星形成ゼミ 2020/7/10 辰馬 #330 1-7
1. Outﬂows, cores, and magnetic ﬁeld orientations in W43-MM1 as seen by
ALMA
2. The velocity structure of Cygnus OB2
3. On the Origin of the Bimodal Rotational Velocity Distribution in Stellar
Clusters: Rotation on the Pre-Main Sequence
4. Formation of Giant Planet Satellites
5. Photoionising feedback in spiral arm molecular clouds
6. Possible evidence of ongoing planet formation in AB Aurigae. A showcase of
the SPHERE/ALMA synergy
7. Protoplanetary Disks in the Orion Nebula Cluster: Gas Disk Morphologies andKinematics as seen with ALMA1

http://arxiv.org/pdf/2005.01779

4

Formation of Giant Planet Satellites
1

2

Konstantin Batygin and Alessandro Morbidelli
1

Division of Geological and Planetary Sciences California Institute of Technology, Pasadena, CA 91125, USA; 2
Laboratoire Lagrange, Université Côte d’Azur, Observatoire de la Côte d’Azur, CNRS, CS 34229, F-06304 Nice,
FranceE-mail contact: kbatygin at gps.caltech.edu
Recent analyses have shown that the concluding stages of giant planet formation are accompanied by the developmentof large-scale meridional flow of gas inside the planetary Hill sphere. This circulation feeds a circumplanetary disk thatviscously expels gaseous material back into the parent nebula, maintaining the system in a quasi-steady state. Here
we investigate the formation of natural satellites of Jupiter and Saturn within the framework of this newly outlined
picture. We begin by considering the long-term evolution of solid material, and demonstrate that the circumplanetary
disk can act as a global dust trap, where s• ∼ 0.1–10 mm grains achieve a hydrodynamical equilibrium, facilitatedby a balance between radial updraft and aerodynamic drag. This process leads to a gradual increase in the system’s
metallicity, and eventually culminates in the gravitational fragmentation of the outer regions of the solid sub-disk into
R ∼ 100 km satellitesimals. Subsequently, satellite conglomeration ensues via pairwise collisions, but is terminatedwhen disk-driven orbital migration removes the growing objects from the satellitesimal feeding zone. The resulting
satellite formation cycle can repeat multiple times, until it is brought to an end by photo-evaporation of the parent
nebula. Numerical simulations of the envisioned formation scenario yield satisfactory agreement between our modeland the known properties of the Jovian and Saturnian moons.
Accepted by ApJ
http://arxiv.org/pdf/2005.08330
2Formation of Giant Planet Satellites
Konstantin Batygin1 and Alessandro Morbidelli2
1

Division of Geological and Planetary Sciences California Institute of Technology, Pasadena, CA 91125, USA; 2
Laboratoire Lagrange, Université Côte d’Azur, Observatoire de la Côte d’Azur, CNRS, CS 34229, F-06304 Nice,
原始惑星系円盤にギャップを作る巨大ガス惑星形成の最終段階では、惑星ヒル半France•E-mailcontact:
kbatyginat
gps.caltech.edu
径内（惑星重力が及ぶ範囲）の子午線流により、周惑星円盤のガスが円盤粘性にRecent analyses have shown that the concluding stages of giant planet formation are accompanied by the development
4より流れ出ていき、ダストがたまっていく。
of large-scale meridional flow of gas inside the planetary Hill sphere. This circulation feeds a circumplanetary disk thatviscously expels gaseous material back into the parent
nebula,maintaining
thesysteminaquasi-steadystate.
HereṀ meridional circulation inside Hill spheremagnetospherictruncationof natural satellites of Jupiter and Saturn within the framework of this newly outlined
we investigate
the formation
picture. We begin byRconsidering
the long-term evolution of solid material, and demonstrate that the circumplanetaryTdisk can act as a global dust trap, where s• ∼ 0.1–10 mm grains achieve a hydrodynamical equilibrium, facilitatedby a balance between radial updraft and aerodynamic drag. This process leads to a gradual increase r
in the system’s
metallicity, and eventually culminates in the gravitational fragmentation of the outer regions of the solid sub-disk into
R ∼ 100 km satellitesimals. Subsequently, satellite conglomeration ensues via pairwise
collisions,ula but is terminated
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when disk-driven orbital migration removes the growing objects fromthesatellitesimalfeeding zone. The resultingTBh↵satellite formation cycle can repeat multiple times, until it is brought to an end by photo-evaporation of the parent
nebula. Numerical simulations of the envisioned formation scenario yield satisfactory agreement between our model
vr > 0 v
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dial flow

Accepted by ApJ
http://arxiv.org/pdf/2005.08330
dust dynamics equilibrium: aerodynamic drag = energy gain from radial wind<latexit sha1_base64="daMJq9gCYia0WSVUo9nInHdhIQc=">AAAB7XicbVDLSgNBEOz1GeMr6tHLYBA8hV0NPm5BLx4jmAckS5idzCZjZmeWmdlACPkHLx4U8er/ePNvnN0sosaChqKqm+6uIOZMG9f9dJaWV1bX1gsbxc2t7Z3d0t5+U8tEEdogkkvVDrCmnAnaMMxw2o4VxVHAaSsY3aR+a0yVZlLcm0lM/QgPBAsZwcZKzXGvGw9Zr1R2K24GtEi8nJQhR71X+uj2JUkiKgzhWOuO58bGn2JlGOF0VuwmmsaYjPCAdiwVOKLan2bXztCxVfoolMqWMChTf05McaT1JApsZ4TNUP/1UvE/r5OY8NKfMhEnhgoyXxQmHBmJ0tdRnylKDJ9Ygoli9lZEhlhhYmxAxSyEqxTn3y8vkuZpxTurVO+q5dp1HkcBDuEITsCDC6jBLdShAQQe4BGe4cWRzpPz6rzNW5ecfOYAfsF5/wK9JY9g</latexit>

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Geological
Planetary
Sciences
Instituteof Technology, Pasadena, CA 91125, USA; 2
dynamics andequilibrium:
aerodynamic
drag =California
energy gain fromradial windt CNRS, CS 34229, F-06304 Nice,
Laboratoire Lagrange, Université Côte d’Azur, Observatoire de la Côte d’Azur,
FranceE-mail contact: kbatygin at gps.caltech.edu

