SFN #341 13-18
担当：土井 聖明 (総研大M2)
13. 1I/ʼOumuamua as an N2 ice fragment of an exo-Pluto surface: I. size and compositional
constraints
14. Modeling chemistry during star formation: Water deuteration in dynamic star-forming
regions
15. The complex organic molecular content in the L1498 starless core
16. Stars with Photometrically Young Gaia Luminosities Around the Solar System (SPYGLASS) I: Mapping Young Stellar Structures and their Star Formation Histories
17. ATOMS:ALMA Three-millimeter Observations of Massive Star-forming regions ‒ III:
Catalogues of candidate hot molecular cores and Hyper/Ultra compact HII regions
18. Membership of Stars in Open Clusters using Random Forest with Gaia Data• 太陽系外から飛来した天体である Oumuamua の組成・サイズについての論文（先週のSFNで紹介された Oumuamua 論文はこのシリーズの2本目）• Oumuamua は重力だけでは説明できない軌道運動をした。
• さまざまな揮発性物質からなる惑星の軌道を計算し、観測と比較した。
• N2氷からなる天体を考えると、軌道運動、他の分子やダストのエミッション(の未検出)、サイズ、アルベドが説明できる。

イントロ：Oumuamuaの特徴・これまでの研究
Oumuamuaの特徴

これまでの研究・高い離心率(e=1.2): 系外天体
このような天体は他には 2I/Borisov(e=3.36) ぐらい
・高い軸比

細長い楕円なら1:10、薄い円盤なら1:5(この方がより良い)

1:5 ~ 1:10
・熱放射が弱い(=天体が小さい)
散乱での強度を考えるとアルベドが高い
・太陽近傍の星との相対速度が小さい(~9 km/s)

若い星なら速度分散が小さい(初期の分子雲の速度分散)

恒星の速度分散は数十km/s
・ガスやダストの検出なし←小惑星っぽい
dust, CO, CO2がnon-detection
2I/Borisovでは CN が明るい(彗星っぽさ)
・非重力的な加速 (~1/d^2)

H2氷が6%ぐらいあれば説明できる

ガスの噴射で加速しているのと整合的(彗星っぽさ)→ N2 氷の天体だと考えてこれらの特徴を説明できるか？

surface temperature of 25 K, this yields Vjet = 80 m s . This is similar to, but slightlydi↵erent from,considered likely by Seligman & Laughlin (2020), whop the jetting speed
manuscript submitted to JGR: Planets
used Vjet =kB T /m, fixed the temperature at 25 K and at 4/3 (5/3 would be more
appropriate), and found Vjet = 99 m s 1 for N2 .

非重力的な加速を説明する天体組成・サイズの推定
非重力的な加速を説明する天体の条件
変数として
・アルベド
検出されているのは散乱光
アルベドを p とすると、天体サイズは p1/2に比例

Rearranging Equation 1 we then obtain the mass loss rate,

dM
L
1
4
= Sm
⇠
(1
p
)
✏
T
[
H
+
H
+
mC
T
]
,
0
B
sub
trans
p
surf
2
dt
4⇡d
and the non-gravitational acceleration,r
⌧ S
8kB mTsurf La=⇠0 (1 pB )
2
3M
⇡
4⇡d

4
✏ Tsurf[ Hsub +Htrans + mCp T ]

(5)

1

. (6)

2.4 Composition of ‘Oumuamua（形状は扁平な軸比1:5を考えて相似変形）

Having set out the equations that govern the mass loss and non-gravitational acceleration
we are now in a position to compute the non-gravitational acceleration for a selection
光の吸収に応じてガスの揮発量も変化
of di↵erent ices and compare the results to observations. Micheli et al. (2018) fit the
non-gravitational acceleration as 4.92 ⇥ 10 4 (d/1 au) 2 cm s 2 over the observational arc
・組成that runs from 14 October 2017 to 2 January 2018. In Figure 1 we plot the non-gravitational
acceleration that we predict at 1.42 au, relative to the observed acceleration, as a function
揮発性が違うとガスの揮発量が変わって加速度が変わる
of albedo (assuming p = pG = pB ) for a variety of pure ice compositions. From the set ofices used by Seligman & Laughlin (2020) in their Table 1 we exclude Ar, Kr and Xe, as
結果
these heavy noble gases have low cosmic abundances and it seems highly unlikely that there
would be large populations of bodies composed of these ices. We add, however, the common
N2のアルベド、揮発量で加速度が説明可能！
astrophysical compounds CH4 , CO and NH3 , so that the complete set of ices we examine
is H2 , Ne, CH4 , CO, N2 , NH3 , O2 , CO2 , and H2 O. The sublimation enthalpies and other(冥王星表面とほぼ同じ)
data for all 9 ices, along with the data sources, can be found in Table A1.

