星形成ゼミ2019/11/15 SFN#322 26-35 (辰馬)26. Gaia 19ajj: A Young Star Brightening Due to Enhanced Accretion + Reduced Extinction
27. The New EXor Outburst of ESO-Hα 99 observed by Gaia ATLAS and TESS
28. Chronology of Episodic Accretion in Protostars - an ALMA survey of the CO and H2O snowlines
29. Understanding the origin of the magnetic ﬁeld morphology in the wide-binary proto- stellar system BHR 71
30. On the origin of wide-orbit ALMA planets: giant protoplanets disrupted by their cores
31. New four-color optical photometry of the young stars V521 Cyg and FHO 27
32. ALMA observations of water deuteration: A physical diagnostic of the formation of protostars
33. A stellar relic ﬁlament in the Orion star forming region
34. Exploring the conditions for forming cold gas giants through planetesimal accretion
35. Origin of hydrogen ﬂuoride emission in the Orion Bar: An excellent tracer for CO-dark H2 gas clouds

1http://arxiv.org/abs/1910.07290

30

On the origin of wide-orbit ALMA planets: giant protoplanets disrupted by their cores
J. Humphries1 & S. Nayakshin1
1

Department of Physics and Astronomy, University of Leicester, Leicester LE1 7RH, UK

E-mail contact: rjh73 at le.ac.uk
Recent ALMA observations may indicate a surprising abundance of sub-Jovian planets on very wide orbits in protoplanetary discs that are only a few million years old. These planets are too young and distant to have been formed via
26 than the gas clumps born in the classical Gravitational
the Core Accretion (CA) scenario, and are much less massive
Instability (GI) theory. It was recently suggested that such planets may form by the partial destruction of GI protoplanets: energy output due to the growth of a massive core may unbind all or most of the surrounding pre-collapse
protoplanet. Here we present the first 3D global disc simulations that simultaneously resolve grain dynamics in the discand within the protoplanet. We confirm that massive GI protoplanets may self-destruct at arbitrarily large separations
from the host star provided that solid cores of mass around 10–20 Earth masses are able to grow inside them during
their pre-collapse phase. In addition, we find that the heating force recently analysed by Masset and Velasco Romero(2017) perturbs these cores away from the centre of their gaseous protoplanets. This leads to very complicated dust
dynamics in the protoplanet centre, potentially resulting in the formation of multiple cores, planetary satellites, andother debris such as planetesimals within the same protoplanet. A unique prediction of this planet formation scenario
is the presence of sub-Jovian planets at wide orbits in Class 0/I protoplanetary discs.
Accepted by MNRAS
http://arxiv.org/pdf/1909.04395

