SFN #355 13-18
担当：土井 聖明 (総研大D1)
13. Resolving the core of R136 in the optical
14. Discovery of a coherent, wave-like velocity pattern for the Radcli e Wave
15. Weather Forecast of the Milky Way: Shear and Stellar feedback determine the livesof Galactic-scale laments
16. Detection of an excess of young stars in the Galactic center Sagittarius B1 region
17. Momentum and energy injection by a wind-blown bubble into an inhomogeneousinter- stellar medium

ff

ff

fi

18. Gas disk interactions, tides and relativistic e ects in the rocky planet formation at
the substellar mass limit

Resolving the core of R136 in the optical

Venu M. Kalari, Elliott P. Horch, Ricardo Salinas, Jorick S. Vink, Morten Andersen, Joachim M. Bestenlehner,
Monica Rubio F The sharpest optical images of the R136 cluster in the Large Magellanic Cloud are presented, allowing

for the first time to resolve members of the central core, including R136a1, the most massive star known. These data
were taken using the Gemini speckle imager Zorro in medium-band filters with eﬀective wavelengths similar to BVRI
achieving angular resolutions between 30-40 mas. All stars previously known in the literature, having V <16 magwithin the central 200 ⇥ 200 were recovered. Visual companions( 40 mas; 2000 au) were detected for the WN5h stars
5
R136 a1, and a3. Photometry of the visual companion of a1 suggests it is of mid O spectral type. Based on new
photometric luminosities using the resolved Zorro imaging, the masses of the individual WN5h stars are estimatedto be between 150-200 M , lowering significantly the present-day masses of some of the most massive stars known.
These mass estimates are critical anchor points for establishing the stellar upper-mass function.

Discovery of a coherent, wave-like velocity pattern for the Radcliﬀe Wave

最も重たく明るい星の質量推定に関する論文
Guang-Xing
Li, Bing-Qiu Chen F Recently studies discovered that part of the Gould Belt belongs to a 2.7 kpc-longcoherent, thin wave consisting of a chain of clouds, where a damped undulation pattern has been identified from・R136a1：最も重たい星、マゼラン雲中のWN5h型星(Wolf-Rayet型で水素輝線を持つ)
the spatial arrangement of the clouds. We use the proper motions of Young Stellar Objects (YSOs) anchored insidetheclouds to study
the kinematic
structureof the Radcliﬀe Wave in terms of vz , and identify a damped, wave-like
・これまで
> 250
M̲sun
だと推定されてきた
pattern from the vz space, which we call "velocity undulation". We propose a new formalism based on the Ensemble
・GeminiEmpirical
Modeによる可視でのスペックル干渉法観測により新たな質量推定を行った
Decomposition (EEMD) to determine the amplitude, period, and phase of the undulation pattern,
and find that the spatial and the velocity undulation share an almost identical spatial frequency of about 1.5 kpc,
・R135a1の伴星を空間分解した：mid-O
type星
and both are damped when measured from one side to the other. Measured for the first cycle, they exhibit a phase
diﬀerenceof around2⇡/3. The structureis oscillating around the midplane of the Milky Way disk with an amplitude
・質量は~ 200M̲sunと再推定(前よりだいぶ軽い)of ⇠ 130 ± 20 pc. The vertical extent of the Radcliﬀe Wave exceeds the thickness of the molecular disk, suggesting・恒星の質量分布の描像に影響
that
the undulation of the undulation signature might originate from a perturbation, e.g. the passage of a dwarf
galaxy.

