SFN #354 65-72
担当：土井 聖明 (総研大D1)

flfi

65. The 30 Doradus Molecular Cloud at 0.4 pc Resolution with the Atacama Large Mil- limeter/submillimeter
Array: Physical Properties and the Boundedness of CO-emitting Structures
66. A new method for direct measurement of isotopologue ratios in protoplanetary disks: a case study of the
12CO/13CO ratio in the TW Hya disk
67. Molecular Gas Structures traced by 13CO Emission in the 18,190 12CO Molecular Clouds from the MWISP
Survey68. Dependence of Molecular Cloud Samples on Angular Resolution, Sensitivity, and Algorithms
69. Two Candidate KH 15D-like Systems from the Zwicky Transient Facility
70. Magnetic Field of Molecular Gas Measured with the Velocity Gradient Technique I. Orion A
71. ATOMS: ALMA Three-millimeter Observations of Massive Star-forming regions – XI. From in ow to infall
in hub- lament systems
72. The Pre-main Sequence: Challenges and Prospects for Asteroseismology

A new method for direct measurement of isotopologue ratios in protoplanetary disks:a case study of the 12 CO/13 CO ratio in the TW Hya disk

Tomohiro C. Yoshida, Hideko Nomura, Kenji Furuya, Takashi Tsukagoshi, Seokho Lee F Planetary systems
are thought to be born in protoplanetary disks. Isotope ratios are a powerful tool for investigating the material origin andevolution from molecular clouds to planetary systems via protoplanetary disks. However, it is challenging to measure theisotope (isotopologue) ratios, especially in protoplanetary disks, because the emission lines of major species are saturated. We
developed a new method to overcome these challenges by using optically thin line wings induced by thermal broadening. Asa first application of the method, we analyzed two carbon monoxide isotopologue lines, 12 CO 3 2 and 13 CO 3 2, fromarchival observations of a protoplanetary disk around TW Hya with the Atacama Large Millimeter/sub-millimeter Array. The
12
CO/13 CO ratio was estimated to be 20 ± 5 at disk radii of 70 110 au, which is significantly smaller than the value observedin the local interstellar medium, ⇠ 69. It implies that an isotope exchange reaction occurs in a low-temperature environment
with C/O > 1 . In contrast, it is suggested that 12 CO/13 CO is higher than ⇠ 84 in the outer disk (r > 130 au), which can be
explained by the diﬀerence in the binding energy of the isotopologues on dust grains and the CO gas depletion processes. Our
results imply that the gas-phase 12 CO/13 CO can vary by a factor of > 4 even inside a protoplanetary disk, and therefore, canbe used to trace material evolution in disks.

Molecular Gas Structures traced by 13 CO Emission in the 18,190 12 CO Molecular Clouds
from the MWISP Survey
原始惑星系円盤TW
Hyaの炭素同位体(12CO/13CO)を観測的に制限

Lixia Yuan, Ji Yang, Fujun Du, Yang Su, Xunchuan Liu, Shaobo Zhang, Yan Sun, Xin Zhou, Qing-Zeng Yan,
Yuehui Ma F After the morphological classification of the 18,190 12 CO molecular clouds, we further investigate the propertiesof their internal molecular gas structures traced by the 13 CO(J = 1 0) line emissions. Using three diﬀerent methods to extract

分子輝線の端の位置での強度比に着目

・円盤内側(<110 au)でISM(~69)よりも小さく(~21)(=同位体が濃縮)・円盤外側(>130 au)でISM(~69)よりも大きい(>84)(=rare
isotopeが減ってる)20I(ν) = B(ν, T)(1 − e −τ(ν))

背景・同位体は原始惑星系円盤の物質トレーサー
・円盤観測と隕石や彗星などの物質のつながりを明らかに
・同位体比の観測的見積りは難しい
・多い方は光学的に厚くなる
wing

・少ない方は感度が足りない・これまでは観測と、全部入りの物理モデルとの比較から推定

centerwing

吉田くん発表資料より

・モデル依存性のない推定法(=輝線のふちの強度比から見積もる)を提案
・TW Hyaの観測に適応して見積もる

すばる プレスリリースより

The Astrophysical2022 June 20 Journal, 932:126 (13pp), 2022 June 20 Yoshida et al
The Astrophysical Journal, 932:126 (13pp),2022 June 20 Journal, 932:126 (13pp),
The Astrophysical

手法
・輝線の強度モデルを作って強度比を波長ごとにプロット・thickだと強度比は実際の密度比と相関しない
・thinだと強度比は密度比に対応

観測・天体：TW Hya
・ほぼface-on (I~5 )2920 28
The Astrophysical Journal, 932:126 (13pp), 2022 June28
t13 calculated
Figure1. Testsimulated
spectra.
t12 and tarefrom theandlinevertical
proﬁlesaxes,
areon thet13 using
Figure 1. Test of the method using simulated
spectra.
t12 ofandthet1229method
calculated
from theline proﬁles
on the horizontal
respectively
12 plotted
29 plotted
28
12
t
t
Figure
1.
Test
of
the
methodusing
simulated
spectra.
tandcalcul1213
12 (7),The
gray predictions
horizontal lines
model
predictions
the grayactualoptical depth
the COCO shows
line. Thehorizontal
lines ofindicatethe line.
simplemodelof R¢indicate
formulated
in12Equation
to which
Color scale shows the actual optical depth Colorof the scale
12the simple
12
CO
line.
The
gray
horizonta
Color
scale
shows
the
actualoptical
depth
of
the
COthe
was
changedtoR =panels
20, 40,K,100
substituted.
The
three panels
the results
when thecolumnwas changed
to be
0.1, 1,densityand 10oftimes
ﬁducialmodel
R = 20, 40,K,100 are substituted. The threeshow theare
results
when thecolumndensityshow
of 12COR = 20, 40,K,100 are substituted. The three panels show the results when the
Yoshida et al.

