星形成ゼミ 2018/3/2
SFN #301 50-52, #302 1-5
崔仁士

1# 301505152# 302

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ALMAでTaurusのprotoplanetary diskをsurvey
disk massを導出し統計的に議論
low mass star (spectarl type M4 – M7) のサンプルを埋めた

観測と結果• ALMA Cycle 1, 885 µm continuum (ALMA Band 7)• samples: Herschelを用いたTBOSS surveyから• M type の Class II のみ24天体• stellar: M4 – M5 の14天体
substellar: M6 – M7の10天体• 空間分解能 ~ 0’’.34x0’’.24• 21天体が8σ以上でdetection，J0414+2811のみ5σでdetectionで，計22天体が受かった• 3σの検出限界は0.27 mJy/beam

Herschel 70 µm flux (mJy)概要

3円盤質量の測定
scaling relation• κ1.3mm = 2.3 cm2 g-1, κν ~ ν0.4
• r = 100 au を仮定→ Mass range~ 0.3−20 Mearth
右上がりの傾向

power-law fitting• Mdust vs M*で正の相関 (∝M*0.94±0.14)• フィッティング結果はAndrews+13 と一致する結果→ low mass でも円盤形成プロセスは同じ• Upper Sco との比較
• slopeはTaurusとほぼ同じ（ ∝M*0.92±0.18，ただし恒星進化モデルに依存）• より進化の進んだUpper Scoではdisk massが減少している4

• MMSN gas massを超えるのは24%• M-star rangeでは17%↔M-dwarf周囲のgas giantの存在頻度は~2-3 %→ gas giantを作る効率は低い• brown dwarf 周りには10Mearthを超えるものも少ない→ brown dwarf周りのplanetary mass companionはdisk起源ではない？
• Kepler で見つかった惑星質量をプロット(Mulders+15，惑星周期は2-50 days)• 見つかった惑星よりもdiskにはもっと質量がある

browndwarf

M-dwarf• Upper ScoではTaurusと比べてdisk massは減少する
が分布は同じ→消えたmassはplanet ?
• 惑星形成は1-2 Myr のTaurusから~10 Myr のUpper
Scoの間で起こっている

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#1
概要
• 大質量形成過程についてよく知りたい• Infrared dark clouds (IRDCs) の一つである IRDC G034.43+0024 を観測を行った• IRDC G034.43+0024• filament 構造の中に複数の重いcores• dense, quiescentなgas• 速度構造からCloud の形成などを議論

観測••
•
•

IRAM 30 m telescope/EMIR
N2H+ (1-0) と C18O (2-1) 輝線を観測
それぞれdense core，dense coreよりさらに広がった
envelopeをtraceすると期待
空間分解能 ~ 0.5 pc

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観測結果
surface density

積分強度

速度分布

速度分散

N2H+
N2H+C18O

C18O

コントア: 積分強度

• ピークがいくつかのコアに対応（MM1, MM3 for N2H+，MM1, MM3, MM7, MM8, F1 for C18O）• 東西方向に速度勾配• 速度分散の振る舞いが異なる• 異なる速度成分を分離する• semi-automated gaussian fitting
Mapをいくつかに分けた領域 (SAA) で複数のGaussianをfit
automated hierarchical clusteringalgorithm
Gaussian fitされた各SAAsの分類を行う
1. 各成分のseparationがbeam size以下
2. 速度差が速度分解能の2倍以下
3. 速度分散の差が0.23 km/s 以下を満たすなら同じ成分とみなす•7

Cloud F の速度成分• N2H+は1成分，C18Oは4成分• N2H+，C18Oの間で同じ成分FPPV4に速度差→ <VN2H+-Vc18o> = +0.32 ± 0.06 km/s
• FPPV1とFPPV2の速度差2.9±0.5 km/s