O2, NH3, CO2, H2O: 加速度が不足

H2, He: 冷たすぎて天体として長持ちしない
CH4, CO: 少ない
N2は冥王星表面の主要な物質→ 系外の冥王星のような天体の破片–7–天体のサイズの進化
太陽の近傍では、太陽放射によるガスの放出で進化(右図)再近接時に大きく変化
質量は1/10へ、軸比は2倍に
遠方でのサイズ進化の要因は？

2.1:1 ratio it is inferred to have upon entry to the Solar System, as well as being consistent withthe average age of an N2 ice fragment. An object like ‘Oumuamua must be ejected from a young
system (< 2 Gyr) to avoid acquiring a large velocity, and probably a very young system < 108 yr,
if the timing of the dynamical instability that depleted the primordial Kuiper belt is typical. Sucha young system is likely to be located in a spiral arm of the Galaxy, especially if the instability
happens at early times ~107 yr. A transit time ~0.4-0.5 Gyr at 9 km s-1 would imply travel over
3.6 kpc, and this distance and the direction of ‘Oumuamua’s approach would seem consistent
with an origin in the Perseus arm.
This sequence of events is summarized in Figure 1, which uses the results from this paper andthe companion paper (Jackson and Desch 2021). The axes upon ejection from its parent system
are consistent with the expected size of collisional fragments, with mean diameter ~70 m, andthe axis ratios thought typical of fragments. The loss of about half its mass in the ISM by erosion
by Galactic cosmic rays is consistent with transit for 0.4 – 0.5 Gyr, about half the time thought
typical. Other aspects of its evolution within the Solar System are discussed in the companion
paper. The extreme mass loss experienced as it passed the Sun accounts for its small size and its
extreme axis ratios.

太陽の影響は弱いが、長期間(~ Gyr)星間空間を飛んできた
Figure 2. Change in ‘Oumuamua’s parameters over time. Clockwise from top left:(もしH2ならもともと数十キロ必要 → N2 が適切) from the Sun, mass, axis ratio (a/c), surface temperature. Times are relative to 27 Octob
・星間ダストの衝突: 効かない(わずか)Perihelion occurs at -48 days.

・光蒸発: 効かない(1 cm/Gyr)・Galactic Cosmic Rays (GCRs)
6 m/Gyr (現在の太陽近傍)
31 m/Gyr (星形成率の変化を考慮)(Fitzsimmons et al., 2018, ACAM (X-shooter)). With the exception of the Fitzsimm
al. (2018) X-shooter data these are consistent with the spectral slopes of Pluto (Loal., 2016), Makemake (Licandro et al., 2006) and Gonggong (Santos-Sanz et al., 20
around 14%/100 nm and presumably attributable to photolyzation of CH4 to form

In terms of other possible trace species, Ye et al. (2017) used ground-based obser
with the Hale Palomar telescope to place upper limits on the production rates of2 ⇥ 1022 molecules per second) and C2 (< 4 ⇥ 1022 molecules per second), but these
expected in the N2 ices that make up the crust of a Pluto-like body. Radio obser
A plausible
historyBankfor ‘Oumuamua
as a collisional
fragmentof N2 ice,
as hypothesized
by Park et al. (2018) Figure
with1.theGreen
Telescopeplace
a looseupper
limit
in this paper and the
27 companion paper by Jackson and Desch (2021). Credit: Sue Selkirk.

Modeling chemistry during star formation: Water deuteration in dynamic star-forming
regions

S. S. Jensen, J. K. Jørgensen, K. Furuya, T. Haugbølle, Y. Aikawa F Recent observations of the HDO/H2 O ratio
toward protostars in isolated and clustered environments show an apparent dichotomy, where isolated sources show higher D/Hratios than clustered counterparts. Establishing which physical and chemical processes create this diﬀerentiation can provide
insights into the chemical evolution of water during star formation and the chemical diversity during the star formation process
and in young planetary systems. Methods: The evolution of water is modeled using 3D physicochemical models of a dynamic
star-forming environment. The physical evolution during the protostellar collapse is described by tracer particles from a 3D
MHD simulation of a molecular cloud region. Each particle trajectory is post-processed using RADMC-3D to calculate thetemperature and radiation field. The chemical evolution is simulated using a three-phase grain-surface chemistry model andthe results are compared with interferometric observations of H2 O, HDO, and D2 O in hot corinos toward low-mass protostars.
Results: The physicochemical model reproduces the observed HDO/H2 O and D2 O/HDO ratios in hot corinos, but shows nocorrelation with cloud environment for similar identical conditions. The observed dichotomy in water D/H ratios requires
variation in the initial conditions (e.g., the duration and temperature of the prestellar phase). Reproducing the observed D/Hratios in hot corinos requires a prestellar phase duration t ⇠1-3 Myr and temperatures in the range T ⇠ 10-20 K prior to collapse.
This work demonstrates that the observed diﬀerentiation between clustered and isolated protostars stems from diﬀerences in
the molecular cloud or prestellar core conditions and does not arise during the protostellar collapse itself.

水の同位体比に関するシミュレーション論文• The
complex organic molecular content in the L1498 starless core
Izaskun Jimenez-Serra, Anton I. Vasyunin, Silvia Spezzano, Paola Caselli, Giuliana Cosentino, Serena Viti F
原始星周りのHDO/H2O
観測からクラスターより孤立天体の方がD/Hが高い
carried out
toward starless andpre-stellar cores have revealed that complex organic molecules
are prevalent
in these• Observations
objects, but it is unclear what chemical processes are involved in their formation. Recently, it has been shown that complex
are preferentially produced at an intermediate-density shell within the L1544 pre-stellar core at radial distances of
3次元の動的な物理化学モデルで水の進化をモデリングし、トレーサー粒子を追って化学進化を見た。
• organics
4000 au with respect to the core center. However, the spatial distribution of complex organics has only been inferred toward
coremass
and it remains
unknown whether these
speciesの水の同位体観測と比較した。
present a similar behaviour in other cores. We report high-sensitivity
lowprotostarのhot
corino• thisobservations carried out toward two positions in the L1498 pre-stellar core, the dust peak and a position located at a distanceofモデルは観測された
11000 au from the center of thecore where the emission of CH OH peaks. Similarly to L1544, our observations reveal that
HDO/H2O、D2O/HDOを再現するが、原始星の環境の違いとの相関はなかっ• small O-bearing molecules and N-bearing species are enhanced by factors 4-14 toward the outer shell of L1498. However, unlike
3•