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solidhave
sub-disksupersolar metallicity
satellitesimalformation
Recent analyses
shown that the concluding
stages of giant planet
formation
are accompanied migrationby the developmentof large-scale meridional flow of gas inside the planetary Hill sphere. This circulation feeds a circumplanetary disk thath•viscously
expels gaseous material back into the parent nebula, maintaining the system in a quasi-steady state. Here
we investigate the formation of natural satellites of Jupiter and Saturn within the framework of this newly outlined
picture. We begin by considering the long-term evolution of solid material,andQ• .
1 demonstrate that the circumplanetary
disk can act as
a 0.1
globals• ∼0.1–10 mm grains gravitational
achieve acollapsehydrodynamical equilibrium,facilitateds• ⇠mm dust trap, where dust
settling
satellite growth
by a balance between radial updraft and aerodynamic drag. This process leads to a gradual increase in the system’s
metallicity, and eventually culminates in the gravitational fragmentation of the outer regionsof the solid sub-disk into
3
Figure1. satellitesimals.
A qualitative sketchof our model.
giant planet ofensues
mass M⇠ 10 Mcollisions,is assumed
to terminatedhave cleared a gap
ガス抵抗により流れ出なかったダストがたまっていくと、ダスト層の重力分裂にR∼
100 kmSubsequently,
satelliteAconglomeration
via pairwise
but iswithinits parentorbital
nebula,resulting removes
in a steady-stateazimuthal/meridionalof gaswithinthe planet’s
Hill sphere. As
whendisk-driven
migration
the growing
objects from the circulation
satellitesimalfeedingzone.
The resulting
nebularmaterial
overflows
the
top
of
the
gap
(at
an
altitudeofapproximatelyonepressure
scale-height
above
the
mid-plane),より半径100
km程度の微衛星が形成される。
satellite formation cycle can repeat multiple times, until it is brought to an end by photo-evaporation of the parent
it free-falls towards the planet – a process we parameterize by an eﬀective mass-flux Ṁ ⇠ 0.1M /Myr. Due to conservation
nebula. Numerical simulations of the envisioned formation scenario yield satisfactory agreement between our modelof成長した微衛星が軌道移動し、他の微衛星を取り込む。
angular momentum, this material spins up, and forms a circumplanetary disk. The inner edge of this disk is truncated byand the known properties of the Jovian and Saturnian moons.
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Acceptedby ApJ disk – parameterized via the standard ↵ ⇠ 10 prescription – the disk spreads viscously and settles into a
circumplanetary
一連の衛星形成サイクルは、原始惑星系円盤が光蒸発により散逸するまで繰り返•
steady pattern of decretion back into the circumstellar nebula.
http://arxiv.org/pdf/2005.08330
T

Jup
4

A balance of viscous heating and radiative losses within the disk determines the system’s aspect ratio, h/r ⇠ 0.1. Theされる。
associated pressure support gives rise to sub-Keplerian rotation of the gas, such that the radial and azimuthal components ofthe circumplanetary flow are vr ⇠ 10 5 vK > 0 and v ⇠ 0.99 vK < vK , respectively. For a critical dust size s• ⇠ 0.1 10 mm,
7 exactly
4
aerodynamic energy loss from the sub-Keplerian headwind
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sha1_base64="yrd2bnyLciGc51efZQy/6ncRvNY=">AAAB/3icbVDLSsNAFJ3UV62vqODGTbAIbqyJra9d0Y3LivYBTSyT6bQdOjMJMxOhxC78FTcuFHHrb7jzb5ykQdR64MLhnHu59x4/pEQq2/40cjOzc/ML+cXC0vLK6pq5vtGQQSQQrqOABqLlQ4kp4biuiKK4FQoMmU9x0x9eJH7zDgtJAn6jRiH2GOxz0iMIKi11zC33mvQZdEMRhCqwxG28f3RQGXfMol2yU1jTxMlIEWSodcwPtxugiGGuEIVSth07VF4MhSKI4nHBjSQOIRrCPm5ryiHD0ovT+8fWrla6Vi8QuriyUvXnRAyZlCPm604G1UD+9RLxP68dqd6pFxMeRgpzNFnUi6ilP03CsLpEYKToSBOIBNG3WmgABURKR1ZIQzhLcPz98jRpHJaccql8VSlWz7M48mAb7IA94IATUAWXoAbqAIF78AiewYvxYDwZr8bbpDVnZDOb4BeM9y86nJW4</latexit><latexit sha1_base64="R95VLhVkLcVdX8RxDpvcJys/qzA=">AAAB+HicbVDLSsNAFJ3UV62PRl26GSyCq5hY8bEQim5cVrAPaEOZTCft0JlJmJkINfRL3LhQxK2f4s6/cZIG8XXgwuGce7n3niBmVGnX/bBKC4tLyyvl1cra+sZm1d7abqsokZi0cMQi2Q2QIowK0tJUM9KNJUE8YKQTTK4yv3NHpKKRuNXTmPgcjQQNKUbaSAO7Oj6UF33JUxwJpZ3ZwK65jpsD/iVeQWqgQHNgv/eHEU44ERozpFTPc2Ptp0hqihmZVfqJIjHCEzQiPUMF4kT5aX74DO4bZQjDSJoSGubq94kUcaWmPDCdHOmx+u1l4n9eL9HhmZ9SESeaCDxfFCYM6ghmKcAhlQRrNjUEYUnNrRCPkURYm6wqeQjnGU6+Xv5L2keOV3fqN8e1xmURRxnsgj1wADxwChrgGjRBC2CQgAfwBJ6te+vRerFe560lq5jZAT9gvX0Cue6TRg==</latexit>

