星形成ゼミ
担当：SFN#333 (1-7)
2020/11/06
竹村英晃（総研大D1）

1. A Novel Survey for Young Substellar Objects with the W-band Filter. I. Filter
Design and New Discoveries in Ophiuchus and Perseus
2. Selected aspects of the analysis of molecular line observation of edge-on
circumbinary disks
3. On the Nature of the T Tauri Triple System
4. Spectroscopic characterization of the known O-star population in Cygnus
OB2. Evidence of multiple star-forming bursts
5. Dense gas formation in the Musca ﬁlament due to the dissipation of asupersonic converging ﬂow
6. A High Angular Resolution Survey of Massive Stars in Cygnus OB2: JHK
Adaptive Optics Results from the Gemini Near-InfraRed Imager
7. The observational impact of dust trapping in self-gravitating discs

2

http://arxiv.org/pdf/2008.00010
http://arxiv.org/pdf/2008.10499

Selected aspects of the analysis of molecular line observation of edge-on circumbinary
disks
Roman Avramenko1 , Sebastian Wolf1 , Tobias F. Illenseer1 and Stig Rehberg1
1

University of Kiel, Institute of Theoretical Physics and Astrophysics, Leibnizstrasse 15, 24118 Kiel, Germany

E-mail contact: ravramenko at astrophysik.uni-kiel.deContext: Inner cavities, accretion arms and density waves are characteristic structures in the density distribution of
circumbinary disks. They are the result of the tidal interaction of the non-axisymmetric gravitational forces of thecentral binary with the surrounding disk and are most prominent in the inner region, where the asymmetry is mostpronounced.
Aims: The goal of this study is to test the feasibility of reconstructing the gas density distribution and quantifying
properties of structures in the inner regions of edge-on circumbinary disks using multiple molecular line observations.
Methods: The density distribution in circumbinary disks is calculated with two-dimensional hydrodynamic simulations.
Subsequently, molecular line emission maps are generated with 3D radiative transfer simulations. Based on these, weinvestigate the observability of characteristic circumbinary structures located in the innermost region for spatiallyresolved and unresolved disks.
Results: We find that it is possible to reconstruct the inner cavity, accretion arms and density waves from spatiallyresolved multi- wavelength molecular line observation of circumbinary disks seen edge-on. For the spatially unresolved
observation only an estimate for the density gradient in the transition area from cavity to inner disk rim can bederived.
Accepted by Astronomy & Astrophysics
http://arxiv.org/pdf/2008.10499• edge-on の circumbinary diskの密度分布を複数の分子輝線 (CO、C18O) の観測をする
18
ことで構築できるか調べた。
• 複数の分子輝線で空間分解できる観測の場合、inner cavity、accretion arm、density
waveの再現が可能。

• 空間分解できない場合に限り、cavity と 円盤のinner rimの間の密度勾配を推定できる。

Selected aspects of the analysis of molecular line observation of edge-on circumbinarydisks
A&A 642, A127 (2020)
Roman Avramenko1 , Sebastian Wolf1 , Tobias F. Illenseer1 and Stig Rehberg1
1

Table 1. Parameters of the hydrodynamic simulation.

University of Kiel, Institute of Theoretical Physics and Astrophysics, Leibnizstrasse 15, 24118 Kiel, Germany

grid-based• 密度、速度分布：2DE-mail contact:ravramenko at hydrodynamic
astrophysik.uni-kiel.de code Fosite
Parameter
Parameter value
Context: Inner cavities, accretion arms thinand density
are characteristic structuresin the density
distributionM of = M [M ]Mass of individual
binary components
1
diskwaves(Lynden-Bell• 垂直方向の密度分布：geometricalcircumbinary disks. They are the result of the tidal interaction of the non-axisymmetricgravitational forces of theM [M ]Initial disk mass
0.02
prim

sec

disk

axis the asymmetry is most a [au]central binary
the surrounding
disk and are most prominent in the innerSemi-major
region, where
1969; Shakura& withSunyaev
1973)
Innerboundaryradiusrin [au]
pronounced.
Outer boundary radiusr [au]
Aims: The goal of this study is to test the feasibility of reconstructing the gas
density distribution and quantifying out "• スケールハイト：垂直方向に等温の円盤を仮定して流体力
Eccentricity
properties of structures in the inner regions of edge-on circumbinary disks usingSimulation
multipletime
molecular line observations. tsim [yr]学シミュレーションで計算。
Methods: The density distribution in circumbinary disks is calculated with two-dimensional hydrodynamic simulations.

Subsequently, molecular line emission maps are generated with 3D radiative transfer simulations. Based on these, weTablestructures
2. Parameterslocatedof the radiativetransfer
simulation.region for spatiallyinvestigate the observability of characteristic circumbinary
in theinnermostresolved and unresolved disks.
Parameter
Results: We find that it is possible to reconstruct the inner cavity, accretion arms
and density waves from spatially
Stellar effective
temperature
T prim = T sec [K]resolved multi- wavelength molecular line observation of circumbinary disks seen edge-on.
For thespatially unresolved
Stellarradiusto inner disk rim
Rprimcan= Rsecobservation only an estimate for the density gradient in the transition area fromcavitybe[R ]
Stellarluminosity
L
=
L
prim
sec [M ]derived.
Inner disk radius
Outer disk radius
Simulation wavelengths

Accepted by Astronomy & Astrophysics
http://arxiv.org/pdf/2008.10499

rin [au]rout [au]sim [µm]

30
0.6 ⇥ a1000
0
5 ⇥ 105

Parameter value
5600
0.98
0.87
0.6 ⇥ a = 0.6 ⇥ 30 = 18
200
0.05 . . . 2000

the velocity fields to generate molecular line emission maps.
18
Based on these maps, we evaluated the feasibility of detecting
the cavity, accretion arms, and density wave.
The paper is divided into two parts. In the first part (Sect. 2),
we give a short overview of the applied density distributions
and radiative transfer simulations. Next, we discuss the simulated observations of the resulting maps in spatially resolved andunresolved cases (Sect. 3). The prime focus lies on the possibilityof reconstructing characteristic structures for the circumbinarydisks.

2. Density distributions and radiative transfer
simulations
In this section, we give a brief overview of the software used to
conduct the hydrodynamic and radiative transfer simulations. A
complete discussion can be found in Avramenko et al. (2017).

Fig. 1. Midplane temperature distribution fo

2.1. Density distributions

The density and gas velocity distributions were calculated using
the 2D grid-based hydrodynamic code Fosite (Illenseer &Duschl 2009). A full discussion of the simulation setup, as
well as the parameter space, is available in Avramenko et al.
(2017), where we investigated the feasibility of observing binary-assumption of a vertically isothermal
appropriate scale height, we iterated bescale height with Fosite using a given
and (b) subsequently calculating the(Ober et al. 2015JET2q1.-25.259920.25

Selected aspects of the analysis of molecular line observation of edge-on circumbinary
disks
1 of edge-on circumbinary 1disks
R. Avramenko
MolecularF.line
observation
Roman Avramenko1 , Sebastian
Wolfet1al.:, Tobias
Illenseerand Stig Rehberg
1

University of Kiel, Institute of Theoretical Physics and Astrophysics, Leibnizstrasse 15, 24118 Kiel, Germany

E-mail contact: ravramenko at astrophysik.uni-kiel.deContext: Inner cavities, accretion arms and density waves are characteristic structures in the density distribution of
circumbinary disks. They are the result of the tidal interaction of the non-axisymmetric gravitational forces of thecentral binary with the surrounding disk and are most prominent in the inner region, where the asymmetry is mostpronounced.
Aims: The goal of this study is to test the feasibility of reconstructing the gas density distribution and quantifying
properties of structures in the inner regions of edge-on circumbinary disks using multiple molecular line observations.
Methods: The density distribution in circumbinary disks is calculated with two-dimensional hydrodynamic simulations.
Subsequently, molecular line emission maps are generated with 3D radiative transfer simulations. Based on these, weinvestigate the observability of characteristic circumbinary structures located in the innermost region for spatiallyresolved and unresolved disks.
Results: We find that it is possible to reconstruct the inner cavity, accretion arms and density waves from spatiallyresolved multi- wavelength molecular line observation of circumbinary disks seen edge-on. For the spatially unresolved
observation only an estimate for the density gradient in the transition area from cavity to inner disk rim can bederived.
Accepted by Astronomy & Astrophysics

(b)

(a)

http://arxiv.org/pdf/2008.10499
18

Selected aspects of the analysis of molecular line observation of edge-on circumbinary
disks
Roman Avramenko1 , Sebastian Wolf1 , Tobias F. Illenseer1 and Stig Rehberg1
University of Kiel, Instituteof TheoreticalA&A 642,A127 (2020) Physics and Astrophysics, Leibnizstrasse 15, 24118 Kiel, Germany
Circumbinarydisk（空間分解）
1E-mail contact: ravramenko at astrophysik.uni-kiel.deFiber-like structure→accretion arm

Context: Inner cavities, accretion arms and density waves are characteristic structures in the density distribution of
circumbinary disks. They are the result of the tidal interaction of the non-axisymmetric gravitational forces of thecentral binary with the surrounding disk and are most prominent in the inner region, where the asymmetry is mostpronounced.
Aims: The goal of this study is to test the feasibility of reconstructing
the gas density distribution and quantifying
R. Avramenko et al.: Molecular line observation of edge-on circumbinary disks
properties of structures in the inner regions of edge-on circumbinary disks using multiple molecular 観測から求めた表面密度分布
line observations.
Methods: The density distribution in circumbinarydisks
is calculatedwith two-dimensional
our results (i.e.,
startingwith the circumstellarcase). Afterward,hydrodynamic simulations.
we connect
the distinctive
elements
in our datatransfer
with the density
Subsequently, molecular line emission maps
are generated
with
3D radiative
simulations. Based on these, we
gradient
expected
to
occur
at
the
inner
edge
of
a
circumbinary
investigate the observability of characteristic circumbinary structures located in the innermost region for spatiallydisk.
resolved and unresolved disks.
The midplane of the disk coincides with the x-y plane. We
Results: We find that it is possible to reconstruct
innercavity,accretion
arms
density waves from spatiallyare discussing theedge-ondisks
with theobserver’s
line andof sight
along
the y axis. of
Allcircumbinarymodels are presumed
to be edge-on.
located at aFor the spatially unresolved
resolved multi- wavelength molecular line
observation
disks seen
distance of
140 pc. in the transition area from cavity to inner disk rim can beobservation only an estimate for the density
gradient
derived.
3.1. Spatially resolved line observations

Accepted by Astronomy & Astrophysics

CO (J=2-1)

http://arxiv.org/pdf/2008.10499

3.1.1. Keplerian disk

CO (J=4-3)

Our simulation results are stored in a 3D data cube with two spatial dimensions (along the x and(a)(b) z axes) for each of the velocity
channels. In this study, we are interested in the spatial distribution of gas in the disk.18
To achieve better contrast and reduce thenumber of necessary plots, we integrated the flux density along
Fig. 4. Derived inner radii plotted onto the initial surface density distrithe vertical extent of the edge-on viewed disk and divide it by the bution. CO: J = 2 1 (black, dash-dotted); CO: J = 4 3 (black, dashed);
number of contributing pixels (see Fig. 2a for an example of an C18 O: J = 2 1 (white, dotted); C18 O: J = 4 3 (white, dashed).
unmodified edge-on Keplerian disk). Due to Keplerian motion,
each part of the disk moves with a specific projected velocity to
the line of sight of the observer, resulting in a frequency shift.
The projected velocity depends on the position along the x axis.
The values of the flux along a straight line through the origin
correspond to the radiation of the gas at a specific radius in the
disk. To determine the radius, one notes the x value in a velocity channel at which the flux falls to zero (for the derivation,
see Appendix A in Dutrey et al. 2017). The contributions fromdifferent radii are given along lines with different slopes in the18
diagram.
This interpretation of the velocity-position diagram is illustrated by the case of a Keplerian disk with a large cavity fromwhich the disk’s inner radius of 60 au and the corresponding
18
Keplerian velocity of ⇠3.6 km s 1 can be derived (Fig. 2b). As
both sides of the edge-on disk are observed, the extent of the
18
18separately (importantcavity in each direction can be determinedfor disks with non-circular cavities).
(c)(d) disk with a radial gap, the innerIn the case of the Keplerian
and outer radii of this gap can be identified (see Fig. 2c). Here,the (seelocation
extentof the gap
Fig. 3. Velocity-resolved surface brightness distribution of a circumbinary disk
Sect.and
3.1.2
for details).
(a)canCObeJdirectly= 2 1. deduced(b) CO Jfrom= 4 3.
18
18
the velocity-position diagram as well. A similar observation was(c) C O J = 2 1. (d) C O J = 4 3.