L1544,
た。large O-bearing organics such as CH3CHO, CH3OCH3 or CH3OCHO are not detected within our sensitivity limits. For
N-bearing organics, these species are more abundant toward the outer shell of the L1498 pre-stellar core than toward the one in
L1544. We propose that the diﬀerences observed between O-bearing and N-bearing species in L1498 and L1544 are due to the
クラスターと孤立天体での違いは、分子雲やprestellar
coreの初期条件の違いによるものであり、
diﬀerent physical structure of these cores, which in turn is a consequence of their evolutionary stage, with L1498 being youngerthan
L1544.
protostellar
collapse段階での進化の違いによるものではないイントロ：水の同位体の特徴
・氷の同位体比はその形成環境に作用されるため、物理的・化学的な進化のトレーサー
・観測事実として・HDO/H2O は、cold envelope では hot corino より高い。
・Hot corino では D2O/HDO > HDO/H2O である。
S. S. Jensen et al.: Modeling chemistry during star formation: Water deuteration in dynamic star-forming regions→ 氷ダストが重水素率が低いマントル部分と、重水素濃縮が進んだ表層から構成されていると考えると説明できる
・孤立原始星では、cluster内と比較して HDO/H2Oが高い

Ice structure:

Observations:→ この理由を探るのが本研究のメイントピック。
考えられる解釈は! ≤ 30K
COLD ENVELOPE
HDO/H2O ~ 10-2

・isolated protostarでは崩壊の時間が長くて
重水素濃縮がよく進む
・clustered protostarでは温度が高い、
もしくは放射が強いことで重水素濃縮が進みにくい→ 3Dの流体シミュレーションと化学進化計算を行う! ≥ 100K

HOT CORINO
HDO/H2O~10-4-10-3
D2O/HDO ~10-2

シミュレーション設定

A&A proofs: manuscript no. water_models

計算設定・流体シミュレーション: RAMSES・輻射シミュレーション：RADMC3D
・化学計算
・3相モデル(mantle, surface, gas)でのrate equation
S. S. Jensen et al.: Modeling chemistry during star formation: Water deuteration in dynamic star-forming regions

・気相反応、表面反応、光化学を導入

tostellar luminosity, is the primary luminosity source at the very
early stages modeled here. Second, the purpose of this work is
to study how variations in environment influences the chemistryduring star formation and does not depend on the exact choiceof PMS model. Additionally, we note that the PMS phase occurs
toward the end of the range of the time-domain studied in thiswork, namely, the ⇠250 kyr of the protostellar collapse after the
initial collapse of the core.
2.2. Calculating extinction in the cores

For photodissociation and photodesorption, rate coefficients are
given as a function of the visual extinction Av . From the calculated mean field intensities, we follow the approach of Visser
et al. (2011) and derive the optical depth ⌧UV at UV wavelengths
from:

図3. 計算設定の外観。
1. 崩壊前の静的な段階,(2)
2. sink形成前：RAMSES (10 ⌧K)= ln F F
3. sink形成後：RAMSES+RADMC3D
where Fis the integrated UV flux from the radiative transfer calculation, and F
is either the integrated UV
flux from the ISRF or from the central protostar, whichever isの3段階のをおこなう。
ramses output with varying accretion luminosities: we created a higher in each grid point. Initially, the UV flux from the proFig. 3. Overview of the di↵erent phases of the model. In the initialprestellar (static) phase, the physical conditions are inferred previous
simulations and observations (e.g., Keto & Caselli 2008). In the precollapse phase, which has a fixed duration of 100 kyr, the physical evolution is derived from ramses, but since the protostar is not yet formed,
no radiative transfer is performed. During the collapse, the physical evolution is derived from ramses and post-processed using radmc-3d. The
duration of the collapse varies between individual tracer particles, withan upper duration of ⇠ 250 kyr.

linear grid of four models, ranging from the lowest accretion rate
to the highest accretion rate associated with any given ramses
output. We calculated the fifth model using the mean accretion
rate during the period between the snapshots. When estimating
the dust temperature for a tracer particle at a given position andtime, we calculated the total luminosity (Lacc + Lprotostar ) of the
protostar at that time, and interpolated the temperature from thevalues provided by the five radmc-3d models. We assume thatthe dust and gas is thermally coupled, such that the gas temperatures and dust temperatures are equal. This approach is reasonable at higher densities present during the protostellar collapse

