星形成ゼミ：2019年8⽉2⽇

古屋 玲 (徳島⼤学・教養教育院)

abundance ratios, and find that the abundance ratio is as high as 40 near the emission front, and decreases to the−3
typical valueALMA
in the solar
system of 5.5 in ofa smallangularStructures
scale of 4” = 2.6×10= 560
au. We alsofind that the in the ρ
Observations
Layereddue
to pcCO
Selective
Dissociation
12
13
I( CO(2–1))/I(
CO(2–1))intensity ratio is veryPDR
high (>21) in the flat-spectrum young stellar object, GY-51, locatedOphiuchi
A Plane-parallelin the PDR. The enhancement
indicates that
the CO isotopologues
1 of the ratios
2
3 the UV radiation
3 significantly aﬀects
3
4
5
M.
Yamagishi
,
C.
Hara
,
R.
Kawabe,F.
Nakamura,
T.
Kamazaki,T.
Takekoshi,
Y.
Shimajiri, H.
via selective dissociationintheoverallρOphiuchi
A
PDR,
and
that
the
ρ
Ophiuchi
A
PDR
has
a
plane-parallel
67
8
Nomura,S.
TakakuwaandJ.
DiFrancesco
structure.
1
Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Chuo-ku, Sagamihara, Kanagawa
Accepted by ApJ
252-5210, Japan; 2 Graduate School of Science, The University of Tokyo, Bunkyo-ku, 113-0033, Tokyo, Japan; 3 Nahttps://arxiv.org/pdf/1903.02192
tional Astronomical Observatory of Japan, National Institutes of Natural Sciences, 2-21-1 Osawa, Mitaka, Tokyo 1814
58588,
Japan;
InstituteofAstronomy,
The
UniversityofTokyo,
2-21-1
Osawa,
Mitaka,Tokyo
181-0015,
Japan;
Lab主な結果
rho
Ophiuchi
Aの光解離領域(解離⾯をちょうど横から⾒ている)で観測されたCO同位体の⽐は,Syntheticoratoire
molecularline observationsof thefirsthydrostatic
core
from chemical
calcuAIM,
CEA/DSM-CNRS-Universit
Paris
Diderot,
IRFU/Service
dAstrophysique,
CEA
Saclay, F-91191 Gif12 CO(2–1) (red),
13
18
Fig.
3.—
Averaged
spectraofCO(2–1)(green),andCO(2–1)(blue)
emissions
6
lations sur-Yvette,selective
dissociationでうまく説明できる.
France;Department of Earth and Planetary Sciences, Tokyo
Institute of Technology, 2-12-1 Ookayama,
−1 ).
7
at
the
layeredstructure(thewhite-box
region
in
Fig.
2,
V
=2.2
km
s
1
1
lsr and Astronomy,
Meguro,1 ,Tokyo,152-8551,
Japan;
Department
Graduate
School of Science and EngineerAlison K. Young
Matthew
R. Bate, Tim
J. Harriesof1 Physics
and David
M. Acreman
8
ing,ofKagoshima
1-21-35
Korimoto,
Kagoshima,
Kagoshima890-0065,
Japan;
NRC
Herzberg Astronomy
11213
18 O(2–1) (blue) emissions
Department
Physics andUniversity,
Astronomy,
UniversityofExeter,
StockerRoad,
Exeter
EX4
4QL,
UK
Fig.
3.—
Averaged
spectraofCO(2–1)(red),
CO(2–1)(green),andC
観測and Astrophysics Research Centre, 5071 W Saanich Road, Victoria BC V9E 2E7, British Columbia,
Canada−1
at the layered structure (the white-box region in Fig. 2, Vlsr =2.2 km s ).
E-mail contact:ayoung at astro.ex.ac.uk
ALMA
12mアレイと森⽥アレイ,
J=2-1 of 12CO, 13CO and C18O, ⾓度分解能~1”E-mail contact: yamagish at ir.isas.jaxa.jp
The first stable object todevelop in thelow–mass star 18formation process has long been predicted to be the first
12
13
CO(J=2–1),
C Oyet(J=2–1),
and 1.3 mm
continuum
maps ofMore
the ρspecificOphiuchi A photohydrostatic We
coreanalyze(FHSC). CO(J=2–1),
Despite much eﬀort,
it has still
to be definitively
observed
in nature.
dissociation
region(PDR)obtainedwith ALMA.
Layeredthe
structuresof thethreefaint,
CO butisotopologues
with an angularobservationalsignatures are
requiredto−3enable observers
to distinguish
FHSC fromyoung,
more evolved
separationof 10”synthetic= 6.6×10spectral
pc =line
1400
au are clearly
detectedaroundtheBe+star,S1(i.e.,calculated
each frontfromof emission shifts
protostars. Here
we present
observations
for
CO,
SO,
CS
and
HCO
that
were
12
13
from the near to far side inorder ofCO, 13CO, and andC18 O).
We Carlo
estimate
the spatial
variations
X(CO)/X(C18 O)
radiation (magneto)hydrodynamical
models,chemicalmodellingMonteradiative
transfer.
HCO+of(1− 0)abundance
ratios, and find that the abundance ratio is as high as 40 near the emission front, and decreases to theand SO (87 −76 ) spectra of the FHSC show variations for observations at a low inclination which may allow a candidate−3
value infrom
the solarsystemof 5.5in a small
angularscaleFHSC
of 4” outflow= 2.6×10
pc = to560beau.
We also find that the
FHSC to betypicaldistinguisheda moreevolvedobject.
We findthat theis unlikely
detectable
12
13
CO(2–1))/I(
CO(2–1))intensitysources
ratio iswith
veryslowhighoutflows(>21) inthat
the flat-spectrum
stellarobject, GY-51, locatedwith ALMA,I(which
would discountthe observed
are currently young
identified
as candidate
the PDR.
enhancementof theratiosobservations
indicates thattheobserved
UV radiation
significantly
aﬀectsthe CO isotopologues
FHSCs. Weincompare
theTheresultsof simulated
ALMA
with
candidate
FHSCs andrecommend
viaandselective
the overall
ρ Ophiuchi
A PDR,
Oph A SM1N
N6-mmdissociation
as the mostinpromising
candidates
to follow
up. and that the ρ Ophiuchi A PDR has a plane-parallel
structure.
Accepted by MNRAS
Accepted by ApJ
https://arxiv.org/pdf/1906.01324
https://arxiv.org/pdf/1903.02192