CO (J=4-3)
CO (J=2-1)

C O (J=4-3)
C O (J=2-1)

C O (J=2-1)

C O (J=4-3)

cal depth between
both
our models,
we assumed the
Selected
aspects
oflines.
the Inanalysisof molecularline observation of edge-on circumbinary
18
abundance
ratioofN(CO)/N(C
O)
=
500.
The
peaks
of
the
line
disks
correspond to the velocity channel reaching the outer edge of the1
Roman
Avramenko, Sebastian Wolf1 , Tobias F. Illenseer1 and Stig Rehberg1
ular line observation of edge-on
circumbinarydisks
disk (Number 3 in Fig. 5). From this we can infer that the shape1of Kiel,of Theoretical
Leibnizstrasse 15, 24118 Kiel, Germany
ofUniversity
the area inwhichInstitutethe opticaldepth ⌧ isPhysics
greater andthanAstrophysics,
unity

光学的厚さ

The linends to theoutwardching theng toward
behavior
locity on
elf on thent (1993),
velocity
ofile. For
lts in thec as well.
a are notat reason,
pectrum.

hape andprofiles.
ng on theepending
ransition
ofiles for= 4 3 forthe samenificantly
e in optiumed thef the line
dge of thehe shape
han unitychannels.
4 3. The
from thece in theologs andough theKeplerian disk

differs contact:
significantly
between at
isotopologs
for the those channels.
E-mailravramenko
astrophysik.uni-kiel.de
Figure 7 shows the optical depth of the line C18 O J = 4 3. The

Context: Inner cavities, accretion arms and density waves are characteristic structures in the density distribution of
black contour indicates the optical depth ⌧ = 1 seen from the
Optical depth for gravitational
the C18 O J = 3forces
2 lineofinthe
the Keplerian disk
circumbinary disks. They are the result of the tidal interaction of Fig.
the 7.
non-axisymmetricobserver (y-axis). In Fig. 8, one can see the difference in the with cavity at ⇠4.0 km s 1 (i.e., a radius of ⇠60 AU). The optical depth
central binary with the surrounding disk and are most prominent in the inner region, where the asymmetry is most
location of the ⌧ = 1 surface between different isotopologs and is measured (i.e., integrated) in the y direction. The black contour line
pronounced.
different lines. At this point we want to note that although the denotes the ⌧ = 1 boundary.
Aims: 18The goal of this study is to test the feasibility of reconstructing the18gas density distribution and quantifying
18
line C O is optically thinner compared to CO, it still reaches anproperties of structures in the inner regions of edge-on circumbinary disks using multiple molecular line observations.
optical depth of ⌧ > 1 in some parts of the disk, as can be seen
Methods: The density distribution in circumbinary disks is calculated with two-dimensional hydrodynamic simulations.
in Figs. 7 and 8.
Subsequently, molecular line emission maps are generated with 3D radiative transfer simulations. Based on these, weFollowing the discussion of the individual line profiles, weinvestigate the observability of characteristic circumbinary structures located in the innermost region for spatially
now discuss the line flux ratios. Figure 9a shows an example
resolved and unresolved disks. 18of the flux ratio for CO and C O for the line J = 4 3. For the
Results: We find that it is possible to reconstruct the inner cavity, accretion arms and density waves from spatially
Keplerian disk,wavelength
the flux ratio
has only two features: at 0.3 andresolved multimolecular line observation of circumbinary disks seen edge-on. For the spatially unresolved
1
2.8 km s , respectively. Comparing
the line profiles, one finds
observation only an estimate
1 for the density gradient in the transition area from cavity to inner disk rim can bethat the feature at 2.8 km s is caused by the difference in radiderived.

実線：τ=1

実線：τ=1C O (J=3-2)

C O (J=4-3)

ating areas between the isotopologs at the maximum extent ofAcceptedby channel
Astronomy& Astrophysics
the velocity(Number
3 in Fig. 5). For this reason, it canbe used to determine the velocity at the disk’s outer edge. Howhttp://arxiv.org/pdf/2008.10499

ever, for a disk with a less sharp edge, we expect this effect tobe less pronounced. The second feature at 0.3 km s 1 is causedby the velocity channel obscuring itself (Number 5 in Fig.
18 5).
Once again, the difference in abundance results in a difference insize of the ⌧ 1 area. This, in turn, results in the self-obscuring
occurring at slightly different velocities.
For the C18 O J = 4 3 to J = 3 2 line ratio (Fig. 9b), thefeatures occur at the same velocity as in Fig. 9a. The effect issmaller in both cases due to smaller differences in optical depth
between the two lines (see Fig. 8). In the previous case, this difference was the result of the difference in abundance between the

CO (J=4-3)

Fig. 8. Normalized density distribution. Plotted are optical depth ⌧ = 1
boundaries for transition lines CO J = 4 3 (green), C18 O J = 4 3(blue), and C18 O J = 3 2 (black).
A127, page 7 of 12

C18Oでも円盤の一部では光学的に厚くなる

Fig. 7. Optical depth for the C18 O J = 3 2 line in the Keplerian disk
with cavity at ⇠4.0 km s 1 (i.e., a radius of ⇠60 AU). The optical depth
is measured (i.e., integrated) in the y direction. The black contour line
denotes the ⌧ = 1 boundary.

Selected aspects of the analysis of molecular line observation of edge-on circumbinary
disks
Roman Avramenko1 , Sebastian Wolf1 , Tobias F. Illenseer1 and Stig Rehberg1
University of Kiel, Institute of Theoretical Physics and Astrophysics, Leibnizstrasse 15, 24118 Kiel, Germany
Keplerian disk（空間分解できないとき）
1

A&A 642,ravramenko
A127 (2020)
E-mail contact:
at astrophysik.uni-kiel.deline proﬁle

輝線強度比

A&A 642, A127 (2020)

J=3：J=4-3

Context: Inner cavities, accretion arms and density waves are characteristic structures in the density distribution of
circumbinary disks. They are the result of the tidal interaction of the non-axisymmetric gravitational forces of thecentral binary with the surrounding disk and are most prominent in the inner region, where the asymmetry is mostpronounced.
Aims: The goal of this study is to test the feasibility of reconstructing the gas density distribution and quantifying
properties of structures in the inner regions of edge-on circumbinary disks using multiple molecular line observations.
Methods: The density distribution in circumbinary disks is calculated with two-dimensional hydrodynamic simulations.
R. Avramenko
et al.: Molecular line observationof edge-on
Subsequently,
molecularline circumbinary
emissiondisks
maps are generated with 3D radiative transfer simulations. Based on these, weinvestigate the observability of characteristic circumbinary structures located in the innermost region for spatiallyresults (i.e., starting with the circumstellar case). Afterward,
andunresolved disks.
connect the distinctive elements in ourresolved
data with thedensitydient expected to occur at the inner edgeof a circumbinary
Results:
We find that it is possible to reconstruct the inner cavity, accretion arms and density waves from spatially.
resolved
multiobservation of circumbinary disks seen edge-on. For the spatially unresolved
The midplane of the disk coincides
withthe x-y plane.
We wavelength molecular line
(a)
(b)
(b)
(a) cavity to inner disk rim can be
discussing edge-on disks with the observer’s
line
of
sight
observation only an estimate for the density gradient in the transition area fromng the y axis. All models are presumed to be located at a
励起温度の違いderived.
ance of 140 pc.

Spatially resolved line observations

Accepted by Astronomy & Astrophysics
http://arxiv.org/pdf/2008.10499

1. Keplerian disk

τの違い

servation of edge-on circumbinary disks

simulation results are stored in a 3D data cube with two spadimensions (along the x and z axes) for each of the velocity
nnels. In this study, we are interested in the spatial distribu18
of gas in the disk. To achieve better contrast and reduce thember of necessary plots, we integrated the flux density along
Fig. 4. Derived inner radii plotted onto the initial surface density distrivertical extent of the edge-on viewed disk and divide it by the bution. CO: J = 2 1 (black, dash-dotted); CO: J = 4 3 (black, dashed);mber of contributing pixels (see Fig. 2a for an example of an C18 O: J = 2 1 (white, dotted); C18 O: J = 4 3 (white, dashed).
modified edge-on Keplerian disk). Due to Keplerian motion,h part of the disk moves with a specific projected velocity toline of sight of the observer, resulting in a frequency shift.
projected velocity depends on the position along the x axis.
(d)
(c)
(d)
(c)
values of the flux along a straight line through the origin
espondtotheradiation
of
the
gas
at
a
specific
radiusinthe18
Fig. 6. Keplerian disk line profile (see Sect. 3.2.1 for details). (a) CO, J = 4 3. (b) C O, J = 4 3. (c) Keplerian disk with cavity. CO J = 4 3 line
Fig. 9. Keplerian disk: selected line emission ratio (see Sect. 3.2.1 for details). (a) CO/C18 O, J = 4 3. The highlighted velocity channels at 0.3. emission.
To determine
the radius,
the x value
in cavity.
a velocFor details,
see Sect.one
3.2. notes(d) Kepleriandisk with
C18 O J = 4 3 line emission. For details, see Sect. 3.2.
and 2.8 km s 1 indicate the features caused by self obscuring and differences in radiating areas between the isotopologs, respectively. (b) C18 O,
channel at which the flux falls to zero (for the derivation,
J = 4 3/J = 3 2. The highlighted velocity channels at 0.3 and 2.8 km s 1 indicate the features caused by self-obscuring and differences in radiating
Appendix A in Dutrey et al. 2017). The contributions fromareas between the isotopologs, respectively. (c) CO/C18 O J = 4 3. The blue highlighted channel at 4.2 km s 1 indicates the velocity at the cavity
As wasshown
by Avramenko
et al.
(2017),
the wavelength
erent
radii
are givenalong lines
withdifferent
slopes in ofthethe cavity. We will first briefly discuss the case of a molecular line outer edge. (d) C18 O J = 4 3/J = 3 2 line emission ratio. The blue highlighted channel at 4.2 km s 1 indicates the velocity at the cavity’s outerdensitywave
isconnected
to
the
basic
parametersofthebinaryin an edge-on disk. After that we will address the line ratios for edge.
gram.
system,such as binary
mass
and binary separation.
the simple case of a Keplerian disk. This will allow us to betterThisinterpretationof thevelocity-position
diagram is illus4. Derived
radii plotted
onto
the initial
ed Fig.
by thecase ofinnera Keplerian
disk
with
a largesurface
cavitydensityfrom distri-identify the features associated with the presence of a gap in thetwo isotopologs. In this case, the difference in the optical depth is velocities in the center of the disk is indicative of the presence ofbution.
CO: Jinner= 2 1radius(black, ofdash-dotted);
4 3 (black, dashed);disk, followed by the case of a circumbinary disk.
ch3.2.
thedisk’s60 au andCO:
theJ =
corresponding
18 Spatially unresolved line observations
caused by the temperature gradient in the disk and the associated the cavity. However, the velocity at which this occurs differs for
1C18 O: J = 4 3 (white, dashed).
C
O:
J
=
2
1
(white,dotted);
In
order
to
understand
the
shape
of
a
molecular
line,
one
has
lerian velocity of ⇠3.6 km s can be derived (Fig. 2b). As
to understand the shape of the area of the disk in each velocity difference in excitation of the individual levels. Those features both isotopologs. Once again, we can attribute this difference tothe ofprevious
section,disk
we discussed
the potentialof spatially
h In
sides
the edge-on
are observed,
the extent
of theare a geometrical effect of the velocity channels distributed in the difference in optical depth. Due to a higher abundance of CO
observations
to constrain separately
selected featuresof the channel. A more detailed discussion of line formation in proto- the disk and the way we observe the line emissions. They will compared to C18 O, the flux level increase is stronger for CO. Thistyresolvedin eachline
direction
can be determined(importantdisk withmorphology,
suchcavities).
as the presence and shape of a central planetary disks is available in Sect. 2.2 of Beckwith & Sargent appear in some form in all graphs presented from now on and results in the maximum flux being reached at a higher velocity,
disks
non-circular
cavity.
However,theangularresolution
sensi- (1993). The exact shape of the covered area can be calculated will be subsequently ignored in the main text.
In the case of the Keplerian disk
with aand/or
radial brightness
gap, the innercorresponding to a smaller radius. Comparing this to the flux
tivity radiiof theofobservations
be insufficientstudy
mor- withouter
this gap canmay
be identified(see toFig.
2c).thisHere,ratio shown in Fig. 9c, one finds that this difference results in aphology.and
Forextent
this reason,
investigate
the feasibilityof deriving
locationof thewegap
can be directlydeducedfromclearly defined maximum in the flux ratio diagram.
GM
star
3.2.2. Keplerian disk with cavity
selected disk parameters
spatially
unresolved
observations.
r( ) =
sin2 ✓ cos2 ,(3)velocity-position
diagramusing
as well.
A similar
observationwas
In the case of the C18 O J = 4 3 to J = 3 2 (Fig. 9d) ratio,v
Toachievethis,
we
calculatedtheratiosbetweentwo
spatiallyobs
ady made by Dutrey et al. (2017), resulting in the identiWe now discuss the case of a Keplerian disk with an inner cavity the maximum is much less pronounced. As in the previous case,integrated
molecularlines. InSaucer
one case,weusingcombined
5. Keplerian disk line CO, J = 4 3 emission. Top: spatially (R = 60 au), which is comparable in size to the depleted region the feature is caused by the difference in optical depth between
tionof a gap
in the Flying
disk
CO Jdata= 2from
1 Fig.
with Gimages
being forthe specificgravitational
constant,
Mstar
the massthethe same isotopolog but for two different transition lines. In the resolved
channels
numbered
1 through5. of
Bottom:in our circumbinary disk. Similar to the previous subsection, we the two lines and the relative level population of both levels.
ervations.
centralobject,The
vobschannels
the average
projected
velocity
toward theinsecond case, we used the same transition line J but considered CO
line
profile.
from
the
top
image
are
highlighted
will address the individual line profiles first before continuing The lines have different excitation energies. This results in the
Indifferent
the finalisotopologs.
example, theKepleriandisk
density
distribution
This allows one to trace regions where the observer, and and ✓ the angles in polar coordinates. Figure 5cavitycavity34line proﬁleとイメージ