UV,RADMC 3D

UV

UV,0

UV,RADMC 3D

UV,0

tostar is quite low owing to the low surface temperature of the
protostar (2000 K) and during this period, the ISRF dominates
the UV flux. Later on, the UV flux from the protostar may inFig. 2. Projected densities in the molecular cloud simulation. A total of 233 protostars, denoted with white crosses, form by the end of thecrease, however, the flux is not able to penetrate the envelope,
because no outflow cavities are resolved in the simulation. simulation (t = 1.65 Myr). Most protostars form in clusters along filaments. The protostars studied in this work are denoted with red circles.
From the optical depth, the visual extinction is calculated
3D
as ARADMC= ⌧UV /3.02. In addition to the extinction calcuv
2.1.2. Radiative transfer models
The protostellar luminosity is interpolated from the pre-main selated with radmc-3d, we assume an ambient extinction everyquence (PMS) models from D’Antona & Mazzitelli (1997). We
where in the molecular cloud, (i.e., surrounding the 30,000 au
The dust temperatures and radiation field around each sink parti- included a 100 kyr o↵set between the onset of core collapse andradiative transfer domain). The total extinction during the col3D
cle was post-processed using the Monte Carlo radiative transfer the PMS age, similar to Young & Evans (2005), corresponding
lapse is then given as Av = Acloud+ ARADMC, where we asvv

sinkができる0.1 Myr前からの0.35 Myrの間について、tracer particleに沿った化学計算を行う。
4

cloud

図2. RAMSESのスナップショット(計算終了時)
Cはclustered、IはIsolatedを意味する。

1D RHD model

結果
10 1

3Dでは10個のトレーサー粒子に沿った
Ratio

HDO/H2O、D2O/HDOをプロット
1D(これまで)と3Dどちらも

10 2
fD1
fD2

・ice mantle が溶けるまでは高い重水素率

10 3

・溶けてからは HDO/H2Oは大きく低下、

105

104

103

102

101

= tfinal - t (yr)

D2O/HDOはさほどかわらず

Fig. 7. M101-C周りの重水素率(気相)Fig. 7. Gas-phase evolution of fD1 and fD2 during protostellar collapse. The left panels shows the evolution of a particle accreted ⇠ 350 kyr after
core collapse
toward a of
1MfD1protostar.
rightprotostellar
panel shows collapse.
ten particleThetrajectories
towardthe 1M
protostars M101-C
in theaccreted
3D simulations.
Fig. 7. Gas-phaseevolutionand fD2The
duringleft panelsshowsthe evolutionof a particle⇠ 350 kyr aft

3Dの特徴

core collapse toward a 1M protostar. The right panel shows ten particle trajectories toward the 1M protostars M101-C in the 3D simulations.

・ice mantle が溶けるまでは分散が大きいが、溶けたあとは分散が小さい
・最初はトレーサー粒子ごとに密度がばらついているので重水素率が異なる

S. S. Jensen et al.: Modeling chemistry during star formation: Water deuteration in dynamic star-forming regions

・ice mantleが溶けると分散が小さくなる
Ice structure:

Observations:! ≤ 30K
COLD ENVELOPE
HDO/H2O ~ 10-2

Fig. 8. M101-C周りの重水素率(固相)! ≥ 100K

HOT CORINO
HDO/H2O~10-4-10-3
D2O/HDO ~10-2

Fig. 8. Ice surface and mantle evolution for fD1 and fD2 during the protostellar collapse phase. The variation in densities for di↵erent trajectories in
the pre-collapse phase induces large shifts in the ratios in the very beginning of the collapse. Once the tracer particles reach the protostellar core,
the D/H ratios in the ice mantle converge to similar values, as the trajectories reach similar densities. The y-axes di↵er between the left and rightpanels.

Fig. 8. Ice surface and mantle evolution for fD1 and fD2 during the protostellar collapse phase. The variation in densities for di↵erent trajectories
the pre-collapse phase induces large shifts in the ratios in the very beginning of the collapse. Once the tracer particles reach the protostellar cor
grain-surface chemistry (see, e.g., Arasa et al. 2015, and refer- fiducial model reproduced the observed f ⇠ 10 3 toward iso-S. S. Jensen et al.: Modeling chemistry during star formation: Water deuteration in dynamic star-forming regions

nbin:
0.00175

177

466

654

377

191

60

sink M048-C

591

620

348

209

130

18

sink M049-C

770

666

380

481

534

491

sink M048-I

fD1

0.001500.001250.00100

fD2

0.03

0.02

0.01
0

100

200

time (kyr)

0

100

200

0

time (kyr)

100

200

time (kyr)Fig. 10. HDO/H2 O ( fD1 ) and D2 O/HDO ( fD2 ) ratios toward three protostars in the simulation, with similar final mass of ⇠ 0.5M . The tracer
particles are binned according to the time at which they reach the hot corino, in bins with a width of 50 kyr. The time corresponds to the time after
the onset of collapse, t0 . The third protostar, sink M048-I, is classified as isolated since no protostar enters within 20,000 au during the simulation,
while sink M048-C and sink M049-C are clustered. Each bar shows the median values of tracer particles accreted in the time interval, and the error
shows the [15.9, 84.1] percentiles. The number of tracer particles within each bin is denoted in blue above the first row.
Table 3. Simulated D/H ratios in the hot corino for a broad range of conditions in the prestellar stage. The reported fD1 and fD2 values are themedian across all tracer particles entering the hot corino.

#
1
2
3
4
5
6

T (K)
10
10
10
10
10
10

Duration (Myr)
1
2
3
3
3
3

⇠H2 (10 17 s 1 )
1
1
1
10
100
1

G0
1
1
1
1
1
10

fD1
5 ⇥ 10 4
1 ⇥ 10 3
1 ⇥ 10 3
7 ⇥ 10 3
3 ⇥ 10 2
1 ⇥ 10fD2
6 ⇥ 10 3
2 ⇥ 10 2
2 ⇥ 10 2
1 ⇥ 10 2
2 ⇥ 10 2

↵
12.0
20.0
20.0
1.4
0.7

while sink M048-C and sink M049-C are clustered. Each bar shows the median values of tracer particles accreted in the time interval, and the error S. S. Jensen et al.: Modeling chemistry during star formation: Water deutera
shows the [15.9, 84.1] percentiles. The number of tracer particles within each bin is denoted in blue above the first row.