72

Sequential Star Formation in the filamentary structures of the Planck Galactic cold
Synthetic molecular line observations of the first hydrostatic core from chemical calcuclump G181.84+0.31
lations
Lixia Yuan1,2,3 , Ming Zhu1,3 , Tie Liu4,5 , Jinghua Yuan1 , Yuefang Wu6 , Kee-Tae Kim4 , Ke Wang7,8 ,18 O)10,11
1
1,2,3 K. Young1 , Matthew
9 R.
Fig. 4.—X(13CO)/X(Cat V
km1 s−1 . Contours are the same
AlisonBate, Tim
J. abundanceHarries1 ratio
and maps
David
M.
Acremanlsr =2.2–2.6
Chenlin Zhou
, Ken’ichi Tatematsu
and
Nario
Kuno
in Fig.
1. ratio
The dashedtheStocker
direction
to calculatethetheabundance
1 13 CO)/X(C18 O) abundanceFig. 4.— X(
mapsline
at indicatesVoflsrExeter,=2.2–2.6
km Road,s−1used. Contours
same ratio profiles
Department of Physicsasand
Astronomy,
University
Exeter
EX4are4QL,
UKin Fig. 5.
as in Fig. 1.
Thecontact:dashedayoung
line indicatesthe direction used to calculate the abundance ratio profiles
E-mailat astro.ex.ac.uk

– 13 –

主な結果
• 13CO/C18O存在⽐の急増は, PDRのthin layer
内に限定される.
• COから推定される密度と温度の不定性を考慮しても, van Dishock & Black (1988),
Visser+09などのモデルと整合する.

レポーターの疑問• 図5で0.2 km/s差の3のプロファイル形状は相似的. しかし, オフセットが顕著. これを較正や
空間分解効果などの系統誤差のためと定性的に結論しているが, 天体(e.g., ガスの何らかの系
統運動)に起因する可能性は？
• チャネルマップに⾒られるC18Oのstriationと磁場ベクトルの向きは？

Fig. 5.— (top) Spatial variations of the X(13 CO)/X(C18 O) abundance ratio at Vlsr =2.2–2.6 km s−1(color-corded lines; left axis) and those of the Spitzer 4.5 µm (squares; right axis) and 1.3 mm
continuum intensities (diamonds; right axis) as a function of the distance from S1. These are
Fig. 5.— (top) ′′Spatial variations of the X(13 CO)/X(C18 O) abundance ratio at Vlsr
calculated from averaged profiles in a rectangular region with a width of 1. 5 along the dashed(color-cordedlines; left
line in Fig. 4. The Spitzer 4.5 µm and 1.3 mm continuum
data are normalized
by theaxis)
maxi-and those of the Spitzer 4.5 µm (squares; right a
mum values of 23.9 MJy sr−1 and 1.0 mJy beam−1 , respectively.
The intensities
dotted line indicatesthecontinuum(diamonds;
right axis) as a function of the distance from
13
18
X( CO)/X(C O) abundance ratio of 5.5 in the solar system (Anders & Grevesse 1989). Note′′ 5 acalculated
fromaveraged
profilesinarectangularregion
with
a
width
of
1.
13
18
−1
that the X( CO)/X(C O) abundance ratios smaller than 5.5 in Vlsr =2.4 and 2.6 km s may be
line
in Fig.
4. variations
The Spitzer
artificial due to absorption and/or spatial filtering of 13 CO.
(bottom)
Spatialof τ13 and4.5 µm and 1.3 mm continuum data are normalizτ18 as functions of the distance from S1. Solid and dashedlines indicate
τ18 , MJy
respectively.
mum
valuesτ13ofand
23.9
sr−1 and 1.0 mJy beam−1 , respectively. The dotted l
The diﬀerent color shows diﬀerent Vlsr as in the top panel. 13
18

X( CO)/X(C O) abundance ratio of 5.5 in the solar system (Anders & GreveFig. 2.— 1.3 mm continuum map and color-composite channel maps of 12 CO(2–1) (red), 13 CO(2–1) (green), and C18 O(2–1) (blue) emissions at Vlsr =1.0–3.0 km s−1 for the yellow dashed box in
Figure 1. Contours are the same as in Fig. 1. The color range in the 1.3 mm continuum map is
12 CO(2–1)
左上以外のパネルは12CO,
0–3 mJybeam−1 , while thechannel
peak intensity
is 37.7
beam−1 associatedwith
GY-51. The colorFig.
2.— 1.3 mm continuum map andcolor-composite
maps
of mJy(red), 13CO(2–range is common among the channel maps−1
and is linear from 0 % to 80% of the peak intensity in1)(green),and C18 O(2–1) (blue) emissionsatV=1.0–3.0kms
for the yellow dashed box in
13CO,
C18Oの三⾊図
lsr
this area (12 CO: 4.98 Jy beam−1 ; 13 CO: 2.43 Jy beam−1 ; C18 O: 1.32 Jy beam−1 ).

Figure 1. Contours are the same as in Fig. 1. The color range in the 1.3 mm continuum map is71

depends on the turbulence anisotropy. When taking into account the partial ionization, we find that the minimum
width of parallel filaments in the cold neutral medium and molecular clouds is determined by the neutral-ion decouplingscale perpendicular
1,2 to magnetic field.
3 In highly supersonic
1 MHD turbulence in molecular clouds, both low-density
Siyao
Xu ,due
Suoqing
Ji turbulent, A. Lazarianparallel filaments
to anisotropic
mixing and high-density filaments due to shock compression exist.