5

1

2

3

4

2

1

5

blue and denoted by a number.

with the flux ratios. Figures 6c and d show line profiles for line

J = 4 3 line having a higher excitation ratio compared to theSelected aspects of the analysis of molecular line observation of edge-on circumbinary
disks
Roman Avramenko1 , Sebastian Wolf1 , Tobias F. Illenseer1 and Stig Rehberg1
A&A 642, A127 (2020)

University of Kiel, Institute of Theoretical Physics and Astrophysics, Leibnizstrasse 15, 24118 Kiel, Germany
Circumbinarydisk（空間分解できないとき）
1E-mail contact: ravramenko at astrophysik.uni-kiel.deContext: Inner cavities, accretion arms and density waves are characteristic structures in the density distribution of
circumbinary disks. They are the result of the tidal interaction of the non-axisymmetric gravitational forces of thecentral binary with the surrounding disk and are most prominent in the inner region, where the asymmetry is mostpronounced.
Aims: The goal of this study is to test the feasibility of reconstructing the gas density distribution and quantifying
properties of structures in the inner regions of edge-on circumbinary disks using multiple molecular line observations.
Methods:
The density
distribution
in circumbinarydisks
is calculated
R. Avramenko
et al.: Molecularline observationof edge-on
circumbinarydisks with two-dimensional hydrodynamic simulations.
Subsequently, molecular
CO (J=4-3)のline
proﬁleline emission maps are generated with 3D radiative transfer simulations. Based on these, weinvestigate the observability of characteristic
circumbinary
locatedHowever,in the innermost
region for spatiallyrequired sensitivity
for thestructures
method presented.
we stillhave to evaluate whether the sensitivity of the current instruresolved and unresolved disks.
ALMA thein particular,
is highenougharms
to observe
the waves from spatially
Results: We find that it is possible toments,
reconstruct
inner cavity,
accretionand density
features, inofthis
case the cavity
in thecenterof the For
disk.the spatially unresolved
resolved multi- wavelength molecular studiedline observation
circumbinary
disks
seen
edge-on.
The
peak
fluxesinthesynthetic
imagespresented
range
betweenobservation only an estimate for the density gradientin the transition area from cavity to inner disk rim can be
0.435 Jy for C18 O line J = 2 1 and 40.9 Jy for CO line J = 4 3.
derived.
However, we are not interested in the regions that contribute to(b)the line maxima, but rather (a)the wings of the line. At these wings,
Accepted by Astronomy & Astrophysics
the flux reaches values of, at most, an order of magnitude below
http://arxiv.org/pdf/2008.10499the line maximum.
Since we are not interested in a high spatial resolution, we
chose the ALMA antenna configuration with the smallest base18
line possible (i.e., configuration
Number 1 from Observational
Cycle 7). This results in a resolution of 3.38 as, 1.47 as, and0.98 as for lines J = 1 2, J = 2 3, and J = 3 4, respectively. The
difference in transition frequency between both isotopologs issmall enough for the resolution to be considered the same in bothFig. 10. Circumbinary disk line CO, J = 4 3 flux (see Sect. 3.2.3 for cases. At an assumed object distance of 140 pc and disk diameterdetails).
of 400 AU, the disk has an angular extent of 2.85 as. However, ata spectral resolution of 141 m s 1 , the area contributing to eachdisk.
The excitation ratio changes further inside the disk. Here individual channel is much smaller. This makes it possible tocavityでもまったくガスが存在しない
the temperature is lower compared to the disk’s outer layer. This cover the contributing regions with a single beam for all three1
lines. As was the case with the synthetic lines in the previous
changemanifests itself in the feature at4⇠4.2
km s
s -1
inの速
Fig. 9d.
わけではないので、>
km
subsection, we integrated the flux over the spatial dimensions
for each velocity channel. We simulated an ALMA observation
度を持つガスも存在する。
3.2.3.
Circumbinary diskof 2 h using the ALMA simulation tool kit CASA (McMullin et al.
(d)(c)
We begin our discussion by once again introducing an unaltered 2007) for three different lines for both isotopologs. For this, we
the default
precipitablevapor
line profile. The emission for CO J = 2 1 for a circumbinary Fig.assumed
11. Circumbinary
disk: value
selectedfor
linetheemissionratio (seewater
Sect. 3.2.3
forof
details). (a) CO to C18 O line J = 4 3. The blue highlighted channel
1
mm5.1andtemperatureof cavity’s
269.0 K.
compar5.1 andkmans ambientindicates thevelocity at theouterByedge.
(b) CO to C18 O line J = 2 1. The blue highlighted channel at 4.7 anddisk is shown in Fig. 10. Similar to the case of a Keplerian disk at 0.5
1 integrated flux values before and after applying CASA, we
km stheindicates the velocity at the cavity’s outer edge. (c) CO line J = 3 2/2 1. The blue highlighted channel at 6.1 and 6.1 km s 1 indicateswith a cavity (Fig. 6c), we detect a flux deficiency for high veloc- 4.8 ing
18
velocityat thethecavity’souter edge. (d) Cup
Otoline= 3 2/2
1. Theblue highlighted
channel at 4.2 and 4.2 km s 1 indicates the velocity at theassureflux conservation
theJ noiselevel.
Figure12
ities compared to the Keplerian disk (Fig. 6a). However, since the cancavity’s outer edge.
the cavity in the circumbinary disk is not completely gas-free, shows an example of a line ratio observed with ALMA. In thiswe still detect a significant flux for velocities above 4 km s 1 . image, one can discern the general form of a flux ratio before it isprocessed
CASAline.
(compareto Fig.
Theandratioscoincideline widthwith
for each
However,as the11a).
binarysinglechannels. Subsequently, we assigned the area of the disk associIt is possible to determine the size of the inner cavity from a totalwellinchannelswithhigherfluxes.
Since
it
is
not
possibleto with a specific channel the line ratio derived in that channel.
starvelocity
profilesdiffer,
this
leads
to
errorsindetermining
ated
simple line profile, as was done by Dutrey et al. (2008). To doSelected aspects of the analysis of molecular line observation of edge-on circumbinary
disks
Roman Avramenko1 , Sebastian Wolf1 , Tobias F. Illenseer1 and Stig Rehberg1
University of Kiel, Institute of Theoretical Physics and Astrophysics, Leibnizstrasse 15, 24118 Kiel, Germany
観測可能性（ALMAで観測できるか）1

E-mail contact: ravramenko at astrophysik.uni-kiel.de• ALMAで空間分解はしないとして、感度が足りるか
Context: Inner cavities, accretion arms and density waves are characteristic structures in the density distribution of
circumbinary disks. They are the18resultof the tidal interaction Jy、COof the non-axisymmetricgravitational
O (J=1-0)で0.435(J=4-3)で40.9
Jyforces of the• 今回のイメージのピーク強度は、C
central binary with the surrounding disk and are most prominent in the inner region, where the asymmetry is mostpronounced.
(速度が速い部分、wing)の場合は、一桁程度小さいと思われる。
• ただし、興味のある領域•

Aims: The goal of this study is to test the feasibility of reconstructing the gas density distribution and quantifying
properties of structures in the inner regions of edge-on circumbinary disks using multiple molecular line observations.
Methods: The density distribution in circumbinary disks is calculated with two-dimensional hydrodynamic simulations.
最も基線長が短くなるALMAのアンテナ配置を仮定
Subsequently, molecular line emission maps are generated with 3D radiative transfer simulations. Based on these, weinvestigate the observability of characteristic circumbinary structures located in the innermost region for spatially
分解能はJ=2-1輝線で3.38
as (arcsec?)、J=3-2輝線で1.47 as、J=4-3輝線で0.98 as
resolved and unresolved disks.
Results: We find that
it is possible to reconstruct the innerasになる。
cavity, accretion arms and density waves from spatially
直径400 pcの円盤を140
pcの距離に置くと、2.85
resolved multi- wavelength molecular line observation of circumbinary disks seen edge-on. For the spatially unresolved
observation only
estimate for the density gradient in the transition area from cavity to inner disk rim can be
速度分解能が141
mans-1のとき、各チャンネルに入ってくるイメージの範囲はビームサイズ以下なので、derived.

•••

3つの遷移の輝線を1ビームで観測することができる。
Accepted by Astronomy & Astrophysics
R. Avramenko et al.: Molecular line observa
http://arxiv.org/pdf/2008.10499• CASAを使って、ALMAで2時間模擬観測する（水蒸気：0.5 mm、ambient temperature 269 K）• 観測可能18
輝線比の最大値は観測できていないので、cavityのサイ•ズはわからない• 4.5 km s-1 付近で輝線比の上昇が見られるので、制限をつけることはできる (upper boundary)Fig. 12. Synthetic observation of a circumbinary disk CO/C18 O line
J = 4 3 emission ratio. Configuration 1 of the ALMA Observational
Cycle 7 is used with the integration time of 2 h and assumed distance of
140 pc. The black error bars indicate a 1 uncertainty.

Fig
sho
sym

4

https://arxiv.org/pdf/2009.03861
http://arxiv.org/pdf/2008.09917

Spectroscopic characterization of the known O-star population in Cygnus OB2. Evidence of multiple star-forming bursts
S.R. Berlanas1,2,3 , A. Herrero2,3 , F. Comerón4 , S. Simón-Díaz2,3 , D.J. Lennon2 et al.
Departamento de Física Aplicada, Universidad de Alicante, 03690 San Vicente del Raspeig, Alicante, Spain; 2
Instituto de Astrofísica de Canarias, 38200 La Laguna, Tenerife, Spain; 3 Departamento de Astrofísica, Universidad
de La Laguna, Tenerife, Spain; 4 ESO, Karl-Schwarzschild-Strasse 2, 85748 Garching bei München, Germany
1E-mail contact: sara.rb at ua.es
Cygnus OB2 provides a unique insight into the high-mass stellar content in one of the largest groups of young massive
stars in our Galaxy. Although several studies of its massive population have been carried out over the last decades, anextensive spectroscopic study of the whole known O-star population in the association is still lacking. In this work, wecreated the most complete spectroscopic census of O stars carried out so far in Cygnus OB2 using already existing andnew spectroscopy. We present the spectra for 78 O-type stars, from which we identify new binary systems, obtain the
distribution of rotational velocities, and determine the main stellar parameters for all the stars in the region that havenot been detected as double-line spectroscopic binaries. We also derive radii, luminosities, and masses for those stars
with reliable Gaia astrometry, in addition to creating the Hertzsprung-Russell Diagram to interpret the evolutionary
status of the association. This work has shown the improvement reached when using accurate spectroscopic parameters
and astrometry for the interpretation of the evolutionary status of a population, revealing, in the case of Cygnus OB2,
at least two star-forming bursts at ∼3 and ∼5 Myr. We find an apparent deficit of very fast rotators in the distributionof rotational velocities. The inspection of the dynamical distribution of the sample has allowed us to identify nine O
stars with peculiar proper motions and discuss a possible dynamical ejection scenario or past supernova explosions in
the region.
Accepted by A&A

OB2 (< 2 kpc) の既知のO型星（Galactic O-Star Spectroscopic Survey,• Cygnus
http://arxiv.org/pdf/2008.09917
GOSSS）の分光観測を行った。
• 78個のO型星のスペクトルを得て、2つの連星を新たに同定した。
19• ~3 Myr前と~5 Myr前に活発な星形成が起きたと考えられる。

• 9個のO型星は特異な固有運動をしており、その原因としてはdynamical ejectionあるいは超新星爆発が考えられる。

Phase 2

17A

July 2017Blue

14.5 < B < 16.0

Spectroscopic characterization of the known O-star population
CygnusOB2.
17B in August
2017 Blue+ Red Evi14.5 < B < 16.0
dence of multiple star-forming
burstsA&A 642, A168
(2020)
S.R. Berlanas

1,2,3, A. Herrero

2,3

12 O-type2 + 14 O-type

Notes. Blue and Red indicate the (3900–5100 Å) and (6100–6800 Å) wavelength regions. Exposure times vary between 150 to 10 000
2,3each star.
on the magnitude of, F. Comerón , S. Simón-Díaz, D.J. Lennon2 et al.