2011). Both analytical work (Nayakshin 2015a) and 3D simulations
After its birth, this protopla(Humphries & Nayakshin
2018) on the&evolutionof GI2018)
protoplanets
ourprotoplanets
paper in Section 7: if rocky cores rapidly fo(Humphries
Nayakshindemonstrate ofthat
the disc. If accreted dust is ain their pebble-rich parent
discs.theNewly
bornofGI
protoplanets
the resultant release of energy may
accretemajoritymm
and above are
sized dustprotoplanets,
grains that enter
settle to the centre and form
1
1
initially very extended withof ∼1 au.
After a characteristic
objects
andleave super-Earth and potentially Satur
J. Humphries & S. Nayakshin
their radii
Hill spheres,considerablyenhancing their total
metal
content.
Nayakshin 2010, 2011). T
cooling time, hydrogen moleculesin thethese
protoplanet
dissociate
andto growstranded
at rapidly
tens to hundreds of au.
Once
accreted,
pebblesareexpected
andsettle
全束縛エネルギーに対する、解放される
potential energy and heat t
1of Physics and Astronomy,
oftheLeicester,
Leicester
LE1
UK coreit collapses toUniversity
a tightly boundanalogue (Bodenheimer
1974;
数Myrの円盤で中心星から遠くにある土星質量くらいの惑星の•Department
insideJupiter
protoplanet,likelybecoming
locked7RH,
into a massive
Assuming that the accretion
重力ポテンシャルエネルギーの割合
Helled et al. 2014). During
this1951;
cooling
phase
protoplanetsare(Kuiper
Boss,
Wetherill& Haghighipour
2002; Helled &surroundinggas
instantaneo
存在が、ALMA観測による円盤ギャップによって示唆されている
2
A
N
A
LY
T
I
C
A
L
E
S
T
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M
AT
E
S
E-mailcontact: rjh73 at le.ac.uk vulnerable to tidal disruption
via 2008;
interactions
centralstar 2010, 2011).
Schubert
Boley withet al.the2010;
Nayakshin
Stevenson 1982; Pollack et
or with other protoplanets, which
may destroyof these
nascent
we estimate
massneeded to unbind
Nayakshin(2016) many
showedvia 1D
populationHere
synthesis
models the core
total
corresponding
feedbac• コア集積では若くて遠すぎるので形成するのが難しい(ペブルplanets if they migrate tothat
separations
closer inside
than 20youngau (Humphries
GI protoplanetwith a radius of !a few au, which is ty
core formation
GI protoplanets may
in fact releaset
et al. 2019).
GM
collapseplanets.
We
assumethattheprotoplanetc Ṁ cenough heat to remove some or all of their gaseous envelopes.
′ can bを使っても若すぎる/十分な量のペブルがない)
5188
J. Humphries
and S.pebble
Nayakshin
Efb =
dt ,
26
↑原始惑星が崩壊する
Additionally,
accretion
plays
a
key
role
in
the
evolutionofa polytropicmaking
sphere with mass Mp , 0radiusrrcp , and adiabaThis process could therefore downsize GI protoplanets,
GI protoplanets. Observations(Tychoniec
et al. 2018)suggestthat for 7/5.
The Virial
theorem tells us that the total energy o
GI
a
more
physicallyplausible
scenario
hatching
ALMA
where M
rc are(Humphries & Nayakshin
2018)
on 0theevolution of GI
protoplanets
ofasourpaper in Section 7: if rocky cores rapidly
form
insideGIthe m• 古典的な重力不安定だと低質量な惑星は形成できない
c and
young
Class
protoplanetary
discs
containasmuchhundreds
its gravitational binding energy and is th(Etot ) is halfplanets. This idea is also attractive because of parallels
withofotherrespectively.
If wetheseassume t
in their pebble-rich parent
discs.
Newlyinborn
GI protoplanetsareprotoplanets,
the resultant
releaseofenergymay
disruptof Earth
massespebble-sizedgrains.
These
will
be
focusedby of their initialastrophysical systems, e.g. galaxies losing much
coreSaturnis constantinitially very extendedinsidewith protoplanets
radii of ∼1 as
au.theyAftera borncharacteristic
objects
andleave super-Earth and potentiallymass andcoreswe tak• 重力不安定で形成された原始惑星の中のコアの成長によって、
are(Boley&Durisen2010)
andgaseous mass due to energetic feedback from supermassive
black
2
3GM
rewrite rc in terms of Mc ancooling time, hydrogenaccreted
moleculesin theprotoplanet
dissociateandstrandedat tens to hundreds of au.p
duringanysubsequentmigration(Johansen&
Lacerda.
holes (Di Matteo, Springel & Hernquist 2005). Etot = −重力エネルギーが周りのガスに渡されることで、原始惑星が崩"# 1/3
it collapses to a tightly2010;
boundOrmel
Jupiter &analogue
1974;
5rp
Klahr (Bodenheimer
2010;
Baruteau,
Meru&
Paardekooper
3 4πρcIn Humphries & Nayakshin (2018), we used a sink particle apHelled et al. 2014). During
this analyticalcooling phase
protoplanets
are and 3D simulations
Efb =
G(Mc
2011). Bothwork
(Nayakshin
2015a)
壊する → コアが残されて惑星が形成できるのでは
proximation to study the accretionofApebbles
ontoGIEprotoplanets.
After
its
birth,
thisEprotoplanet
is5able toaccrete gas a
3
2
A
N
LY
T
I
C
A
L
S
T
I
M
AT
S
vulnerable to tidal disruption
via interactions
with2018)
the central
star that protoplanets(Humphries& Nayakshin
demonstrate
the disc.
accreted
The sink particle approach provides a reliable estimate
forIfthetotal dust is able to grow large enough,where
weahaveassumedthator with other protoplanets,
which
may
destroymanyandof these
nascent
accretethemajority
of
mm
above
sized
dust
grains
that
enter
Here
we
estimate
the
core
mass
neededtounbindnewlyborn
円盤内と原始惑星内の粒子の力学を分解して、3次元で円盤全体
settletothecentre
and
form
a
core
(Helled,Podolak&mass of pebbles captured by a protoplanet, but it does not allow us•~
10地球質量is liberated
instantaneously.
planets if they migratetheir
to separations
closerthan 20 au(Humphries
Hill spheres,considerablyenhancing
their
total
metal
content.
GI
protoplanet
witharadius
of
a
few
au,
which
is
typical
Nayakshin2010,
willprereleaseto study their subsequent evolution. In this paper,
we improveon 2011). This process forのシミュレーションを行った
as a canfraction
ofregionsthe total
et al. 2019).
Once accreted, these pebbles
are expected
growandcollapse
settleplanets. Wehydrodynamically,
assume thatthe protoplanet
be modelledasofenerg
potential
energyand heat thecentralthe
コア質量
our previous
worktobymodelling
therapidly
protoplanet"index# 1/3
Additionally, pebbleinsideaccretion
plays a key roleintheevolutionofthe protoplanet,likelybecoming
lockedintoamassivecoreapolytropic
sphere
with
mass
M
,
radiusr,
andadiabaticγ=ppAssumingthat
theaccretionenergy
of
the
core
is
thus resolving both gas and dust
dynamics
withingravitationalit. Nevertheless,it energyEfrom
Figure1. Liberated
potential
core formation
ρc as relefb
(Kuiper 1951;
Boss, etWetherill
Haghighipour
2002;
Helled& theorem
GI protoplanets. Observations(Tychoniecal.
2018)&
suggestthat computational= 1.3
The ofVirialtells
that
the totalenergyofa donepolytrope• まず、コアからのフィードバックなしで計算を行い、コア成surrounding
gas instantaneously,
as
is
in
the
CA
remains
beyondcurrentmeans
to resolvetheus
growinga7/5.
fraction
protoplanet
bindingenergyfromequation(4).
The
protoplanet−3Etot
5 g cmSchubert discs
2008; contain
Boley etasal.much
2010;asNayakshin
2010, 2011).
young Class 0 protoplanetary
hundreds
−3
)
is
half
of
its
gravitationalbindingenergyandistherefore
givena et a(E
tot
Stevenson
1982;
Pollack
et
al.
1996;
Mordasini
has
a
mass
of
5
M
and
a
solid
core
centraldensity
of
5
g
cm
.
It
takes
solid
core
in
such
simulations,
and
so
we
introduceadust-sinkinJ
長への影響が最も高いペブルサイズを決める
Nayakshin grains.
(2016) showed
via 1D
population
synthesis
modelsof Earth masses in pebble-sized
These
will
be
focusedalternatively,by
totalenergycoreof
17 core.
M⊕ toAs
unbindthiscorresponding
protoplanet
has ora radiusof 1 (Eau.fb ) increases a
the protoplanet centre to model thepebbles
accrete onif itfeedback
insideyoung
GI 2010)
protoplanets
may in fact releaseinside protoplanets asthat
theycore
areformation
born (Boley&
Durisenand"#2! energy
to the core, we pass the liberated gravitational
potential
to
2
t
3GMp
Mc
rp
GMc Ṁ c ′ Efb• 1サイズのペブルを用いてコアからのフィードバックありで計
enough heatmigration
to remove(Johansen
some or &all Lacerdaof their gaseous envelopes.
accreted during any subsequent
.(1)
Ethe
dt , for GI=
Etot grow= − faster.simulations
the surrounding gas in the protoplanet.
Ourthanthereforefb =cancoolingtime-scale
protoplanets
then
This
process
could therefore
downsize
GI protoplanets, making
Etot
Mp
rc
rc
5rp
0
2010;
Ormel
&
Klahr
2010;
Baruteau,
Meru&
Paardekooper
also aim to explore the effects
ofhavecorethefeedback
astointroduced
inunbind them.
算を行う
they
potential
completelya (Nayakshin
more physicallyplausible
scenario for hatching ALMA
2011). Both analyticalGI
work
2015a)
and3D
simulations
where
Mc andrc aretheLetmass
andof the lu
Nayakshin (2016).
us
protoplan
After
its birth, this protoplanet
is ableto accrete
gasconsider
andradius
dusta fromp:
原始惑星、c:コア
planets.2018)
This idea
is also attractive
because of parallels with other(Humphries & Nayakshin
demonstrate
that
protoplanets
respectively.
we assumethat core
theitrate
dust Maccre
The paper3 is structured theas follows.
In Section
2 ablewe briefly
withofrapidly
mass
disc. If accreted
dust
istoIfgrowlargerocky
enough,will
c =systems,losingaccrete the majority ofastrophysicalmm and above
sized e.g.
dust galaxies
grains thatentermuch of their initialcore is constant and we take a constant core densit