On the formation of density filaments in the turbulent interstellar medium
1
Accepted by ApJ

Department of Astronomy, University of Wisconsin, 475 North Charter Street, Madison, WI 53706, U
3
http://arxiv.org/pdf/1905.06341
TAPIR & Walter Burke Institute for Theoretical Physics, California Institute of Technology,
主な結果 Fellow;
91125, USA; Sherman Fairchild Fellow
部分電離も考慮すると, cold neutral mediumと分⼦雲において,磁場に平⾏なﬁlamentのE-mail contact: sxu93 at wisc.edu
最⼩幅は磁場に直交する⽅向のneutral-ion decoupling scaleで決まる.
This study is motivated by recent observations on ubiquitous interstellar density filaments and guidetheories of compressible magnetohydrodynamic (MHD) turbulence. The interstellar turbulence shapes
45
研究の⽬的density structures. As the fundamental dynamics
of compressible MHD turbulence, perpendicular turof density
fluctuations
entails elongated density structures alignedwith the local magnetic field, accou
multi-phase
ISMのうち,低密度領域では磁場に平⾏なﬁlament状ガス,
⾼密度領域では直交する
density parallel filaments seen in diﬀuse atomic and molecular gas. The elongation of low-density par
ﬁlament状ガスが⾒られる. それぞれの形成機構は？
depends on the turbulence anisotropy. When taking into account the partial ionization, we find thatwidth of parallel filaments in the cold neutral medium and molecular clouds is determined by the neutral-i
天体と著者の主な着眼点
scale perpendicular to magnetic field. In highly supersonic MHD turbulence in molecular clouds, botparallel filaments due to anisotropic
mixingand high-density
filaments
due tocompres• 低密度・磁場に平⾏ﬁlament：(i) cold HIturbulent
ﬁlaments
in warm
neutral medium(WNM),(ii)shockStriation
Acceptedby ApJin diﬀuse
regionsof molecular clouds (MCs), (iii) sub ﬁlaments in molecular cloudsにおいてはDynamicsof Alfveʼn modes in sub/super sonic turbulence
http://arxiv.org/pdf/1905.06341• ⾼密度・磁場に直交ﬁlament： いわゆるフィラメント状分⼦雲の形成に超⾳速乱流がいかに寄与し, その痕跡がフィラメント内重⼒場をどのように特徴付け(他の研究では考慮していないと主張している), それが
ﬁlamentの密度勾配と速度勾配を測定したとき, どのようなものとして観測されるか？
TABLE 1PARAMETERS IN DIFFERENT PARTIALLY IONIZED INTERSTELLAR PHASES

WNM
CNM
MC

nH [cm
0.4
30
300

3]

ne /nH
0.1
10 3
10 4

B0 [µ G]
5
5
5

T [K]
6000
100
20

Ms
1.1
8.5
28.9

MA
0.6
5
15.9

45

Lst [pc]
11.1
0.2
7.5 ⇥ 10 3l⌫,? [pc]2.3 ⇥ 10 3-lni, dec,? [pc]2.3 ⇥ 10 4
9.3 ⇥ 10 5