truncation radius<latexit

h/r⌃0 = 4000 g/cm

= RT ⇠ 5 RJup
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2⌃ (g/cm )22⌃ (g/cm )Formationof
Giant
PlanetSatellites
disk temperature
where W = r ⌫ ⌃ @⌦/@r is identified as the vertically106
1
2
Konstantin
Batyginand
Alessandro
Morbidelli
730K
integrated viscous stress tensor.
300K
100K
1
2
DivisionofGeologicalandPlanetary
Sciences
California
InstituteofTechnology,
Pasadena,
CA91125,
USA;
Equation(5)
isreadilysolvedforWasafunction
of
5
0.3
10
周惑星円盤の面密度と温度• theLagrange,
Laboratoire
Université
Côte d’Azur,
Observatoire de la Côte d’Azur, CNRS, CS 34229, pF-06304
Nice,
gas
Of course,
underlying
assumptionsof equationowerr, uponspecificationofasingleboundary
condition.
To-lawdisk temperature
Francefit:0) are10only
sensible if viscous heating dominates over
6
⌃/
4
10
this
end,
we
assumethattheviscoustorquevanishes
at
r 5/4
0.1
E-mailcontact:
kbatyginat
gps.caltech.edu
anetary irradiation in 300K
the region
100Kof interest.
30K Quantipower-law fit: h/r = const.
theRecent
outer
edge
of
the
disk,
such
that
W
=
0
at
r
=
R
.
H
5
tively,this
physicalregimeisappropriate
if
the
ratio
10
analyses have shown that the concluding stages of giant planet formation areaccompaniedbythedevelopment
3
dust
10
p
o
w
We
have:meridional
er-la heating
ofthenlarge-scaleflow
gas inside the planetary Hill sphere.0.03
This circulation feeds a circumplanetary disk that
tween
radiativeand viscous
w of
fit:
⌃ / back into the parent nebula, maintaining the system in a quasi-steady
ice condensation
4viscously
expelsgaseousmaterialstate. Here
r
10
r 5/4
✓
◆
sub-solar metallicity
Z
4
3
-2
2
10
Ṁ T ofR natural
RH satellites of Jupiter and Saturn
we investigate the formation
within 10
the framework of this newly outlined
16
-3
10
p
L
=begin(11) of solid
W
=
⌦
1
.
(6)
3
picture.
Webyconsideringthelong-term
evolutionmaterial,
anddemonstratethatthecircumplanetary
102⇡( RH /r r 1)
9 G M Ṁ
10-2
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disk can act as a ice
globaldust trap, where s• ∼ 0.1–10 mm grains 10
achievea hydrodynamical
equilibrium, facilitated101
condensation
10-1 0.3
0.01
0.03
0.1
super-solar
metallicity
by10a2 balance
betweenradialupdraft
and foraerodynamic
drag. This process leads to a gradual increase in the system’s
significantly
smallerthanunity.
Indeed,planetary
Noting
that
@⌦/@r
=
3⌦/(2
r)
and
cancelling
the
de1
r
(R
)
metallicity, and eventually culminates
of
the
outer
regions
of
the
solid
sub-disk
into
r0 in the gravitational fragmentation
Hill
-4
10
rameters
of
T
=
1,000
K
and
R
=
2
R
,
L
<
1
Jup we obtain thependencein the above
expression,
0.01
0.03
0.1 is terminated0.3
1
R10∼1 100onkm ⌦satellitesimals.
Subsequently,
satellite conglomeration ensues via pairwise
collisions,
but
r
.
R
/2,
albeitonly
byafactor
of
a
few.
This
0.01 orbital
0.03
0.1removes
0.3
1 objects from theHr (Rdensity
) The
when
disk-driven
migration
thegrowingsatellitesimalfeedingzone.
resultingFigure2. Surface
profileof our model circHill
surface density profile of the disk (Figure 2):r (Reanssatellitethat eventhoughfrom thecentralHill )
formation
cycleirradiationcanrepeatmultipletimes,
until it is brought to etaryan enddisk.
by photo-evaporationof the(equation
parent
The exact solution7) – corre
Figure3.
Aspectratio
ofthecircumplaentary
nebula.
r
Numerical
simulationsoftheenvisioned
formation
scenarioyield
satisfactory
agreement
betweenourmodelanetnebula.
does notdominatethe disk’s
thermalenergybal✓◆
to a constant-Ṁ decretion ↵ model is shown wit
Figure2.
Surfacedensity
profile
of
our
model
circumplanWithin the framework of our model, the vertical thickness
Ṁ
R
and
the
known
properties
oftheJovianandSaturnian
moons.
Hce, it can contributeanotablecorrection(e.g.,
minor
purpleAnreflects
indexits temperature
5/4 power-law
fit to this⌃ =solution (equation 7) 1– corresponding.
(7)
etary disk. The exactof the gaseous
diskline.
merelystructurep3⇡⌫r
Accepted
by
ApJ
ring)
to
the
aspectratio
profile(10),especiallyinthe(equation
depicted
with energy
a dashed
dark ora
to a constant-Ṁ decretion ↵ model is shown with a solid(via h/r =cs /vK / 12)
T ).is Because
viscousdissipa2
terregionsofthecircumplanetarynebula.
Here,howhttp://arxiv.org/pdf/2005.08330
The
reference
surfacedensity
⌃
=
4,000
g/cm
a
purple
line.
An
index
5/4
power-law
fit
to
this
solution0tion
dominatesoverplanetaryirradiation(equation11),
the
M一定のα粘性モデル。
er,
we noteneglecttechnicality
tokeep dark
the modelasWe
hereinlies aan
importantdiﬀerence(equation12)thatisthisdepicted
withdashedorangeline. beenceradiusr0 is=determined
0.1RH areby
markedwiththin dot
temperature
profileitselfequating
turbu2温度は粘性加熱と放射冷却のバランスでThe
reference
surfacedensity
⌃
=
4,000
g/cm
refer-For an
mple
as constantpossible. Ṁ accretion0 and decretionand
lent heating
the disk
to black-bodyradiative
losses
Thewithin(assumedvertically
isothermal)
temperaturetween
disks.
ence radiusrmarkedwiththindottedlines.
70 = 0.1R
H are
at
The
top
panel
shows
the
exact
solutionfor
5 its surface.
Whileequations
(7)
and
(10)
provideexact
solutions
the
disk
is
represented
at
the
top
of
the
figurewit
決まり、鉛直方向に等温とする。
accretion disk where Ṁ is negative, the relation<latexit sha1_base64="vpi31QTYv52pgp3RCRe0jab675w=">AAAB6nicbVDLSsNAFL2pr1pfUZduBovgqiRWfOyKblxWtA9oQ5lMJ+3QySTMTIQS+gluXCji1i9y5984SYOo9cCFwzn3cu89fsyZ0o7zaZWWlldW18rrlY3Nre0de3evraJEEtoiEY9k18eKciZoSzPNaTeWFIc+px1/cp35nQcqFYvEvZ7G1AvxSLCAEayNdCcHzsCuOjUnB1okbkGqUKA5sD/6w4gkIRWacKxUz3Vi7aVYakY4nVX6iaIxJhM8oj1DBQ6p8tL81Bk6MsoQBZE0JTTK1Z8TKQ6Vmoa+6QyxHqu/Xib+5/USHVx4KRNxoqkg80VBwpGOUPY3GjJJieZTQzCRzNyKyBhLTLRJp5KHcJnh7PvlRdI+qbn1Wv32tNq4KuIowwEcwjG4cA4NuIEmtIDACB7hGV4sbj1Zr9bbvLVkFTP78AvW+xcZ0I3Q</latexit><latexit sha1_base64="tfbFvunelg5DQMTaE4i5k7TujSs=">AAAB+3icbVDLSsNAFJ34rPUV69LNYBHqpqRWfOyKbrqsYh/QhDCZTtqhk0mYmYgl5FfcuFDErT/izr9xkgZR64ELh3Pu5d57vIhRqSzr01haXlldWy9tlDe3tnd2zb1KT4axwKSLQxaKgYckYZSTrqKKkUEkCAo8Rvre9Drz+/dESBryOzWLiBOgMac+xUhpyTUrwoa1WzexRZC0KWNpeuyaVatu5YCLpFGQKijQcc0PexTiOCBcYYakHDasSDkJEopiRtKyHUsSITxFYzLUlKOASCfJb0/hkVZG0A+FLq5grv6cSFAg5SzwdGeA1ET+9TLxP28YK//CSSiPYkU4ni/yYwZVCLMg4IgKghWbaYKwoPpWiCdIIKx0XOU8hMsMZ98vL5LeSb3RrDdvTqutqyKOEjgAh6AGGuActEAbdEAXYPAAHsEzeDFS48l4Nd7mrUtGMbMPfsF4/wJ8ipQ6</latexit><latexit sha1_base64="tfbFvunelg5DQMTaE4i5k7TujSs=">AAAB+3icbVDLSsNAFJ34rPUV69LNYBHqpqRWfOyKbrqsYh/QhDCZTtqhk0mYmYgl5FfcuFDErT/izr9xkgZR64ELh3Pu5d57vIhRqSzr01haXlldWy9tlDe3tnd2zb1KT4axwKSLQxaKgYckYZSTrqKKkUEkCAo8Rvre9Drz+/dESBryOzWLiBOgMac+xUhpyTUrwoa1WzexRZC0KWNpeuyaVatu5YCLpFGQKijQcc0PexTiOCBcYYakHDasSDkJEopiRtKyHUsSITxFYzLUlKOASCfJb0/hkVZG0A+FLq5grv6cSFAg5SzwdGeA1ET+9TLxP28YK//CSSiPYkU4ni/yYwZVCLMg4IgKghWbaYKwoPpWiCdIIKx0XOU8hMsMZ98vL5LeSb3RrDdvTqutqyKOEjgAh6AGGuActEAbdEAXYPAAHsEzeDFS48l4Nd7mrUtGMbMPfsF4/wJ8ipQ6</latexit><latexit sha1_base64="tfbFvunelg5DQMTaE4i5k7TujSs=">AAAB+3icbVDLSsNAFJ34rPUV69LNYBHqpqRWfOyKbrqsYh/QhDCZTtqhk0mYmYgl5FfcuFDErT/izr9xkgZR64ELh3Pu5d57vIhRqSzr01haXlldWy9tlDe3tnd2zb1KT4axwKSLQxaKgYckYZSTrqKKkUEkCAo8Rvre9Drz+/dESBryOzWLiBOgMac+xUhpyTUrwoa1WzexRZC0KWNpeuyaVatu5YCLpFGQKijQcc0PexTiOCBcYYakHDasSDkJEopiRtKyHUsSITxFYzLUlKOASCfJb0/hkVZG0A+FLq5grv6cSFAg5SzwdGeA1ET+9TLxP28YK//CSSiPYkU4ni/yYwZVCLMg4IgKghWbaYKwoPpWiCdIIKx0XOU8hMsMZ98vL5LeSb3RrDdvTqutqyKOEjgAh6AGGuActEAbdEAXYPAAHsEzeDFS48l4Nd7mrUtGMbMPfsF4/wJ8ipQ6</latexit>•