On the origin of wide-orbit ALMA planets: giant protoplanets disrupted by their cores

On the origin of wide-orbit ALMA planets: giant protoplanets disrupted by their cores
J. Humphries1 & S. Nayakshin1
1

Department of Physics and Astronomy, University of Leicester, Leicester LE1 7RH, UK

E-mail contact: rjh73 at le.ac.uk

26

6

http://arxiv.org/pdf/1909.04056

34

Exploring the conditions for forming cold gas giants through planetesimal accretion
Anders Johansen1 and Bertram Bitsch2
1

Lund Observatory; 2 Max Planck Institute for Astronomy

E-mail contact: anders at astro.lu.se
The formation of cold gas giants similar to Jupiter and Saturn in orbit and mass is a great challenge for planetesimaldriven core accretion models because the core growth rates far from the star are low. Here we model the growth andmigration of single protoplanets that accrete planetesimals and gas. We integrated the core growth rate using fits inthe literature to N -body simulations, which provide the eﬃciency of accreting the planetesimals that a protoplanet
migrates through. We take into account three constraints from the solar system and from protoplanetary discs: (1)the masses of the terrestrial planets and the comet reservoirs in Neptune’s scattered disc and the Oort cloud areconsistent with a primordial planetesimal population of afew Earth masses per AU, (2) evidence from the asteroid
28 planetesimal diameter is 100 km, and (3) observations
belt and the Kuiper belt indicates that the characteristicof protoplanetary discs indicate that the dust is stirred by weak turbulence; this gas turbulence also excites theinclinations of planetesimals. Our nominal model built on these constraints results in maximum protoplanet masses of
0.1 Earth masses. Ignoring constraint (1) above, we show that even a planetesimal population of 1,000 Earth masses,
corresponding to 50 Earth masses per AU, fails to produce cold gas giants (although it successfully forms hot andwarm gas giants). We conclude that a massive planetesimal reservoir is in itself insuﬃcient to produce cold gas giants.
The formation of cold gas giants by planetesimal accretion additionally requires that planetesimals are small and thatthe turbulent stirring is very weak, thereby violating all three above constraints.
Accepted by Astronomy & Astrophysics
http://arxiv.org/pdf/1909.10429
7

Exploring the conditions for forming cold gas giants through planetesimal accretion12

Anders Johansen and Bertram Bitsch

微惑星によるコア集積で木星や土星のような冷たい巨大ガス惑星を形成することは、コア成長速度が中心星から遠•Lund
Observatory; 2 Max Planck Institute for Astronomy

1

いほど遅いので難しい
E-mail contact: anders at astro.lu.se

Theformation of cold gas giants similar to Jupiter and Saturn in orbit and mass is a great challenge for planetesim• 微惑星とガスを降着する1つの原始惑星の成長と軌道移動を考えた
driven core accretion models because the core growth rates far from the star are low. Here we model the growth a
コア成長速度は先行研究のN体計算の結果を用いた•
migration of single protoplanets that accrete planetesimals and gas. We integrated the core growth rate using fitsthe •literature
to N -body simulations, which provide the eﬃciency of accreting the planetesimals that a protoplan
太陽系と原始惑星系円盤の観測から3つの制限を考慮した
migrates through. We take into account three constraints from the solar system and from protoplanetary discs:• (1) 地球型惑星と彗星の総質量が初期の微惑星総質量と一致すること(1 auあたり数地球質量)kmであること• (2) 小惑星帯とカイパーベルトから、微惑星の特徴的な直径は10028• (3) 円盤観測から、ダストは弱い乱流によりかき乱されていること(同時に微惑星の傾きも増加させる)• 考慮したのは、原始惑星のタイプI軌道移動、微惑星の降着、ガス乱流と微惑星同士の散乱による離心率と傾きの進化、ガス降着(10地球質量で開始)、円盤進化(粘性降着率、サイズ)• 円盤の粘性加熱は無視できるものとする