A⌫
46.0
-

Adec
10.0
4.3

cascade.
compression
the andspectrumof density
fluctuations
2005; Kowaldeforms
et al. 2007)
accounts
for the formationof to as the shock propagation distance reduced by the compression
thefilament,
width ofcan be as
estimatedratio. In
Foraddition,
an obliquethedense
widthfilaments
can be estimatedbedifferent
from
that
of
turbulentvelocities(Beresnyak
et
al.
dense
filaments
in
MCs(Robertson&
Goldreich
2018;
Mocz
• シュミレーション結果の解析がなく,
オーダー評価のみ.
もっとも肝⼼な結論部は,
議論 2005;
the shockpropagation distance reduced by the compression& Burkhart
Kowal2018)
et al.4 . 2007) and accounts for the formation of (Eq.as(16)),
L the width can be estimated asratio. For an oblique filament,
Thefilaments
density contrast
the shockdense
in MCsacross(Robertson& isGoldreich 2018; Mocz
p
⇠
,
(18)
o
(Eq.
(16)),
4
2MA1& Burkhart 2018) . ⇢2 pL
⇡ the
2Mshock(16)
A1
The density contrast ⇢across
is
p
which
dependsonthemagnetization
andthe ,filament orienta⇠(18)o1
2MA1 by assuming aption. For the densest perpendicular filaments,⇢2
when the magnetic pressure⇡dominates
2MA1in the downstream re-(16) constant compression ratio determined by Ms1 (⇠ Ms ), we
which depends on the magnetization and the filament orienta⇢1gion, andcanapproximately have the filament width as (Eq. (17))⇢2tion. For the densest perpendicular filaments, by assuming a2⇡
Ms1(17) rewhen the magnetic pressure
dominatesin the downstream
constant compression ratioLdetermined by Ms1 (⇠ Ms ), we
⇢
1
• 結局,
,
(19)
gion,
and この研究だけからは明瞭な結論を引き出すのは困難と述べている.
? ⇠the filament2
canapproximately
have
width
as
(Eq.
(17))
M
s
⇢2dominates
when
thethermalpressure
inthedownstream
re2✓…fully understandthe
turbulence
dynamics
in multi-phase
ISM,alonga modelfor(upper
two-phaseturbulence⇡Mof(17)viewedofdensityfluctuations
at different
times,
z-axispanel)MHD
and x-axis(lower should
panel). be applied…
s1
gion, where (a)⇢1 Sliceand ⇢plots
aredensities
theupstream
and
downL
2
which depends on the compressibility of medium. Provided
⇢1
(19)
? ⇠
streammedia,
M
is
the
shock
AlfvénMach
numbercorre✓…densityA1
gradient is not always a good indicator L(で,⇠ 速度勾配は？)…
10 pc and Ms ⇠ 10 (Schneider
et2 ,al. 2013; Henshaw
M
when
the thermalpressurecomponent
dominatesofinupstream
the downstream
sponding
to the transverse
magnetic re- et al. 2016), we find that ? is of the ordersof 0.1 pc, consistent
field,whereand M
is ⇢theshocksonic ofMach
number (seegion,
⇢1s1anddensities
the upstream
and Apdown- withwhichobservations
by,one.g.,
et al.of(2011);
Koch
2 are
depends
theArzoumaniancompressibility
medium.
Providedpendixmedia,
A for thedetailedThe
above
compresstream
MA1
is the derivation).
shock AlfvénMachnumbercorre- & Rosolowsky
L ⇠ 10 pc(2015).
and Ms ⇠ 10 (Schneider et al. 2013; Henshaw
sion
ratiosareconsistentwithearlierstudiesonisothermal
sponding to the transverse component of upstream magnetic
et al. 2016), we find that ? is of the order of 0.1 pc, consistentshocks(see,e.g.,Draine2011).
In
highlysupersonicMHD
DISCUSSION
field, and Ms1 is the shock sonic Mach number (see Apwith observations5. by,e.g., Arzoumanian et al. (2011); Kochturbulence,theshock-compressed
densityvariesindifferent
pendix A for the detailed derivation). The above compres& Rosolowsky(2015).
Motivatedby ample
observations of interstellar density filturbulence
regimes.
sion ratios are consistent with earlier studies on isothermal aments, there have been numerous theoretical arguments and(1) M
MsDraine
1. 2011).
In a weakly
magnetized
medium,A e.g.,
shocks(see,
In highly
supersonic
MHD numerical experiments on theirformation mechanisms (e.g.,
5. DISCUSSION
the shock compression in MHD turbulence is similar to that
turbulence,the shock-compressed
densitydensity
varies enhancein different Lazarian 1993; Hennebelle 2013; Smith et al. 2014; Ntorin hydrodynamic
turbulence. The resulting
Motivatedbyample
observationsofinterstellar
density filmousi
et
al.
2014;
Inoue
&
Inutsuka
2016;
Smith
et
al.
2016;
turbulence
regimes.
ment solely depends on Ms1 (⇠ Ms ) (Eq. (17), see Padoan &aments,thereBanda-Barragánhave been numerous
theoreticalargumentsandFederrath
2016;
et
al.
2018).
In
this
work,
(1)
M
M
1.
In
a
weaklymagnetized
medium,As
Nordlund 2011; Federrath & Banerjee 2015; Federrath 2016;
numerical
experimentsdynamics
on theirofformationon the fundamental
Alfvénic mechanisms
turbulence, (e.g.,theshock compression
MHDWeturbulenceis similar
to that based
Robertson& Goldreich in2018).
note that the
weak magHennebelle
2013;
Smith et al.
2014; Ntorwe Lazarian
propose a 1993;
formationmechanismof low-density
parallelinnetic
hydrodynamic
turbulence.
The
resulting density
enhancefield can be amplified
by thedownstream
turbulence(Xumousiinettheal.ISM.
2014; Inoue & Inutsuka 2016; Smith et al. 2016;
ment
solely depends
on Ms1 (⇠ Ms ) (Eq. (17), see Padoan & filaments& Lazarian
2016, 2017a).
Federrath
2016;inBanda-Barragán
et numericalal. 2018).studies,
In this work,
Cold
HI filaments
the WNM. Based on(2) Ms2011;
MFederrath
MBanerjee
1 >2015;MA . Federrath
In a strongly
Nordlund2016;
A > 1 or &s
Saury et al.on(2014)
argued that thedynamics
dynamics of the
WNM andthe fundamental
Alfvénic
turbulence,magnetized&medium,
Eq.2018).
(16) applies
to thethat
shock
Robertson
Goldreich
We notethe compresweak mag- the based
CNM
are tightly
coupled, andthe velocity
be- parallel
we
proposea formation
mechanismof dispersion
low-density
netic field can be amplified by the downstream turbulence (Xu tween
CNM clumps
close to the velocity dispersion within
4 In 3D supersonic turbulence, due to the interaction of density inhomofilamentsin the is
ISM.
&geneities
Lazarian
2016,
2017a).
the extended
WNM.
It implies
thatthe Based
denser on
CNM
embed- studies,with multiple shocks and turbulent mixing (Pan & Scannapieco
ColdHI
filaments
in
the
WNM.
numerical(2) M
Mor Mofs 2D sheet-like
1 > Ms
A > 1instead
A . In a2010),
filamentary
structures
structures
arestrongly
more
ded in the etdiffuseWNMargued
is dynamically
mixed by the
turbual. (2014)
that the dynamics
of the
WNM andlikely to be generated.
magnetized
medium, Eq. (16) applies to the shock compres- lentSaury
velocities
in
the
WNM,
and
thus
the
cold
HI
filaments
the CNM are tightly coupled, and the velocity dispersion between CNM clumps is close to the velocity dispersion within
4 In 3D supersonic turbulence, due to the interaction of density inhomothe extended WNM. It implies that the denser CNM embedgeneities with multiple shocks and turbulent mixing (Pan & Scannapieco2010), filamentary structures instead of 2D sheet-like structures are moreded in the diffuse WNM is dynamically mixed by the turbulikely to be generated.
velocities
inalong
the WNM,
andpanel)thusandthex-axis
cold (right
HI filaments(b) Slice plots of density fluctuations superposed with magnetic field lines at t = lent
6 teddy,L, viewed
z-axis (leftpanel).
F IG . 2.— The structures of density fluctuations and magnetic fields.