結果: 形成環境のD/Hへの影響

tostellar luminos
early stages mod
to study how var
during star formof PMS model. A
toward the end owork, namely, th
initial collapse oTable 3. Simulated D/H ratios in the hot corino for a broad range of conditions in the prestellar stage. The reported fD1 and fD2 values are themedian across all tracer particles entering the hot corino.

Fiducial →

2
3
4
5
6
7
8
9
10
11
12
13a
14a

T (K)
10
10
10
10
10
10
10
20
30
20
30
10
15
20

Duration (Myr)
1
2
3
3
3
3
3
1
1
3
3
1.5
1.5
1.5

⇠H2 (10 17 s 1 )
1
1
1
10
100
1
1
1
1
1
1
1
1
1

G0
1
1
1
1
1
10
100
1
1
1
1
1
1
1

fD1
5 ⇥ 10 4
1 ⇥ 10 3
1 ⇥ 10 3
7 ⇥ 10 3
3 ⇥ 10 2
1 ⇥ 10 3
3 ⇥ 10 3
1 ⇥ 10 3
2 ⇥ 10 3
2 ⇥ 10 3
1 ⇥ 10 3
7 ⇥ 10 4
7 ⇥ 10 4
3 ⇥ 10 4

fD2
6 ⇥ 10 3
2 ⇥ 10 2
2 ⇥ 10 2
1 ⇥ 10 2
2 ⇥ 10 2
2 ⇥ 10 2
3 ⇥ 10 2
1 ⇥ 10 2
7 ⇥ 10 3
3 ⇥ 10 2
5 ⇥ 10 3
8 ⇥ 10 3
6 ⇥ 10 3
2 ⇥ 10 3

↵
12.0
20.0
20.0
1.4
0.7
20.0
10.0
10
3.5
15.0
5.0
11.0
8.6
6.7

S. S. Jensen et al.: Modeling chemistry during star formation: Water deuteration in dynamic star-forming regions

2.2. Calculating

sink M048-I, mass: 0.48 M
2

fD1

prestellarを #
1
短く →

10

3

10

3

6

10 4

4
3

10 4
10 4

prephase: 1 Myr

prephase: 2 Myr

prephase: 3 Myr

Fig. 3. Overview of the di↵erent phases of the model. In the initialprestellar (static) phase, the physical conditions are inferred previous
simulations and observations (e.g., Keto & Caselli 2008). In the precollapse phase, which has a fixed duration of 100 kyr, the physical evolution is derived from ramses, but since the protostar is not yet formed,
no radiative transfer is performed. During the collapse, the physical evolution is derived from ramses and post-processed using radmc-3d. The
duration of the collapse varies between individual tracer particles, withan upper duration of ⇠ 250 kyr.