8

A&A 631, A70 (2019)

Exploring the conditions for forming cold gas giants through planetesimal accretion1

γ = 10−42

Anders Johansen and Bertram Bitsch

降着効率
•Lund
Observatory; 2 Max Planck Institute for Astronomy

1E-mailcontact:
andersparameterat astro.lu.se
stirring• turbulent

The formation
of
cold
gas
giantssimilarto
JupiterandSaturn
in
orbit
and
mass
is
a
great
challengeforplanetesim
もしくはdriven core accretion models because the core growth rates far from the star are low. Here we model the growth amigrationof single protoplanets that accrete planetesimals and gas. We integrated the core growth rate using fits
• 木星、土星形成領域に注目すると、
the 降着効率は0.0001から0.03程度
literature to N -body simulations, which provide the eﬃciency of accreting the planetesimals that a protoplan
migrates through. We take into account three constraints from the solar system and from protoplanetary discs:• 降着効率を上げるには• 乱流を弱くする(左→右)28• 星への降着率を下げる(下→上)• 原始惑星の軌道移動が遅くなるから

9Mpla = 977 ME

3.0e−09 3.0000
100.0
30.0
30.0
1.2e−08 cold
1.0000
A. Johansen and B. Bitsch: Forminggas giants through planetesimal accretion

100.0

•
•

10

10-3

6

7

8

9

10

1.0e−07 0.0001
1.0e−071001
10.0

3.0e-09
1.5e-0830.0

1.0e-06
100

10
r0 [AU]

1.0e−07100

Mpla = 209 ME

3.00001.0000300.01000.0

10.0

5

1.5

10

9.9e-0720

9.6e−08

-4

1
5
10

1.0e−07 0.0010

10.0
10

9.1e-07-2

100.0

1.0e-09
5.2e-0930.0

11.2e-070.01008.1e-070.01006.7e-079.8e-070.00101.0e-06100

0.0001

1

10
r0 [AU]

30.0
100.0
300.0
1000.0

10.0

3.0
20

10

1
5

0.00101

10
r0 [AU]

30.0
20
100.0
300.0
1000.00.10005

2.6e-0710.10003.0

t0 [Myr]

4.7e-076.7e−082010

20 10.0log(M/ME)

9.6e−08 0.0100

10.0

0.0001• 黄線は円盤サイズ

3.0e−09
1.2e−0830.0

1

惑星が形成されてしまう

103

6.7e−08 0.1000

dM*/dt [MO• yr-1]

3.00001.0000• 白の等高線は原始惑星の最終的な位• 左上以外は、hot & warmなガス巨大

0.0010 R
disc
10
Q
rf r0 [AU]0.0001
1 Mpla = 434 ME 10
0.r00 [AU]
00.0

3.0
Mpla = 977 ME

10
10.0

める位置

置

−1
−2
−3

5

• 横軸は原始惑星が微惑星を降着し始5る星の降着率

0.01001

10.0010 R
disc
Q
rf
0.0001
1

t0 [Myr]

28
始める時間、縦軸(右)はそれに対応す

10.0

log(M/ME)

t0 [Myr]

•

1

5

3
The formation of cold gas giants similar to Jupiter and Saturn in orbit and mass is a greatchallenge for2 planetesimalMpla = 211 ME
0.1000driven coreaccretion models because the core growth rates far from the star are low. Here we model the
最終的な原始惑星質量
1 growth
3.0000 and
100.0
300.0
migration of single protoplanets that accrete planetesimals and gas. We integrated the core growth rate using
fits in
1.0000
4
0
the literature to N -body simulations, which provide the eﬃciency of accreting the planetesimals that a protoplanet 3
0.0100−1 discs: (1) 2
migrates through. We take into account three constraints from the solar system and from protoplanetary
縦軸(左)は原始惑星が微惑星を降着し−2 0.1000
1
−3
0

1

• 色は円盤が3 Myrで散逸したあとの

E-mail contact: anders at astro.lu.se

1.0e-08
4.7e-08

10.0

dM*/dt [MO• yr-1]

Mpla = 211 ME

3.0

Exploring the conditions for forming cold gas giants through planetesimal accretion
3.0000Anders Johansen1 and Bertram Bitsch2
300.0
11.0000Lund Observatory; 2 Max Planck Institute for Astronomy
49.6e-079.9e-07
100

Fig. 2. Growth maps for protoplanet growth by planetesimal accretion, with gas accretion commencing after 10 ME is reached. The maps sh
赤線はガスのToomre Q
final mass (i.e. the mass reached when the disc has dissipated after 3 Myr) as continuous colours and the final positions as white contour la function of the starting position of the protoplanet and the starting time. We additionally show the size of the protoplanetary disc (yelloand the Toomre Q of the gas (red contour lines). The panels show the results for four values of the initial mass accretion rate through the d
左上: 標準モデル、右上: 降着率↑、
the mass accretion rate after 3 Myr. The instantaneous stellar mass accretion rate is shown on the right axis. Each panel is also labelled w
total mass of the planetesimals in the models; we assume here that 1% of the initial gas surface density profile is converted into planetesi
下2つ: 初期降着率↑円盤サイズ↓
t = 0. The nominal model (upper left) achieves protoplanet growth only up to 0.1 ME , approximately the mass of Mars. The three other mwhere planetesimals form at the gravitationallyunstable phase of protoplanetary disc evolution, successfully form hot and warm gas giants10of 2 AU, but are not able to form any cold gas giants in the 5–10 AU region (see inset in the upper right panel).

giants.