Formation of Giant Planet Satellites
Konstantin Batygin1 and Alessandro Morbidelli2
Division of Geological and Planetary Sciences California
Institute of Technology, Pasadena, CA 91125, USA; 2
9
Laboratoire Lagrange, Université Côte d’Azur, Observatoire de la Côte d’Azur, CNRS, CS 34229, F-06304 Nice,
France1E-mail contact: kbatygin at gps.caltech.edu
Recent analyses have shown that the concluding stages of giant planet formation are accompanied by the developmentof large-scale meridional flow of gas inside the planetary Hill sphere. This circulation feeds a circumplanetary disk thatviscously expels gaseous material back into the parent nebula, maintaining the system in a quasi-steady state. Here
we investigate the formation of natural satellites of Jupiter and Saturn within the framework of this newly outlined
picture. We begin by considering the long-term evolution of solid material, and demonstrate that the circumplanetary
disk can act as a global dust trap, where s• ∼ 0.1–10 mm grains achieve a hydrodynamical equilibrium, facilitatedby a balance between radial updraft and aerodynamic drag. This process leads to a gradual increase in the system’s
metallicity, and eventually culminates in the gravitational fragmentation of the outer regions of the solid sub-disk into
R ∼ 100 km satellitesimals. Subsequently, satellite conglomeration ensues via pairwise collisions, but is terminatedwhen disk-driven orbital migration removes the growing objects from the satellitesimal feeding zone. The resulting
satellite formation cycle can repeat multiple times, until it is brought to an end by photo-evaporation of the parent
nebula. Numerical simulations of the envisioned formation scenario yield satisfactory agreement between our modeland the known properties of the Jovian and Saturnian moons.
Accepted by ApJ
http://arxiv.org/pdf/2005.08330

76

Formation of Giant Planet Satellites
Konstantin Batygin1 and Alessandro Morbidelli2
1

Division of Geological and Planetary Sciences California Institute of Technology, Pasadena, CA 91125, USA; 2
Laboratoire
Lagrange, Université Côted’Azur,Observatoireを用いた数値計算
de la Côte d’Azur, CNRS, CS 34229, F-06304 Nice,particle-in-a-box
code
BoulderFrance3000
E-mail contact:
A kbatygin at gps.caltech.edu

Bsatellite embryos•

17

proto-satellites

debrismergers withmassive
107formation are accompanied by the development
Recent analyses have shown that the concluding
stagesof giant planet
satellite embryosof large-scale meridional flow of gas inside the planetary Hill sphere. This circulation feeds a circumplanetary disk thatviscously2000
expels gaseous material back into the parent nebula, maintaining the system in a quasi-steady state. Here105
we investigate the formation of natural satellites of Jupiter and Saturn within the framework of this newly outlined
cumulative sizepicture. We begin by considering the long-term evolution of solid material,frequency
and demonstratethatthecircumplanetary
distribution
disk can act as a global dust trap, where s• ∼ 0.1–10 mm grains achievea hydrodynamical equilibrium, facilitated310
secondlargestembryoby a balance
1000 between radial updraft and aerodynamic drag. This process leads to a gradual increase in the system’s
metallicity, and eventually culminates in the third
gravitational
fragmentation of the outer regions of the solid sub-disk intolargest embryo
R ∼ 100 km satellitesimals. Subsequently, satellite conglomeration 10
ensues via pairwise collisions, but is terminatedt = 84000 years
dynamical excitation of satellitesimal disk
when disk-driven orbital migration removes the growing objects from the satellitesimal feeding zone. The resulting
0
satellite formation
cycle can repeat multiple times,
until
it
is
brought
to
an
end
by
photo-evaporationoftheparent
60000
0.1
1
10
100
1000
0
20000
40000
80000
nebula. Numerical simulations of the envisioned formation scenario yield satisfactory agreement between our modelt ( yearsand) Saturnian moons.
and the known properties of the Jovian<latexit sha1_base64="gRnU2iBSB2H9aMqAIMOJHrr1nAs=">AAAB/nicbVDLSsNAFJ34rPUVFVduBotQoZREi49d0Y3LCvYBTSiT6aQdOpmEmYkQQsFfceNCEbd+hzv/xkkaRK0HLhzOuZd77/EiRqWyrE9jYXFpeWW1tFZe39jc2jZ3djsyjAUmbRyyUPQ8JAmjnLQVVYz0IkFQ4DHS9SbXmd+9J0LSkN+pJCJugEac+hQjpaWBua8cWHVq0BFBmhAk5BQ6teOBWbHqVg44T+yCVECB1sD8cIYhjgPCFWZIyr5tRcpNkVAUMzItO7EkEcITNCJ9TTkKiHTT/PwpPNLKEPqh0MUVzNWfEykKpEwCT3cGSI3lXy8T//P6sfIv3JTyKFaE49kiP2ZQhTDLAg6pIFixRBOEBdW3QjxGAmGlEyvnIVxmOPt+eZ50Tur2ab1x26g0r4o4SuAAHIIqsME5aIIb0AJtgEEKHsEzeDEejCfj1XibtS4Yxcwe+AXj/QtiNJSd</latexit>