Cloud H (IRDC: G035.39 – 00.33) との比較

• Cloud H にも同じ解析，C18Oで5成分• いくつかの共通点• 同様の2.9±0.3 km/sの速度差をもつ2成分が存在• HPPV4でN2H+とC18Oの間に速度差 +0.26 ± 0.02 km/s
→ 同じ形成シナリオで説明できる？
• Cloud H はfilament merging senario?
• 高速度の成分 (HPPV1,2)と低速度の成分 (HPPV3)がmergingして中間速度の成分 (HPPV4)が形成• N2H+は高速度成分に押されたdenseな場所 → C18Oより高速度になる
1414Barnes, Henshaw, Caselli, Jiménez-Serra, Tan, Fontani, Pon, Ragan

Barnes, Henshaw, Caselli, Jiménez-Serra, Tan, Fontani, Pon, Ragan

GMC scales for Cloud F• large scale の観測と今回の観測がよく一致• Cloud F はより大きなGiant
Molecular Filamentの一部の可能性がある

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#2概要

• 分子雲から円盤形成の数値シミュレーション• 初の原始星円盤のpopulation synthesis studyを行なった

計算について• 3D SPHコードでradiative hydrodynamicsの計算• 初期条件• 一様密度の分子雲• 質量: 500 Msun
• スケール: 0.404 pc• 密度: 1.2x10-19 g cm-3
• tff = 6.0x1012 s ~ 1.90x105 yr• T = 10.3 K• 乱流あり（rms: M=13.7）••••• 円盤の条件• r < 2000 au かつ軌道の離心率e < 0.3のSPH粒子• 次のものは除外- Mdisk < 0.003 Msun 以下，全円盤質量の63%を含む半径が300 au以上，63%を含む半径が50%を含む半径の3倍以上• 円盤半径- 全円盤質量の63.2%を含む半径

計算は1.20 tff ~ 0.23 Myr まで
最も進化した protostar は 0.9x105 yr
分解能は円盤サイズ 10 au
最終的に 84のsingle protostarと40のmultiple systems（28 binary, 5 triple, 7 quadruple）が形成

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結果
多様な円盤
• misaligned systems, spiral, warped disks, etc.
• 典型的に• M* ~ 0.02 - 0.4 Msun
• Mdisk ~ 0.003 - 0.5 Msun
• Rdisk ~ 20 – 100 au
all systems

Figure 12. The evolution of the disc radii of isolated protostars (sink particles) as a function of age. Each line represents the evolution of the discaround a particular protostar. Lines may stop and start, for example, if theprotostar becomes part of a multiple system, or is expelled from a multiplesystem, respectively.

Diversity and properties of protostellar discs

Figure 12. The evolution of the disc radii of isolated protostars (sink particles) as a function of age. Each line represents the evolution of the discaround a particular protostar. Lines may stop and start, for example, if theprotostar becomes part of a multiple system, or is expelled from a multiplesystem, respectively.

15Figure 13. The evolution of the ratio of the disc mass to protostellar (sinkparticle) mass as a function of age for isolated protostars. Each line represents the evolution of the disc around a particular protostar. Lines may stopand start, for example, if the protostar becomes part of a multiple system,
or is expelled from a multiple system, respectively.