Exploring the conditions for forming cold gas giants through planetesimal accretion
1 current positions of the giant planets
2 in the solar system. Start-

104

Anders Johansen ing
andBertram
Bitschat 5 AU and with planetesimals of 50 km, we can only form

γ = 10−4, Rpla = 50 km
γ = 10−5, Rpla = 50 km
γ = 10−6, Rpla = 50 km
γ = 10−4, Rpla = 5 km
γ = 10−5, Rpla = 5 km
γ = 10−6, Rpla = 5 km

32
10Jupiter-massplanets
endingin(warm)
1
AU
orbits.
Starting
far太陽系と原始惑星系円盤の観測からの3つの制限を考慮すると、原始惑
•Lund
Observatory; Max Planck Institute for Astronomy
ther out at 10 AU, smaller planetesimals help in promoting the2星の最大質量は0.1
地球質量にしかなれない
10
growthoftheprotoplanet,butthenominalplanetesimal
radiusE-mail contact: anders at astro.lu.seof 50 km and the smaller planetesimals with radius 5 km both1
10
to produce
1 ME inandmass.Saturn& warmな巨大The
formation of coldfailgas
giantsprotoplanets
similar beyond
to Jupiterin orbit and mass is a great challenge for planetesim• 微惑星総質量を増やして星への降着率も増やすと、hotIn order to explore the role of the migration rate on the
0are low. Here we model the growth adrivencore
accretionmodelsbecausethecore
growth
rates
far
from
the
star
10
ガス惑星が作られてしまう
outcome of planet formation, we produced additional growth
tracks with the migration
multipliedplanetesimals
by a reduction factor
fmig gas.
=migration of single protoplanetsthat accreteandWe integrated
the core growth rate using fits
−1
10
0.2
for
all
protoplanet
masses.
We
also
ignoredthetransition
微惑星総質量を増やして、乱流を非常に弱くして、微惑星サイズも小さ• literature to N -body simulations, which provide the eﬃciency of accreting the planetesimals that a protoplan
theto shepherding in this experiment because shepherding might−2
Mpla = 965 ME
10く(半径5km)すれば木星や土星のコアを形成することができる
migrates through. We
take intowhen
account
constraints
from the solar system and from protoplanetary discs:
be suppressed
multiple three
protoplanets
scatter planetesimals
t0 = 0 Myr−3between them (Kokubo & Ida 2000; Thommes et al. 2003). The
10
result is shown with yellow curves in Fig. 3. The reduced migra• この結論は3つの制限を全て無視してしまっている1
10
100
tion has a weak positive effect on the growth tracks starting at
rf [AU]
5 AU; they now produce gas giants in 2–3 AU orbits.28
The effect
成長中の原始惑星同士の相互作用が必要か？
•
is overall negative farther out, however. Lowering the migration Fig. 4. Final planetary mass as a function of the final planetary orbit
speed leads to a higher efficiency of accreting planetesimals, but for protoplanets starting to accrete at t = 0 in the massive planetesimal• 円盤の粘性加熱を考慮しないといけないか？
the flux of planetesimals that the protoplanets migrates over is population model with two different planetesimal radii (50 and 5 km)
4
5
and
three
valuesoftheturbulentstirring
coefficient
(10
,
10
, and
also reduced, which reduces the overall growth rate.
6
4
10
).
The
solid
blue
line
(
=
10
/Rpla = 50 km) corresponds to a cut
外側への軌道移動が必要か？
In Fig. 3 we show with dash-dotted blue lines the growth•
tracks when we started with a larger protoplanet mass of Mp,0 = at t0 = 0 of the upper right panel of Fig. 2. The planetesimal inclinations
are
here
set
as
the
maximumoftheinclinations
given
byturbulent
0.1 ME . These protoplanets experience rapid migration towards• ペブル降着によって形成されたのか？
stirring and by mutual planetesimal scattering. Planetesimals with athe star. This has the positive effect of bringing the protoplanets nominal radius of 50 km can only form Jupiter-mass planets interior
into the regions of higher accretion efficiency closer to the star, of 3 AU, even when the turbulent stirring is very weak with = 10 5
but increasing the protoplanet mass does not help to create giant or extremely weak with = 10 6 , because of inclination stirring by
planets in cold orbits.
mutual planetesimal scattering. Lowering the planetesimal radius to
We show the final planet mass as a function of the final posi- 5 km allows the formation of Jupiter analogues when the turbulenttion forming in the massive planetesimal population model in stirring coefficient is = 10 5 or = 10 6 .
Fig. 4 for lower values of the turbulent stirring .11We assumed

M [ME]

1

Gaia
19ajj:A
Young
Star
BrighteningDueto26 Enhanced Accretion + Reduced Extinction
Lynne A. Hillenbrand1 , Bo Reipurth2 , Michael Connelley2 , Roc M. Cutri3 and Howard Isaacson4,5
1