These results may be due to the fact that the global collapse of the extended filamentary structure S242 is driven by
Sequential
Star
Formationin theof the Planck
Galactic
an edge eﬀect,
for which thefilament
edges collapse
first filamentary
and then furtherstructures
trigger star formation
activities inward.
We coldclump
G181.84+0.31
identify threesubstructuresin G181.84 and estimate their critical masses per unit length, which are ∼ 101±15 M⊙
1
4−1 1,2,3 , Ming Zhu−1
Yuan
Tie Liu4,5 , Jinghua
Yuan
, all
Yuefang
Wu6the, Kee-Tae, Ke
Wang7,8 ,pc−1 , 56±8LixiaM⊙ pc
and 28±4 M⊙ pc 1,3,, respectively.
These values
arelower thanobservedKim
values(∼ 2009
10,11Zhou, Ken’ichi
Tatematsu
and Nario Kuno
M⊙ pc−1 ), Chenlin
suggestingthat1,2,3
these
sub-structures
are gravitationallyunstable.

74

Accepted by MNRAS
https://arxiv.org/pdf/1905.12258

46

One
Solution to the Mass Budget Problem for Planet Formation: Optically Thick Disks
観測と使⽤データwith Dust Scattering

SCUBA-2 850 micron, Herschell, WISE, Spitzer（以上は連続波）, 野辺⼭45m鏡でN2H+ and HCO+輝線

Zhaohuan Zhu1 , Shangjia Zhang1 , Yan-Fei Jiang2 , Akimasa Kataoka3 , Tilman Birnstiel4 , Cornelis P.
Dullemond5, Sean M. Andrews6 , Jane Huang6 , Laura M. Pérez7 , John M. Carpenter8 , Xue-Ning Bai9 ,David J. Wilner6 and Luca Ricci10
1

Department of Physics and Astronomy, University of Nevada, Las Vegas, 4505 S. Maryland Pkwy, Las Vegas,
観測事実
NV
89154, USA; 2 Kavli Institute for Theoretical Physics, University of California, Santa Barbara, CA, USA; 34
National
Astronomical
ObservatoryofJapan,
Osawa
2-21-1,
Mitaka,Tokyo
181-8588,
Japan;
University Observatory,
1. フィラメントに沿って分⼦雲コアが形成されている⼀⽅, フィラメントが交差する中⼼領域ではすでFaculty of Physics, Ludwig-Maximilians-Universität München, Scheinerstr. 1, 81679 Munich, Germany; 5 Zentrum fürに若い星が存在する.
Astronomie,
Heidelberg University, Albert Ueberle Str. 2, 69120 Heidelberg, Germany; 6 Harvard-Smithsonian Center
7
for Astrophysics,
60 Garden Street, Cambridge, MA 02138,
Departamento
de=Astronomı́a,
Universidad de
2. フィラメントと中⼼領域で⼤局的な速度勾配(~1USA;kms/s
per pc, error
0.05 km/s)が存在する.
Chile, Camino El Observatorio 1515, Las Condes, Santiago, Chile; 8 Joint ALMA Observatory, Avenida Alonso deCórdova 3107, Vitacura, Santiago, Chile; 9 Institute for Advanced Study and Tsinghua Center for Astrophysics,
Tsinghua University, Beijing 100084, China; 10 Department of Physics and Astronomy, California State University
Northridge,
18111 Nordhoﬀ Street, Northridge, CA 91130, USA
著者の主張
E-mail contact: zhaohuan.zhu at unlv.edu

1. surveys
連鎖的星形成ALMA
have suggested that the dust in Class II disks may not be enough to explain the averaged solid mass
2. globalundercollapsein exoplanets,
the assumption that the mm disk continuum emission is optically thin. This optically thinassumption seems to be supported by recent DSHARP observations where the measured optical depths of spatiallyresolved disks are mostly less than one. However, we point out that dust scattering can considerably reduce the emission
from an optically thick region. If that scattering is ignored, the optical depth will be considerably underestimated.
An optically thick disk with scattering can be misidentified as an optically thin disk. Dust scattering in more inclinedFigure1. Left panel:molecular
cloud is anstructure
elongated filamentary
structure(length ⇠ 25pc)
et redal. 2017
Figure 1. Left panel: The S242
molecular
cloud isThe
anS242
elongatedfilamentary(length ⇠ 25pc)(Dewangan
et al.(Dewangan2017). The
circle, standtriangle,
respectively
standforregion,
the IRAS
sources,
HII region,
sources,
thewhite
black crosses
stars andrepresent
white crosse
circle, triangle, square respectively
forsquare
the IRAS
sources,HII
submm
sources,the submm
black stars
anddark clouds and white reflection Nebula. All of them are retrieved from the SIMBAD Astronomical Database. The PGC
dark clouds and white reflection
Nebula. All of them are retrieved from the SIMBAD Astronomical Database. The PGCC G181.84
region is outlined with dashed-cyan box. Upper right panel: SCUBA-2 850 µm continuum emission map for PGCC G18
region is outlined with dashed-cyanbox. Upper right panel: SCUBA-2 850 µm continuum emission map for PGCC G181.84+0.31
with contour levels from 10% to 90% by step interval of 15% of the peak value (350 mJy/beam). Magenta ellipses denote thwith contour levels from 10% sources
to 90%extracted
by step fromintervalof 15%
thepeakcircle
value
mJy/beam).
Magentaellipsesdenotethesize
compact
850 µmmap. ofThe
orangein (350
the right
corner shows
the SCUBA-2
e↵ective
beam
for SCUB
sources extracted from 850 µmµm.
map.
orange circle
the right
the SCUBA-2
e↵ectivebeam
size for SCUBA-2
at 850 rig
TheThecyan-dashedboxes inlabeled
as Fa,corner
Fb andshowsFc, represent
three major
emissionsub-structuresin G181. Lowerµm. The cyan-dashed boxes labeled
as Fa,
Fc,
represent
major
sub-structures
Lower
right
panel:
Three-colors
mapFb
for andG181,
madeusing thethree
SCUBA-2
850emissionµm in red,
SPIRE 250 µmin
in G181.
green, PACS
70 µm
in blue.
Three-colors map for G181, made using the SCUBA-2 850 µm in red, SPIRE 250 µm in green, PACS 70 µm in blue.