For photodissoc
given as a functculated mean fie
et al. (2011) and
from:
⌧UV =

FUV,
ln
F

観測された孤立天体とclusterでの D/H の違いは、崩壊前の物理状態の違いによるもの

fD2

where FUV,RADM
tive transfer calc
10 2flux from the IS
温度上げた →
ramses output with varying accretion luminosities: we created a higher in each glinear grid of four models, ranging from the lowest accretion rate tostar is quite lo
310
to thehighest accretion rate associated with any given ramses protostar (2000
Notes.a For these models, the minimum
temperatureduring the protostellar collapse was
fixed at the temperature of the prestellar
phase,
as notedTable
3. パラメータを変えた時の
D/H
the UV flux. La
We calculated
the0 fifth model
using
accretion0output.100
200
100
200 the mean
0
100
200
n the table.
time (kyr)time (kyr)time (kyr) crease, however,rate during
the period between thesnapshots. When estimating
becauseno outfl
the toward
dustthetemperature
forM048-I
a tracerparticlea durations.
given position
andare binned
Fig. 12. fD1 and fD2 ratios
isolated protostar sinkfor varying
prestellarat
phase
The tracer particles
accordingto the time at which time,they reachwe
the hotcorino, in bins witha totalwidth ofluminosity
50 kyr. The time corresponds
toLthe time after
the onset
of collapse,Fromt0 . Each the op
calculated
the
(L
+
)
of
the
acc
protostarFig.
12.
崩壊前の時間を変更。
bar showsthe median values of tracer
particles accreted in the time interval, and the error shows the [15.9, 84.1] percentiles.
ion of > 1.5 Myr. Overall, temperatures in the range T . 20 K by higher densities or through external forces
acceleration
3D=
protostarthe
at that time, and interpolated the temperature from the as ARADMCv
can reproduce the observed D/H ratios.
collapse (e.g., Ward-Thompson et al. 2007; theEnochet values
al. of2008).
lated
providedby ofthefiveradmc-3dmodels.
We assumethat isolated
1
Myrだと濃縮があまり起こらない。
high binding energy
water,bulk
di↵usionwater
is likely
protostellar
cores are largely
similar between
and withclus- radmand thecane↵ect
is occurunlikelyalter theinheritance
tered protostars,
owingtheto thephysicalprocesses wherethat dominate
in the mothe dust
andto gasis strongthermally
coupled,such thatgastemperregions
These models do not self-consistently predict the physical Similarly, higher temperatures in clusteredinefficient
the stability of cloud cores (e.g., Ku↵meier et al. 2017).
shown in the models.
aturesanddusttemperaturesareequal.
This approach is reason- radiative transfe
2
Myrだと3Myrに近い。
through
irradiationfromnearbymassive
protostars
orthroughFuruya et al. (2017) suggest that ↵ is a better tool for disand chemical evolution during the molecular cloud and static
lapse is then giv
able at higher densities present during
protostellar
collapsetinguishingthe
betweeninheritance andresetting of the deuteriumshock
heatinginturbulent
cloud
environments(e.g.,
Krumholz
4.3.
Inheritance
of
water
D/H
ratio
core phase, however, both a shorter static phase and higher temfractionation,
theiryield ↵ > 1 sume
under prestelAcloud=5(n & 104 , Goldsmith 2001), but may
not besincevalidinsimulations
the prestellarv
lar conditions, while resetting of the chemistry in the protoplanambient extincti
Determining whether
the D/H
ratio isdensities
inherited orare
resetlower.
during The limitations of the model are
phase
where
peratures are feasible variations in dynamic molecular clouds. 2014).
etary disk leads to ↵ < 1. Our results confirm that ↵ > 1 in thestar and planet formation is critical for our understanding of
D. TheISRF
column d
discussed in Sect. 4.2. A lower limit
the temperatureofphase10 K
case ofon
inherited
D/H from the staticwhen standard
the evolution and delivery of water to young planets (e.g., vanA shorter collapse timescale for clustered sources can be driven
and cosmic-ray ionization rates are considered. Thisfurthermo-= A ⇥tion
Nis setthroughout
chemical
Dishoeck et al. 2014).
Throughsimulations theof waterdeuterium modeling. While lower temperaHVtivates the study of D2 O/HDO ratios in hot corino to provide
fractionation in atures
protoplanetarydisk, Cleeves
etcenteral. (2014)&fromSavagecanoccur
in theof dense
cores, thisa reasonably
further constrainson theischemicalevolution of water
cloud 1994)
showedthatcometary
D/Hratios
are
too
high
to
originate
from
Article number,
page13
oftemperature23
to core.
self-shielding fu
averagefor ofdense
local processing within
the disk.
Hence, some degree
inher- cores (e.g., Pagani et al. 2007).
itance is necessaryFurthermore,
to reproduce the deuterium
fractionation inin theIf chemical
the deuteriumnetwork
fractionationareof waterin thecal
hot corino
ismodels.
many
reactionsvalithe Solar System, including the Earth’s oceans. In a later work, inherited, the D/H ratio of water at later stages in the star anddated
to evolution
a loweroflimit
10ofK.
mentione
Furuya et al. (2017)
study thethe D/Hofratio
wa- planet formation process could be linked to the initialAsconditer, combining 1D protostellar collapse models with a 2D ax- tions in the cloud environment prior to the onsetof star for- includ
trajectory
Along
with
the
thermaldust
calculation,
the
mean
UV
radiaisymmetric protoplanetary disk model. These authors find that mation. However, the nature of hot corinos, and the chemical
ofwelltheestabsink partic
tion
field
calculateddisk
in theradmc-3d
gridmcmono routhe majority of thewater
in theisprotoplanetary
remained
link fromhot withcorino theto protoplanetary
disk is not

The complex organic molecular content in the L1498 starless core

Izaskun Jimenez-Serra, Anton I. Vasyunin, Silvia Spezzano, Paola Caselli, Giuliana Cosentino, Serena Viti F
Observations carried out toward starless and pre-stellar cores have revealed that complex organic molecules are prevalent in theseobjects, but it is unclear what chemical processes are involved in their formation. Recently, it has been shown that complex
organics are preferentially produced at an intermediate-density shell within the L1544 pre-stellar core at radial distances of4000 au with respect to the core center. However, the spatial distribution of complex organics has only been inferred toward
this core and it remains unknown whether these species present a similar behaviour in other cores. We report high-sensitivity
observations carried out toward two positions in the L1498 pre-stellar core, the dust peak and a position located at a distanceof 11000 au from the center of the core where the emission of CH3 OH peaks. Similarly to L1544, our observations reveal that
small O-bearing molecules and N-bearing species are enhanced by factors 4-14 toward the outer shell of L1498. However, unlike
L1544, large O-bearing organics such as CH3CHO, CH3OCH3 or CH3OCHO are not detected within our sensitivity limits. For
N-bearing organics, these species are more abundant toward the outer shell of the L1498 pre-stellar core than toward the one in
L1544. We propose that the diﬀerences observed between O-bearing and N-bearing species in L1498 and L1544 are due to thediﬀerent physical structure of these cores, which in turn is a consequence of their evolutionary stage, with L1498 being younger
than L1544.