12
13
situations.
CO
and
CO
3–2 linesanwere
targeted
becausethey
an interval
20,wasandchanged
the colsituations. CO and CO 3–2 lines were targeted because
theyinterval
andcolumn densityof 12ofCO
12of 20,13 thesituations.
CO andstructure
CO 3–2 lines were targeted because theyarethestrongest
isotopologue
lines.
The
temperature
to be 0.1,
1, and10 columntimes
are the strongest isotopologue lines. The temperature structure
to
be
0.1,
1,
and
10
times
the
ﬁducialmodel.
These
are the strongest
isotopologue
lines. The temperature structure
12
12
and
the
ﬁducialCOdensity
structure
were
taken
from
a
densities
correspondto theop
and the ﬁducial CO density structure were taken from adensities
correspond
of
the
line
centersof
3a
12 to the optical depths
andtheﬁducialCOdensity
structure
were
taken
from
modelinofLee
the TW 33,
Hyaanddisk
presented
inscaleLee shows33,
and330.optical
The colorscale
thermochemical model of the TWthermochemicalHya disk presented
330.
The
color
the
actualdepth,
τ12
13
thermochemical
model
of
the
TW
Hya
disk
presented
inLee
et structureal. (2021),was
andcreated
the CO
was created
et al. (2021), and the 13CO density
suchdensityinstructure
in indicate
the model,
and the fromgray
13 suchR¢ derived
themodel,
and
the
gray
lines
12
13
et
al.
(2021),
andtheCO
density
structurewascreatedsuch
CO/uniform12(7)in usingthe
The in thethe inuniform
the CO
disk.ratios
The were Equationthat the 12CO/13CO ratios werethat
Equation
(7)
using
the
values13 disk.
R¢
thevaluesmodel.
When
wederive12
13
CO/CO
ratioswere
uniform
in
the
disk.
The
that
the
12
13
radiative
equationsat r = 100
au forthe CO
andCO
radiative transfer equations at r = 100
au fortransfer
the COand COfrom
Equation
12 (7), wefrom
Equation
(7),
we
have
a 100
nontrivial
parameterof 13τhave
0,12
radiative
transfer
equations
at
r
=
au
for
the
CO
and
CO
by assuming
LTE andthea formulation
turbulence oflines were solved by assuming lines
LTE wereand solved
a turbulenceofBecausetheformulationofBecauseof Equation(7)
follows
the homolines
weresolvedbyassumingLTEandaturbulence
of
0.1×
the
local
thermalspeed(Flahertyetal.
2018).
We
note
0.1× the local thermal speed (Flaherty et al. 2018). We noteshgeneousslab
τ0,12
shouldbe takenas2018).
amodel,representative
geneousslab model,
τ0,12
0.1×
the
local
thermalspeed(Flaherty
et
al.
We
note
that the would
effect beof (subsonic)
would
be negligiblethat the effect of (subsonic) turbulence
negligible turbulencevalue
towould
approximate
the devalue
toapproximate
the detailed
model
with
abeslab
model
that
the
effectof(subsonic)
turbulence
negligible
such inturbulence
the exponent in Equation (4)because such turbulence changes because
the exponent
Equationchanges(4)
Therefore,
wethe
ﬁrst
speciﬁedt
Therefore,
weturbulenceﬁrst speciﬁedthe velocity
where
opticaldepthbecausesuchchangestheexponentinEquation(4)
12slightlyeven if we
account12(Appendix A). The
only slightly even if we take it intoonly
account(Appendix
A).take
Theit into ofCObecomes
of
the
CO
line
becomesoneasτ(v) = line
1 (τ12(v) isothe
12 τ=1τ=1Theonlyslightly
even
if
we
take
it
into
account(AppendixA).
was input assuming the Keplerianline-of-sight velocity was inputline-of-sight
assuming velocity
the Kepleriancalculated
using
model),
calculated
using
the
model),
andthenconvertedit thebyline-of-sightvelocitywas
input
assuming
theKeplerianFigure4.
Stackedspectra
of
CO
3–2
and
CO
3–2
at
each
radius.
The
blue
and
red
steps
indicate
the
CO
and
CO
lines,
respectively.
Errorsare shown in therotation
withana inclination
stellar massofof 0.81 Me and an inclination ofrotation with a stellar mass of 0.81
M and
12

13

・ビーム内のケプラーシアがほとんどない・輝線：CO(J=3-2) 13CO(J=3-2)・方位角方向にスタック

12

13

12

13

13

depends on the distance from the Galactic center and scatters
from
high
enough.
They
also
constrained
the
snow
line
The Astrophysical Journal, 932:126 (13pp), 2022 June 20
Yoshida et al.
sourcesource,even
similardistance(e.g.,& 6 but with
FigureLanger
8. Same as Figure
step-function-likeratio 6 but with28
6. t12 vs. tofrom atthe astackedproﬁlest1229 28
t13 calculated
to thebefrom
∼27 K
at8.isotopologuetheInthethiscase, C/
FigureSame midplane.
as Figurestep-function-likeisoFigure line
6. t12
vs. t1229fromt13 calculated from the stacked line proﬁles(solid lines).
ations (points), and models with the ﬁxed observations
isotopologue (points),
ratio of and
69 models13(solid lines). 12
withthe (2016)
ﬁxed isotopologue explain
ratio of 69 the observed
Penzias
1990;
Milam
et
al.
2005).
Meanwhile,
Bergin
et
al.
CO/
CO
ratio,
assumingtd lines).結果
Different colors indicate different disk
radii.
(dashed lines). Different colors indicate different disk radii.
suggested that the C/O ratio exceeds unity used.
basedTheon
the
13
12
reactionin Equation
(17),
and
the
temperaturein
13theCO density model
was createdbydividing
CO
used. The CO density model was created by dividi
Hya bydisk,
in local ISM
observations of bright C2H emission in the TWdensity
69 (thevalue;isWilson
1999)
uniformly.
region∼30
K.
However,
becauseC/O
might
density
by
69
(the
local
ISM
value;
Wilson1999
・内側で13COが多く、
we Suchadopteda the dust distribution describedin adopted
Lee et al.
contrast
to the solar ratio of 0.59 (Asplund et al. Also,2021).
Also,
we
the
dust
distribution
described
iinside
the
CO
snow
line
due
to
the
CO
ice
subli
(2021). Notably, the effect of the dust continuumon the line
(2021).
Notably,
the effect of the dust continuum
high C/O
ratio has also been suggested in some emission
protoplanetary
外側で13CO減ったモデルで観測を再現
whetherthe exchange
is negligible at r unclear> 70 au. We
usedthe only
RADMC-3D
emissionis negligible
at r > 70 au.reaction
We used canthe Rdisks and can be interpreted as a result of locking oxygen
intothe2012) to create(Dullemondet al.
assuming ettheal.same(Dullemond2012) to create image cubes, assum
ratio.image cubes,
such as the inclination angle of parameters,
the TW Hyasuch
disk,asasthe inclination angle of the TW
arge dust grains along with settling and migrationparameters,of the grains
Hily-Blant
et al. (2019)
measured the HCN/
described
above.
The
channelmaps
were
convolved
withandescribed above. The channel maps were convolv
e.g.,議論
Bergin et al. 2016; Bergner et al. 2019; Miotello
et
al.
2019;
5), relatively
and the observational
lineinner
proﬁlesregionateach(0observational beam (0 5 ×at0 a
(r
<
60
au).
The
result
5
×
0
5),
and
the
line
proﬁ
beam
−1
Bosman et al. 2021). If C/O > 1, it is possible thattheisotopeGaussian.
Then,with a 0.06 km s−1 FWHM Gau
pixel were smoothed with a 0.06 km s FWHM
pixel
were
smoothed
whichishigher
than
the
local
ISM
value.
If
we
we analyzed them in the same manner as theexchange
reaction of・内側ではCOの同位体濃縮が起きた
weanalyzed themThein 12
the sameas the obser
13 observations.
+ 13manner+CNinheritsC/
C(Langerethe6 show
HCN/H
colored dashed lines in Figure
the results.
Intheopticallycolored dashed lines in Figure 6 show the results. In
13C+ + 12CO  12C+ + 13CO + 35 K
29 28
toa relationshipthin range, it (is17foundthe obtained(18)t12thinmay
t13 are) that Equation
providerange,
itlikelyis foundthat the obtainedbetween
t1229 28 t13 H
converge to a constant value, which is a converge
completely
different
13
toaconstant
value,
whichisacomplet12
13
without
assuming
R.
Taking
HCN/H
C
and
R
CO
ele
featurefromtheobservations(coloredpoints).
Therefore,themakes CCO/
CO
lower
(e.g.,
Langer
et
al.
1984;
Woods
&
> O であるfeature from the observations (colored points). Th
1213
12 which
13=
20,
obtainT∼
24
K,
isconsistCO/CO= 69wecannotexplaintheconstant ISM value of R
CO
CO/
CO
=
69
cannotconstant
ISM
value
of
Willacy 2009; S. Lee et al. 2022, in preparation)observationalin the warm
results. We reran
the simulations
by settingresults.
aTherefore,
step- We reranthe
observational
the simulations
byrea
seobserved
temperature.
exchange+1213molecular layer. If we assume that only C and
CO are CO/
the CO distribution as function-like 12CO/13CO distribution asfunction-likeFigure8. Same value,as Figure 6 butevenwith the step-function-likeisotopologue
ratio
Figure 6. t vs. t
from the stacked theline proﬁlesfromt calculated explain
thoughwedoobserved
R・外側ではCOのダストへの凍結が起きたCO(solid lines).
observations (points), and models with the ﬁxed isotopologue ratio of 69
carbon carriers, we can derive the relation
12(dashed lines). Different
different(diskradii.100 au)
20r<
12 CO][ COcolors] indicate
20 (r < 100 au)
value.
actual
R
[
⎧
ele
=
,
(
16
)
⎧
89
(ISM)
model was created by dividing ,the CO
used. The CO density=
CO氷上のbinding
energyは13CO>CO
13
12
+
12
100
(
r
>
100
au
)
⎨
13CO
[ CO]
100
(r >
1001999)au)uniformly.
⎩
[
]
[
]
35
K
CO
7. Same as Figure 6[but C
using] the spectrum stacked
withinR=
70–110densityby69 (the
ISM value;Wilson[] local⎨⎩Figure7.
Sameas
Figure
6
but
using
the
spectrumstackedwithinR=
70–110⎛au.R¢ The
Also, we adopted the dust distribution described in Lee et al.
(),
18
and grayits⎞uncertainty,
e gray line and shadow show =the exp
averageandits
uncertainty,line
andshadowshow
theaverageR¢
13CO](2021). Notably, the effect of the dust continuum on the line
andanalyzed
in
the
same
way.
ively. 13COが選択的に氷上に凍結？
[13C+][
T⎝respectively. ⎠and analyzed
the sameway.
emissionin
is negligible
at r >
70 au. We used the RADMC-3D
12