Department of Astronomy, California Institute of Technology, USA; 2 Institute for Astronomy, University of Hawaii
at Manoa, USA; 3 IPAC, California Institute of Technology, USA; 4 Astronomy Department, University of California,
Berkeley, USA; 5 University of Southern Queensland, Australia
E-mail contact: lah at astro.caltech.edu
We report on the source Gaia 19ajj, identifying it as a young star associated with a little-studied star-forming region
seen along a complex line-of-sight through the Gum Nebula. The optical lightcurve recently recorded by Gaia exhibitsa slow and unsteady 5.5 mag rise over about 3 years, while the mid-infrared lightcurve from NEOWISE over thesame time period shows a 1.2 mag rise having similar structure. Available color information is inconsistent with pureextinction reduction as the cause for the photometric brightening. Optical spectroscopic characteristics in the current
bright phase include: little in the way of absorption except for the hallmark LiI 6707 Å signature of youth plus weake.g. Ca I and notably Ba II; strong wind/outflow in Ca II, Mg I b, Na I D, Hα, K I, O I; jet signatures in [O I], [SII], [Ca II], [Fe II], and [Ni II]; and narrow rest-velocity emission in neutral species such as Fe I, Ni I, and Mg I. The
infrared spectrum is also characterized by outflow and emission, including: a hot He I wind, jet lines such as [Fe II]
and H2 ; and weak narrow rest-velocity atomic line emission. The 12 CO bandheads are weakly in emission, but there
is also broad H2 O absorption. Gaia 19ajj exhibited a previous bright state in the 2010-2012 time frame. The bodyof photometric and spectroscopic evidence suggests that the source bears resemblance to V2492 Cyg (PTF 10nvg)
and PV Cep, both of which similarly experience bright phases that recur on long timescales, with large-amplitude
photometric variations and emission-dominated spectra. We interpret the behavior of Gaia 19ajj as caused by cycles
of enhanced disk accretion accompanied by reduced extinction.
24
Accepted by Astronomical Journal (AJ)
http://arxiv.org/pdf/1910.05790

12

27

The New EXor Outburst of ESO-Hα 99 observed by Gaia ATLAS and TESS
Klaus W. Hodapp1 , Bo Reipurth1 , Bertil Pettersson2 , John Tonry3 , Larry Denneau3 , Patrick J. Vallely4 ,Benjamin J. Shappee3 , James D. Armstrong5 , Michael S. Connelley1 , C. S. Kochanek4 , MichaelFausnaugh6 , Rolf Chini7 , Martin Haas7 and Catalina Sobrino Figaredo7
1

University of Hawaii, Institute for Astronomy, 640 N. Aohoku Place, Hilo, HI 96720, USA; 2 Department of Physics
and Astronomy, Uppsala University, Box 516, SE-751 20 Uppsala, Sweden; 3 University of Hawaii, Institute for
Astronomy, 2680 Woodlawn Drive, Honolulu, HI 96822, USA; 4 Department of Astronomy, The Ohio State University,
140 West 18th Avenue, Columbus Ohio, 43210-1173, USA; 5 University of Hawaii, Institute for Astronomy, 34 Ohia Ku
St., Pukalani, HI 96768, USA; 6 MIT Kavli Institute for Space and Astrophysics Research, 77 Massachusetts Avenue,
37-241, Cambridge, MA 02139, USA; 7 Astronomisches Institut, Ruhr-Universität Bochum, Universitätsstraße 150,
44801 Bochum, Germany
E-mail contact: hodapp at hawaii.edu
We report photometry and spectroscopy of the outburst of the young stellar object ESO-Hα 99. The outburst was
first noticed in Gaia alert Gaia18dvc and later by ATLAS. We have established the outburst light curve with archival
ATLAS “Orange” filter photometry, Gaia data, new V -band photometry, and J, H, and Ks photometry from IRIS
and UKIRT. The brightness has fluctuated several times near the light curve maximum. The TESS satellite observed
ESO-Hα 99 with high cadence during one of these minor minima and found brightness fluctuations on timescales ofdays and hours. Imaging with UKIRT shows the outline of an outflow cavity, and we find one knot of H2 1 − 0 S(1)emission, now named MHO 1520, on the symmetry axis of this nebula, indicating recent collimated outflow activity
from ESO-Hα 99. Its pre-outburst SED shows a flat FIR spectrum, confirming its early evolutionary state and its
similarity to other deeply embedded objects in the broader EXor class. The pre-outburst luminosity is 34 L⊙ , amuch higher luminosity than typical EXors, indicating that ESO-Hα 99 may be a star of intermediate mass. Infraredand optical spectroscopy show a rich emission line spectrum, including HI lines, strong red CaII emission, as well as
infrared CO bandhead emission, all characteristic EXors in the broadest sense. Comparison of the present spectrawith an optical spectrum obtained in 1993, presumably in the quiescent state of the object, shows that during thepresent outburst the continuum component of the spectrum has increased notably more than the emission lines. The
Hα equivalent width during the outburst is down to one half of its 1993 level, and shock-excited emission lines aremuch less prominent.
Accepted by The Astronomical Journal

13

28

Chronology of Episodic Accretion in Protostars - an ALMA survey of the CO and H2Osnowlines
Tien-Hao Hsieh1 , Nadia M. Murillo2, Arnaud Belloche3 , Naomi Hirano1 , Catherine Walsh4 , Ewine F.
van Dishoeck2,5 , Jes K. Jørgensen6 and Shih-Ping Lai7
1