イントロ・超大質量星(> 100 M̲sun)の形成過程は未解明
・連星率や最大質量は形成機構解明の手がかりとなる・大マゼラン雲中の R136 は多くの大質量星を含む
・1”=0.2 pc 中に ~10^4 M̲sunの星を含む
・巨大な星は宇宙初期には多いと考えられており、宇宙初期解明の手がかりにもなる・大マゼラン雲は金属量が低く(<1/4）、宇宙初期のテンプレートとして最適
・これまでも多くの高空間分解能観測
・望遠鏡名未記載(スペックル干渉法)、HST(宇宙)、VLT SPHERE(AO)

The Astrophysical Journal, 935:162 (11pp), 2022 August 20

K

観測・Gemini 8.1 m
・スペックル干渉法(Zorro)・medium band lter
(466, 562, 716, 832 nm)
・分解能：30-40 mas
・感度：V~16 mag

結果・これまでに見つかっていた全てのV < 16 magの星は見つかった・R136a1の伴星を分解した
・R136a3の伴星も見つかった

fi

Figure 1. Zorro EO832 imaging of R136. R136 resolved stars from Weigelt & Baier (1985) are marked. Arrows mark the resolved companions to the W

The Astrophysical Journal, 935:162 (11pp), 2022 August 20

Kalari et al.

結果 (つづき)・これまでの質量推定と比べて小さい・恒星質量の観測的な上限が小さくなった
Figure 7. Spectral energy distribution of the three WN stars in R136, labeled. Underlying theoretical models are from Bestenlehner et al. (2020). Observed Zorro
photometry are given by red circles, with the blue circles representing HST or Ks photometry from Khorrami et al. (2021), plotted in AB magnitude units. Gray circles
or carets (lower limits) are K magnitudes from Rubio-Díez et al. (2017). All error bars are of 0.1 mag, except when greater.
Table 3
Luminosities and Masses of the Central WN5h Stars
WB85a

log L
(Le)

Mass
(Me)

Referenceb

R136 a1

6.67 ± 0.13
6.79 ± 0.1
6.94 ± 0.09

+34
19627
+48
25131
+60
31550

This work
Bestenlehner et al. (2020)
Crowther et al. (2016)

R136 a2

6.55 ± 0.13
6.75 ± 0.1
6.63 ± 0.09

+27
15116
+31
21132
+35
19530

This work
Bestenlehner et al. (2020)
Crowther et al. (2016)

R136 a3

6.56 ± 0.13
6.63 ± 0.1
6.58 ± 0.09

+25
15518
+29
18131
180 ± 30This work
Bestenlehner et al. (2020)
Crowther et al. (2016)

Notes.
aBased on the nomenclature from Weigelt & Baier (1985).
b
All spectral parameters except luminosity are the same with Bestenlehneret al. (2020). Crowther et al. (2016) adopted effective temperatures of

Figure 2. Grayscale thumbnails of the central core of R136 (0 8 × 0 8) centered on R136a1, at highest available angular resolutions in the optical and infrared (IR).
The instrument or telescope, and the ﬁlter of the images are given in the lower left-hand corner of each thumbnail, and from top to bottom, left to right are HST
F336W, and F555W images (Hunter et al. 1995), IR adaptive optics (AO) images from the MAD and SPHERE instrument taken at the VLT in Ks (Campbell
et al. 2010; Khorrami et al. 2021), optical AO imaging using the integral ﬁeld spectrograph MUSE (Castro et al. 2021) and the Zorro images. Apparent is the improved
angular resolution from AO imaging in IR, and the vastly improved resolution from Zorro compared to other optical images. All images are in linear scale, withintensity chosen to best separate the central components visually.

autocorrelation of R136 to arrive at its power spectrum,
dividing it by the average power spectrum of the point-source
calibrators, and taking the square root.
What remains from that point in order to reconstruct theimage of the target is the phase of R136 in the Fourier domain.
However, the image morphology of the target is complex, andthe phase function is difﬁcult to reconstruct using normal
speckle methods such as bispectral analysis. On the other hand,progress can be made by comparing the speckle data with IR
images of the same ﬁeld taken in the IR. The inverse-Fouriertransform of the modulus shows peaks at the location of eachsmaller diffraction limit in the visible range of the spectrum. In
total, we were able to identify 41 peaks in common with the Hband image in images of the ﬁeld taken through the EO832
ﬁlter, and 24 peaks in common when observing through theEO562 ﬁlter.
We next ﬁtted the collection of peaks with Gaussianfunctions of various heights and positions on the image planein the modulus. Only peaks with the quadrants that matched
actual sources in the IR image were ﬁtted. The result was a listof positions and heights in the modulus that represented theactual star positions. To insure a robust ﬁt, we ﬁtted the three