29 28
12

13

13

12

The solid colored lines in Figure 8 show theresultsthat(Dullemondetare
al. 2012)
to create
image cubes,
assumingthe
the same
5.1.2.
Enhancing
Mechanisms
The
solid
coloredlines
inFigure
8
show
res
12
13
parameters, such as the inclination angle of the TW Hya disk, asmatched
The relative
error to channel
n chemical
equilibrium.
Here,
RCO ≡ [ CO]/[ reasonablyCO], RC/O≡ to the observations.reasonably
matchedtheobservations.
redescribed
above. The
maps were convolvedThewith an
4.2. Comparison
with Synthetic
Analysis4.2. Comparison
withAnalysis
12 +
13 +
12
13
12
13 Synthetic
betweenthe stacked
spectra ofobservations
andlowerthemodelis spectra
5 ×the0 5),
andthe line region
proﬁles ateach(tobservational
beam
(0
The
inferred
limit
at
outer
betweenthestackedofobservations
and−1[exclude
C ] the+ [possibility
C ] +that[ analysis
CO] +such[ CO])/([
CO]
+
[
CO]),
and
FWHM Gaussian. Then,
pixel
were
smoothed
with
a
0.06
km
s
as
stacking
the
less
than
40%
at
the
line
wing
at
r
<
170
au.
In
the
outermost
12
13
the
less
thanwe40%at themthe inline
wing
at ras<the170
au. InThethanalyzed
the samemannerobservations.
12 +
12
13 To
+ exclude
13 the possibility that analysis such as stacking
CO/
CO
>
84,
is
signiﬁcantly
higher
than
th
Raele
≡ ([the results,
C ] +we[ createdCO])/([
C image]+[cubes.
CO]).
After
some
algeaffects
simulatedcoloreddashedthelines in Figure 6 show the results. In the optically(r simulated
> 170
au),
the cubes.
observations
fromspectraaffects
theTheresults,
weregioncreatedimage
The deviate moreMagnetic Field of Molecular Gas Measured with the Velocity Gradient Technique I.
Orion A

Mengke Zhao, Jianjun Zhou, Yue Hu, A. Lazarian, Xindi Tang, Willem A. Baan, Jarken Esimbek, Yuxin He,
Dalei Li, Weiguang Ji, Kadirya Tursun F Magnetic fields play an important role in the evolution of molecular clouds
and star formation. Using the Velocity Gradient Technique (VGT) model, we measured the magnetic field in Orion A using
the 12CO, 13CO, and C18O (1-0) emission lines at a scale of 0.07 pc. The measured B-field shows an east-west orientationthat is perpendicular to the integral shaped filament of Orion A at large scale. The VGT magnetic fields obtained from 13CO
and C18O are in agreement with the B-field that is measured from the Planck 353 GHz dust polarization at a scale of 0.55 pc.
Removal of density eﬀects by using a Velocity Decomposition Algorithm can significantly improve the accuracy of the VGT in
tracing magnetic fields with the 12CO (1-0) line. The magnetic field strength of seven sub-clouds, OMC-1, OMC-2, OMC-3,
OMC-4, OMC-5, L 1641-N, and NGC 1999 has also been estimated with the Davis-Chandrasekhar-Fermi (DCF) and MM2technique, and these are found to be in agreement with previous results obtained from dust polarization at far-infrared andsub-millimeter wavelengths. At smaller scales, the VGT proves a good method to measure magnetic fields.

Velocity Gradient Technique (VGT)を用いたOrion Aの磁場の推定
・分子輝線の勾配から磁場構造を推定する 21
・0.07 pcスケール(=高空間分解)での磁場構造の推定を行なった
・Planckによるダスト偏光と整合的
・Davis-Chandrasekhar-Fermi(DCF)とTwo Mach Numbers Method (MM2)を用いた磁場の強度は赤外-ミリ波の偏光と整合的

背景
The Astrophysical Journal, 934:45 (11pp), 2022 July 20

・円盤磁場構造は分子雲の形成・進化や星形成に重要
・近傍大質量星形成領域のOrion Aの磁場構造を解明する

Figure 1. Distribution of H2 column density derived from Herschel continuum
data in Orion A (Poglitsch et al. 2010; Grifﬁn et al. 2010; Roy et al. 2013;
Polychroni et al. 2013). The white contour level represents 3 × 1021 cm−2. The