Note that there are few isolated protostars older than 30,000 yrs
when the calculation is stopped. Also, after ⇡ 104 yrs, it is clearthat the disc masses around some protostars rapidly decline (dueto accretion, encounters with other protostars, and/or ram-pressure
stripping). Some protostars also suddenly become isolated as theyare ejected from multiple systems and these usually have low disc
Figure 11. The time evolution of the disc masses of isolated protostars (sink Figure 12. The evolution of the disc radii of isolated protostars (sink parmasses.
Figure 13. The evolution of the ratio of the disc mass to protostellar (sinkparticles) during the calculation. The top panel gives the disc mass versus ticles) as a function of age. Each line represents the evolution of the disc
In Fig. 12 we plot the disc radii of isolated protostars particle)
versus mass as a function of age for isolated protostars. Each line reprethe (linear) time in the calculation, while the bottom panel gives the disc around a particular
protostar.
Linesthere
may stop
start, forexample,
if theage. As withdisc mass,
is aandgeneraltrend
for discradii
tomass versus the age of the protostar (using a logarithmic time scale). For protostar
sents
becomes part of a multiple system, or is expelled from a multiple 3 the evolution of the disc around a particular protostar. Lines may stop
larger with time. They range from radii of 10–50 au at 10yrs
comparison with the top panel, the middle panel provides the time evolu- system,getandstart,for example, if the protostar becomes part of a multiple system,respectively.
old to 20–100 au at 104 yrs old. Note that even though the orcalcution of the protostellar mass (i.e. sink particle mass) of the isolated protois expelled from a multiple system, respectively.
stars whose disc masses are given in the top panel. Each line represents thelation does not treat magnetic fields (which could provide angular
evolution of the disc around a particular isolated protostar. Lines may stop
momentum transport by magnetic braking), the disc radii are notand start, for example, if the protostar becomes part of a multiple system,
unusually large. We will discuss this further in Section 6. Note that there are few isolated protostars older than 30,000 yrs
or is expelled from a multiple system, respectively.
In Fig. 13 we plot the ratio of the disc mass to the protostellar
when the calculation is stopped. Also, after ⇡ 104 yrs, it is clearthat the disc masses around some protostars rapidly decline (duec 0000 RAS, MNRAS 000, 000–000
to accretion, encounters with other protostars, and/or ram-pressurestripping). Some protostars also suddenly become isolated as they
are ejected from multiple systems and these usually have low disc
Figure 11. The time evolution of the disc masses of isolated protostars (sinkmasses.
particles) during the calculation. The top panel gives the disc mass versus
In Fig. 12 we plot the disc radii of isolated protostars versus
the (linear) time in the calculation, while the bottom panel gives the discage. As with disc mass, there is a general trend for disc radii tomass versus the age of the protostar (using a logarithmic time scale). For
get larger with time. They range from radii of 10–50 au at 103 yrs
comparison with the top panel, the middle panel provides the time evoluold to 20–100 au at 104 yrs old. Note that even though the calcution of the protostellar mass (i.e. sink particle mass) of the isolated protostars whose disc masses are given in the top panel. Each line represents thelation does not treat magnetic fields (which could provide angularFigure 15. The cumulative distributions of discmass(left),radius(centre),and protostar.
the discLines
to stellar(right)transport
for circumstellarof thesingle
evolutionof thedisc arounda particularisolated
may stopmass ratio
momentumby magnetic discs
braking),disc protostars
radii are notand start,
example,the protostar
becomespart of a multiple
system,that have never had another object within 2000
au.forThe
solidiflines
give thedistributions
for all
protostellar
masses.
The
dashed,long-dashed,anddot-dashedunusually large. We will discuss this further in Section
6.
or is expelled from a multiple system, respectively.
Fig. ,13we plot the ratioof theprotostars
disc mass towith
the protostellarlines give the distributions for single protostars
in three mass ranges: < 0.1 M , 0.1 0.3 M , and > 0.3InM
respectively.
Singlegreater

No encounters

Diversity and properties of protostellar discs

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disk mass• 時間とともに増加
disk radii
disk/stellar mass ratio
34• 典型的に10 yr – 10 yrで3倍程度• rc ∝ M*~0.25• Md/M* ~ 0.1 -2
masseshave
substantiallymore
massivediscs,
suchthatthedisctostar
mass
ratio
distribution
isessentiallyindependent of protostellar mass. More massiveまで成長
protostars also tend to have slightly larger
discs, but
is weak.
• M*< the0.1effectMsunでrc=20をき• 時間によらず一定
4• 10 yrより先はdisk massが減少
る小さな円盤は~ 50 %• M* 0.1 – 0.3 で高い傾向
the top left panel of Fig. 14• Md ∝ M*~0.85 (M* < 0.5tion
Mincreasessun) or not. For example,• inM*>0.3
Msunでは ~protostars
10 % in multiple systems (Bate & Bonnell 1997; Bate 2000).
c 0000 RAS,
MNRAS
000–000
Figure13. The000,
evolutionof the ratio of the disc mass to protostellar (sinkparticle) mass as a function of age for isolated protostars. Each line represents the evolution of the disc around a particular protostar. Lines may stopand start, for example, if the protostar becomes part of a multiple system,
or is expelled from a multiple system, respectively.