4

Table 2. 03690
Telescopes,San
instruments,and settings
in this work.
Departamento de Física Aplicada, Universidad de Alicante,
Vicentedel used
Raspeig,
Alicante, Spain; 2
Instituto de Astrofísica de Canarias, 38200 La Laguna, Tenerife, Spain; 3 Departamento de Astrofísica, Universidad
Instrument bei
Grating
Telescope
Resolving power
de La Laguna, Tenerife, Spain; 4 ESO, Karl-Schwarzschild-Strasse 2, Source
85748 Garching
München,Germany

1

1
ISIS
600B
WHT
3000
2
TWIN
1200
CAHA-3.5m
3000
3Albireo1800
OSN-1.5m
2500
Cygnus OB2 provides a unique insight into the high-mass stellar content
of young massive
4a in one
HRSof the largest
600g4739 groups
HET
30 000
HRS carried
600g4739
HET last decades,
30 000 anstars in our Galaxy. Although several studies of its massive population4bhave beenout over the
4c
HRS
600g6302
HET
30 000extensive spectroscopic study of the whole known O-star population in4dthe associationis still lacking.
HRS
600g6302HETIn this work,
30 000 wecreated the most complete spectroscopic census of O stars carried out 5a
so far in
Cygnus OB2
using alreadyexisting
andISIS
H2400B
WHT
13 6005b
ISISR1200R
WHT
9300
new spectroscopy. We present the spectra for 78 O-type stars, from which we identify new binary systems, obtain the
6a
IDS
R1200B
INT
5000
distribution of rotational velocities, and determine the main stellar parametersstars in thehave
6b
IDSfor all the
H1800V
INTregion that
7200

E-mail contact: sara.rb at ua.es

S /Nrange (Å)# Stars⇠300

3900–5500
3900–5100
3900–5100
3800–4700
4700–5700
5300–6300
6400–7400
3900–5100
5500–6800
3900–5100
6100–6800

20
15
3
12
12
12
12
15
15
27
66

⇠300

⇠300
100
100
100
100
>100
>150
>100
>150

not been detected as double-line spectroscopic binaries. We also derive radii, luminosities, andTotal
massesthose!stars
numberforof spectra
209
Total
number
of
stars
!
158
with reliable Gaia astrometry, in addition to creating the Hertzsprung-Russell Diagram to interpret the evolutionary
Total number of stars (not repeated) ! 78
status of the association. This work has shown the improvement reached when using accurate spectroscopic parameters
Notes. ofSpectrafor the detected binarystars are included
table.
data fromsources 1, 2, and 3 belong to the GOSSS cataand astrometry for the interpretation of the evolutionary statusa population,
revealing,in thein thecaseofSpectral
CygnusOB2,
et al. (2011) and Maíz Apellániz et al. (2016) for further observing details.
at least two star-forming bursts at ∼3 and ∼5 Myr. We find an apparent deficit of very fast rotators in the distributionof rotational velocities. The inspection of the dynamical distributionof the sample has allowed us to identifyAnineO
spectra at R ⇠ 2500–3000. The GOSSS data used in this work
brief summary of the data used in this work istars with peculiar proper motions and discuss a possible dynamicalejectionor pastwere observed
between scenario
2007 and 2014
using supernova
three different explosions
Table 2. Theinfinal spectral sample is composed of
instruments: the Albireo spectrograph at the 1.5 m telescope of stars (12 of them previously classified as SB2) whthe region.
Accepted by A&A
http://arxiv.org/pdf/2008.09917

Fig. 2. Example of the new SB2 detections: HeI lines in stars

the Observatorio de Sierra Nevada (OSN), the TWIN spectrograph at the 3.5 m telescope of Calar Alto Observatory (CAHA,
Centro Astronomico Hispano-Aleman), and the ISIS spectroFig.
1. arm)Inverse8 µm Telescope
image showing
graph
(blue
at the Spitzer
William Herschel(WHT) ofthe theObservatorio
del
Roque
de
los
Muchachos(ORM).
location of the known O-type population
WeCygnusalso haveOB2
accessspectrarepresented
from The Hobby-Eberly
in(78to stars
by green
Telescope (HET) obtained by A. Pellerin. These data weredots). throughout
The solid 2012line circle
1 degreeobserved
in fourdelimits
different the
spectralrangesradiusarea
adoptedfortheassociation.
For
ref19(3800–4700, 4700–5700, 5300–6300 and 6400–7400 Å) using
erence,thedashed-dottedline
circleshows
thethe High-Resolution Spectrograph (HRS) at R ⇠30 000 andthe
600g4739/6302
gratings.
have eta totalof 48 spectraarea consideredby We
Wrightal. (2015)
indicat-for
12 stars(onecorein eachspectralrange). The S/N of these spectra
ing theof theassociation.
is variable, ranging from 100 to 300.
Finally, we also include spectra observed by us in different runs at the WHT using the ISIS spectrograph (a total of
separated spectra for#5A and
For and
theredtrapezium-like30 spectra,
15 in#5B.
each bluearms). These datasyswere
acquiredintwodifferent
observing
runs.
For
2015,
we
chose
tem Cyg OB2 #22 Maíz Apellániz (2010) has identified a total
the H2400B grating for the blue arm, which provides a resolvingof ten componentspower
andoftheGOSSS
has provided⇠13 600
at 4500 Survey
Å. As the dichroic
allows us tospecobserve
tral data for the first
five O components
B, C,
D andgratingE).
simultaneouslywith the red arm,(A,we usedthe R1200R(R ⇠ 9300
at 6500
Å). Additionally
we beenincludedstars observed
At least four O-typevisualcomponents
havedetectedinby A. Herrero in 2003 also using ISIS at the WHT with the same
the Cyg OB2 #8 trapezium-likesystem(Maízgratings).
Apellániz
et specal.
configuration (H2400B
and R1200R
All ISIS
2012). The first component,#8A,(fromhas100been
identified
tra have S /N >100
to 200,depending as
on a
theSB2stellarmagnitude).
star composed by two early O-type stars (De Becker et al. 2004;

Maíz Apellániz et al. 2019). Both Cyg OB2 #8 and #22 havebeen traditionally treated as multiple stars but as already pointed
out by Bica et al. (2003), they should be considered as two clusters likely constituting the core of Cygnus OB2 and hosting thebrightest stars of the area. A recent analysis by Maíz Apellániz

distribution is shown in Fig. 1. The main data and p
information are presented in Table A.1.
3.1. Binary fraction

A large number of multiplicity studies among massiv
been conducted during the last years (see Sana 2017,
overview) where the number of detected massive O
ries has been continuously revised and updated. T
OB2 Radial Velocity Survey is one of the most rel
tiplicity census carried out in this association (Kim
2007, 2008, 2009, 2012, 2015; Kobulnicky et al.

Spectroscopic characterization of the known O-star population in Cygnus OB2. Evidence of multiple star-forming bursts
S.R. Berlanas1,2,3 , A. Herrero2,3 , F. Comerón4 , S. Simón-Díaz2,3 , D.J. Lennon2 et al.
Departamento de Física Aplicada, Universidad de Alicante, 03690 San Vicente del Raspeig, Alicante, Spain; 2
Instituto de Astrofísica de Canarias, 38200 La Laguna, Tenerife, Spain; 3 Departamento de Astrofísica, Universidad
de La Laguna, Tenerife, Spain; 4 ESO, Karl-Schwarzschild-Strasse 2, 85748 Garching bei München, Germany
1E-mail contact: sara.rb at ua.es

Accepted by A&A
http://arxiv.org/pdf/2008.09917

19

S. R. Berlanas et al.: Spectroscopic characterization of the known O stars in Cygnus OB2

Cygnus OB2 provides a unique insight into the high-mass stellar content in one of the largest groups of young massive
stars in our Galaxy. Although several studies of its massive population have been carried out over the last decades, anextensive spectroscopic study of the whole known O-star population in the association is still lacking. In this work, wecreated the most complete spectroscopic census of O stars carried out so far in Cygnus OB2 using already existing andnew spectroscopy. We present the spectra for 78 O-type stars, from which we identify new binary systems, obtain the
distribution of rotational velocities, and determine the main stellar parameters for all the stars in the region that havenot been detected as double-line spectroscopic binaries. We also derive radii, luminosities, and masses for those stars
with reliable Gaia astrometry, in addition to creating the Hertzsprung-Russell Diagram to interpret the evolutionary
status of the association. This work has shown the improvement reached when using accurate spectroscopic parameters
and astrometry for the interpretation of the evolutionary status of a population, revealing, in the case of Cygnus OB2,
at least two star-forming bursts at ∼3 and ∼5 Myr. We find an apparent deficit of very fast rotators in the distributionof rotational velocities. The inspection of the dynamical distribution of the sample has allowed us to identify nine O
stars with peculiar proper motions and discuss a possible dynamical ejection scenario or past supernova explosions in
the region.

Spectroscopic characterization of the known O-star population in Cygnus OB2. Evidence of multiple star-forming bursts
A&A 642, 2,3
A168(2020)
S.R. Berlanas1,2,3 , A. Herrero, F.
Comerón4 , S. Simón-Díaz2,3 , D.J. Lennon2 et al.
1
Departamentode Física Aplicada,
Universidad de Alicante, 03690 San Vicente del Raspeig, Alicante, Spain; 2This study
O+B(Berlanas etal. 2019) 分布
3

Instituto de Astrofísica de Canarias, 38200 La Laguna, Tenerife, Spain; Departamento de Astrofísica, Universidad
de La Laguna, Tenerife, Spain; 4 ESO, Karl-Schwarzschild-Strasse 2, 85748 Garching bei München, Germany• 遠ざかっていく固有運動の原因

E-mail contact: sara.rb at ua.es

Cygnus OB2 provides a unique insight into the high-mass Fig.
stellarcontent
in one oflargest groupsof young massive
9. Spatial
distributionof thethe samples
は超新星爆発かdynamicalin B19(left) and havethis paper(right).
Coordistars in our Galaxy. Although several studies of its massive
population
been
carriedout over the last decades, annates are from the Gaia DR2 catalog. Colextensive spectroscopic study of the whole known O-star populationin the association is still lacking.
In this work,
weejection
かもしれない。
ors identify the different groups. Group 1
created the most complete spectroscopic census of O stars members
carried areoutrepresented
so far in by
Cygnus
OB2 using already existing andblue symbols.
Groupsfrom
2, 0, which
and 3 bywe
red,identify
cyan andnew
greenbinary systems, obtain the
new spectroscopy. We present the spectra for 78 O-type stars,
symbols.
Stars
with RUWE
in
distribution of rotational velocities, and determine the mainstellarparametersfor>1.4
all (only
the stars
in the region that havethe right plot) are represented with grey
観測領域から遠ざかる固有運動
not been detected as double-line spectroscopic binaries. We
also derive radii, luminosities, and masses
for those stars
symbols.
with reliable Gaia astrometry, in addition to creating the Hertzsprung-Russell Diagram to interpretthe evolutionaryを持つO型星の年齢は2Myrでstatus of the association. This work has shown the improvement reached when using accurate spectroscopic parameters
1.35
pc
固有運動
and astrometry
for the interpretation of the evolutionary statusof a population,
revealing, in the あり、いずれのシナリオでも説case of Cygnus OB2,
at least two star-forming bursts at ∼3 and ∼5 Myr. We find an1.35
apparentof very
pcdeficit- 1.76
pc fast rotators in the distributionof rotational velocities. The inspection of the dynamical distribution of the sample has allowed 明できる
us to identify nine O
1.76
pcstars with peculiar proper motions and discuss a possible dynamical ejection scenario or past supernova explosions in
the region.
それ以外•• ただし、観測領域が狭いため、

Accepted by A&A
http://arxiv.org/pdf/2008.09917

Fig. 10. Gaia DR2 proper motion distribution of the samples in B19 (left) and thispaper (right). Colors identify the groups as
in Fig. 9 and light gray is used for stars with
19
RUWE
>1.4.