the column density of one region is greater than this density,(Yuen & Lazarian 2017b; Hu et al. 2020). Therefore theself-gravity could be dominating. This dense region in Orion A
velocity gradient orientation angle in gravity-dominated region
includes the large integral shaped ﬁlament (hereafter, ISF),
will be rerotated 90°. It is calculated bydense clumps, L1641-N and NGC1999, and the gas around
21−2
S
VELOCITYGRADIENTS
AS
A
TRACERFORMAGNETICFIELDS
)
(>3
×
10
cm
).
them
that
has
a
high
columndensityN(H2y B = yB + p 2,
(10)
Diego F. González-Casanova and A. Lazarian
Assume
that
Orion
A
is
a
long
cylinder, the volume density of
・速度勾配が磁場に垂直になる(右の論文)
S
21−2
where y B is VGT orientation angle in the case of self-gravity
N-DPFs’ transition point (column density ∼3 × 10 cm ;3
−3
ABSTRACT
and
ψ
is
the
pseudomagneticﬁeld
angle
measuredby
VGT
in
Spilker et al. 2021)
is around ×10 cm by estimating theB
・MHD乱流が磁場に垂直方向に発達する(Alfven波)
Strong Alfvénic turbulence develops eddy-like motions perpendicular to the local direction of magnetic ﬁelds. This
local alignment induces velocity gradients perpendicular to the local direction of the magnetic ﬁeld. We use thisthe case of turbulence-dominated regions. The orientation ofeffective radiusof a cloudpc;of magnetic
forﬁeldsdetails
fact to propose
new technique of(∼0.61
studying the direction
from observations,see
which we thecall thevelocity gradient technique. We test our idea by employing the synthetic observations obtained via 3D・磁場と垂直方向に速度構造(=速度勾配)を持つAppendix). This
resultisinagreement
with
that
Hu
magnetohydrodynamical(MHD)
numerical
simulations for different
sonic andAlfvén fromMach numbers.
We
the turbulence velocity gradient will be parallel to the magnetic
calculate the velocity gradient, W, using the velocity centroids. We ﬁnd that W traces the projected magnetic ﬁeld
forthe synthetic themaps obtainedwith sub-Alfvénic
simulations
and provides good
point-wisecorrespondence
et al. (2021), inbest
which
VGT
methodrevealsthatthe
selfﬁeld orientation.
between the magnetic ﬁeld direction and the direction of W. The reported alignment is much better than the
3 that it−3alignment between the density gradients and the magnetic ﬁeld, and we demonstrate
can be used to ﬁnd the
10cm
Howgravity is occurring
atvolumedensitynmagnetic ﬁeld strength with an analog of the Chandrasekhar–Fermi
not require
0 method. This new technique. does
dust polarimetry, and our study opens up a new way of studying magnetic ﬁelds using spectroscopic data.
ever, self-gravity
could
beandmore
localized
to the clumps
andKey words:
ISM: kinematics
dynamics – ISM:
magnetic ﬁelds – magnetohydrodynamics(MHD) – turbulence
3.2.
Velocity
Decomposition
Algorithm
・しかし、自己重力が効くようになると速度構造が磁場と整列する
cores while the envelope
may be morediffuse. There is a 64, &in pow
1. INTRODUCTION
yet been demonstrated with observational data (see Yan
VDA (Yuen et al. 2021) is a new method to separate velocity
Lazarian 2015).
lags large
established that gravitational
the interstellar medium (ISM) contractionispossibility turbulent,
ofIt is awellwhich
global(Larson1981;
Therefore there is intense interest in developing presents
newtaffects the dynamics of different astrophysicaltechniques. For instance, the anisotropy analysis of statisticaland density ﬂuctuations from a PPV cube using its statisticalerror on th
phenomena such as starformation,
cosmic-ray
acceleration,
Ballesteros-Paredes
et
al.
2011;
Kauffmannetproperties of variationsin the al.
observable2013;
Doppler-shifted lines
galaxy evolution, and feedback (Ferrière 2001; Elmegreen &greater& pr(Lazarian et al. 2002; Heyer & Brunt 2004; Esquivel
properties (Lazarian & Pogosyan 2000). The sonic Mach
Scalo 2004; de Avillez & Breitschwerdt 2005; McKee &Lazarian
2005, 2009;
Burkhart
et al. 2015)
proved to maximum
be aVázquez-Semadeni
et
al.
2019)
that
could
cause
an
inﬂow
(Hu
Ostriker
2007;
Falgaroneetal.
2008).
Widelyusedevidenceof・ある密度以下では速度勾配
磁場
interpolati
promising way of obtaining the mean magnetic ﬁeld as well as
the turbulence in the ISM is seen in the so-called big power law
number in star formation regions is usually greater than unity,
four angl
the media magnetization (see also Esquivel et al. 2015; Kandelthesky (Armstrong
et al. 1995;
Chepurnov& Lazarian of the velocity gradient.
et al. 2020)in2010),
andchangethedirectiont
et al. 2016a, 2016b). The difference in the velocities ofpractice,ionswhich reﬂects the Kolmogorov spectrum of electron
and neutrals that is caused by the difference in their damping
on in
the scand the supersonic version of the VDA algorithm makes it
ﬂuctuations
in work
nonthermal Doppler
broadening (seeA magnetohydrodynamic
・ある密度以上では速度勾配//磁場This regiondensity
of
this
in
Orion
is
dominatedbyself(MHD) turbulence has been suggested
become im
Draine 2011), in the power-law scalings of the ﬂuctuations
asanotherwayofstudying
magnetic
ﬁelds
(Li
&
Houde
2008).
to r ~ 8).
possible to only obtain the velocity ﬂux structure from a PPV
measured in position–position velocity (PPV) space (seeThequantitative
treatmentofthetechniqueshows,
however,velgravity where
thegravitationallycould occur at the of The
Lazarian &Pogosyan
2000; Stanimirović & Lazariancollapse
2001;
that it has its limitations (see Xu et al. 2015). New approaches
the maPadoan et al. 2009; Chepurnov et al. 2010, 2015) (see Lazariancube using the thin channel formulation of the VGT method.
として磁場構造を推定した
for studying magnetic ﬁelds using synchrotron intensity and(see Miesch
2009, forgravitationallya review), and in velocity centroids contractioncoreʼs scaleetet al.al.andcould
at thepolarization
have been occur
suggested in Lazarian& Pogosyan
1999; Miville-Deschênes et al. 2003).
(2012, 2016). All in all, the search of new ways of studying
The VDA allows a separation of the pure velocity caustics from
W is there
The
study
of
the
directionandmeasurementsoftheintensity
magneticﬁelds is characterized
by intensive inresearch; allcolumndensity
cloudʼs scale.
The
distribution
of
the
H
2
directionof magnetic ﬁelds present a challenging problem. Polarization
techniques have some shortcomings and limitations.
・ここでは
cm^-2
を境界にしたthe PPV cube. In 3x10^21
theory, the VGTorientation
applied the VDA
arising from grains aligned with longer axes perpendicular to a
Thecovered
Chandrasekhar & by
Fermi (1953,
C–F)
methodﬁeld.
can Figu
Figure 1 suggests
that
the
whole
regiontheCOmagnetic ﬁeld allows to estimate the direction of the magnetic
and thedetermine magnetic ﬁeld strengths by estimating the variations
ﬁeld, but the existing uncertainties in grain alignment theory
accounts
method (hereafter, VGT-VDA) would be closer to the plasma
in the directions of the magnetic ﬁeld lines, assuming Alfvénic
andthefailureof
grainalignment
atlarge
opticaldepthslimit
lines (Kongthe etal. 2018) in Orion A has motions
a highdensityet al. 2008;
gradients(Ostrikercolumn
et al. 2001; Falceta-Gonçalvesability of the technique to trace magnetic ﬁelds without
Houde et al. 2009; Novak et al. 2009). The C–F method observein its a
21ambiguities−2
motion direction and better trace the local magnetic ﬁeld.
(see
Lazarian
2007;
Lazarianetal.
2015a,
foraestimates the magnetic ﬁeld strength
cmThis also
) andcould dominatedsimplest
byfromself-gravity.
Oneas velocity(>3 × 10 review).
affects the Chandrasekhar–Fermi (C–F)
Figure 1).
The supersonic VDA algorithm to get the pure velocity
technique, which is used to determine the intensity of magnetic
B
»
4
pr
d
v
df
,
) treathing to note
isthethat
PLdirection
DPF
model remains a statistical the(We1polariﬁelds when
variationsthe
in polarizationand velocity
・Velocity
Decomposition
Algorithm(VDA)を用いた補正をした
dispersion are both known.
caustics structures (Lazarian & Pogosyan 2000) for the eachdf iswhere ρ is the density, dv is the velocity dispersion, and we
do noOther techniquesthat are used N-DPFs
to study magnetic ﬁelds
in the overall region, it isconcept. Whenplottingofthey trace
the polarization angle dispersion. An improved C–F techniquemolecular clouds, e.g., based on the Zeeman effect or on thealignment
channel of PPV cube is based on the following expression:in (Falceta-Gonçalves et al. 2008) was shown to be able
toGoldreich–Kylaﬁs effect, have their own limitations (see(速度勾配と密度勾配を切り分けるらしい?)
possible that
some
small
subregionsaredominatedbycandetermine the intensity of the magnetic ﬁeld with anuse th
Crutcher 2012). Faraday rotation is able to measure thefull isangle
uncertainty lower than a 20%. In the case when turbulence
intensity of the ﬁeld along the line of sight (LOS) in ionizedmagnetic
turbulenceandareinjected on small scales, Cho & Yoo (2016) provide anothermedia(Padoanet overwhelmed.
al. 2001; Ostriker 2003, pp. 252–270;
¶
Ch
(
X,
v,
D
v
)
FigureCrutcher 2012). The atomic/ionic alignment technique promodiﬁcation of the C–F method.
V (X, v, Dv) = - c2s,(11)
un-normavides a promising approachfor studiesof theappliedmagnetic ﬁeld, to measure
In a strongly magnetizedturbulentmedium, the turbulent
Severalmethods
have
been
the
magneticized centr
eddies rotate preferentially about the local direction of the
but the ability of the technique to trace magnetic ﬁeld has not¶v
and the a