Discovery of a coherent, wave-like velocity pattern for the Radcliﬀe Wave

Guang-Xing Li, Bing-Qiu Chen F Recently studies discovered that part of the Gould Belt belongs to a 2.7 kpc-longcoherent, thin wave consisting of a chain of clouds, where a damped undulation pattern has been identified fromthe spatial arrangement of the clouds. We use the proper motions of Young Stellar Objects (YSOs) anchored inside
the clouds to study the kinematic structure of the Radcliﬀe Wave in terms of vz , and identify a damped, wave-likepattern from the vz space, which we call "velocity undulation". We propose a new formalism based on the Ensemble
Empirical Mode Decomposition (EEMD) to determine the amplitude, period, and phase of the undulation pattern,
and find that the spatial and the velocity undulation share an almost identical spatial frequency of about 1.5 kpc,
and both are damped when measured from one side to the other. Measured for the first cycle, they exhibit a phase
diﬀerence of around 2⇡/3. The structure is oscillating around the midplane of the Milky Way disk with an amplitudeof ⇠ 130 ± 20 pc. The vertical extent of the Radcliﬀe Wave exceeds the thickness of the molecular disk, suggestingthat the undulation of the undulation signature might originate from a perturbation, e.g. the passage of a dwarf
galaxy.

注：過去のSFNを確認→SFN #353 #31と同じ論文

Weather Forecast of the Milky Way: Shear and Stellar feedback determine the lives ofGalactic-scalefilaments
Radcli e Waveの位置速度が波打っていることを発見した
Guang-Xing Li, Ji-Xuan Zhou, Bing-Qiu Chen F The interstellar medium (ISM) is an inseparable part of the Milkyff

・GaiaによるYSOの固有運動をもとに、cloudの速度構造を解明
Way
ecosystem whose evolutionary history remains a challenging question. We trace the evolution of the molecular
ISM using a sample of Young Stellar Objects (YSO) association –molecular cloud complex (YSO-MC complex). We
・位置の波と同波長で2/3πの位相差の波構造を持っていることが明らかに
derive their three-dimensional (3D) velocities by combining the Gaia astrometric measurements of the YSO associations
andthe CO observations of the associated molecular
clouds. Based on the 3D velocities, we simulate the motions
・銀河円盤の厚みよりも厚い、130pc程度の振幅で波打っているof the YSO-MC complexes in the Galactic potential and forecast the ISM evolution by tracing the motions of the・dwarfgalaxyの通過など、外部からの撹乱によって引き起こされている可能性
individualcomplexes,
and reveal the roles of shear and stellar feedback in determining ISM evolution: Galactic shear
stretches Galactic-scale molecular cloud complexes, such as the G120 Complex, into Galactic-scale filaments, and it
also contributes to the destruction of the filaments; while stellar feedback creates interconnected superbubbles whoseイントロ
used to compute the mass and model the 3D shape of the structure
are described in Methods. We name the structure the Radcliffe Wavein honour of both the early-20th-century female astronomers from
Radcliffe College and the interdisciplinary spirit of the current Radcliffe
Institute, which contributed to this discovery. The structure can also beseen at lower resolution in recent all-sky 3D dust maps15–17 (see Fig. 2).
A second linear structure, the ‘split’16, is about 1 kpc long and seems tocontain the Sco-Cen, Aquila and Serpens clouds, as well as a previously

unidentified complex. The functional form of the split is different,
however, in that it is largely confined to the Galactic plane over muchof its length and does not seem to be undulating.
The interactive figure in Supplementary Information, which displays
the 3D location of the Gould Belt18, illustrates that with the improved
distances, this structure is a poor fit to the data, which comprise only
clouds from Sco-Cen and Orion—the traditional anchors of the Gould
Belt. This fact alone challenges the existence of a belt, as two points can・銀河中に、Radcli e waveと呼ばれる2.7 kpcにおよぶ連なったフィラメント状の波が発見された(Alves et al. 2020 Nature)・z(銀河面に対して鉛直方向)に周期2 kpcで波打っていることもわかった