A&A 642, A168
(2020)
showsa strong stellar concentration, whereas the other groups
5.3. Spatial and dynamical distribution from Gaia DR2

In B19, the spatial substructure of the
Cygnus OB2 associa固有運動tion using parallaxes from Gaia DR2 was explored. The sample
used for the analysis comprised known OB members. Using a
Bayesian methodology B19 found evidence of two different stellar groups superposed on the association but separated along
the line-of-sight by ⇠400 pc. Taking into account the spectral
analyses and the two age bursts of O-type stars found in thiswork, we explore further the relationship between both groups
and their dynamical state. We note that B19 include objects withconfirmed OB spectra and RUWE 1.4, whereas in the present
work we only include the O stars, but independently of their
RUWE value. Thus, B19 include 200 objects, whereas we only
consider 78.
5.3.1. Spatial distribution

singel-lined
SBpossible toare much more dispersed. Beyond
that, it is not
spatially separate the groups found by B19.
double-lined
SB of ourIn the right panel, we present
the spatial distribution
sample (the 78 O stars) where we included the group of stars withpoor parallax measurements single
for which star
we have stellar parameters (and that are not in the left plot). We see the same groups
Fig.spatial
11. Left:spatial distribution
properas in the full sample. The
featuresremain theandsame
asmotionarrows
for
the
O
stars
in
Cygnusin the full sample, except that now a small concentration ofcandidates ofarethatrepresented
O stars around Cyg OB2OB2.
#11Runaway(to the northeast
aroundinpurple.
Right:
Gaia
DR2
properthe Cyg OB2 #8 complex) is more apparent. We note thatmotion
there
distribution of our sample divided by binary
is only one representative star of the B19 Group 3 (that is comstatus. Cyan: SB1 systems; purple: SB2 sysposed by foreground andtems;
backgroundobjects)
is precisely
light gray:single andstars.it We
note that
J20272428+4115458, thethe
B0IV
star
that
we
decidedtoinordinate scale is different as in keep
the preour sample (see Sect. 3.2).
Therefore
weincludefind that
O starsvious
figures to
CygallOB2#22B.that
we see belong to the Cygnus star forming complex.

Cyg OB2 から離れていくかど
うかは、さらに広い範囲を観測して調べる必要がある。

• binaryの固有運動とsingle starの固有運動の分布が似ており、固有運動はbinaryの運動の影響を受けていないと考えられる。

5https://www.aanda.org/articles/aa/pdf/2020/09/aa37104-19.pdf

Dense gas formation in the Musca filament due to the dissipation of a supersonic converging flow
L. Bonne1 , N. Schneider2 , S. Bontemps1 , S. D. Clarke2 , A. Gusdorf3,4 , A. Lehmann3 , M. Steinke2 , T.
Csengeri1,5 , S. Kabanovic2 , R. Simon2 , C. Buchbender2 and R. Guesten5
Laboratoire d’Astrophysique de Bordeaux, Université de Bordeaux, CNRS, B18N, alle Geoffrey Saint-Hilaire, 33615
Pessac, France; 2 I. Physikalisches Institut, Universität zu Köln, Zülpicher Str. 77, 50937 Köln, Germany; 3 Laboratoirede Physique de l’Ecole Normale Supérieure, ENS, Université PSL, CNRS Sorbonne Université de Paris, Paris, France;
4
Observatoire de Paris, PSL University, Sorbonne Université, LERMA, 75014 Paris, France; 5 Max-Planck-Institut
für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
1E-mail contact: lars.bonne at u-bordeaux.fr
Observations with the Herschel Space Telescope have established that most star forming gas is organised in filaments, afinding that is supported by numerical simulations of the supersonic interstellar medium (ISM) where dense filamentary
structures are ubiquitous. We aim to understand the formation of these dense structures by performing observations
covering the 12 CO(4→3), 12 CO(3→2), and various CO(2-1) isotopologue lines of the Musca filament, using the APEX
telescope. The observed CO intensities and line ratios cannot be explained by PDR (photodissociation region) emission
because of the low ambient far-UV field that is strongly constrained by the non-detections of the [CII] line at 158 µm
and the [OI] line at 63 µm, observed with the upGREAT receiver on SOFIA, as well as a weak [CI] 609 µm line detectedwith APEX. We propose that the observations are consistent with a scenario in which shock excitation gives rise towarm and dense gas close to the highest column density regions in the Musca filament. Using shock models, we findthat the CO observations can be consistent with excitation by J-type low-velocity shocks. A qualitative comparisonof the observed CO spectra with synthetic observations of dynamic filament formation simulations shows a good
agreement with the signature of a filament accretion shock that forms a cold and dense filament from a converging
flow. The Musca filament is thus found to be dense molecular post-shock gas. Filament accretion shocks that dissipate
the supersonic kinetic energy of converging flows in the ISM may thus play a prominent role in the evolution of coldand dense filamentary structures.
Accepted by A&A

ﬁlamentを観測して、ﬁlament の形成過程を調べる。
https://www.aanda.org/articles/aa/pdf/2020/09/aa37104-19.pdf• APEXでMusuca• （SOFIAなどで）far-UVが観測されなかったので、PDRではﬁlament形成は説明でき
A High Angular Resolution Survey of Massive Stars in Cygnus OB2: JHK Adaptive
ない。
Optics Results from the Gemini Near-InfraRed Imager
1
2
3
4,5
6
S.M.
Caballero-Nieves
,
D.R.
Gies
,
E.K.
Baines,A.H.
Bouchez,
R.G.
Dekanyet al.
ﬁlament• COのスペクトルと、converging ﬂowによってﬁlamentを形成するdynamic
Department of Physics and Space Sciences, Florida Institute of Technology 150 University Blvd, Melbourne, FL
formationのシミュレーションの結果はよく一致した。
32901, USA; 2 Center for High Angular Resolution Astronomy, Department of Physics and Astronomy, Georgia State1

Dense gas formation in the Musca filament due to the dissipation of a supersonic converging flow
2
1
2
3,4
3
2
L. Bonne1 , N.
Schneider, S. Bontemps, S. D.
Clarke,gas
A.formation
Gusdorfin, A.
Lehmann, due
M.toSteinke, T. of a supersonic converging flow
A&A
641,
A17
(2020)
L.
Bonne
et
al.:
Dense
the
Musca
filamentthedissipation
1,5
2
2
2
5
Csengeri , S. Kabanovic , R. Simon , C. Buchbender and R. Guesten

Laboratoire d’Astrophysiquede Bordeaux,
Université
decomponent
Bordeaux, CNRS,
B18N,
alle Geoffrey
33615
a blueshifted
excessvelocity
best visible
towards
the Saint-Hilaire,23
Pessac, France; I. Physikalisches Institut, Universität zu Köln, Zülpicher Str. 77, 50937
Köln, Germany; Laboratoire
filament crest and strands. A detailed analysis of this 0 blueshiftedde Physique de l’Ecole Normale Supérieure,
ENS, Université PSL, CNRS Sorbonne Université de Paris, Paris, France;0component is the objective of this paper.
4
Observatoire de Paris, PSL University, Sorbonne Université, LERMA, 75014 Paris, France; 5 Max-Planck-Institut
Here, we present a non-LTE CO excitation analysis of the
für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
1

blueshifted component, as well as complementary observations

E-mail contact: lars.bonne atof u-bordeaux.fr
the far-infrared fine structure transitions of carbon ([C I]), oxy-