4.3
4.3 Gravitational
Gravitationalfragmentation
fragmentationofofsub-filamen
sub-filamAs
As shown
shown inin Figure
Figure 12,
12,G181G181contains
containssub-filament
sub-filame
9th
9 densedense cores
cores embedding
embeddingininthem.
them.ToToinvestigate
investigate
mentation of sub-filaments and hence the format
mentation of sub-filaments and hence the form
dense cores, we compare the sub-structures of G181
dense cores, we compare the sub-structures of G18
model of a collapsing isothermal cylinder, supported
model of a collapsing isothermal cylinder, support
ther thermal or non-thermal motions. André et al.
ther thermal or non-thermal motions. André et a
has suggested that thermally supercritical filaments,
has masssuggestedthatlength
thermally
supercriticaltheper unit
is greaterthan thefilamencriticathe mass ;perunit length is greater than the criti(Mline,crit i.e., Mline > Mline,crit ), are associated wi(Mline,crit; i.e., Mline> starMline,crit), areactivities.
associatedstellarclumps/coresandformationHostellarare
clumps/coresstar formation
activities.
there
few Herschelandpre-stellar
clumps/cores
and ethereprotostars
are few Herschelpre-stellar
clumps/coresanddedassociatedwith thermallysubcritic
ded protostars
associatedwith thermally subcrit
ments(Mline < Mline,crit ).
ments). criticalFor(Mthermalsupport,mass per unit
line < M
line,crit the+ (1-0)Figure 13. The centroid
velocityofHCO
emission dis2 /G;For
thermalsupport,thecritical
mass
per
un
(M
=
2c
where
c
is
the
isothermalsoundline,critstributedalong the skeletonsof the sfilament network extracted+ (1-0)point(M=centroid
2c2s /G;
csofisis thetheisothermalistheThegravitationallyismergingneededfor souna fi
byG
FilFinder.
The
zero
pointwhereat constant)x-axisfor
Figure13.
velocity
HCO
emissionline,crittheto
sub-structure(Fb)andsouthern(Fc).
gravitationallyunstableto sub-structureradialcontractio
Gnorthern
isbe
thegravitationallyconstant)
is neededforatributedalong
the skeletonsofthefilament
networkextr
The x-axis increasing direction is from the merging point at Fa
by FilFinder.
The zeropoint
at x-axis
ismergingpoinfragmentationalong
its unstable
length(Inutsuka& Miyama
to be gravitationallyto theradialcontracsub-structure respectively along sub-skeletons to the northern and
Figure 12. The skeletons of the filament network extracted with the northernsub-structure(Fb)andsouthernThethermalline
mass
is error⇠ 16
Mfragmentation
along
itsalong
length(Inutsuka&
Miyamline,critsub-structuresouthernend. The criticalshadedarea
linesMrepresent
thelimthe FilFinder,color-codedwiththe centroid
the Theitsx-axis
increasing
directionisfrommergingigure
12. The skeletonsof thefilament
networkvelocities
extractedofwith
(T
/10
for
gas
filaments(Andréet al.
forgasthefittedK)
centroid
velocity.
magentaboxes
respectively
ThethermalcriticallineThemass
Mthe
is2014).
⇠point16 T
Mline,crit
+
HCO
(1-0)
spectralline.
Magentaellipses
represent
the
SCUBArespectively
alongsub-skeletons
tothenorthershow
the /10dense
cores,
andthewidthsof (Andrétherepresent
the p
he FilFinder, color-coded with the centroid velocities of the sub-structure
mentary
structures
of
G181
have
anboxes
observed
mass
(T
K)
for
gas
filamentsetal.
2014).
gas
2 compact
sources.line.
Green
contours
showrepresent
the distributionof the southern+ (1-0) spectral
1alongspatialdistribution
of M
dense
along
the represent
filaments,
theend.
shadedarea
lines
theboxerro
COMagentaellipses
the
SCUBAlength
ofThe
⇠ 200
pccores(Dewangan
et al. 2017).
T+
mentary
structures
of
G181
have
an
observed
mass
HCO
integrated
intensity,
levels
are
from
10%
to
90%
by
the
heights
represent
the
range
of
averagecentroid
velocityfor
dense
the fitted
centroid
velocity.
magentaboxesofrespec
compact sources. Green contours show the distributionof the its forserved
1 The
value
largely
exceeds
criticalvalue⇠the16+ (1-0)+the1length
of
⇠
200
M
pc
(Dewanganetal.
2017).
cores
fitted
by
HCO
and
N
H
(1-0)
lines,
asshown
inintervalof 15% of the peak value (13 K km s ).
2+
CO integrated intensity, levels are from 10% to 90% by the show
the1A3denseandK).
the widths of the boxes represenpc(atTcores,= largely
10-30
FigureandA4.
servedvalue
exceeds
thecriticalvalue of ⇠the1
terval of 15% of the peak value (13 K km s 1 ).
spatial distribution
of
dense
cores
along
the
filaments,
into
account
additional supports from tur
1Taking
pc
(at
T
=
10-30
K).
フィラメントを同定, そこで形成されている分⼦雲コアの質量も調べた.
heights
represent
the
range
of
averagedispersion
centroid velocity
forpressure,
the
total
1D
velocityiscalculate+ (1-0)+ (1-0)wheremtheintomassof anda Hydrogenatom,
and asµ =2.33 itTakingaccount
additional
supports
from[観測からもとめられたフィラメントの線質量] > [⾮熱的速度分散まで考慮した線質量]なのでclyndricalfragmentation
HbyisHCO
cores
fittedN
Hlines,
shown2
thefollowing
equation(Fuller
&
Myers
1992)
is pressure,theweightthe velocity
mean molecule.
Accordingtothetotalof 1D
dispersion
is calcula
FigureA3atomicand A4.
でコアはできた, と主張しているが, 誤解があろう. この線質量はradialcollapseに対する安定性の指標,
axial
collapseにtheobserved
linewidthand dust
temperatures
mentionedinthefollowing
equation(Fuller
&
Myers
1992)
よってどれほどの質量のコアがどれほどの間隔で⽣まれたかは,
height,
Hを求め,sgradients along Fb and Fc in the northern end of EFS S242 図12からscalesection 3.5.2,
we calculated
the図13から求められる代表
of✓ 1D velocity dispersions◆
2
vobs
的な間隔の何倍になっているかで判定せよ(inclinationの不定性も込みで).
, which are⇠ 0.47±0.07, 0.35±0.05
andkm
may be caused by the gas motion in the end-dominated col- where1
1 0.25±0.07
T OT
m
is
the
mass
of
a
Hydrogen
atom,
and
µ =
H
s
=
+
k
T
radients
along
Fb
and
Fc
in
the
northern
end
of
EFS
S242
1
BFbkinTrespectively
OT
s
,
for
Fa,
and
Fc.
The
uncertainties
arelapse.
✓µm H molecule.
8ln(2)
mobs ◆ Accordin
プランク衛星のDBから天体を選んだおであれば, なぜglobalな偏波の向きも解析しないのか？
is the atomic weightof the mean
v2