for ages > 10000 yrs, the cumulative line passes
through 0.78 at
However, in the hydrodynamical calculation, numerical viscous
Note that there are few isolated protostars older than 30,000 yrs
M ⇡ 0.01 M and rises to unity, so the median value for proevolution4 also plays a role (see Appendix B). Viscously evolving

pair のdisks，軌道,中心星spinのaligenment
Diversity
properties of protostellar discs
22 M.andR. Bate

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Figure 19. Distributions of the relative orientation angle between the two circumstellar discs in bound protostellar pairs. Pairs include both binaries and boundFigure 20. Distributions of the relative orientation angle between each circumstellar disc and the orbital plane in bound protostellar pairs. Pairs include
pairs in hierarchical triple or quadruple systems. In the top left panel, we plot the relative orientation angle of each pair versus its semi-major axis, with binary
both binaries and bound pairs in hierarchical triple or quadruple systems. In the top left panel, we plot the relative orientation angle of each pair versus
systems in black, pairs in triples in red, and pairs in quadruples in blue. In the remaining panels, we give the cumulative distributions of the orientation angles.
its semi-major axis, with binary systems in black, pairs in triples in red, and pairs in quadruples in blue. In the remaining panels, we give the cumulative
In the top-right panel, we give the cumulative distributions for all pairs and pairs in three different age ranges. We also give separate distributions for binary
distributions of the orientation angles. In the top-right panel, we give the cumulative distributions for all pairs and pairs in three different age ranges. We alsosystems, for pairs in triple or quadruple systems, and for pairs for which at least one of the components was created by disc fragmentation. In the bottom-leftgive separate distributions for binary systems, for pairs in triple or quadruple systems, and for pairs for which at least one of the components was created bypanel, we plot the cumulative distributions for four ranges of semi-major axes for all pairs, and we also plot the separate distributions of binaries, and pairs thatdisc fragmentation. In the bottom-left panel, we plot the cumulative distributions for four ranges of semi-major axes for all pairs, and we also plot the separate
are components of triples or quadruples. In the bottom-right panel, we plot the cumulative distributions for semi-major axes a < 100 au and a > 100 au for
distributions of binaries, and pairs that are components of triples or quadruples. In the bottom-right panel, we plot the cumulative distributions for semi-major
all pairs, binaries, and pairs that are components of triples or quadruples. The circumstellar discs become more aligned with increasing age. The circumstellar
axes a < 100 au and a > 100 au for all pairs, binaries, and pairs that are components of triples or quadruples. The circumstellar discs become more aligned
discs of pairs also tend to be more closely aligned in high-order multiple systems than in binaries.
with the orbital plane pair with increasing age. The circumstellar discs of pairs also tend to be more closely aligned with the orbital plane in high-order multiple
systems than in binaries. However, both of these trends are weaker than when comparing the relative orientations of the two discs in a pair.

それぞれのcircumstellar diskはpairのseparationが大きいほどmisaligned

for all pairs and for subsets depending on their ages, separations,and separating binaries and pairs in higher-order multiple systems.
The circumstellar discs tend to be more aligned with each other inpairのseparationが大きいほど強くmisalignedin these pairs are well aligned. Three quarters of these pairs haveseparations
less than
100discau, fragmentation,
and all have separations
220
systemsoriginate
fromin whichless
it isthannaturalau. theSecond,the orbital
timescalediscs
is muchshorter
for closer
systems,
forresulting
circumstellar
to bealignedwith theorbit.

separationに関係なく50%ほどのpairで円盤とspinがmisaligned

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misaligned discs than there are discs that are highly misalignedwith orbits. For example, only ⇡ 7% of discs are misaligned by

観測との比較

dust massvs Class II disks• disk mass: ~ 104 yrの若いdiskの方がClass IIのdiskに比べて30 – 300倍重い• disk radius: 分布は観測とシミュレーションでよく一致

vs Class 0 disks

gas mass• disk mass: 観測から0.05 – 0.2 Msun (Jorgensen+9,Enoch+11), 0.09 - 0.36 Msun (Segura-Cox+16)• シミュレーション（0.02 - 0.4 Msun）とコンシステント• disk radius も比較的コンシステント• disk mass は disk radiusにはあまり依らない• Class 0からClass IIへはdisk radiusを保ったまま質量のみを減らして進化する

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