• これまでの観測からstarless coreやprestellar coreにはcomplex organic

•

•
•
•
•

The COM content in L1498
moleculesが存在していることがわかった。これらがどのようにして作られたのか
Stars with Photometrically Young Gaia Luminosities Around the Solar
System (SPYは未解明。
GLASS) I: Mapping Young Stellar Structures and their Star Formation Histories
Ronan Kerr, Aaron
C. Rizzuto,
Adam L. Kraus, au、中程度の密度のシェ
Stella S. R. Oﬀner F Young stellar associations hold a star formation
先行研究から、L1544
prestellar
coreで、中心から4000
record that can persist for millions of years, revealing the progression of star formation long after the dispersal of the natal
ルで複雑有機分子が作られていることが明らかとなった。ただし、空間分布がわ
cloud. To identify nearby young stellar populations that trace this progression, we have designed a comprehensive framework
かってるのはこの天体だけ。
for the identification of young stars, and use it to identify ⇠3⇥104 candidate young stars within a distance of 333 pc using Gaia
DR2. Applying theprestellar
HDBSCANclustering algorithm to this sample, we identify 27 top-level groups, nearly half of which have
本研究では、L1498
coreに対して、ダストのピークと中心から
little tono presence in previous literature. Ten30mof thesegroups have visible substructure, including notable young associations
11000
auの箇所の高感度観測を行なった(IRAM
telescope)。
such as Orion, Perseus, Taurus, and Sco-Cen. We provide a complete subclustering analysis on all groups with substructure,(L1544と同じく)Nや小さいOを含む分子は外側と比べて4-14倍増加している
using age estimates to reveal each region’s star formation history. The patterns we reveal include an apparent star formation
origin for Sco-Cen along a semicircular arc, as well asnon-detection
clear evidence for sequential star formation moving away from that arc(L1544と違って)大きいOを含む分子は今回の観測ではwith a propagation speed of ⇠4 km s 1 (⇠4 pc Myr 1 ). We also identify earlier bursts of star formation in Perseus and Taurus
L1544とL1498の物理構造の違いによるもの、L1498はより若いthat predate current, kinematically identical active star-forming events, suggesting that the mechanisms that collect gas can

5Stars with Photometrically Young Gaia Luminosities Around the Solar System (SPYGLASS) I: Mapping Young Stellar Structures and their Star Formation Histories

Ronan Kerr, Aaron C. Rizzuto, Adam L. Kraus, Stella S. R. Oﬀner F Young stellar associations hold a star formation
record that can persist for millions of years, revealing the progression of star formation long after the dispersal of the natal
cloud. To identify nearby young stellar populations that trace this progression, we have designed a comprehensive framework
for the identification of young stars, and use it to identify ⇠3⇥104 candidate young stars within a distance of 333 pc using Gaia
DR2. Applying the HDBSCAN clustering algorithm to this sample, we identify 27 top-level groups, nearly half of which havelittle to no presence in previous literature. Ten of these groups have visible substructure, including notable young associations
such as Orion, Perseus, Taurus, and Sco-Cen. We provide a complete subclustering analysis on all groups with substructure,using age estimates to reveal each region’s star formation history. The patterns we reveal include an apparent star formation
origin for Sco-Cen along a semicircular arc, as well as clear evidence for sequential star formation moving away from that arc
with a propagation speed of ⇠4 km s 1 (⇠4 pc Myr 1 ). We also identify earlier bursts of star formation in Perseus and Taurusthat predate current, kinematically identical active star-forming events, suggesting that the mechanisms that collect gas canspark multiple generations of star formation, punctuated by gas dispersal and cloud regrowth. The large spatial scales and longtemporal scales on which we observe star formation oﬀer a bridge between the processes within individual molecular clouds andthe broad forces guiding star formation at galactic scales.

•
•
•
•
•
•
•
•
•
•

若い星の集団は星形成の記録を保持しており、星形成の進行を明らかにすることにつながる。
近傍の若い星の数を特定するために、若い星を若い星を同定するための包括的なフレームワークを構築した。

6
Gaia DR2 のデータから、333 pc以内の ~ 3 x 10^4 の若い星の候補を特定した。
HDBSCAN を使ってクラスタリングすると、 27のトップレベルグループが同定され、そのうち半分は先行研究で指摘されていないものであった。
10個のクラスターは、目に見えるようなsubstructureを持っている。
星形成史の解明のため、年齢の見積もりからsubstructureを持つ天体に対してsubclusteringを行った。
Sco-Cenでは半円に沿って星形成が起き、~ 4 km/s (4 pc/Myr)で形成領域が外側に伝播していることが明らかとなった。
Perseus と Taurus では、現在の星形成イベントの前に、星形成バーストが起きていることが明らかとなった。
ガスの集積が、ガスの拡散や分子雲の再成長により中断されながら、複数の世代の星形成を引き起こすことを示唆する。
大きな空間、時間スケールでの星形成の観測は、分子雲内と銀河全体の星形成をつなぐことにつながる。

ATOMS:ALMA Three-millimeter Observations of Massive Star-forming regions – III:
Catalogues of candidate hot molecular cores and Hyper/Ultra compact HII regions

ATOMS survey - Hong-Li Liu et al. F We have identified 453 compact dense cores in 3 mm continuum emission maps in
the ATOMS (ALMA Three-millimeter Observations of Massive Star-forming regions) survey, and compiled three catalogues ofhigh-mass star forming cores. One catalogue, referred to as H/UC-HII catalogue, includes 89 cores that enshroud hyper/ultra
compact (H/UC) HII regions as characterized by associated compact H40alpha emission. A second catalogue, referred to as pures-cHMC, includes 32 candidate Hot Molecular Cores (HMCs) showing rich spectra (N>20lines) of complex organic molecules(COMs) but not associated with H/UC-HII regions. The third catalogue, referred to as pure w-cHMC, includes 58 candidate
HMCs with relatively low levels of COM richness and not associated with H/UC-HII regions. These three catalogues of dense
cores provide an important foundation for future studies of the early stages of high-mass star formation across the Milky Way.
We also find that nearly half of H/UC-HII cores are candidate HMCs. From the number counts of COM-containing and H/UCHII cores, we suggest that the duration of high-mass protostellar cores showing chemically rich features is at least comparable
to the lifetime of H/UC-HII regions. For cores in the H/UC-HII catalogue, the width of the H40alpha line increases as thecore size decreases, suggesting that the non-thermal dynamical and/or pressure line-broadening mechanisms dominate on thesmaller scales of the H/UC-HII cores.
8 H.-L. Liu et al.