手法

The Astrophysical Journal, 835:41 (11pp), 2017 January 20

doi:10.3847/1538-4357/835/1/41© 2017. The American Astronomical Society. All rights reserved.

Astronomy Department, University of Wisconsin-Madison, 475 North Charter Street, Madison, WI 53706-1582, USA; casanova@astro.wisc.edu,
lazarian@astro.wisc.edu
Received 2016 August 19; revised 2016 November 29; accepted 2016 November 29; published 2017 January 17

The Astrophysical Journal, 835:41 (11pp), 2017 January 20

Figure 1. First row: projected magnetic ﬁeld, B. Second row: gradient ﬁeld forthe un-normalized centroids, W S . Third row: gradient ﬁeld for the unnormalized centroids rotated 90°in black, and the B in red for comparacing,and fourth row: angle between the two vector ﬁelds, f S . From left to right thedifferent models decrease in magnetic ﬁeld strength. All plots correspond to a
subregion of 1002 cells of the simulation. The ﬁgure shows the technique of thevelocity gradient applied to a subsection of the simulation.

The Astrophysical Journal, 934:45 (11pp), 2022 July 20

結果

Zhao et al.

・細かい磁場構造がわかった
・本当に磁場構造をトレースしてるのか？
→次ページへThe Astrophysical Journal, 934:45 (11pp), 2022 July 20

Zhao et al.

spectral lines, 12CO(1-0), 13CO(1-0), and C18O(1-0) fromCARMA-NRO Orion Survey (Kong et al. 2018), where
CARMA observations were combined with single-dish datafrom the Nobeyama 45 m telescope to provide extended images
at about 0.01 pc resolution. The ﬁnal maps have an angularresolution of about 8″ (from 6″ to 10″) and a pixel size of 2″. The
velocity resolution is 0.25 km s−1 for 12CO and 0.22 km s−1 for13
CO and C18O.
2.2. The Polarization Data
The Planck satellite9 provides the 353 GHz thermal dust
polarized emission (Planck Collaboration et al. 2020a, 2020c)
tracing the large scale magnetic ﬁeld in Orion A. Based on theobservations of the High-Frequency Instrument (HFI) at
353 GHz, the Stokes parameters I, Q, and U and theirdispersion value (σI, σQ, and σU) maps have been obtained.
The resolution of these maps is 5′ and the pixel size is ∼1 71.
The polarization angle from the HFI Stokes maps may be
calculated asy Planck = 0.5 ´ arctan (U , Q) ,(1)

where ψPlanck varies from −90° to 90° with the HEALPix
convention. One has to use ψ = 0.5 × arctan(−U, Q) to convert
the Planck measurement to this IAU convention. The magnetic
ﬁeld (hereafter, the B ﬁeld) orientation can be obtained byadding 90° to the polarization angle: ψB = ψPlanck + 90°.
Furthermore, the B-ﬁeld orientation in equatorial coordinates
Figure 1. Distribution of H2 column density derived from Herschel continuum
Threeline integral
convolution(LIC;theCabral& Leedom1993)relation
Cabrallic maps from VGT using the 12CO (left), 13CO (middle), C18O (right) emission. The
data in Orion A (Poglitsch et al. 2010; Grifﬁn et al. 2010; Roy et al. 2013;Figure 2.
(FK5,
J2000)
isobtainedusing
followingangle
has been shown in the lower right corner of each panel. The top panels present the magnetic ﬁeld morphology measured with the VGT method. The bottom
Polychroni et al. 2013). The white contour level represents 3 × 1021 cm−2. Thebeam size
(Corradi
et al. 1998):
panels are the B-ﬁeld distributions measured with the combined VGT-VDA method. The color backgrounds are the intensity maps for 12CO, 13CO, and C18O(1-0)

orange contours show the region covered by the CARMA-NRO Orion Survey
integrated from VLSR = 1 to 15 km s−1. cos (l - 32.9)(Kong et al. 2018).

The Astrophysical Journal, 934:45 (11pp), 2022 July 20

Zhao et al.

結果・偏光の結果と比較して程度よく一致している
AM：一致度の指標(-1~1)

議論・12COより13COや18COの方がよく一致している
・偏光：opacityで重みづけされている(=高密度のところをトレース)
・輝線：12COは薄いところ、
13COや18COは濃いところをトレース→偏光とより近いところをトレースしている
13COやC18Oが偏光とよく一致(さらに、得られた磁場構造をもとにDCF法での磁場強度も推定してた)

Figure 3. The magnetic ﬁelds using the CO data and the Planck HFI data. Top: results of magnetic ﬁeld orientation from Planck polarization (white vectors) and CO
VGT (red vectors) in Orion A. Bottom: white and black vectors are for the Planck polarization and the red vectors show the magnetic ﬁeld directions derived from
VGT-VDA method for three molecular tracers 12CO 1-0 (left), 13CO 1-0 (middle), and C18O 1-0 (right). The beam size has been shown in the bottom right corners ofeach panel. The background are same as Figure 2. The mean AM values and their uncertainties are shown in the top left corner of each panel.

be used to trace material evolution in disks.

Molecular Gas Structures traced byfrom the MWISP Survey

13

CO Emission in the 18,190

12

CO Molecular Clouds

Lixia Yuan, Ji Yang, Fujun Du, Yang Su, Xunchuan Liu, Shaobo Zhang, Yan Sun, Xin Zhou, Qing-Zeng Yan,
Yuehui Ma F After the morphological classification of the 18,190 12 CO molecular clouds, we further investigate the propertiesof their internal molecular gas structures traced by the 13 CO(J = 1 0) line emissions. Using three diﬀerent methods to extract
the 13 CO gas structures within each 12 CO cloud, we find that ⇠ 15% of 12 CO clouds (2851) have 13 CO gas structures and these12
CO clouds contribute about 93% of the total integrated flux of 12 CO emission. In each of 2851 12 CO clouds with 13 CO gas
structures, the 13 CO emission area generally does not exceed 70% of the 12 CO emission area, and the 13 CO integrated flux does20
12
not exceed 20% of the CO integrated flux. We reveal a strong correlation between the velocity-integrated intensities of 12 COlines and those of 13 CO lines in both 12 CO and 13 CO emission regions. This indicates the H2 column densities of molecular13
13
12
clouds are crucial for the CO lines emission. After linking the CO structure detection rates of the 18,190 CO molecular
clouds to their morphologies, i.e. nonfilaments and filaments, we find that the 13 CO gas structures are primarily detectedin the 12 CO clouds with filamentary morphologies. Moreover, these filaments tend to harbor more than one 13 CO structure.
That demonstrates filaments not only have larger spatial scales, but also have more molecular gas structures traced by 13 COlines, i.e. the local gas density enhancements. Our results favor the turbulent compression scenario for filament formation, in
which dynamical compression of turbulent flows induces the local density enhancements. The nonfilaments tend to be in the
low-pressure and quiescent turbulent environments of the diﬀuse interstellar medium.