Accepted
by 8.
ApJ
最も大きい微衛星の成長。
FigureParticle-in-a-box calculation of satellite accretion within the circumplanetary disk. Panel A depicts a time-seriesof the largest satellite embryo’s physical radius. Facilitated by eﬃcient gravitational focusing, the embryo experiences rapid
http://arxiv.org/pdf/2005.08330
最終半径2600 kmは木星衛星ガニメデと同様。

initial growth. However, the rate of accretion slows down in time, as the velocity dispersion of the satellitesimal disk becomes
progressively more excited. Intermittent jumps in radius correspond collisions of the proto-satellite with other massive embryos
within the system. 84,000 years into simulation time, the proto-satellite attains a radius of 2,600 km – comparable to that of7
7
Ganymede. Panel B shows the cumulative size-frequency distributionof the system at t = 84,000 years. Importantly, this panel

N体計算• 初期条件は1000個の質量1021 kgの微衛星。重力不安定により形成されるのは1019 kgで半径100 kmなのでそれよりは大きい。

• 初期はe ~ i ~ 10-3
• ガリレオ衛星のうち3つ（イオ、エウロパ、ガニメデ）のタネとなる微小質量の天体を0.1 RHから0.3 RHにランダムに置く。

• ガリレオ衛星の質量を再現できた計算 →

8
Figure 9. Formation of the three inner Galilean satellites. An initially dynamically cold (e ⇠ i ⇠ 10 3 ) disk of 1,000 super-https://www.aanda.org/articles/aa/pdf/2020/05/aa38008-20.pdf

7
Protoplanetary Disks in the Orion Nebula Cluster: Gas Disk Morphologies and Kinematics as seen with ALMA
Ryan D. Boyden1 and Josh A. Eisner1
1

Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721, USA

E-mail contact: rboyden at email.arizona.edu
We present Atacama Large Millimeter Array CO (3–2) and HCO+ (4–3) observations covering the central 1!! × 1.!! 5
region of the Orion Nebula Cluster (ONC). The unprecedented level of sensitivity (∼0.1 mJy beam−1 ) and angularresolution (∼0.!! 09 ≈ 35 AU) of these line observations enable us to search for gas-disk detections towards the known
positions of submillimeter-detected dust disks in this region. We detect 23 disks in gas: 17 in CO (3–2), 17 in HCO+
(4–3), and 11 in both lines. Depending on where the sources are located in the ONC, we see the line detections inemission, in absorption against the warm background, or in both emission and absorption. We spectrally resolve thegas with 0.5 km s−1 channels, and find that the kinematics of most sources are consistent with Keplerian rotation.
We measure the distribution of gas-disk sizes and find typical radii of ∼50–200 AU. As such, gas disks in the ONC
are compact in comparison with the gas disks seen in low-density star-forming regions. Gas sizes are universallylarger than the dust sizes. However, the gas and dust sizes are not strongly correlated. We find a positive correlation
between gas size and distance from the massive star θ1 Ori C, indicating that disks in the ONC are influenced byphotoionization. Finally, we use the observed kinematics of the detected gas lines to model Keplerian rotation andinfer the masses of the central pre-main-sequence stars. Our dynamically-derived stellar masses are not consistent
with the spectroscopically-derived masses, and we discuss possible reasons for this discrepancy.
Accepted by ApJ
http://arxiv.org/pdf/2003.12580
9Protoplanetary Disks in the Orion Nebula Cluster: Gas Disk Morphologies and Kinematics as seen with ALMA
Ryan D. Boyden1 and Josh A. Eisner11

240 240 au、灰色: continuum、緑: CO、紫: HCO+（3-5σ）

6
Boyden et al.
吸収線、実線:
輝線、★:
uv AZ
cutなし100
kλ uv cutあり
Steward Observatory, University of Arizona,
933破線:
North
Cherry Avenue,
Tucson,85721, USACO(3-2)E-mail contact:rboyden &at email.arizona.edu• ALMA

CO
CO
HCO+
CO
CO
HCO+
HCO+
HCO+
+
We present Atacama Large Millimeter Array CO (3–2) and HCO (4–3) observations covering the central 1!! × 1.!! 5

CO
HCO+

HCO+(4-3)を用いてregion of the Orion Nebula Cluster (ONC). The unprecedented level of sensitivity (∼0.1 mJy beam−1 ) and angular!!
resolution(∼0.
09 ≈ 35AU) of these line observations enable us to search for gas-disk detections towards the known
Orion Nebula
Clusterpositions of submillimeter-detected dust disks in this region. We detect 23 disks in gas: 17 in CO (3–2), 17 in HCO+
HCO+
CO
CO
CO
CO
HCO+
(4–3), and 11 in both lines. Depending on where the sources are located in the ONC, we see the line detections in(ONC)を観測した
emission, in absorption against the warm background, or in both emission and absorption. We spectrally resolve the（sensitivityは~0.1 and find that the kinematics of most sources are consistent with Keplerian rotation.
gas with 0.5 km s−1 channels,
We measure the distribution of gas-disk sizes and find typical radii of ∼50–200 AU. As such, gas disks in the ONC
mJy/beam、分解能は~ gas disks seen in low-density star-forming regions. Gas sizes are universallyare compact in comparison with the
CO
CO
CO
CO
CO
HCO+
larger than the dust sizes. However, the gas and dust sizes are not strongly correlated. We find a positive
correlation
HCO+
HCO+
HCO+
HCO+
1
35
au）。
between gas size and distance from the massive star θ Ori C, indicating that disks in the ONC are influenced by•photoionization. Finally, we use the observed kinematics of the detected gas lines to model Keplerian rotation and
104の連続波検出天体に
infer the masses of the central pre-main-sequence stars. Our dynamically-derived stellar masses are not consistent
with the spectroscopically-derived masses, and we discuss possible reasons for this discrepancy.

