provided by supervised machine learningalgorithms, which can be trained to classify large samples of YSOs much faster than via SED analysis.

We attempt to classify a sample of Orion YSOs (the parent sample size is 330) into different classes, where each source has already been classified using
multiwavelength SED analysis.
We used eight different learning algorithms to classify the target YSOs, namely a decision tree, random forest, gradient boosting machine (GBM), logistic regression, naive
Bayes classifier, k-nearest neighbour classifier, support vector machine, and neural network.
The classifiers were trained and tested by using a 10-fold cross-validation procedure. As the learning features, we employed ten different continuum flux densities
spanning from the near-infrared to submillimetre wavebands (3.6 - 870 μm).
With a classification accuracy of 82% (with respect to the SED-based classes), a GBM algorithm was found to exhibit the best performance. The lowest accuracy of 47%
was obtained with a nave Bayes classifier.
Our analysis suggests that the inclusion of the 3.6 μm and 24 μm flux densities is useful to maximise the YSO classification accuracy.
Although machine learning has the potential to provide a rapid and fairly reliable way to classify YSOs, an SED analysis is still needed to derive the physical properties ofthe sources (e.g. dust temperature and mass), and to create the labelled training data.
The machine learning classification accuracies can be improved with respect to the present results by using larger data sets, more detailed missing value imputation, andadvanced ensemble methods (e.g. extreme gradient boosting).
Overall, the application of machine learning is expected to be very useful in the era of big astronomical data, for example to quickly assemble interesting target source
samples for follow-up studies.
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