gen Space([O I])Telescopeand ionised([C II]),which
a warmObservations with the Herschel
havecarbon
establishedthat
most reveals
star forming
gasgasis organised in filaments, aaround the
We showthat theexcitation
finding that is supported by component
numerical simulationsof filament.
the supersonicinterstellar
medium(ISM)ofwhere dense filamentary
thisaimwarm
gas can bethe
explainedbyofa thesefilament
accretion
shock,
structures are ubiquitous. We
to understandformation
dense
structuresby performing observations
12
12
covering the CO(4→3), CO(3→2),
and various shockCO(2-1)isotopologue
lines of on
theaMusca
filament, using the APEX
that is, a low-velocity
due
to mass accretion
filament
telescope. The observed COfrom
intensities
and line ratios
cannotbeexplainedby
PDR(photodissociation
region) emission
a converging
flow
in
an
interstellar
cloud.
(2020)
Fig. 1. Herschel column density map of the
because of the low ambient far-UV field that is strongly
constrainedbythenon-detections
of
the
[CII]
line at 158 µm
Musca filament (Cox et al. 2016) inserted
and the [OI] line at 63 µm, observed with the upGREAT
on SOFIA,as a weak
the receiver
extinction
map of as
thewellMuscacloud[CI] 609 µm line detected
2. Observationsinto consistent
with APEX. We propose that the observations arewithascenarioinwhich(Schneider et al. 2011), which is scaled toshock
the excitation gives rise towarm and dense gas close to2.1.
theAPEXhighest columnHerscheldensity regions
in
the
Musca
filament.
Using
column density map. The filament shock models, we find2that the CO observations can be consistent withcrest
excitation
by as
J-typeis defined
N > low-velocity
3 ⇥ 1021 cm shocks.
(purpleA qualitative comparison
used
the FLASH460
onoutlined
the APEXof the observed CO spectraWe
withsynthetic
observationsofdynamic
filament
simulations shows a goodand white).receiverThe
regionbyformation
a redtelescope
rectan(Güsten
et al. 2006;
et al.
2014),
obtaineda single
gleKleinis thezoom
displayed
in
Fig.
2.and
Thedense
ambient
agreement with the signatureof a filamentaccretion
shock
that
formsanda coldfilament from a converging
3 cloud
displayedin green
and blue.
The northP1 -3molecular
P0is at609post-shockµm
towards
the Musca
fila- shocks that dissipate
flow. The Musca filament is pointing
thus foundinto[CbeI]densegas.
Filament
accretion
h
m
s
0
00
ern
and
southernareas
mappedwith
FLASH+
the supersonic kinetic energyof converging
in thea prominentment
at ↵2000 =flows
12 28
55 ISMand may= play71 16
55 , usingrole
thein the evolution of cold
2000thus
Fig.
1.
Herschelcolumnaredensitymaptheh APEX
m
0 in
00of
on
the
indicatedblack.
and dense filamentary structures.
OFF position ↵2000 Musca= 12
41filament
38s telescopeand(Cox=71
1100(Hacar2000et al. 2016) inserted
00
The triangle
indicates
thespectral
location resolutionof the onlyisetal.
2016).
The
beamsize
is
13
and
the
Accepted by A&A
into
extinction
mapof the Musca
cloud
YSOthein theMusca filament.
1⇠0.05 km s . The(Schneider
data reduction
was donewith
the CLASSetal.
2011),
whichisscaledtothehttps://www.aanda.org/articles/aa/pdf/2020/09/aa37104-19.pdf
2
software1 . A main Herschelbeam efficiency⌘mb = 0.49
column density
map.wasTheapplied
filamentfor
2[C I], a baseline of crest
orderisone
was removed,correction
definedas N > 3 ⇥and1021a cm
(purplefor
FUV field, these lines may also serve as a tracer for low-velocity
andwhite).
The
regionoutlinedbyared
rectana 490 kHz shift in the FLASH460
instrument
was performed
High Angular
Massive Stars
in Cygnus
OB2: JHK Adaptive
shocks. The Musca filament is located atAa distanceof 140 pc Resolution Surveygleof
is the priv.
zoomcomm.).
displayedin Fig. 2.the
The
(see
Paper
I, F. Near-InfraRed
Wyrowski,
Fitting[CambientI] single
OpticsResultsfromtheGeminiImager(Franco 1991). We adopt the nomenclature from Cox et al. (2016)
clouda isGaussian
displayedin greenprovides
andblue.aThenorthpointing (Fig. 3) withprofilepeak
tem-6 et al.
3
4,5
S.M. Caballero-Nieves
Baines, A.H. areas
Bouchez, withR.G.FLASH+
Dekanyfor the different features of the Musca filament
and we indicate 1 , D.R. Gies2 , E.K.ern
andsouthern
mapped1
peraturebrightness
T
=
3.5
K
and
FWHM
=
0.8
km
s
(or
mb
1 2016). First, there isthem in Fig. 2 (see also Fig. 2 in Cox et al.
on thetelescope
are indicatedblack.
7Sciences,
1 Florida
2 APEX
1
Department of Physics andSpace
Instituteof Technology
150 inUniversity
Blvd, Melbourne, FL
3.4
⇥
10
erg
s
cm
sr
).
2 21 cm 2
the high column density filament crest with
N
>
3
⇥
10
The
triangle
indicates
thelocation
of
the
only
32901, USA; Center for High Angular
Astronomy,
Departmentof Physicsinand
Astronomy, Georgia StateThe COResolution
observations
with
APEX
are presented
more
3
YSO in USA;
the
Musca
filament.
(similar value to the one used by Cox etal. (2016)P. which
University,
O. Boxis5060,detail
Atlanta,
GA
30302-5060,
RemoteSensing
Division,
Naval
in Paper I, but here we shortly summarise the most Research Laboratory,2
18
N > 2.7 ⇥ 1021 cm).
Inaddition,C
O(2–1)
emissionbasically
4555
Overlook
AvenueSW,
Washington,
DCAll
20375,
South
Fig. 1. Herschel column density map of theimportant facts.
dataUSAwas 4GMTO
obtained Corporation,in 2017 and 251
2018,usingLake Avenue, Pasadena,
5 filadisappears belowMusca
this column
densityvalue.
Attachedtothe
CA 2016)91101,USA;of the Carnegie Institution for Science,
813 Santa
Barbara Street, Pasadena, CA
filament (Cox et al.
inserted Observatories
FLASH345
and FLASH460 for the 12 CO(3–2)
and 12 CO(4–3)
621 cm 2 )FUVlinesthemayextinction
also
serve
as aoftracerfor
mentfield,
crest these
are intermediate
columndensity(N ⇠Musca
2USA;⇥low-velocity
1091101,
California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
into
map
the
cloud
mapping of the northern and southern regions (Fig. 1). The Fig. 3. Top: APEX CO and [C I] spectra in the northern map, averaged
shocks.
Muscafilament
ata asize
distanceof
140 pc.
pc
hair-likeThestructures
calledstrands,
withofcontact:⇠0.2–0.4(Schneider
et isal. located2011),
which
is scaled
to theE-mailscaballero atFLASH345
fit.edu(FLASH460) observations have a spectral resolution over the filament crest (N > 3 ⇥ 1021 cm 2 ). Bottom: APEX CO spec(Franco1991).outwards
We
adoptatthe
nomenclature
from
Coxstraight
et al. (2016)
Herschelcolumndensity map.
Thefilament
Even further
largerdistances,
narrow
struc00
averaged thatover wethe southern map and the 7-pixel averaged SOFIA
0.033 (0.05)
km surveys 1 andofanmassive
angularOB
resolutionof 18(1400OB2). tra21present
resultsof a highofangularresolution
stars in the
Cygnusassociation
fortheofdifferent
featuresof lengths,
the Musca
and2 weindicate
crestparsec
is definedas N called> filament
3 ⇥We
10
cm
(purpletures
up to a few
striations(Goldsmith
[C
II
]
and
[O
I
]
lines
that are not detected above the 3 level. We note
Main andbeam
efficienciesof ⌘optics(0.49)
were
appliedto theconducted
with
the
NIRI
ALTAIR
adaptive
systemof theGeminiNorth
telescope. We observed 74
mb = 0.65
andalsowhite).
regionoutlinedby a red
rectanthem
Fig. Palmeirim
2 (see22013;
inCox
et al.
2016).
First,
thereis camera
et al. in2008;
etFig.
al.TheAlves
deOliveira
et al.
2014;
theprominent
blueshiftedvelocity component around 2.8 km s 1 in the1212antennatemperatures.
We
here
use
data
sampled
to
0.1
km
s
Oand
early
B-type
stars
in
Cyg
OB2
in
the
JHK
infrared
bands
in
order
to
detectbinaryandmultiplecompanions.
gle
is
the
zoom
displayed
in
Fig.
2.
The
ambient1
thehigh
withetNal.>2016)3 ⇥ 10arecm
Heyer
et column
al. 2016;density
Cox et filamental. 2016; crest
Malinenseen.
north and at 2.5 km s in the south, only visible in the 12 CO lines.
00
!!
and
smoothed
toaresolution
of
28
.
This
allowsabettercomparcloudisdisplayed
in
green
and
blue.
The
northTheobservationsaresensitivetoequal-brightnesspairs
atseparations
as
small
as
0.
08,
and
progressively
fainter(similartoorthogonal
the one usedbycrestCoxandet al.
(2016)
whichis
They arevalue
mostlyto thelocatedin theambi!! taken with the PI230
with
FLASH+
21 ern2and southern areas
18 mapped
ison
to
the
CO(2–1)
APEX
data
which
were
companionsaredetectable
out
to
∆K
=
9
mag
at
a
separation
of
2
.
This
faint
contrast
limit
due
to
readnoise
Nent
> 2.7
⇥ 10
). In addition,
C refers
O(2–1)
basically
cloud.
The cmambient
cloudtelescopethento emission
the environmental!!
on the APEX
are continues
indicatedinblack.
out
to 10edge ofthespectral
detector.
We assigned
a simple isprobabilityalignment
to each to determine the main beam efficiencies ofreceiver.
The
resolution
for CO(2–1)
0.08 km sof1 chance
at usedas a calibrator
disappears
thiscolumnmap
densityvalue.
Attached tothefila-near thegas, tracedbelow
by theTheextinction
in
Fig.
1,
embeddingthedenser00
triangle indicates the locationof theonlyuponcompanion
based
andmagnitudedifferencefromthecentraltarget
star
and
upon
areal
star
counts21
2 its separationanangularresolution
of
28
.
Here,
we
appliedamain
beam
effithe individual
pixels. The fitted water vapor column was typment
crest
are intermediate
columndensity(N ⇠ crest2 ⇥ 10cm )Muscafilament
crest
and
The
filament
is velocityYSO in
thestrands.
Musca filament.
forthegeneral
star
field
of
Cyg
OB2.
Companion
stars
with
a
field
membershipprobability
of
less
than
1%
are
ciency
of
⌘
=
0.68.
The
center(0,0)
position
of
the
maps
is
icallyaround10µm. All the intensities reported here are onmb
hair-likecalledsizeof ⇠0.2–0.4
pc.
coherent structures(Hacar et al.
2016)strands,
and haswith
only aone
young
stellarobjecthms
000
assumed to be physical companions.
This
assessment
indicates
that
47%
of
the
targets
have
at
least
one
resolved
↵
=
12
28
58
,
=
71
16
55
for
the
northernmap
the main beam temperature scale. The [O I] and [C II] observa2000
2000
Even
furtheroutwards
at larger end
distances,
narrow straight(YSO)
locatedat the northern(e.g. Vilas-Boasal.struchbound.
ms Including known spectroscopic
000
companion etthatis1994,
probablyand
gravitationallybinaries,
our tionssampleincludes27 beam size of 6.300 and 14.100 , respectively,
↵
=
12
24
46
,
=
71
47
20
for
the
southernhavea main
2000
2000
tures
of It
upwas
to arecently
few parsec
lengths,
striations(Goldsmith
Fig. 1).
proposed
thatcalledMusca
is a sheet
seen edgebinary,
12 triple,
and 9 systems
with
four
or
more
components.
These
results
confirmstudies
of
high
mass
stars
in were smoothed to a spectral resolution ofmap.
and both data setset2008; &
Palmeirim
et al. However,
2013; Alveset resultsal. 2014;
onal.(Tritsis
Tassis 2018).
onedeotherofOliveira
theenvironments
main
of
1
that find that massive stars are born with a high multiplicity fraction. The results
0.3 kmares important.
Heyer
et al. 2016;
Coxet al. 2016;
al. 2016)Paperare seen.
a companion
paper(Bonneet al., Malinen
in prep., ethereafterI), is Fig. 2. Zoom (red box in Fig. 1) into the Herschel 250 µm map of
There
is no detection of the [C II] and [O I] lines
They
are Musca
mostly orthogonal
to thecrest andlocatedwith
in thea ambithat thefilament crest
is moreconsistentcylin- Musca,
2.2. SOFIA
indicating the striations, strands and the filament crest (Cox et al.
(Appendix A) in the individual pixels (Fig. A.1) or in the arrayent
cloud.
The ambient
cloud ofthen
dricalgeometry
at a density
nH2refers⇠ 104 tocmthe3 . environmental
Because other 2016).
20
In June 2018, the upGREAT instrument (Risacher et al. 2018)averaged spectra (Fig. 3). The 3 upper limits for the two lines

Dense gas formation in the Musca filament due to the dissipation of a supersonic converging flow
1
2 flow
L. Bonne et al.: Dense gas formation
the Musca
filament
due to 2thedissipationof a 1supersonicconverging
L. in
Bonne
, N.
Schneider, S.
Bontemps, S. D. Clarke, A. Gusdorf3,4 , A. Lehmann3 , M. Steinke2 , T.

Csengeri1,5 , S. Kabanovic2 , R. Simon2 , C. Buchbender2 and R. Guesten5

Laboratoire d’Astrophysique de Bordeaux, Université de Bordeaux, CNRS, B18N, alle Geoffrey Saint-Hilaire, 33615
A&A 641, A17 (20Pessac, France; 2 I. Physikalisches Institut, Universität zu Köln, Zülpicher Str. 77, 50937 Köln, Germany; 3 Laboratoirede Physique de l’Ecole Normale Supérieure, ENS, Université PSL, CNRS Sorbonne Universitéde 1.Paris,
Paris, France;
Table
Linewidth,
integrated brightness and velocity for the average
45
Observatoire de Paris, PSL University, Sorbonne Université, LERMA, 75014 Paris, France;
Max-Planck-Institut
12
CO blueshifted component in the northern and southern map after
für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
fitting 3 gaussians to the spectrum.
1

blueshifted成分について

E-mail contact: lars.bonne at u-bordeaux.fr

R

Observations with the Herschel Space Telescope have established that most star forming gas is organisedin filaments,
line
FWHM
(kmas 1 )T dv (K km s 1 ) vblue (km s 1 )finding that is supported by numerical simulations of the supersonic interstellar medium (ISM) where dense filamentary
structures are ubiquitous. We aim to understand the formation of these dense structures by performing observations
North
covering the 12 CO(4→3), 12 CO(3→2), and various CO(2-1) isotopologue lines of the Musca12filament, using the APEX
CO(2–1)region) emission
0.35
2.0
2.7
telescope. The observed CO intensities and line ratios cannot be explained by PDR (photodissociation
12
CO(3–2)
0.31
0.98
2.8
because of the low ambient far-UV field that is strongly constrained by the non-detections of the [CII] line at 158 µm
12
0.42
0.73
2.9
and the [OI] line at 63 µm, observed with the upGREAT receiver on SOFIA, as well as a weak CO(4–3)[CI] 609 µm line detectedwith APEX. We propose that the observations are consistent with a scenario in which shock excitation gives rise toSouthwarm and dense gas close to the highest column density regions in the Musca filament. Using shock models, we find
0.71
4.6
2.5
that the CO observations can be consistent with excitation by J-type low-velocity shocks.12ACO(2–1)
qualitative comparison
12of the observed CO spectra with synthetic observations of dynamic filament formation simulations
a goodCO(3–2) shows 0.35
1.7
2.5
12
agreement with the signature of a filament accretion shock that forms a cold and dense filamentfromaconverging
CO(4–3)
0.33
0.63
2.5
flow. The Musca filament is thus found to be dense molecular post-shock gas. Filament accretion shocks that dissipate
the supersonic kinetic energy of converging flows in the ISM may thus play a prominent role in the evolution of coldand dense filamentary structures.

ambient cloud down to at least nH2 ⇠ 4 ⇥ 102 cm 3 in a weakFUV-field. More extensive [C I] observations will be required tohttps://www.aanda.org/articles/aa/pdf/2020/09/aa37104-19.pdf
better understand the physical conditions traced by [C I] in the
ISM. This is particularly important for comparison with simA High Angular Resolution Survey of Massive Stars in Cygnus OB2:
ulationsJHK
sinceAdaptive
the physical conditions traced by [C I] remain
Optics Results from the Gemini Near-InfraRed Imager
uncertain in simulations (e.g. Glover et al. 2015; Franeck et al.
6
S.M. Caballero-Nieves1 , D.R. Gies2 , E.K. Baines3 , A.H. Bouchez4,5 , R.G. Dekanyetal. et al. 2019).
2018;
Clark
周囲のガスの柱密度はN~ 1021 cm-2

Accepted by A&A

Fig. 5
3)/12 C
northeindicadashe

Table3)/12 Cfor th•• 周囲の雲のサイズがﬁlamentよりも小さ

Department of Physics and Space Sciences, Florida Institute of Technology 150 University Blvd, Melbourne, FL
32901, USA; 2 Center for High Angular Resolution Astronomy, Department of Physics and Astronomy,
Georgia State
3.4. 12 CO(4–3) excess emission in the blueshifted velocity
University, P. O. Box 5060, Atlanta, GA 30302-5060, USA; 3 Remote Sensing Division, Naval Research Laboratory,component
4555 Overlook Avenue SW, Washington, DC 20375, USA 4GMTO Corporation, 251 South Lake Avenue, Pasadena,
12
CA 91101,USA; 5 Observatories of the Carnegie Institution for Science, 813 Santa Barbara
Pasadena,
The Street,CO(3–2)and 12CA
CO(4–3) transitions have relatively high691101, USA; California Institute of Technology, 1200 East California Boulevard, Pasadena,
CA 91125,USA
excitation
temperatures(33 and 55 K respectively; Müller et al.
1