対して、23のガス円盤をAccepted by ApJ
検出（COが17、HCO+
http://arxiv.org/pdf/2003.12580
が17、両方が11）。

CO
HCO+

HCO+

CO
HCO+

CO
HCO+

An Analytic Model for an Evolving Protoplanetary Disk with a Disk Wind
John Chambers

1

10

HCO+

Protoplanetary Disks in the Orion Nebula Cluster: Gas Disk Morphologies and Kinematics as seen with ALMA
Ryan D. Boyden1 and Josh A. Eisner1
1

Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721, USA• スペクトル分解能0.5E-mail contact: rboyden at email.arizona.edu

回転

回転

回転

7

回転

We present Atacama Large Millimeter Array CO (3–2) and HCO+ (4–3) observations covering the central 1!! × 1.!! 5
km/sでケプラー回転も確
region of the Orion Nebula Cluster (ONC). The unprecedented level of sensitivity (∼0.1 mJy beam−1 ) and angular
認できた。
resolution (∼0.!! 09 ≈ 35 AU) of these line observations enable us to search for gas-disk detections towards the known•

positions of submillimeter-detected dust disks in this region. We detect 23 disks回転in gas: 17 in回転
CO (3–2), 17 in HCO+
各チャンネル3σ以上の輝(4–3), and 11 in both lines. Depending on where the sources are located in the ONC, we see the line detections inemission, in absorption against the warm background, or in both emission and absorption. We spectrally resolve the−1線/吸収線を用いて作成。
gas
with
0.5
km
s
channels, and find that the kinematics of most sources are consistent with Keplerian rotation.
Boyden et al.
We measure the distribution of gas-disk sizes and find typical radii of ∼50–200 AU. As such, gas disks in the ONC
回転
回転star-forming回転are compact in comparison with the gas disks seen
in low-density
regions. Gas sizes are universallylarger than the dust sizes. However, the gas and dust sizes are not strongly correlated. We find a positive correlation
between gas size and distance from the massive star θ1 Ori C, indicating that disks in the ONC are influenced byphotoionization. Finally, we use the observed kinematics of the detected gas lines to model Keplerian rotation andinfer the masses of the central pre-main-sequence stars. Our dynamically-derived stellar masses are not consistent
回転 possible回転回転with the spectroscopically-derived masses, and we discuss
reasons for this discrepancy.

回転

回転

Accepted by ApJ
http://arxiv.org/pdf/2003.12580

An Figure
Analytic
Model
for
an
Evolving
Protoplanetary
Disk
with
a
Disk
Wind
7. CO(3 2) moment 1 maps of the cluster members

ONC region, taken
ong et al. 2018).
t velocities vLSR =0

ONC Gas Disk Properties

159-350 and HC482 (top and1 bottom rows, respectively). At

John Chambers

11

Figure 4. Moment 1 maps (intensity-weighted velocity) of gas for ALMA-detected ONC cluster members. These are generated

For Taurus, the gas-disk radii are taken from Najita &Bergin (2018), who compiled measurements across multiple studies/observations in order to obtain a sample ofspatially-resolved gas disks for the region.
When generating the CDF for the ONC, we recompute
the gas-disk radius to match the definition employed by
Ansdell et al. (2018), who define the gas-disk radius as
the aperture semi-major axis that encloses 90% of thetotal flux of a source (i.e., a curve-of-growth method).
We find that the new radii are typically smaller but instatistical agreement with the Gaussian HWTMs, which
we adopt as the gas-disk radii. Because the di↵erent
quantities are in agreement, we only use the Ansdell etal. (2018) definition when comparing the disk size distributions between regions (i.e., this section). In othersections, we continue to use the Gaussian HWTM as ourdefinition of gas radius.
Furthermore, because our ONC line observations typically have lower S/N than the Lupus or Taurus data, weinvestigate how our measurements of gas radius are limited by the achieved S/N. We generate a grid ofFigure
2D ellip- 14. Gas radius (Rgas ) vs. dust radius (Rdust ) for
tical Gaussians with HWTMs ranging from ⇠ 50 700
the ONC sources that were detected and spatially resolved
AU. For each model Gaussian, we introduce di↵erent
in gas. R
is universally larger than Rdust . CO gas sizes
levels of noise and then measure the gas radius via the gas
+
are
shown
in
green,
andHCO
gas sizes are shown in purple.
curve-of-growth method. For a S/N ratio of ⇠ 4.5,
the typical S/N of an ONC detection, we findDashedthat the green and purple lines indicate linear least-squares“observed” gas radius underestimates the HWTM
fits bytoas
the CO and HCO+ data, respectively, and they suggest
much as ⇠ 30%. At a higher S/N of ⇠ 10, weak
the typicorrelations between Rgas and Rdust . The fitted trend
cal S/N of a Lupus gas disk, the observed gas radius isto the CO data is (Rgas / AU) = (64 ± 9) + (0.1 ± 0.3) (Rdust
typically ⇠ 15% smaller than the HWTM. When we ap+
/
AU),
and
the
fitted
trend
to
the
HCO
data is (Rgas /ply correction factors to the various radii measurementsthat account for the di↵erences in the achievedAU)
S/N, =we (46 ± 9) + (0.5 ± 0.2) (Rdust / AU).
recover larger gas radii (in all regions) as shown in Figure 13. After these corrections, the distribution of ONC
gas-disk size remains distinct and more compact than12
the distributions seen in lower-density
regions.

• (上) ONCとLupusのガス円盤半径のcumulative
distribution function• (中) S/Nの低さによる

HWTM (half-widthtenth-maximum: 1/10
値半幅)の過小評価を補
正: ONCで30%、
Lupusで15%の過小評
価• (下) 空間分解できた円盤のみ、S/N補正済み• ガス円盤半径は ~ 50-200 au

で、ガス円盤とダスト円盤のサイズに強い相関はなかった。

• ダスト円盤半径はsubmmのHWTM

Protoplanetary Disks in the Orion Nebula Cluster: Gas Disk Morphologies and Kinematics as seen with ALMA
Ryan D. Boyden1 and Josh A. Eisner1
1

ONC Gas Disk Properties

19

Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721, USA

E-mail contact: rboyden at email.arizona.edu
We present Atacama Large Millimeter Array CO (3–2) and HCO+ (4–3) observations covering the central 1!! × 1.!! 5
region of the Orion Nebula Cluster (ONC). The unprecedented level of sensitivity (∼0.1 mJy beam−1 ) and angularresolution (∼0.!! 09 ≈ 35 AU) of these line observations enable us to search for gas-disk detections towards the known
positions of submillimeter-detected dust disks in this region. We detect 23 disks in gas: 17 in CO (3–2), 17 in HCO+
(4–3), and 11 in both lines. Depending on where the sources are located in the ONC, we see the line detections inemission, in absorption against the warm background, or in both emission and absorption. We spectrally resolve thegas with 0.5 km s−1 channels, and find that the kinematics of most sources are consistent with Keplerian rotation.
We measure the distribution of gas-disk sizes and find typical radii of ∼50–200 AU. As such, gas disks in the ONC
are compact in comparison with the gas disks seen in low-density star-forming regions. Gas sizes are universallylarger than the dust sizes. However, the gas and dust sizes are not strongly correlated. We find a positive correlation
between gas size and distance from the massive star θ1 Ori C, indicating that disks in the ONC are influenced byphotoionization. Finally, we use the observed kinematics of the detected gas lines to model Keplerian rotation andinfer the masses of the central pre-main-sequence stars. Our dynamically-derived stellar masses are not consistent
Figure 15. Left: Rgas vs. projected distance from ✓1 Ori C (dtoc ). The color scheme for the CO and HCO+ data points are thewiththe 14.
spectroscopically-derived
masses,andwe ddiscusspossiblereasons
for±this
discrepancy.
1
same as thatofFigureWeseeapositivecorrelation
between
CO
gas
size
and
,
(Radius
/
AU)
=
(30
±
11)
+
(5.6
1.6)
tocCからの距離に正の相関があり、光電離の影
ガス円盤サイズと大質量星θ
Ori(dtoc / 0.01 pc), which is plotted as a dashed black line. The trend of HCO+ gas size vs. dtoc is constrained to: (Radius / AU)
AcceptedbyApJ= (90 ± 30) + ( 2.4 ± 2.9) (d / 0.01 pc). Right: R
vs. d , but here we standardize the gas radii in order to compare the•