ff

・どのようにして作られたのか、どのような運動をしているのかは不明

手法
・Radcli e wave中のYSOの固有運動を調べる
・YSOは若いため、形成時から運動がそれほど変わっておらず、分子雲の運動速度の情報を保っている

ff

・Gaiaを用いて固有運動を調べた

Kinematic structure of Radcliffe wave

結果・議論

Figure 1. A top-down view of the the Milky Way disc in the Solar vicinity.
The Milky Way centre is at (X, Y) = (0, 0) kpc, and the Sun sits at (−8.34,
0) kpc. The blue circles are the catalogue clouds taken from Chen et al.
(2020). The ‘+’ signs represent the locations of Class I/II YSOs, selectedfrom Marton et al. (2016), where YSOs associated with the Radcliffe wave
are coloured in red and the rest in yellow.

sources from the Marton et al. (2016) catalogue that are classified
as Class I or Class II YSOs, which are the youngest stars that can

L103

Weather Forecast of the Milky Way: Shear and Stellar feedback determine the lives ofGalactic-scale filaments
Guang-Xing Li, Ji-Xuan Zhou, Bing-Qiu Chen F The interstellar medium (ISM) is an inseparable part of the Milky

Way ecosystem whose evolutionary history remains a challenging question. We trace the evolution of the molecular
ISM using a sample of Young Stellar Objects (YSO) association –molecular cloud complex (YSO-MC complex). We
derive their three-dimensional (3D) velocities by combining the Gaia astrometric measurements of the YSO associations
and the CO observations of the associated molecular clouds. Based on the 3D velocities, we simulate the motionsof the YSO-MC complexes in the Galactic potential and forecast the ISM evolution by tracing the motions of theindividual complexes, and reveal the roles of shear and stellar feedback in determining ISM evolution: Galactic shear
stretches Galactic-scale molecular cloud complexes, such as the G120 Complex, into Galactic-scale filaments, and it
also contributes to the destruction of the filaments; while stellar feedback creates interconnected superbubbles whose
expansion injects peculiar velocities into the ISM. The Galactic-scale molecular gas clumps are often precursors of thefilaments and the Galactic-scale filaments are transient structures under a constant stretch by shear. This evolutionary
sequence sets a foundation to interpret other gas structures. Animations are available at https://gxli.github.io/ISM6D/movie.html.

銀河でのISMの進化を3次元の運動から解明
Detection of an excess of young stars in the Galactic center Sagittarius B1 region

Francisco Nogueras-Lara, Rainer Schödel, Nadine Neumayer F The Milky Way’s center is the closest galaxy

・ISMは銀河の進化において重要
nucleus and the most extreme environment of the Galaxy. Although its volume is less than 1% of that of the Galactic

disk, up to 10% of all new-born stars in the Galaxy in the past 100 Myr formed there. Therefore, it constitutes aperfect laboratory to understand star formation under extreme conditions, similar to those in starburst or high-redshift
galaxies. However, the only two known Galactic center young clusters account for <10% of the expected young stellar
mass. We analyze the star formation history of Sagittarius (Sgr) B1, a Galactic center region associated with strong
HII emission, and find evidence for the presence of several 105 solar masses of young stars, that formed ⇠10 Myr ago.
We also detect the presence of intermediate age stars (2-7 Gyr) in Sgr B1 that appear to be rare (or absent) in the
inner regions of the nuclear stellar disk, and might indicate inside out formation. Our results constitute a large step
toward a better understanding of star formation at the Galactic center, such as the fate of young clusters, and thepossibly diﬀerent initial mass function in this region.