いとは考えにくいので、最小のサイズはnorth
south
~
0.4
pc
2005). This allows us to investigate the presence of warm gas
E-mail contact: scaballero at fit.edu
in OB2the Musca
cloud.
Wewefocus on the blueshifted component for
We present results of a high angular resolution survey of massive OB stars in the Cygnus
associationthat12
周囲の雲の密度の上限値は~ be anH2could
CO(4–3)
is observed
over the full map.n
This
conducted with the NIRI camera and ALTAIR adaptive optics system of the Gemini •Northwhich
telescope.
We observed
74of quite
uniform heating by e.g. a FUV field, though 12 CO
O- and early B-type stars in Cyg OB2 in the JHK infrared bands in order to detect binaryindicationand multiple
companions.
2-3
8there10cm fainterareindicationsof spatial variations in the data. However, tive v
The observations are sensitive to equal-brightness pairs at separations as small as 0. 08,
andprogressively!!

becausethetonoisein the spatially resolved map, we will notcompanions are detectable out to ∆K = 9 mag at a separation of 2 . This faint contrast
limitofdue
readnoise!!
onalignment
these possible
spatial variations in this paper. To furcontinues out to 10 near the edge of the detector. We assigned a simple probability offocus
chanceto eachthe heatingcompanion based upon its separation and magnitude difference from the central target starther
and investigate
upon areal star
counts that leads to the 12 CO(4–3) emission,
12
for the general star field of Cyg OB2. Companion stars with a field membership probabilityof less
1% are12 CO(2–1) and 12 CO(4–3)/12 CO(3–2)
we study
the thanCO(4–3)/assumeddust
to bephysical map.
companions.
This assessment
the =targets brightness
have at least
one resolved
temperature
ratios. In the previous section, we notedmFig. 4. Top: 12 CO(4–3) spectra overlaid on the Herscheltemperature
The (0,0) positionof the mapindicatesis ↵2000 =that
12h 2847%
58s ,of 2000
000
12companion
thatisprobably
gravitationallybound.
Includingknown
spectroscopic
binaries,
oursampleincludes
27
that it is important to take care comparing the integrated
71 16 55 Middle: CO(4–3) spectra overlaid on the northern Herschel column density map. The white contours indicate Musca filament crest
12
binary,12 oftriple,and 9displayed
systemsbelow.
with Below:
four orzoom
more
These
resultsinconfirm
studiesof highstars inwith 12 CO(3–2) and 12 CO(4–3) in the(N > 3 ⇥ 1021 cm 2 ). The black squares indicate thelocationsthe spectra
intocomponents.
spectra at selected
positionsthebrightness
ofmassCO(2–1)12
12
other emission
environmentsthat findthatmassive componentstars are bornwithhigh multiplicity fraction.blueshifted
The resultscomponent
are important
map. This shows that there is CO(4–3) and CO(3–2)
at the velocityof theblueshifted
over thefullamap.
because of their difference in linewidth.
!!

*光学的に厚く、自己吸収が効くモデルではスペクトルを再現できない。
to estimate the density upper limit is to combine the maximal
3.3.2. Density for the blueshifted component
20

column density associated with the ambient cloud, which is

Furthermore, the noise in the 12 CO(3–2) and 12 CO(4–3) spectra
makes it impossible to confidently fit a spectrum for every pixelin the map, even when spatially smoothing the data. Because

3.4.1

We c
3)/12 C
comp
allow
Sect.
<1 G
ature
5 low

Dense gas formation in the Musca filament due to the dissipation of a supersonic converging flow
L. Bonne1 , N. Schneider2 , S. Bontemps1 , S. D. Clarke2 , A. Gusdorf3,4 , A. Lehmann3 , M. Steinke2 , T.
Csengeri1,5 , S. Kabanovic2 , R. Simon2 , C. Buchbender2 and R. Guesten5
1

Laboratoire d’Astrophysique de Bordeaux, Université de Bordeaux, CNRS, B18N, alle Geoffrey Saint-Hilaire, 33615

2
3
L. Bonne et al.:Dense
formation in
the Musca
filament
due to Str.
the77,
dissipationof a supersonicconverging flow
Pessac,France;gas
I. Physikalisches
Institut,
Universität
zu Köln, Zülpicher
50937 Köln, Germany;
Laboratoirede Physique de l’Ecole Normale Supérieure, ENS, Université PSL, CNRS Sorbonne Université de Paris, Paris, France;
PDRでの輝線比についてのモデル
RADEXを用いた輝線比の計算結果 (non-LTE)
Observatoire de Paris, PSL University, Sorbonne Université, LERMA, 75014 Paris, France; Max-Planck-Institut
4

5

für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
E-mail contact: lars.bonne at u-bordeaux.fr
Observations with the Herschel Space Telescope have established that most star forming gas is organised in filaments, afinding that is supported by numerical simulations of the supersonic interstellar medium (ISM) where dense filamentary
structures are ubiquitous. We aim to understand the formation of these dense structures by performing observations
covering the 12 CO(4→3), 12 CO(3→2), and various CO(2-1) isotopologue lines of the Musca filament, using the APEX
telescope. The observed CO intensities and line ratios cannot be explained by PDR (photodissociation region) emission
because of the low ambient far-UV field that is strongly constrained by the non-detections of the [CII] line at 158 µm
and the [OI] line at 63 µm, observed with the upGREAT receiver on SOFIA, as well as a weak [CI] 609 µm line detectedwith APEX. We propose that the observations are consistent with a scenario in which shock excitation gives rise towarm and dense gas close to the highest column density regions in the Musca filament. Using shock models, we find
12A qualitative comparison 12that the CO observations can be consistent with excitation by J-type low-velocity shocks.
of the observed CO spectra with synthetic observations of dynamic filament formation simulations shows a good
agreement with the signature of a filament accretion shock that forms a cold and dense filament from a converging
flow. The Musca filament is thus found to be dense molecular post-shock gas. Filament accretion shocks that dissipate
the supersonic kinetic energy of converging flows in the ISM may thus play a prominent role in the evolution of coldand dense filamentary structures.

T CO(J=4-3)/T CO(J=2-1)

Accepted by A&A
https://www.aanda.org/articles/aa/pdf/2020/09/aa37104-19.pdf

A High Angular Resolution Survey of Massive Stars in Cygnus OB2: JHK Adaptive
Optics Results from the Gemini Near-InfraRed Imager

12Caballero-Nieves1 , 12
12 Baines3 , A.H. Bouchez4,5 , R.G. Dekany6 et al.
S.M.
Gies2 , E.K.
Fig. 6. Observed 12 CO(4–3)/
CO(2–1) and D.R.
CO(4–3)/CO(3–2)
12
12
Fig.
7.
CO(4–3)/CO(2–1)brightness temperature ratios predicted1
DepartmentofPhysicsandSpace
Sciences,
FloridaInstituteofTechnology
150
University
Blvd, Melbourne, FL
ratios compared with predictions by 2the PDR Toolbox. The shaded
RADEX
for theplausibleGeorgia
rangeStateof physical conditions in the ambi32901, USA; Center for High Angular Resolution Astronomy,with
Departmentof Physics
and Astronomy,
areas, constructed by logarithmic
interpolation between the points USA;in 3 Remote
University, P. O. Box 5060, Atlanta, GA 30302-5060,
Sensing
Division,
Naval
Research
Laboratory,
ent cloud of the Musca filament. The lines connect the RADEX models
12
the PDR Toolbox density grid,show Avenue
the evolutionof theCO(4–4555 Overlook
SW, Washington,
DC 20375,
USA 4GMTO Corporation, 251 South Lake Avenue, Pasadena,12
withidentical
densityandtemperatureforvarying
CO column densi121212 91101,USA; 5 Observatories of the Carnegie Institution forCA
Science,813
Santa
BarbaraStreet,Pasadena,CA
3)/ CO(2–1) and CO(4–3)/ CO(3–2)
brightness temperature ratio as6
91101, USA; California Institute of Technology, 1200 East California
Boulevard,
Pasadena,
CA 91125,predicted
ratioswith USARADEX show a huge discrepancy witha function of the FUV field in
the allowed density range of the Musca ties. The
12
12E-mail contact: scaballero at fit.edu
cloud. At a typical density nH2 = 4 ⇥ 102 cm 3 of the ambient cloud the observed CO(4–3)/ CO(2–1) ratio towards the Musca cloud (indiWe present results of a high angular resolution survey of massive
OBby
stars
in dashed
the Cygnus
OB2 associationthat wedeviation of the observed values
cated
the
line).
The standard(dashed line) for the allowed conducted
FUV field(<1 G
the predicted
0 ),with strength
the NIRI camera
and
ALTAIR
adaptive optics system of the Gemini North telescope. We observed 74
from the average is indicated by the grey area. The same is observed forandtheearlyobserved
B-type stars onesin Cyg inOB2thein the
JHK infrared bands in order to detect binary and multiple companions.
line ratios are only a fractionO- ofblueshifted
12
12 !!
the
CO(4–3)/brightness
temperature ratio.
The observations are sensitive to equal-brightness pairs at separations
as small as CO(3–2)
0. 08, and progressively
faintercomponent.
companions are detectable out to ∆K = 9 mag at a separation of 2!! . This faint contrast limit due to readnoisecontinues out to 10 near the edge of the detector. We assigned a simple probability of chance alignment to eachblueshifted成分の輝線比を再現できない。
衝突/ star放射加熱のみでは、blueshifted成分
companion based upon its separation and magnitude difference from the central
targetand upon areal star counts!!

for the general star field of Cyg OB2. Companion stars with a field membership probability of less than 1% are

4
approach because the highassumed
critical(nH2 > 5This⇥ 10
cm 3indicates) 12 CO(3–2)
brightness
temperature
to bedensity
physical companions.
assessmentthat 47%の輝線比を説明できないof thetargets have atleast one resolvedratios assuming that there is
12
12companion
thatisprobably
gravitationallybound.
Includingknown
spectroscopic
binaries,
oursample27of CO(3–2) and CO(4–3) implies that these lines are sub- only collisional and radiativeincludes
heating.
binary, 12 triple, and 9 systems with four or more components. These results confirm studies of high mass stars inthermally
For RADEX
analysis
wethatusemassivea FWHM
ofwith a high multiplicity
other(J=3-2)の強度を大きく変えずに、COenvironmentsthat findstars are born
fraction. The results are important
CO1excited.
(J=2-1)やCO(J=4-3)の強度を大きくするためには、
0.4 km s , temperatures between 15 and 25 K, and represenK)層が必要
tative 温かいdensities (>50
for theambient cloud: nH2 = 3 ⇥ 102 , 5 ⇥ 102 ,20 3.5. A warm and dense gas component

density we plot
ratio for a column
Dense gas formation in the Musca filament due to theeachdissipationof athesupersoniccon- density such that the predicted brightness of 12 CO(4–3) by RADEX is roughly similar to theverging flow

observedMusca(T mb2 ,=T.
1.5–3 K) at the temperatures
3,4 brightness towards
L. Bonne1 , N. Schneider2 , S. Bontemps1 , S. D. Clarke2 , A. Gusdorf, A. Lehmann3 , M.
Steinkeobtain5 sufficiently high brightness ratios. The lowest three densities
Csengeri1,5 , S. Kabanovic2 , R. Simon2 , C. Buchbender2 and R. that
Guesten
3
3
3
3
15
2
(nH2 = 10 , 3 ⇥ 10 and 5 ⇥ 10 cm ) use N12 CO = 1.1 ⇥ 10

cm , and3 Geoffrey
14
Laboratoire d’Astrophysique de Bordeaux, Université de Bordeaux, CNRS,
33615
nH2 =B18N,
7 ⇥ 10alle
cm 3 uses Saint-Hilaire,
N12 CO 3= 9 ⇥ 10
cm 2 . The black horizontal
2
Pessac, France; I. Physikalisches Institut, Universität zu Köln, Zülpicherline
Str. indicates77, 50937theKöln,
Germany;
Laboratoire
averageobserved
ratio towards Musca, and the grey
A&A 641, A17 (2020)de Physique de l’Ecole Normale Supérieure, ENS, Université PSL, CNRSarea
Sorbonne
UniversitédeParis,
Paris,
France;indicatesthestandard
deviation.
12 France; 5 Max-Planck-Institut
12
4
Observatoire de12
Paris, PSL University, Sorbonne Université, LERMA, 75014 Paris,
Table
3. Predicted [C I] brightness temperatures (4), calculated with
für Radioastronomie, Auf dem Hügel 69, 53121 Bonn,
Germany1

温かいガスの輝線比についてのRADEXを用いた計算

T12CO(J=4-3)/T CO(J=2-1)

E-mail contact: lars.bonne at u-bordeaux.fr

T CO(J=4-3)/T CO(J=3-2)

RADEX for various temperatures (1) and densities (2) for theblueshifted velocity component.