Dependence of Molecular Cloud Samples on Angular Resolution, Sensitivity, and Algorithms

Qing-Zeng Yan, Ji Yang, Yang Su, Yan Sun, Xin Zhou, Ye Xu, Hongchi Wang, Shaobo Zhang, Zhiwei Chen
F In this work, we investigate the observational and algorithmic eﬀects on molecular cloud samples identified from positionposition-velocity (PPV) space. By smoothing and cutting oﬀ the high quality data of the Milky Way Imaging Scroll Painting(MWISP) survey, we extract various molecular cloud samples from those altered data with the DBSCAN (density-based spatial
clustering of applications with noise) algorithm. Those molecular cloud samples are subsequently used to gauge the significance of sensitivity, angular/velocity resolution, and DBSCAN parameters. Two additional surveys, the FCRAO Outer Galaxy
Survey (OGS) and the CfA-Chile 1.2 m complete CO (CfA-Chile) survey, are used to verify the MWISP results. We foundthat molecular cloud catalogs are not unique and the boundary and therefore the number shows strong variation with angular背景・分子雲は星間物質の基本的な形態の一つ
低温(~10 K)で高密度(>30 cm^-3)
・Herschelから星形成にはフィラメント構造が重要
・Purple Mountain Observatoryを用いたMWISPサーベイでCOとその同位体の無バイアスサーベイが行われた
・18190個の分子雲が同定
・COで形態分類(フィラメントかそうでないか)が行われた
・フィラメントは数では10%程度だが放射の90%を担っている・フィラメントかそうでないかの空間分布に偏りはある一方、平均的なH2柱密度は空間的に偏りはない
・より高密度のガスのトレーサーである13CO観測から、これらの物理的背景を探る

The Astrophysical Journal Supplement Series, 261:37 (29pp), 2022 August

結果

Table 1The Number Detection Rates, Area Ratios, and Total Flux Ratios between the13
12
CO and CO Line Emission from Three Methods

・13COで同定されたのは右表

Methods

・1つの12CO分子雲中に複数のClipping
DBSCAN
Moment Mask

13COピークを持つものもある(~40%)
・13COで見つかった天体は、より大きく(空間、速度)、

Number Detection Rates

Area Ratios

Flux Ratios

13.5%
15.7%
15%

10.8%
20.3%
20.7%

4.1%
6.3%
7.3%

The Astrophysical Journal Supplement Series, 261:37 (29pp), 2022 August

傾向が見られた13

The C
three methcloud belo
12
within a
structures.
structuresof the extr
The mean1
within aof each p
its corresp
S (Vspan (l,grated ﬂux
an individ
0.166 × 0.
13
the CO l
and dv = 0(Tpeak,13 CO )1
extracted
The num
velocity s
intensities
by the thre
Yuan et al.

Note. The number detection rate is the number of 12CO clouds having 13CO
structures divided by the total number of 18,190. The area ratio is the ratio
between the total angular area of the extracted 13CO structures and the total
12
12
CO angular area of the 18,190 CO clouds. The ﬂux ratio is the total
integrated ﬂux of the extracted 13CO line emission divided by that of the 12CO
line emission.

より明るく
より温度が高い3

13

molecular clouds are identiﬁed to have CO emission. The
13
moment mask extracts CO line emission in 2735 molecular
clouds. The number detection rates in all of the 18,190
molecular clouds by the three methods are listed in Table 1.

・13COの分子雲は主に12COでの

13
12
Figure 5. The number distributions of the angular areas( 12CO ), velocity spans(Vspan, 12CO ), peak intensities (Tpeak, 12CO ), and integrated ﬂuxes (F 12CO ) of 12CO line
emission for 12CO molecular clouds with and without 13CO structures. The green histograms represent 12CO molecular clouds not having 13CO structures (non-13COdetects). The magenta ones are the 12CO molecular clouds having 13CO structures (13CO-detects).

3.3.3. Area Ratios between the
フィラメント構造を持つものの中にある

CO andCO Line Emission

12

The total angular area for the 18,190 CO molecular clouds
また、多くの場合複数の13COのクランプを持つ
2
The Physical Parameters ofTable 3
CO Line Emission for Non-13CO-detects and 13CO-detects

12

clouds, i.e., GMCs represent molecular cloud samples themselves.

Two Candidate KH 15D-like Systems from the Zwicky Transient Facility

Wei Zhu, Klaus Bernhard, Fei Dai, Min Fang, J. J. Zanazzi, Weicheng Zang, Subo Dong, Franz-Josef Hambsch,
Tianjun Gan, Zexuan Wu, Michael Poon F KH 15D contains a circumbinary disk that is tilted relative to the orbital
plane of the central binary. The precession of the disk and the orbital motion of the binary together produce rich phenomena in
the photometric light curve. In this work, we present the discovery and preliminary analysis of two objects that resemble the key
features of KH 15D from the Zwicky Transient Facility. These new objects, Bernhard-1 and Bernhard-2, show large-amplitude(> 1.5 mag), long-duration (more than tens of days), and periodic dimming events. A one-sided screen model is developed
to model the photometric behaviour of these objects, the physical interpretation of which is a tilted, warped circumbinary
disk occulting the inner binary. Changes in the object light curves suggest potential precession periods over timescales longer
than 10 years. Additional photometric and spectroscopic observations are encouraged to better understand the nature of theseinteresting systems.

Magnetic Field of Molecular Gas Measured with the Velocity Gradient Technique I.
Orion A

Mengke Zhao, Jianjun Zhou, Yue Hu, A. Lazarian, Xindi Tang, Willem A. Baan, Jarken Esimbek, Yuxin He,
Dalei Li, Weiguang Ji, Kadirya Tursun F Magnetic fields play an important role in the evolution of molecular clouds
and star formation. Using the Velocity Gradient Technique (VGT) model, we measured the magnetic field in Orion A using
the 12CO, 13CO, and C18O (1-0) emission lines at a scale of 0.07 pc. The measured B-field shows an east-west orientationthat is perpendicular to the integral shaped filament of Orion A at large scale. The VGT magnetic fields obtained from 13CO
and C18O are in agreement with the B-field that is measured from the Planck 353 GHz dust polarization at a scale of 0.55 pc.
Removal of density eﬀects by using a Velocity Decomposition Algorithm can significantly improve the accuracy of the VGT in
tracing magnetic fields with the 12CO (1-0) line. The magnetic field strength of seven sub-clouds, OMC-1, OMC-2, OMC-3,
OMC-4, OMC-5, L 1641-N, and NGC 1999 has also been estimated with the Davis-Chandrasekhar-Fermi (DCF) and MM2technique, and these are found to be in agreement with previous results obtained from dust polarization at far-infrared andsub-millimeter wavelengths. At smaller scales, the VGT proves a good method to measure magnetic fields.