7

6

FHSC to be distinguished from a more evolved object. We find that the FHSC outflow is unlikely to be detectable
Synthetic molecular line observations of the first hydrostatic core from chemical calcuwith ALMA, which
would discount the observed sources with slow outflows that are currently identified as candidate
lations
FHSCs. We compare the results of simulated ALMA observations with observed candidate FHSCs and recommend
1
1
1
1
AlisonK. Young, Matthew
R. Bate, TimtoJ.follow
Harries
Oph A SM1N andN6-mm
as the mostpromisingcandidates
up. and David M. Acreman
1
Department of Physics and Astronomy, University of Exeter, Stocker Road, Exeter EX4 4QL, UK
Accepted by MNRAS

73
Maximum Density [g cm 3 ]E-mail contact: ayoung at astro.ex.ac.uk 要旨
https://arxiv.org/pdf/1906.01324
The first stable object to develop in the low–mass star formation process has long been predicted to be the first
10 2
g•itRadiation
magnetohydrodynamical
modelMore(RHD)にhydrostatic
core(FHSC).
Despitemuch
eﬀort,
has
still
yet
to
be
definitively
observed
innature.
specific
RHD
Sequential
Star
Formationinthefilamentary
structuresofthePlanckGalactic
cold
10 4
MHD
observational signatures are required to enable observers
to distinguish the FHSC fromyoung, faint, but more evolved
化学進化モデルを組み込み,
ALMAによる分⼦輝線でのclump
G181.84+0.31
610
protostars. Here1,3
we present synthetic
spectral line observations
for CO,
SO, CS and HCO4 + that were calculated
from
1,2,3
4,5
1
6
7,8
d
ファースト静⽔圧平衡核(FHSC,
以下FC)観測を疑似観測.
Lixia 8 Yuan radiation, Ming(magneto)hydrodynamical
Zhu , Tie Liu,
Jinghua
Yuan,
Yuefang
Wu,
Kee-Tae
Kim
,
Ke
Wang
,
c 9
models, chemical
modelling and Monte Carlo radiative transfer. HCO+ (1 − 0)
10
1,2,3
10,11
Chenlin Zhouand SO, Ken’ichi
Tatematsu
and Nario
Kunob(87 −76 ) spectraof the FHSC
show variations
for observations at a low inclination which may allow a candidate- 初期条件として⺟体分⼦雲の回転も考慮.
10 10
FHSC to abe distinguished from a more evolved object. We find that the FHSC outflow is unlikely to be detectable
12- ただし, ダスト表⾯反応は組み込んでいないので, 気相10with ALMA, which would discount the observed sources with slow outflows that are currently identified as candidate
10 14への放出へダストが関与する分⼦の評価は今後の課題.
FHSCs. We compare the results of simulated
observations with observed candidate FHSCs and recommend
46 ALMA
Oph A SM1N and N6-mm as the most promising candidates to follow up.
10 16
Central Temperature [K]104

Accepted by MNRAS
https://arxiv.org/pdf/1906.01324- 化学モデルは10-800Kで有効なものを<1AU以下には外挿して適⽤している点は今後の課題.

• 分⼦輝線のスペクトル形状は先⾏研究と⼤きく異なる
Sequential Star Formation in the filamentary structures of the Planck Galactic cold
ケースもある., e.g., X(CS)=const.を仮定したTomisaka
clump G181.84+0.31
1
7,8
102
& Tomida
2011と本研究のCSのプロファイルなど.
[論⽂
Lixia Yuan1,2,3 , Ming Zhu1,3 , Tie Liu4,5 , Jinghua
Yuan, Yuefang Wu6 , Kee-Tae Kim4 , Ke Wang
,
1,2,3
9
10,11
Chenlin Zhou
, Ken’ichi Tatematsu and中の個別コメントを参照]
Nario Kuno
101
• FCをlow-inclination angle (i=0は分⼦流の軸⽅向から⾒
26
27
28
29
30
31
32
33
たとき)で,
HCO+(1-0)とSO(87-76)で観測した場合, FC
46
Time [kyr]と原始星は区別しやすい.
Figure 1. The time evolution of the maximum density (top) and
Figure1. Thetime evolutionof the for
maximum
density(top)
and lines)
centraltemperature(bottom)
the RHDmodel(solid• CO分光撮像から分⼦流ローブのmorphologyを知ること
entraltemperature(bottom)lines).
for theRHD model
and MHDmodel (dashedSnapshotswere(solid
takenlines)
from thesendmodels
MHD model(dashedlines).
Snapshots density
were takenfrom these evoluは難しいと予想される.
at certain
valuesof maximum
for comparing
103

models at certain values of maximum density for comparing evolutionary stages and simulating observations. These are indicated foronary stages and simulating observations. These are indicated for
the RHD model. Snapshot (a) is taken just before the FHSC forms.
he RHD model. Snapshot (a) is taken just before the FHSC forms.
The density and temperature increase more slowly after this point
he density and temperature increase more slowly after this point
beforerapidly
increasing
duringthe second
collapse.
efore
rapidly
increasing
againagain
duringthe second
collapse.