響が示唆される。
toc

gas

toc

best-fit of http://arxiv.org/pdf/2003.12580
Rgas vs. dtoc to that of Rdust vs. dtoc . The fitted trend between the standardized CO gas radii and dtoc is (Radius/ z-score) = ( 1.5 ± 0.4) + (19.2 ± 5.5) (dtoc / pc). In blue, we plot the observed correlation between Rdust and dtoc , (Radius/ z-score) = ( 0.5 ± 0.7) + (6.1 ± 4.5) (dtoc / pc). This relationship is taken from Eisner et al. (2018), rescaled to matchour definition of Rdust (see Section 5.2.1), and standardized using the Eisner et al. (2018) sample mean and variance. After
standardizing the data, Rgas appears more sensitive to dtoc than Rdust by ⇠1.3 .

z-score? ダスト円盤サイズと大質量星からの距離の相関は弱い。
• An
Analytic Model for an Evolving Protoplanetary Disk with a Disk Wind

the relationship between the HCO1+ gas size and cluster

John Chambers

13

Protoplanetary Disks in the Orion Nebula Cluster: Gas Disk Morphologies and Kinematics as seen with ALMA
Ryan D. Boyden1 and Josh A. Eisner1
1

Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721, USA

E-mail contact: rboyden at email.arizona.edu

•

•

+
!!
!!
We
present
Atacama
Large
Millimeter
Array
CO
(3–2)
and
HCO
(4–3)
observations
covering
thecentral1
×1.
5
ケプラー回転から求め
region of the Orion Nebula Cluster (ONC). The unprecedented level of sensitivity (∼0.1 mJy beam−1 ) and angular!!
resolution(∼0.
09 ≈ 35 AU) of these line observations enable us to search for gas-disk detections towards the known
られた中心星質量は分positions of submillimeter-detected dust disks in this region. We detect 23 disks in gas: 17 in CO (3–2), 17 in HCO+
光観測による質量と一(4–3), and 11 in both lines. Depending on where the sources are located in the ONC, we see the line detections inemission, in absorption against the warm background, or in both emission and absorption. We spectrally resolve the
致しなかった。
gas with 0.5 km s−1 channels, and find that the kinematics of most sources are consistent with Keplerian rotation.
We measure the distribution of gas-disk sizes and find typical radii of ∼50–200 AU. As such, gas disks in the ONC
もっと高感度の観測がare compact in comparison with the gas disks seen in low-density star-forming regions. Gas sizes are universallylarger than the dust sizes. However, the gas and dust sizes are not strongly correlated. We find a positive correlation
必要である。
between gas size and distance from the massive star θ1 Ori C, indicating that disks in the ONC are influenced byphotoionization. Finally, we use the observed kinematics of the detected gas lines to model Keplerian rotation andinfer the masses of the central pre-main-sequence stars. Our dynamically-derived stellar masses are not consistent
with the spectroscopically-derived masses, and we discuss possible reasons for this discrepancy.

Accepted by ApJ
http://arxiv.org/pdf/2003.12580

An Analytic Model for an Evolving Protoplanetary Disk with a Disk Wind
John Chambers

114Outflows, cores, and magnetic field orientations in W43-MM1 as seen by ALMA
C. Arce1 , F. Louvet1,2 , P. C. Cortes3,4 , F. Motte5 , C. L. H. Hull3,6,7 , V. J. M. Le Gouellec8,2 , G. Garay1 ,T. Nony5 , P. Didelon2 and L. Bronfman1
1

Universidad de Chile, Camino el Observatorio 1515, Las Condes, Santiago de Chile; 2 Laboratoire AIM Paris-Saclay,
CEA/IRFU - CNRS/INSU - Université Paris Diderot, Service d’Astrophysique, Bât 709, CEA-Saclay, 91191 Gif-surYvette; 3 Join ALMA Observatory, Alonso de Cordova 3107, Vitacura, Santiago, Chile; 4 National Radio Astronomy
Observarory, Charlottesville, VA 22903, USA; 5 Univ. Grenoble Alpes, CNRS, IPAG, F-38000 Grenoble, France; 6National Astronomical Observatory of Japan, NAOJ Chile, Alonso de Cordova, Santiago, Chile; 7 NAOJ Fellow; 8European Southern Observatory, Alonso de Cordova 3788, Santiago, Chile
E-mail contact: fabien.louvet at cea.fr
It has been proposed that the magnetic field, pervasive in the ISM, plays an important role in the process of massive
star formation. To better understand its impact at the pre and protostellar stages, high-angular resolution observationsof polarized dust emission toward a large sample of massive dense cores are needed. To this end, we used the Atacama
Large Millimeter Array in Band 6 (1.3 mm) in full polarization mode to map the polarized emission from dust grains ata physical scale of ∼distribution from the core scale down to the inner part of the circumstellar disks where outflows are triggered.

2

Accepted by A&A
https://arxiv.org/pdf/2005.12921

The velocity structure of Cygnus OB2
Becky Arnold1,2 , Simon P. Goodwin1 and Nick J. Wright3
1

Department of Physics and Astronomy, University of Sheffield, Sheffield S3 7RH, UK; 2 Department of Astronomy,
University of Massachusetts, Massachusetts, 01003, USA; 3 Astrophysics Group, Keele University, Keele, Staffordshire,
ST5 5BG, UK
E-mail contact: kpoppenhaeger at aip.de
The kinematic structure of the Cygnus OB2 association is investigated. No evidence of expansion or contraction isfound at any scale within the region. Stars that are within ∼0.5 parsecs of one another are found to have more similar
velocities than would be expected by random chance, and so it is concluded that velocity substructure exists on thesescales. At larger scales velocity substructure is not found. We suggest that bound substructures exist on scales of ∼0.5
parsecs, despite the region as a whole being unbound. We further suggest that any velocity substructure that existed
on scales > 0.5 parsecs has been erased. The results of this study are then compared to those of other kinematicstudies of Cygnus OB2.
Accepted by MNRAS

6

http://arxiv.org/pdf/2005.10260

On the Origin of the Bimodal Rotational Velocity Distribution in Stellar Clusters: Rotation on the Pre-Main Sequence
1