Institute of Astronomy and Astrophysics, Academia Sinica, P.O. Box 23-141, Taipei 106, Taiwan; 2 Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA, Leiden, the Netherlands; 3 Max-Planck-Institut für Radioastronomie,
Auf dem Hügel 69, 53121 Bonn, Germany; 4 School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT,
UK; 5 Max-Planck-Institut für extraterrestrische Physik, Giessenbachstraße 1, 85748, Garching bei München, Germany; 6 Niels Bohr Institute, University of Copenhagen, Øster Voldgade 57, DK 1350 Copenhagen K., Denmark; 7Institute of Astronomy, National Tsing Hua University (NTHU), Hsinchu 30013, Taiwan
E-mail contact: shawinchone at gmail.com
Episodic accretion has been used to explain the wide range of protostellar luminosities, but its origin and influence on
the star forming process are not yet fully understood. We present an ALMA survey of N2 H+ (1 − 0) and HCO+ (3 − 2)
toward 39 Class 0 and Class I sources in the Perseus molecular cloud. N2 H+ and HCO+ are destroyed via gas-phasereactions with CO and H2 O, respectively, thus tracing the CO and H2 O snowline locations. A snowline location at
25 luminosity suggests that an accretion burst has occurreda much larger radius than that expected from the current
in the past which has shifted the snowline outward. We identified 18/18 Class 0 and 9/10 Class I post-burst sourcesfrom N2 H+ , and 7/17 Class 0 and 1/8 Class I post-burst sources from HCO+ . The accretion luminosities during thepast bursts are found to be ∼ 10 − 100 L⊙ . This result can be interpreted as either evolution of burst frequency or
disk evolution. In the former case, assuming that refreeze-out timescales are 1000 yr for H2 O and 10,000 yr for CO,
we found that the intervals between bursts increases from 2400 yr in the Class 0 to 8000 yr in the Class I stage. Thisdecrease in the burst frequency may reflect that fragmentation is more likely to occur at an earlier evolutionary stage
when the young stellar object is more prone to instability.
Accepted by ApJ
https://arxiv.org/pdf/1909.02706

14

29

Understanding the origin of the magnetic field morphology in the wide-binary protostellar system BHR 71
Charles L. H. Hull1,2,11 Valentin J. M. Le Gouellec3,4 Josep M. Girart5,6 John J. Tobin7,8,9 Tyler L.
Bourke101

National Astronomical Observatory of Japan, NAOJ Chile, Alonso de Córdova 3788, Oﬃce 61B, 7630422, Vitacura,Santiago, Chile; 2 Joint ALMA Observatory, Alonso de Córdova 3107, Vitacura, Santiago, Chile; 3 European Southern Observatory, Alonso de Córdova 3107, Vitacura, Santiago, Chile; 4 AIM, CEA, CNRS, Université Paris-Saclay,
Université Paris Diderot, Sorbonne Paris Cité, F-91191 Gif-sur-Yvette; 5 Institut de Ciències de l’Espai (ICE-CSIC),
Campus UAB, Carrer de Can Magrans S/N, E-08193 Cerdanyola del Vallès, Catalonia; 6 Institut d’Estudis Espacials
de Catalunya, E-08030 Barcelona, Catalonia; 7 National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, Virginia 22903, USA; 8 Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma,
440 W. Brooks Street, Norman, OK 73019, USA; 9 Leiden Observatory, Leiden University, P.O. Box 9513, NL-2300RA
Leiden, The Netherlands; 10 Square Kilometre Array Organization, Jodrell Bank Observatory, Lower Withington,
Macclesfield, Cheshire SK11 9DL, UK; 11 NAOJ Fellow

E-mail contact: chat.hull at nao.ac.jp

We present 1.3 mm ALMA observations of polarized dust em12Tm(564009p(u)0.9(ll)]ro)-59.96264009.96264323.161461.52Tm[(Y(o5.723cmBT/T

Accepted by MNRAS

31
http://arxiv.org/pdf/1909.04395
New four-color optical photometry of the young stars V521 Cyg and FHO 27
Sunay Ibryamov1 and Evgeni Semkov2
1

Department of Physics and Astronomy, Faculty of Natural Sciences, University of Shumen, 115, Universitetska Str.,
9700 Shumen, Bulgaria; 2 Institute of Astronomy and National Astronomical Observatory, Bulgarian Academy of
Sciences, 72, Tsarigradsko Shose Blvd., 1784 Sofia, Bulgaria
E-mail contact: sibryamov at shu.bg
Results from new BVRI photometric observations of the pre-MS stars V521 Cyg and FHO 27 collected during theperiod from February 2015 to July 2019 are presented. These stars are embedded in the LDN 935, dubbed “The Gulf
of Mexico” in the active star-forming complex NGC 7000/IC 5070. Previous studies revealed them as variables withlarge amplitude brightness variations. Our new observations show that the stars continue to exhibit strong photometricvariability and fading events in the brightness. On the basis of the new data received and the data available in theliterature, we were able to specify the periodicity in the brightness variations of V521 Cyg. In the case of FHO 27, wefound a significant peak in its periodogram corresponding to 893 days period.
Accepted by Bulgarian Astronomical Journal
http://arxiv.org/pdf/1909.01458

ALMA observations of water deuteration: A physical diagnostic of the formation of
protostars
16

32

ALMA observations of water deuteration: A physical diagnostic of the formation of
protostars
S. S. Jensen1 , J. K. Jørgensen1 , L. E. Kristensen1 , K. Furuya2 , A. Coutens3 , E. F. van Dishoeck4,5 , D.
Harsono4 and M. V. Persson6
1