・YSOとmolecular cloudの観測から3次元の運動を解明

・運動をシミュレーションすることで、ISMの進化を予想

・銀河のシアと星からのフィードバックの役割を解明する

・シアは分子雲を引き伸ばしてフィラメントにし、さらにフィラメントを破壊する・星からのフィードバックはバブルを作り、拡大に伴い分子雲に速度を与える

L36

手法・結果
・YSO-MC complex: 観測的に3次元速度を明らかにする
・視線速度：MCのCO観測から・天球面での速度：YSOのGaiaによる固有運動の観測から・YSOは出来て時間が経っていないのでMCと同じ運動をしていると仮定できる
G.-X. Li, J.-X. Zhou, and B.-Q. Chen結果・観測された位置と速度を初期条件に時間発展を解いて分子雲進化を予想

Weather forecast of the Milky

・銀河のポテンシャルを考慮
・自己重力、星からのフィードバックは考慮しない
・銀河スケールの構造はシアによって進化する
・分子雲→フィラメント→分裂
・G120 complex→Radcli e wave→Spilt
・bubbleはさらに分裂を促進する可能性もG.-X. Li, J.-X. Zhou, and B.-Q. Chen

Figure 3. Forecasting the evolution of molecular ISM. Here, different structures are indicated by different symbols. We forecast thmodelling the motions of the individual YSO–MC complexes in the Galactic potential. At t ≈ 30 Myr, The ‘split’ and the Radcliffe Wa
significantly, while the G120 Complex can evolve into a long filament of width L ≈ 1 kpc. In the first panel, we added a colour-scale image otraced by dust, and the 3D velocities measured in the LCF for reference.
ff

L38

6D/movie.html.

Detection of an excess of young stars in the Galactic center Sagittarius B1 region

Francisco Nogueras-Lara, Rainer Schödel, Nadine Neumayer F The Milky Way’s center is the closest galaxy

nucleus and the most extreme environment of the Galaxy. Although its volume is less than 1% of that of the Galactic
disk, up to 10% of all new-born stars in the Galaxy in the past 100 Myr formed there. Therefore, it constitutes aperfect laboratory to understand star formation under extreme conditions, similar to those in starburst or high-redshift
galaxies. However, the only two known Galactic center young clusters account for <10% of the expected young stellar
mass. We analyze the star formation history of Sagittarius (Sgr) B1, a Galactic center region associated with strong
HII emission, and find evidence for the presence of several 105 solar masses of young stars, that formed ⇠10 Myr ago.
We also detect the presence of intermediate age stars (2-7 Gyr) in Sgr B1 that appear to be rare (or absent) in the
inner regions of the nuclear stellar disk, and might indicate inside out formation. Our results constitute a large step
NATURE ASTRONOMY
toward a better understanding of star formation at the Galactic center, such as the fate of young clusters, and thepossibly diﬀerent initial mass function in this region.
~42′

・2-7000万年前に形成されたやや若い星の集団も発見
・inside-outに星形成が起こった可能性を示唆

X174711.4

X174712.2~18′

銀河中心近傍での若い星が多く存在していることを発見
・銀河中心では過去１億年間で、たった1％の体積で610%の星形成活動が起きている。
・しかし、星形成領域は期待される量よりも少ない(2領域、期待される10%以下)
・Sagittarius B1領域で1000万年前に10^5M̲sunの星形成が起きた証拠を発見

ARTIC

N
E

Control

ArchesSgr B1
Sgr A*
CentralQuintuplet
Nuclear stellar disk~200 pc

Momentum and energy injection by a wind-blown bubble into an inhomogeneous interstellar medium
J. M. Pittard F We investigate the eﬀect of mass-loading from embedded clouds on the evolution of wind-blown

bubbles. We use 1D hydrodynamical calculations and assume that the clouds are numerous enough that they can betreated in the continuous limit, and that rapid mixing occurs so that the injected mass quickly merges with the global
flow. The destruction of embedded clouds adds mass into the bubble, increasing its density. Mass-loading increases
the temperature of the unshocked stellar wind due to the frictional drag, and reduces the temperature of the hot
shocked gas as the available thermal energy is shared between more particles. Mass-loading may increase or decrease
the volume-averaged bubble pressure. Mass-loaded bubbles are smaller, have less retained energy and lower radial
momentum, but in all cases examined are still able to do significant P dV work on the swept-up gas. In this latter
respect, the bubbles more closely resemble energy-conserving bubbles than the momentum-conserving-like behaviourof “quenched” bubbles.