• ATOMSサーベイ(大質量星形成領域への3mm観測)から、3mm連続波で453個のdense coreを同定した。
Membership
of
Stars
in
Open
Clusters
using
RandomForest
with
Gaia
Data
3つのカタログを作成、銀河系での大質量星形成のための研究の基礎となるカタログ•
Md Mahmudunnobe, Priya Hasan, Mudasir Raja, S N Hasan F Membership of stars in open clusters is one of theコンパクトなH40α、98個が同定• H/UC-HIIコア:
most
crucial parametersin studies of star clusters. Gaia opened a new window in the estimation of membership because of its
COMs(complex
organic study,
molecules)が豊富なHot
Molecular
Cores、32個が同定
unprecedented
6-D
data. In the present
we used publishedmembershipdata of nine open star clusters as a training set• pure s-cHMC:
tonewmembers
from Gaia DR2 data using a supervised random forest model with a precision of around 90%. The number
pure
w-cHMC:
COMが豊富ではないHMC、58個が同定• findof new members found is often double the published number. Membership probability of a larger sample of stars in clusters is• aH/UC-HIIの半数はHMCsの候補
major benefit in determination of cluster parameters like distance, extinction and mass functions. We also found members
COMsを含むコアとH/UC-HIIコアの数から、化学的にリッチな大質量原始星コアの寿命はH/UC-HII領域の• in
the outer regions of the cluster and found sub-structures in the clusters studied. The color magnitude diagrams are more
寿命と同程度
populatedand enriched by the addition of new members making their study more promising. Figure 5. VennFig.
5 それぞれのコアの数を
diagram showing
the relation between 138 COM-containing
and 89 H/UC-HII cores. The 138 COM-containing cores consist of 58 pure
• H/UC-HIIカタログのコアサイズが小さいほどH40αの線幅が大きいので、非熱的な運動や圧力による線幅 and 24 H/UC-H表したベン図
II –associated w-cHMCs and 32 pure and 24 H/UC-H II –の広がりがH/UC-HIIコアで支配的

associated s-cHMCs.

Compact Disks: an explanation to faint CO emission in Lupus disks

smaller scales of the H/UC-HII cores.

Membership of Stars in Open Clusters using Random Forest with Gaia Data

Md Mahmudunnobe, Priya Hasan, Mudasir Raja, S N Hasan F Membership of stars in open clusters is one of themost crucial parameters in studies of star clusters. Gaia opened a new window in the estimation of membership because of its
unprecedented 6-D data. In the present study, we used published membership data of nine open star clusters as a training set
to find new members from Gaia DR2 data using a supervised random forest model with a precision of around 90%. The numberof new members found is often double the published number. Membership probability of a larger sample of stars in clusters isa major benefit in determination of cluster parameters like distance, extinction and mass functions. We also found membersin the outer regions of the cluster and found sub-structures in the clusters studied. The color magnitude diagrams are more
populated and enriched by the addition of new members making their study more promising.

Compact Disks: an explanation to faint CO emission in Lupus disks
Anna
Miotello, Giovanni Rosotti, Megan Ansdell, Stefano Facchini, Carlo F. Manara, Jonathan P. Williams,• 散開星団において、星の構成は最も重要なパラメータ。
Simon Bruderer F A large fraction of observed protoplanetary disks in nearby Star-Forming Regions (SFRs) are fainter than
• 機械学習で星の分類を行う。
expectedin CO isotopologue emission. Disks not detected in 13CO line emission are also faint and often unresolved in thecontinuum
emissionatanangularresolutionofaround0.2
arcseconds.
Focusing
on
the
Lupus
SFR,
the
aim
of
this
work
is
to
9つの星団に関する星の構成を学習データにして、Gaia
DR2から新しいメンバーを作成した。
•
investigate whether the population of CO-faint disks comprises radially extended and low mass disks - as commonly assumed• farこれまでのデータより2倍の数のメンバーを見つけたso- or if it is of intrinsically radially compact disks, an interpretation that we propose in this paper. The latter scenario
was サンプル数の充実は、距離や吸収、質量関数を決定する上でメリットがある。
already proposed for individual sources or small samples of disks, while this work targets a large population of disks in a•single SFR for which statistical arguments can be made. A new grid of physical-chemical models of compact disks has been run• クラスターの周りでもメンバーが見つかった
with
DALI in order to cover a region of the parameter space that had not been explored before with this code. Such models
haveクタスターの中にsubstructureが見つかった
been compared with 12CO and 13CO ALMA observations of faint disks in Lupus. Disks that are not detected in 13CO•
emission and with faint or undetected 12CO emission are consistent with compact disk models. For radially compact disk, the• カラーマグニチュード図はより一層充実したものにemissionof CO isotopologues is mostly optically thick and it scales with the surface area: i.e., it is fainter for smaller objects.
The fraction of compact disks is potentially between roughly 50% and 60% of the entire Lupus sample. Deeper observationsof 12CO and 13CO at a moderate angular resolution will allow us to distinguish whether faint disks are intrinsically compact,
or if they are extended but faint, without the need of resolving them. If the fainter end of the disk population observed by