The Astrophysical Journal Letters, 933:L21 (7pp), 2022 July 1

as the disk properties,
value of the inner bou
The best-ﬁt mode
seem to match the arc
in the lower-right panof the system light cu
the circumbinary dis
Winn et al. 2004; Po
failure of our overly
observations are enco
light-curve evolution.
As shown in theexcess in the SED ocold disk component
that a stellar binary
ary disk.

背景・KH 15D：特異な天体
非常に長い減光時間
傾いたwarped diskを持つか？
The Astrophysical Journal Letters, 933:L21 (7pp), 2022 July 1

同様の特徴を持つ天体をZTF variable star カタログから探した

結果
2天体発見した
The Astrophysical Journal Letters, 933:L21 (7pp), 2022 July 1
Table 1
Candidate Information

ZTF identiﬁer
R.A.J2000
Decl.J2000
Parallaxa (mas)P (days)tin (MJD)
tout (MJD)
vin (Rå/day)vout (Rå/day)

Bernhard-1

Bernhard-2

J202055.22+381323.1
20h20m55 22+3813¢ 23. 1
0.59 ± 0.16
192.10 ± 0.02
58227.81 ± 0.07
58339.29 ± 0.04
0.134 ± 0.003
0.150 ± 0.002

J071445.39-090152.1
07h14m45 39-901¢ 52. 1
0.34 ± 0.16
63.358 ± 0.003
59155.24 ± 0.04
59181.18 ± 0.03
0.416 ± 0.010
0.291 ± 0.003

Note.
a
Taken from Gaia Early Data Release 3 (Gaia Collaboration et al. 2021).
These values are not changed in Gaia DR3.

signals that closely resemble the occultation light curve of KH

Apart from a shor
several similar feature
Zhu et al.
of occultation, asymmof rebrightening at thegress regions in the
scatterings. Together
explain the archival
suggest the precession
sided screen model.
We attempted to ob
observations of Ber
ground. A few nights
32 inch telescope at th
at the Remote O
Hambsch 2012), andObservatory Global T
2021 December, wheearly 2022, more syst
1 m LCOGT telescoegress region. The
AstroImageJ (Col
Figure 1. Schematic of the one-sided, fully opaque screen model used in thiswork. The model is described by ﬁve parameters: the time and perpendicular
indicating a rather sm
velocity of the star at epochs of ingress (with subscript “in”) and egress (withoutside of the occulta
subscript “out”), respectively, and the orbital period of the star. The bottom
tions are available aspanel shows an example light curve from the model.
We observed Bern
Spectrometer on theemergence of the companion star, as was seen in the case of
UT 07:42 on 2022 Ja
KH 15D. If the central object is indeed a binary, one possible
occultation. At a see
explanation then is that the binary has fairly large eccentricity
without the iodine csuch that the companion star does not emerge when the primarysolution for that nighis deepest into the occulting disk. This is supported by the longN) of ∼18 per resolu
duration (i.e., >50% of the binary period) of the occultation
parameters, we selec
and the asymmetric ingress/egress features. Additionally,
5350–5500, 5500–5
eccentric binaries can help keep the surrounding circumbinary
6670–6780 Å, respec
disk misaligned (e.g., Martin & Lubow 2017; Zanazzi &ELODIE library (PruLai 2018; Smallwood et al. 2019). Alternatively, the compaeffective temperaturenion star may be very faint or even dark. Future spectroscopic
of log g = 4.37  0
observations may help resolve this issue.
K1.3 ± 0.5 type preWith a binary period of P = 192 days, the separation between
jek 2013). This spec
the binary components should be a = 0.65 au (Mtot M)1 3,
the broadband colors
where Mtot is the combined mass of the binary. Because theTable 2), assuming acircumbinary disk is likely tidally truncated (e.g., Lubow et al.
2017). Unlike the spe
2015; Miranda & Lai 2015), its inner radius is likely
the spectrum of Bern
astronomical units. Better knowledge of the binary, as wellconﬁrms the result

The Astrophysical Journal Letters, 933:L21 (7pp), 2022 July 1

Zhu et al.

disk occulting a binary star at an exterior orbit, as seen in EE
Cephei, ò Aurigae, and a few other similar systems (e.g.,
Mikolajewski & Graczyk 1999; Dong et al. 2014; Zhou et al.
2018). Additionally, the occultation periods, 192 and 63 days,
are too short to be explained by a precessing disk occulting one
single central object. Therefore, we conclude that thecircumbinary disk occulting a central binary is the mostplausible explanation for both systems. They are therefore KH
15D–like.
Given the scarce photometric observations, we do not apply
the detailed precessing disk model, as was developed for thecase of KH 15D (e.g., Chiang & Murray-Clay 2004; Winnet al. 2006; Poon et al. 2021). Instead, a simpliﬁed one-sided,
fully opaque screen model, as illustrated in Figure 1, is used to3
describe the time evolution of the occultation event. This model
involves ﬁve primary parameters: tin (tout) and vin (vout) are theepoch and projected perpendicular velocity of the star at the
Figure 3. Similar to Figure 2 but for the Bernhard-2 s
Figure2.
Bernhard-1
light
curves.
The
upper
panel
shows
the
available
data
from
the
ZTF
surveyandthearchival
Pan-STARRS(PS) data release 2. The out-ofmiddle of ingress (egress), respectively, and P is the period ofmodels, motivating future careful treatment of this important process.

The 30 Doradus Molecular Cloud at 0.4 pc Resolution with the Atacama Large Millimeter/submillimeter Array: Physical Properties and the Boundedness of CO-emitting
Structures

Tony Wong, Luuk Oudshoorn, Eliyahu Sofovich, Alex Green, Charmi Shah, Rémy Indebetouw, Margaret
Meixner, Alvaro Hacar, Omnarayani Nayak, Kazuki Tokuda, Alberto D. Bolatto, Mélanie Chevance, Guido De
Marchi, Yasuo Fukui, Alec S. Hirschauer, K. E. Jameson, Venu Kalari, Vianney Lebouteiller, Leslie W. Looney,
Suzanne C. Madden, Toshikazu Onishi, Julia Roman-Duval, Mónica Rubio, A. G. G. M. Tielens F We present
results of a wide-field (approximately 60 x 90 pc) ALMA mosaic of CO(2-1) and 13 CO(2-1) emission from the molecular cloud
associated with the 30 Doradus star-forming region. Three main emission complexes, including two forming a bowtie-shaped
structure extending northeast and southwest from the central R136 cluster, are resolved into complex filamentary networks.
Consistent with previous studies, we find that the central region of the cloud has higher line widths at fixed size relative to therest of the molecular cloud and to other LMC clouds, indicating an enhanced level of turbulent motions. However, there is noclear trend in gravitational boundedness (as measured by the virial parameter) with distance from R136. Structures observedin 13 CO are spatially coincident with filaments and are close to a state of virial equilibrium. In contrast, CO structures vary
greatly in virialization, with low CO surface brightness structures outside of the main filamentary network being predominantly
unbound. The low surface brightness structures constitute 10remnants of previously star-forming gas clumps, or alternatively
the CO-emitting parts of more massive, CO-dark structures.