1

16
2

Nate Bastian , Sebastian Kamann , Louis Amard , Corinne Charbonnel3,4 , Lionel Haemmerlé3 and3On the Origin of the Bimodal Rotational Velocity Distribution in Stellar Clusters: Rotation on the Pre-Main Sequence
Nate Bastian1 , Sebastian Kamann1 , Louis Amard2 , Corinne Charbonnel3,4 , Lionel Haemmerlé3 andSean P. Matt2
1

Astrophysics Research Institute, Liverpool John Moores University, 146 Brownlow Hill, Liverpool L3 5RF, UK; 2
University of Exeter, Department of Physics & Astronomy, Stoker Road, Devon, Exeter EX4 4QL, UK; 3 Departmentof Astronomy, University of Geneva, Chemin de Pégase 51, 1290 Versoix, Switzerland; 4 IRAP, UMR 5277 CNRS andUniversité de Toulouse, 14, Av. E.Belin, 31400 Toulouse, France
E-mail contact: N.J.Bastian at ljmu.ac.uk
We address the origin of the observed bimodal rotational distribution of stars in massive young and intermediate age
stellar clusters. This bimodality is seen as split main sequences at young ages and also has been recently directly
observed in the V sin i distribution of stars within massive young and intermediate age clusters. Previous models haveinvoked binary interactions as the origin of this bimodality, although these models are unable to reproduce all of
the observational constraints on the problem. Here we suggest that such a bimodal rotational distribution is set up
early within a cluster’s life, i.e., within the first few Myr. Observations show that the period distribution of low-mass(<∼2 M! ) pre-main sequence (PMS) stars is bimodal in many young open clusters and we present a series of models
to show that if such a bimodality exists for stars on the PMS that it is expected to manifest as a bimodal rotational
velocity (at fixed mass/luminosity) on the main sequence for stars with masses in excess of ∼1.5 M! . Such a bimodal
period distribution of PMS stars may be caused by whether stars have lost (rapid rotators) or been able to retain(slow rotators) their circumstellar discs throughout their PMS lifetimes. We conclude with a series of predictions forobservables based on our model.
Accepted by MNRAS
http://arxiv.org/pdf/2005.01779
175
Photoionising feedback in spiral arm molecular clouds
Thomas J. R. Bending1 , Clare L. Dobbs1 and Matthew R. Bate1
1

School of Physics and Astronomy, University of Exeter, Stocker Road, Exeter EX4 4QL, UK

E-mail contact: tb457 at exeter.ac.uk
We present simulations of a 500 pc2 region, containing gas of mass 4 × 106 M! , extracted from an entire spiralgalaxy simulation, scaled up in resolution, including photoionising feedback from stars of mass >18 M! . Our region
is evolved for 10 Myr and shows clustered star formation along the arm generating ≈ 5000 cluster sink particles ≈ 5%of which contain at least one of the ≈ 4000 stars of mass >18 M! . Photoionisation has a noticeable effect on the gas
in the region, producing ionised cavities and leading to dense features at the edge of the HII regions. Compared to
the no-feedback case, photoionisation produces a larger total mass of clouds and clumps, with around twice as manysuch objects, which are individually smaller and more broken up. After this we see a rapid decrease in the total massin clouds and the number of clouds. Unlike studies of isolated clouds, our simulations follow the long range effects ofionisation, with some already-dense gas becoming compressed from multiple sides by neighbouring HII regions. This
causes star formation that is both accelerated and partially displaced throughout the spiral arm with up to 30% of
our cluster sink particle mass forming at distances >5 pc from sites of sink formation in the absence of feedback. At
later times, the star formation rate decreases to below that of the no-feedback case.
Accepted by MNRAS
https://arxiv.org/pdf/2005.06234

Possible evidence of ongoing planet formationin AB Aurigae.
18

A showcase of the6Possible evidence of ongoing planet formation in AB Aurigae.
SPHERE/ALMA synergy

A showcase of theA. Boccaletti1 , E. Di Folco2 , E. Pantin3 , A. Dutrey2 , S. Guilloteau2 , Y.W. Tang4 , V. Piétu5 , E. Habart6 ,J. Milli8, T.L. Beck7 and A.-L. Maire9
1

LESIA, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, Univ. Paris Diderot, Sorbonne Paris
Cité, 5 place Jules Janssen, 92195 Meudon, France; 2 Laboratoire d’Astrophysique de Bordeaux, Université de Bordeaux, CNRS, B18N, Allée Geoffroy Saint-Hilaire, 33615 Pessac, France; 3 Laboratoire CEA, IRFU/DAp, AIM, Université Paris-Saclay, Université Paris Diderot, Sorbonne Paris Cité, CNRS, 91191 Gif-sur-Yvette, France; 4 Academia
Sinica, Institute of Astronomy and Astrophysics, 11F of AS/NTU Astronomy-Mathematics Building, No.1, Sec. 4,
Roosevelt Rd, Taipei, Taiwan; 5 IRAM, 300 rue de la piscine, Domaine Universitaire, 38406 Saint-Martin d’Hères,France; 6 Institut d’astrophysique spatiale, CNRS UMR 8617, Université Paris-Sud 11, 91405 Orsay, France; 7 Space
Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA; 8 CNRS, IPAG, Univ. Grenoble
Alpes, 38000 Grenoble, France; 9 STAR Institute, Université de Liege, Allée du Six Août 19c, 4000 Liege, Belgium
E-mail contact: anthony.boccaletti at obspm.fr
Context. Planet formation is expected to take place in the first million years of a planetary system through various
processes, which remain to be tested through observations. Aims. With the recent discovery, using ALMA, of two
gaseous spiral arms inside the ∼120 au cavity and connected to dusty spirals, the famous protoplanetary disk around
AB Aurigae presents a strong incentive for investigating the mechanisms that lead to giant planet formation. A
candidate protoplanet located inside a spiral arm has already been claimed in an earlier study based on the same
ALMA data.
Methods. We used SPHERE at the Very Large Telescope to perform near-infrared high-contrast imaging of AB Aur inpolarized and unpolarized light in order to study the morphology of the disk and search for signs of planet formation.
Results. SPHERE has delivered the deepest images ever obtained for AB Aur in scattered light. Among the many
structures that are yet to be understood, we identified not only the inner spiral arms, but we also resolved a featurein the form of a twist in the eastern spiral at a separation of about 30 au. The twist of the spiral is perfectly
reproduced with a planet-driven density wave model when projection effects are accounted for. We measured anazimuthal displacement with respect to the counterpart of this feature in the ALMA data, which is consistent with
Keplerian motion on a 4 yr baseline. Another point sxce is detected near the edge of the inner ring, which is likely
the result of scattering as opposed to the direct emission from a planet photosphere. We tentatively derived massconstraints for these two features.
Conclusions. The twist and its apparent orbital motion could well be the first direct evidence of a connection between
a protoplanet candidate and its manifestation as a spiral imprinted in the gas and dust distributions.
Accepted by Astronomy & Astrophysics (A&A 637, L5, 2020)8
https://www.aanda.org/articles/aa/pdf/2020/05/aa38008-20.pdf
19