Gas disk interactions, tides and relativistic eﬀects in the rocky planet formation at thesubstellar mass limit

Mariana B. Sanchez, Gonzalo C. de Elia, Juan J. Downes F Our main goal is to study the formation of rocky

planets and the first 100 Myr of their dynamical evolution around a star with mass 0.08M close to the substellar mass
limit. We developed two sets of N -body simulations assuming an embryo population aﬀected by tidal and generalrelativistic eﬀects refined by the inclusion of the spin-up and contraction of the central star, and immerse in a gas diskduring the first 10 Myr. Each set of simulations incorporates a diﬀerent prescription from literature to calculate theinteraction between the gas-disk and the embryos: one widely used prescription based on results from hydrodynamics
simulations, and a recent prescription based on the analytic treatment of dynamical friction. We found that givena standard disk model, the dynamical evolution and the final architectures of the resulting rocky planets is strongly

Gas disk interactions, tides and relativistic eﬀects in the rocky planet formation at thesubstellar mass limit

Mariana B. Sanchez, Gonzalo C. de Elia, Juan J. Downes F Our main goal is to study the formation of rocky

planets and the first 100 Myr of their dynamical evolution around a star with mass 0.08M close to the substellar mass
limit. We developed two sets of N -body simulations assuming an embryo population aﬀected by tidal and generalrelativistic eﬀects refined by the inclusion of the spin-up and contraction of the central star, and immerse in a gas diskduring the first 10 Myr. Each set of simulations incorporates a diﬀerent prescription from literature to calculate theinteraction between the gas-disk and the embryos: one widely used prescription based on results from hydrodynamics
simulations, and a recent prescription based on the analytic treatment of dynamical friction. We found that givena standard disk model, the dynamical evolution and the final architectures of the resulting rocky planets is strongly
related with the prescription used to treat the interaction within the gas and the embryos, having a big impact on
the resulting close-in planet population and particularly on those located inside the habitable zone. We found a good
agreement within the distribution of period ratio of adjacent confirmed exoplanets observed around very low mass stars
and brown dwarfs and those obtained from our simulations only when the prescription based on dynamical friction for
gas-embryo interaction is used. Our results also reproduce a close-in planet population of interest located inside thehabitable zone. A fraction of those planets will be exposed for a long period of time to the stellar irradiation inside
the inner edge of the evolving habitable zone until the zone reaches them.

Star Forming Regions

小質量星周りでの岩石惑星の形成へのガスと潮汐、相対論的な効果を検討した論文
Salvatore Sciortino (see Reviews section) F Since the ’80s the Einstein observatory has shown the Young Stellar
Objects (YSOs), emit X-rays with luminosities, in the 0.3–8 keV bandpass, up to 103 –104 times than the Sun andthat the X-ray emission is highly variable. ROSAT has confirmed the pervasiveness of X-ray emission from YSOs
and ASCA has provided evidence that the emission of Class I YSOs is largely originating from optical thin-plasma
at temperature of 1-50 ⇥106 K. These intrinsic, unexpected, properties and the transformational capabilities of the
Chandra and XMM-Newton observatories has made X-rays a powerful tool to trace the star formation process up
to distance of a few kpc around the Sun. Starting from the early evidences of the ’80s and the intriguing questions
they raised, I will summarize the results obtained and how they have influenced our current understanding of physicalprocesses at work and I will discuss some of the still open issues and some of the likely avenues that next generation
X-ray observatory will open.

・0.08M̲sunの星の周りでの微惑星のN体計算

・流体との相互作用のモデル(Cresswell2008、Ida2016)に結果が大きく影響
・Ida2016のモデルを用いた場合にのみ、系外惑星の軌道周期や共鳴を再現
・ハビタブルゾーン中に存在する近接惑星も再現

Environmental Eﬀects on the Dynamical Evolution of Star Clusters in Turbulent Molec-