Synthetic molecular line observations of the first hydrostatic coreaがFC形成時, bとdは断熱収縮期, gは２回⽬のcollpase後で原始星期なので,gがbやdと区別がつくか？

(=進化段階を判定する指標となりうるか？)右と左のパネルで差が⾒えるか？ (＝どっちの⽅向から⾒ると確実に判定できるか？)
上下のパネルで優劣が顕著か？ (=どっちの分⼦を選ぶ？)

レポーター感想：n(H2)を知るために必要な塵熱輻射諸元の不定性も考えると, アバンダンス⼀桁の差を検出してもそれが有意であることを⽰すのは難しそう. ⼀⽅, 分⼦雲コア中⼼部に初めて光学的に厚い核ができたときの変化は劇的.

log [ n (HCO+) / n (H2) ]分⼦流の軸⽅向から覗き込んだとき (横軸の単位はAU)
CO

CN

-10.0
-12.0
-14.0
-16.0
-18.0
-20.0
1

1

+

-8.0

10

10

100

100

1000
NH3

a
b
d
g

-7.0
-9.0
-11.0
-13.0
-15.0
-17.0a-19.0b
-21.0d-23.0g
-25.0
1000
1

CS

log [ n (CS) / n (H2) ]

a
b
d
g

log [ n (CN) / n (H2) ]

-7.0
CS
-4.0
-9.0
-11.0MNRAS 000, 1–14 (2019) -5.0
-6.0
-13.0
-15.0
-7.0
-17.0
-8.0
-19.0
-9.0
-21.0
-10.0
-23.0
-11.0
-25.0
-12.0
1
10
100
1000
-13.0

log [ n (CO) / n (H2) ]log [ n (CS) / n (H2) ]Figure 5. Average abundances of selected species calculated for the RHD mode
hetic molecular line observationsof thefirstcore direction
15 (parallel to the rotation axis).
Figure 6. Sameas forFig. hydrostatic
5 but in the vertical

a
b
d
g

10

100

1000

log [ n (HCO+) / n (H2) ]log [ n (H2CN) / n (H2) ]log [ n (NH3) / n (H2) ]

HCO
-8.0
-8.0
-10.0
H2CN
HCO+
-8.0
-9.0
-11.0
-10.0
-9.0
-10.0
-12.0
-11.0
-10.0
-13.0
-12.0
-14.0
-12.0
-11.0
a
a
-15.0
-14.0
-13.0
-12.0
b
-16.0 ba
-14.0
-13.0d
-16.0-17.0 db
-15.0
-14.0g-18.0 g
d
-16.0
-18.0
-19.0
-15.0
1
10
100
1000
1
10
100 g
1000
-20.0
-7.0
-16.0
-8.0
1 a
10
100
1000
1
10
100
1000
OCS
SO
-9.0
-10.0
b
-7.0
+
-11.0
N
H
-12.0
2
d
Figure 5. Average abundances of selected
species calculated
for the RHD model perpendicular to the OCS
rotation axis.

a
b
d
g

)]

-9.0

(H2) ]2) ]n (H2) ]分⼦流やenvelopeを横からみたとき (横軸の単位はAU)

-9.0

a

bはFC形成後2000年, dはFC形成後4000年(2nd collapse直前)

Figure 17. Evolution of the SO (87 76 ) line profile in the MHD
model for RHD model (top) and MHD model (bottom). Eachspectrum is averaged over pixels within a central 0.35 arcsec
diameter
circular beam. Solid lines: i = 0 , dashed lines:
A.(53
K.AU)
Young
et al.
i = 90 .

Figure 19. HCO+ (1 0) Integrated intensity
Middle: RHD model; Bottom: MHD model

MHDのみ
分⼦流軸⽅向

RHDのみ

MHDのみ

17. Evolution of the SO (87

Figure 23. Synthetic ALMA spectra of the MHD model in the
Figure 23.
Synthetic
spectrathe integration,
MHD model iface–on direction.
Top:SO (87ALMA76 ), 8hours of
total
face–on direction.
Top: SO(87 76 ), 8spectra
hours total
out14 configuration.
It is possible
to distinguishearly integr
and
out14
configuration.
is outflow
possible develops.
to distinguishspectraearllate in FHSC
stage
at i = 0 asItthe
Bottom:MHD
late+in(1-0),
FHSC8stage
attotali = 0 integration,
as the outflow
develops.
model HCO
hours
0.21
⇥ 0.25 Bottom:
arcsec+HCOgrows(1-0),
8 hours
total integration,
0.21 ⇥ and0.25 abeam. Asmodel
the FHSC
emissionincreasesat the line centre
beam.
the+ FHSC
grows
emissionincreases
atdiscernible
the line
centr
Figure19. AsHCO(1the0)blue
Integrated
intensity
snapshot(d).
becomesbrighter
than
peak
and
this
isforstill+
Figure20.theHCO(10) andspectrafor
RHDdiscermodbecomesbrighter
than
blue
peak
this
is
still
Middle:RHD
model;
Bottom:MHD
model76 ) line profile in the MHD in the synthetic interferometric spectra.
model(bottom) within
a 0.67 arcsec aperturein the synthetic
interferometric
spectra.