A new method for direct measurement of isotopologue ratios in protoplanetary disks:
12
13
a case study of the CO/ CO ratio in the TW Hya disk

Tomohiro C. Yoshida, Hideko Nomura, Kenji Furuya, Takashi Tsukagoshi, Seokho Lee F Planetary systems
are thought to be born in protoplanetary disks. Isotope ratios are a powerful tool for investigating the material origin andevolution from molecular clouds to planetary systems via protoplanetary disks. However, it is challenging to measure theisotope (isotopologue) ratios, especially in protoplanetary disks, because the emission lines of major species are saturated. We
developed a new method to overcome these challenges by using optically thin line wings induced by thermal broadening. Asa first application of the method, we analyzed two carbon monoxide isotopologue lines, 12 CO 3 2 and 13 CO 3 2, fromarchival observations of a protoplanetary disk around TW Hya with the Atacama Large Millimeter/sub-millimeter Array. The
12
CO/13 CO ratio was estimated to be 20 ± 5 at disk radii of 70 110 au, which is significantly smaller than the value observedlow-pressure and quiescent turbulent environments of the diﬀuse interstellar medium.

Dependence of Molecular Cloud Samples on Angular Resolution, Sensitivity, and Algorithms

Qing-Zeng Yan, Ji Yang, Yang Su, Yan Sun, Xin Zhou, Ye Xu, Hongchi Wang, Shaobo Zhang, Zhiwei Chen
F In this work, we investigate the observational and algorithmic eﬀects on molecular cloud samples identified from positionposition-velocity (PPV) space. By smoothing and cutting oﬀ the high quality data of the Milky Way Imaging Scroll Painting(MWISP) survey, we extract various molecular cloud samples from those altered data with the DBSCAN (density-based spatial
clustering of applications with noise) algorithm. Those molecular cloud samples are subsequently used to gauge the significance of sensitivity, angular/velocity resolution, and DBSCAN parameters. Two additional surveys, the FCRAO Outer Galaxy
Survey (OGS) and the CfA-Chile 1.2 m complete CO (CfA-Chile) survey, are used to verify the MWISP results. We foundthat molecular cloud catalogs are not unique and the boundary and therefore the number shows strong variation with angularresolution and sensitivity. At low angular resolution (large beam sizes), molecular clouds merge together in PPV space, while
low sensitivity (high cutoﬀs) misses small faint molecular clouds and takes bright parts of large molecular clouds as single ones.
At high angular resolution and sensitivity, giant molecular clouds (GMCs) are resolved into individual clouds, and their diﬀuse
components are also revealed. Consequently, GMCs are more appropriately interpreted as clusters or aggregates of molecular
clouds, i.e., GMCs represent molecular cloud samples themselves.

Two Candidate KH 15D-like Systems from the Zwicky Transient Facility

Wei Zhu, Klaus Bernhard, Fei Dai, Min Fang, J. J. Zanazzi, Weicheng Zang, Subo Dong, Franz-Josef Hambsch,
Tianjun Gan, Zexuan Wu, Michael Poon F KH 15D contains a circumbinary disk that is tilted relative to the orbital
plane of the central binary. The precession of the disk and the orbital motion of the binary together produce rich phenomena in
the photometric light curve. In this work, we present the discovery and preliminary analysis of two objects that resemble the key
features of KH 15D from the Zwicky Transient Facility. These new objects, Bernhard-1 and Bernhard-2, show large-amplitude(> 1.5 mag), long-duration (more than tens of days), and periodic dimming events. A one-sided screen model is developed
to model the photometric behaviour of these objects, the physical interpretation of which is a tilted, warped circumbinary
disk occulting the inner binary. Changes in the object light curves suggest potential precession periods over timescales longer
than 10 years. Additional photometric and spectroscopic observations are encouraged to better understand the nature of theseinteresting systems.

ATOMS: ALMA Three-millimeter Observations of Massive Star-forming regions – XI.
From inflow to infall in hub-filament systems

Jian-Wen Zhou et al. F We investigate the presence of hub-filament systems in a large sample of 146 active proto-clusters,
using H13 CO+ J=1-0 molecular line data obtained from the ATOMS survey. We find that filaments are ubiquitous in protoclusters, and hub-filament systems are very common from dense core scales (⇠0.1 pc) to clump/cloud scales (⇠1-10 pc). The
proportion of proto-clusters containing hub-filament systems decreases with increasing dust temperature (Td ) and luminosityto-mass ratios (L/M ) of clumps, indicating that stellar feedback from Hii regions gradually destroys the hub-filament systems
as proto-clusters evolve. Clear velocity gradients are seen along the longest filaments with a mean velocity gradient of 8.71 km
s 1 pc 1 and a median velocity gradient of 5.54 km s 1 pc 1 . We find that velocity gradients are small for filament lengths larger
than ⇠1 pc, probably hinting at the existence of inertial inflows, although we cannot determine whether the latter are driven bylarge-scale turbulence or large-scale gravitational contraction. In contrast, velocity gradients below ⇠1 pc dramatically increase
as filament lengths decrease, indicating that the gravity of the hubs or cores starts to dominate gas infall at small scales. We
suggest that self-similar hub-filament systems and filamentary accretion at all scales may play a key role in high-mass starformation.

The Pre-main Sequence: Challenges and Prospects for Asteroseismology

Konstanze Zwintz, Thomas Steindl F Stars do not simply pop up on the main sequence. Before the stars arrive on thezero-age main sequence, they form in the collapses of molecular clouds, gain matter through accretion processes, and compress
their cores until hydrogen can burn in full equilibrium. Although this evolutionary phase lasts a relatively short time, it is theimprint of these important physical processes that is often ignored by simplified assumptions. While asteroseismology oﬀers agreat tool to investigate these physical processes, studying pre-MS oscillations in turn has the potential to further advance thefield. Asteroseismology of pre-main sequence stars faces observational and theoretical challenges. The remnants of their birthenvironment which is often still surrounding the young stars causes variability that can interfere with the signal of pulsations.
The lack of long time-base satellite observations in addition limits the applications of the method. Theoretical models of premain sequence stars include several assumptions and simplifications that influence the calculation of pulsation frequencies andexcitation properties of pulsation modes. Keeping all this in mind, the prospects for pre-main sequence asteroseismology are
manifold. An improved understanding of the structure of young stellar objects has the potential to answer some of the open

The Pre-main Sequence: Challenges and Prospects for Asteroseismology

Konstanze Zwintz, Thomas Steindl F Stars do not simply pop up on the main sequence. Before the stars arrive on thezero-age main sequence, they form in the collapses of molecular clouds, gain matter through accretion processes, and compress
their cores until hydrogen can burn in full equilibrium. Although this evolutionary phase lasts a relatively short time, it is theimprint of these important physical processes that is often ignored by simplified assumptions. While asteroseismology oﬀers agreat tool to investigate these physical processes, studying pre-MS oscillations in turn has the potential to further advance thefield. Asteroseismology of pre-main sequence stars faces observational and theoretical challenges. The remnants of their birthenvironment which is often still surrounding the young stars causes variability that can interfere with the signal of pulsations.
The lack of long time-base satellite observations in addition limits the applications of the method. Theoretical models of premain sequence stars include several assumptions and simplifications that influence the calculation of pulsation frequencies andexcitation properties of pulsation modes. Keeping all this in mind, the prospects for pre-main sequence asteroseismology are
manifold. An improved understanding of the structure of young stellar objects has the potential to answer some of the open
questions of stellar evolution, including angular momentum transport and the formation of magnetic fields. While gyrochronology, for example, struggles to determine the ages of the youngest clusters, pulsations in pre-main sequence stars can function as
an independent age indicator yielding higher precision for single stars. The increasing interest of stellar astrophysics in general
to investigate the formation and early evolution of stars and planets illustrates the growing importance of pre-main sequence
asteroseismology.