Niels Bohr Institute & Centre for Star and Planet Formation, University of Copenhagen, Øster Voldgade 5-7, DK1350 Copenhagen K, Denmark; 2 Center for Computational Sciences, University of Tsukuba, Japan; 3 Laboratoired’Astrophysique de Bordeaux, Univ. Bordeaux, CNRS, B18N, alle Geoﬀroy Saint-Hilaire, 33615 Pessac, France; 4Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands; 5 Max–Planck Institute für
extraterrestrische Physik (MPE), Giessenbachstrasse, 85748 Garching, Germany; 6 Department of Space, Earth andEnvironment, Chalmers University of Technology, Onsala Space Observatory, 439 92 Onsala, Sweden
E-mail contact: sigurd.jensen at nbi.ku.dk
How water is delivered to planetary systems is a central question in astrochemistry. The deuterium fractionation ofwater can serve as a tracer for the chemical and physical evolution of water during star formation and can constrain
the origin of water in Solar System bodies.
The aim is to determine the HDO/H2 O ratio in the inner warm gas toward three low-mass Class 0 protostars selected
to be in isolated cores, i.e., not associated with any cloud complexes. Previous sources for which the HDO/H2 O
ratio have been established were all part of larger star-forming complexes. Determining the HDO/H2 O ratio toward
three isolated protostars allows comparison of the water chemistry in isolated and clustered regions to determine theinfluence of local cloud environment.
27
We present ALMA Band 6 observations of the HDO 31,2 –22,1 and 21,1 –21,2 transitions at 225.897 GHz and 241.562 GHz
along with the first ALMA Band 5 observations of the H18
2 O 31,3 –22,0 transition at 203.407 GHz. The high angularresolution observations (0.3′′ -1.3′′ ) allow the study of the inner warm envelope gas. Model-independent estimates for
the HDO/H2 O ratios are obtained and compared with previous determinations of the HDO/H2 O ratio in the warm gas
toward low-mass protostars. We successfully detect the targeted water transitions toward the three sources with S/N ¿5. We determine the HDO/H2 O ratio toward L483, B335 and BHR71–IRS1 to be (2.2 ± 0.4)×10−3, (1.7 ± 0.3)×10−3,
and (1.8 ± 0.4)×10−3, respectively, assuming Tex = 124 K. The degree of water deuteration of these isolated protostars
are a factor of 2–4 higher relative to Class 0 protostars that are members of known nearby clustered star-forming
regions.
The results indicate that the water deuterium fractionation is influenced by the local cloud environment. This eﬀect
can be explained by variations in either collapse timescales or temperatures, which depends on local cloud dynamics
and could provide a new method to decipher the history of young stars.
Accepted by A&A
https://arxiv.org/pdf/1909.10533

17https://arxiv.org/pdf/1909.10533

33

A stellar relic filament in the Orion star forming region
Tereza Jerabkova1,2,3 , Henri M.J. Boﬃn1 , Giacomo Beccari1 , and Richard I. Anderson1,4
1

2

European Southern Observatory, Karl-Schwarzschild-Straße 2, 85748 Garching bei München, Germany; Helmholtz
Institut für Strahlen und Kernphysik, Universität Bonn, Nussallee 14-16, 53115 Bonn, Germany; 3 AstronomicalInstitute, Charles University in Prague, V Holesovickach 2, CZ-180 00 Praha 8, Czech Republic; 4 Départementd’Astronomie, Université de Genève, 51 Ch des Maillettes, 1290 Sauverny, Switzerland
E-mail contact: tjerabkova at gmail.com
We report the discovery of the oldest stellar substructure in the Orion star forming region (OSFR), the Orion relicfilament. The relic filament is physically associated with the OSFR as demonstrated by Gaia DR2 photometry andastrometry, as well as targeted radial velocity follow-up observations of a bright sub-sample of proper-motion selectedcandidate members. Gaia DR2 parallaxes place the Orion relic filament in the more distant part of the OSFR, ≈430pc from the Sun. Given its age, velocity dispersion, spatial extent, and shape, it is not possible for the Orion relicfilament to have formed as a single stellar cluster, even taking into account residual gas expulsion. The relic filament isalso too young to be a tidal stream, since Galactic tides act on much longer time scales of order 100 Myr. It therefore
appears likely that the structure formed from a molecular cloud filament similar to Orion A in the OSFR and retained
its morphology despite decoupling from its natal gas. Hence, the Orion relic filament bears witness to the short-lived
evolutionary phase between gas removal and dispersion due to shears and tides, and provides crucial new insights into
how stars are formed in molecular clouds.
Accepted by MNRAS
http://arxiv.org/pdf/1909.04056
18

35 Origin of hydrogen fluoride emission in the Orion Bar: An excellent tracer for CO-dark
H2 gas clouds

Umit Kavak1,2 , F.F.S. van der Tak2,1 , A.G.G.M. Tielens3 and R.F. Shipman2,11

Kapteyn Astronomical Institute, University of Groningen, P.O. Box 800, 9700 AV Groningen, The Netherlands;
2
SRON Netherlands Institute for Space Research, Landleven 12, 9747 AD Groningen, The Netherlands; 3 Leiden
Observatory, Leiden University, PO Box 9513, NL-2300RA, Leiden, the Netherlands
E-mail contact: kavak at astro.rug.nl

The hydrogen fluoride (HF) molecule is seen in absorption in the interstellar medium (ISM) along many lines of sight.
Surprisingly, it is observed in emission toward the Orion Bar, which is an interface between the ionized region aroundthe Orion Trapezium stars and the Orion molecular cloud. We aim to understand the origin of HF emission in theOrion Bar by comparing its spatial distribution with other tracers. We examine three mechanisms to explain the HF
emission: thermal excitation, radiative dust pumping, and chemical pumping. We used a Herschel /HIFI strip map of
the HF J = 1 → 0 line, covering 0.5′ by 1.5′ that is oriented perpendicular to the Orion Bar. We used the RADEX
non-local thermodynamic equilibrium (non-LTE) code to construct the HF column density map. We use the Meudon
PDR code to explain the morphology of HF. The bulk of the HF emission at 10 km s−1 emerges from the CO-darkmolecular gas that separates the ionization front from the molecular gas that is deeper in the Orion Bar. The excitationof HF is caused mainly by collisions with H2 at a density of 105 cm−3 together with a small contribution of electrons
in the interclump gas of the Orion Bar. Infrared pumping and chemical pumping are not important. We conclude
that the HF J = 1 → 0 line traces CO-dark molecular gas. Similarly, bright photodissociation regions associated withmassive star formation may be responsible for the HF emission observed toward active galactic nuclei.
Accepted by Astronomy and Astrophysics (A&A) on September 23, 2019.
http://arxiv.org/pdf/1910.00707
19