Observations with the Herschel Space Telescope have established that most star forming gas is organised in filaments, afinding that is supported by numerical simulations of the supersonic interstellar medium (ISM) where dense filamentary3
2
structures are ubiquitous. We aim to understand the formationT of(K)these ndense
structuresby(cmperforming) NCI) Tobservations
H2 (cmmb (K)
12
12
covering the CO(4→3), CO(3→2), and various CO(2-1) isotopologue
lines(2)of the Musca filament,using(4)the APEX(1)(3)
telescope. The observed CO intensities and line ratios cannot be explained by PDR (photodissociation region) emission
because of the low ambient far-UV field that is strongly constrained by the non-detectionsof the [CII] line at 158 µm
Ambient cloud
and the [OI] line at 63 µm, observed with the upGREAT receiver on SOFIA, as well as a weak [CI] 609 µm line detected2
20 a scenario
5 ⇥ 101016
1.0 rise towith APEX. We propose that the observations are consistent within which shock
excitation gives
216
7.5 ⇥filament.
10
10 shock models,
1.2 we findwarm and dense gas close to the highest column density regions 20
in the Musca
Using
that the CO observations can be consistent with excitation by J-type low-velocity shocks. A qualitative comparison
Warm gas layerof the observed CO spectra with synthetic observations of dynamic filament formation simulations shows a good
3 dense filament
agreement with the signature of a filament accretion shock that60
forms a coldandconverging
7 ⇥ 109 ⇥ 1014 from a0.16
flow. The Musca filament is thus found to be dense molecular post-shockgas.
accretion
shocks thatdissipate90
7 ⇥Filament103
9 ⇥ 1014
0.15
the supersonic kinetic energy of converging flows in the ISM may thus play a prominent role in the evolution of coldand dense filamentary structures.
16
2

Notes. This indicates a [C I] column density (3) of ⇠10 cm for the
1212
12
Fig. 8. Predicted brightness
temperature
Accepted
by A&A ratio of CO(4–3)/ CO(2–1)
Predicted brightness
temperature
ratiotooftheCO(4–3)/12 CO(3–2)
ambient cloud, whileFig.
the9.contribution
from the warm
gas layer
by RADEX as a function of temperature for different densities. Thisby RADEX
for the same models that are presented in Fig. 8. It confirms
https://www.aanda.org/articles/aa/pdf/2020/09/aa37104-19.pdf
observed [C I] emission
is negligible.
demonstrates the need for a warm and dense CO layer to at least
the need for high temperatures (>50 K) and densities (5–7 ⇥ 103 cm 3 )reach the observed brightness ratios in the blueshifted component. For
to reach the observed excitation of 12 CO(4–3). The black horizontal line
each density we plot theforAngulara column density
such thatSurvey
the pre- of Massive Starsindicates
A ratioHigh
Resolution
in Cygnus
OB2:
JHK ratio
Adaptivethe averageobserved
towards Musca, and the grey area
predicta physical
sizedeviation.
of the warm gas layer
dicted brightness of 12Optics
CO(4–3)Resultsby RADEX
is roughly
similar toNear-InfraRed
the shock models
fromthe Gemini
Imagerindicatesthestandard
around1015 cm, whichfits with the estimatedphysical sizes forobserved brightness towards Musca (T mb = 1.5–31K) at the temperatures
2
3
4,5
6
S.M. Caballero-Nieves , D.R. Gies , E.K. Baines, A.H. Bouchez, R.G.
Dekanysize,et thatal. is the layer thickthe
RADEX
models.
Theestimatedthat obtain sufficiently high brightness ratios. The lowest three densities
1
densities
required
to reachthe observed
ratios. The 12 CO(4–Physics
FloridaInstitute
Technology
150areUniversity
Blvd,
Melbourne,FLness,of the ofmodelsthatmanagetoreachtheobserved
brightness(nH2 = 103 , 3 ⇥ 103 and 5Department⇥ 103 cm 3 )ofuse
N12 CO and= 1.1Space⇥ 1015Sciences,
cm 2 , and122ratio,
to high densities and32901,
USA;
for2High
Resolution Astronomy,
Department
Physics8 andAstronomy,
GeorgiaState
nH2 = 7 ⇥ 103 cm 3 uses
N12 CO= 9 ⇥Center
1014 cm. TheAngular
black horizontal
temperature
ratios3)/inofCO(3–2)
Figs.
and
9 inareparticular,
1.3⇥ 1015points
cm and3
University,
P.
O.
Box
5060,
Atlanta,
GA
30302-5060,
USA;
RemoteSensing
Division,
Naval
Research
Laboratory,
15
3
3
temperature,
see
Fig.
9,
in
order
to
reach
the
line indicates the average observed ratio towards Musca, and the grey 2.2 ⇥ 10 cm, respectively at nH2 = 7 ⇥ 10 cm (with N12 CO =observed ratios.
4555 deviation.
Overlook Avenue SW, Washington, DC 20375, USA 14
3the RADEX
demonstrates
the need forarea indicates the standard
9 ⇥ 10 4GMTO
cm 2 ) Corporation,and 5 ⇥Though
103 251
cm South(withLake
N12 Avenue,=analysis
1.1Pasadena,⇥ 1015cm 2 ).
CO Pasadena, CA
12
CA 91101,USA; 5 Observatories of the Carnegie Institution for Science,
813 Santa
BarbaraStreet,
warm
and
dense
gas
to obtain
the observedTo
calculatethephysical
size
of
the
RADEX
modelsan abun- CO(4–3) bright6
91101, USA; California Institute of Technology, 1200 East California
Boulevard,
Pasadena,
CA91125,
USA⇥ ⇤ ⇥12 ness
⇤ in the blueshifted component, we can not narrow down

shock models praround 1015 cm, w
the RADEX mod
ness, of the modetemperature ratio
2.2 ⇥ 1015 cm, res
9 ⇥ 1014 cm 2 ) an
To calculate the p⇥ ⇤⇥dance of H2 / 12
for weakly irradia
Lastly, we notand thus likely un

3.5.2. CI column

We noted in Fig
blueshifted comporder of 1–1.5 K.
the [C I] column dperature of 20 K,
for the ambient
NCI ⇠ 1016 cm 2
models for 12 CO
we find that at lestill found in its a
On the otherwarm and dense
12
CO(4–3) emiss[C I] emission.
We thus emph
two contributions– the ambient
emission;– a warm gas
emission that is redance of H / CO = 10 was used, which is a typical value• 温かくて高密度なガスがあれば、輝線比を再現できる
more
precisely
the temperature and density range because there 3.6. Shock mode
for weakly irradiatedmoleculargas.
higher-J
CO
observations
the moment.
Lastly, Lesaﬀre
we notearethatnothis
warm
gas2013)
is observedの予想と一致
inatbothmaps This warm andetal.
For an in-depth• 遅いガスのショックによる加熱 (Pon et al. 2012;
dense gasexactlyfits withthe predictions
and thus likely universallypresent
aroundthe Musca
filament. for gas heated by
low-velocity shocks (Pon et al. 2012; Lesaffre et al. 2013), and preferable to hav-1)であれば、100
slow-typemagnetizedshock(v=1-3kms
K程度まで加熱できる(Lehmann•so-called
slow-type (with regard to their phasevelocity) magne- &(J > 4) CO lin
3.5.2. CI column density in the blueshifted component

Wardle 2016)42

E-mail contact: scaballero at fit.edu

We present results of a high angular resolution survey of massive OB stars in the Cygnus OB2 association that we
conducted with the NIRI camera and ALTAIR adaptive optics system of the Gemini North telescope. We observed 74
O- and early B-type stars in Cyg OB2 in the JHK infrared bands in order to detect binary and multiple companions.
The observations are sensitive to equal-brightness pairs at separations as small as 0.!! 08, and progressively fainter1companions are detectable out to ∆K = 9 mag at a separation of 2!! .tised
Thisshocks
faint contrast
with vs limit= 1–3due
kmtos readnoise
can easily reach temperatures!!
continues out to 10 near the edge of the detector. We assigned a simple probability of chance alignment to eachas high as 100 K (Lehmann & Wardle 2016). These slow-typecompanion based upon its separation and magnitudeWe
difference
targetstar andofuponstar counts
notedfromin theFig.central
3 thepresence[C areal
I] emission
in thefor the general star field of Cyg OB2. Companionblueshiftedstars with acomponent
field15
membershipprobability
of
less
than
1%
are
with8 ofa 16
brightness temperature of theA17, page
assumed to be physical companions. This assessment
indicates
that
47%
of
the
targets
at least we
onehereresolvedorder of 1–1.5 K. From this weak [Chave
I] emission
estimate
1 27
companion that 3is probably
gravitationallybound.
Includingknown
spectroscopic
binaries,
oursampleincludes
-3
14
-2
the
[C
I] column
density.
We
use
a
FWHM=
0.4
km
s
, 15
a temH2 binary, 12 triple, and 9 systems with
12CO
four or more components. These results confirm studies of high mass stars 2inperature of 20 K, and typical densities nH2 = 5–7.5 ⇥ 10 cm 3other environments that find that massive stars are born with a high multiplicity fraction. The results
are important• slow-type shockでは、温かいガスの層の厚さは ~ 10 cm• Fig. 8より、n = 7 10 cm 、N =9 10 cm のとき、厚さ ~ 1.3 10 cm
the 15ambient
cloud with RADEX.
This points-2のとき、厚さ
10cmMusca~ 2.21015to cm• Fig. 9より、nH2 = 5 103 cm-3、N12CO=1.1forN ⇠ 10 cm , see Table 3. Comparing this with the same
CI

16

2

12
models20 for CO emission from the ambient cloud in Sect. 3.4,

up2016) since 12 CO
sion in the blueshDense gas formation in the Musca filament due to the dissipation of a supersonic converging flow
L. Bonne1 , N. Schneider2 , S. Bontemps1 , S. D. Clarke2 , A. Gusdorf3,4 , A. Lehmann3 , M. Steinke2 , T.
Csengeri1,5 , S. Kabanovic2 , R. Simon2 , C. Buchbender2 and R. Guesten5
Laboratoire d’Astrophysique de Bordeaux, Université de Bordeaux, CNRS, B18N, alle Geoffrey Saint-Hilaire, 33615
converging ﬂowによるﬁlament形成のシミュレーション(Clarkeet50937
al.Köln,2018)
Pessac, France; I. Physikalisches Institut, Universität zu Köln, Zülpicher
Str. 77,
Germany; Laboratoire
A&A 641,(2020)Normale Supérieure, ENS, Université PSL, CNRS Sorbonne Université de Paris, Paris, France;de PhysiquedeA17
l’Ecole（Musuca ﬁlamentよりも少し密度が高い、Taurasにあるようなﬁlamentについてのシミュレーション）
Observatoire de Paris, PSL University, Sorbonne Université, LERMA, 75014 Paris, France; Max-Planck-Institut
1

2

3

4

blueshifted

5

für Radioastronomie, Auf dem Hügel 69, 53121
Bonn, Germany
18

Fig. 11. Bottom: C O(2–1) integrated intensity map of the simulation (Clarke et al. 2018), with the black square indicating the region that is studied

E-mail contact: lars.bonne at in
u-bordeaux.fr
this figure. The red box indicates the region displayed in Fig. 12. Left: 12 CO(4–3) and C18 O(2–1) spectra extracted from the square which show
a blueshifted 12 CO(4–3) component (blue) in addition to the component related to the bulk emission of the filament crest (red). The two velocity

Observations with the Herschelintervals
Spaceused
Telescope
haveonestablishedmostinstar
gas is physicalorganisedin filaments,
a of sight of the gas in the velocity
for the plot
the right arethat
indicated
blueforming
and red. Right:
locationalong the line
finding that is supported by numericalsimulations
oflargerthe supersonicinterstellar
wheredense filamentaryintervals, showingthat theblueshifted velocity
intervalmedium
covers a (ISM)small region
comparedto the filament and that it is located at the border offilament
where the density
strongly increases
becauseof astructures
filament accretion
shock.
structures are ubiquitous. Wethis
aim
to understandthe formationof thesedense
by performing
observations
12
12
covering the CO(4→3), CO(3→2), and various CO(2-1) isotopologue lines of the Musca filament, using the APEX
telescope. The observed CO intensities and line ratios cannot be explained by PDR (photodissociation region) emission
filament.
The
simulation
includeshydrodynamics,
self-gravity,
because of the low ambient far-UV
field
that
is strongly
constrainedby the non-detectionsof the [CII] line at 158 µm
andheatingandcooling
coupledwith
non-equilibrium
chemand the [OI] line at 63 µm, observed with the upGREAT receiver on SOFIA, as well as a weak [CI] 609 µm line detectedistry. From this self-consistent CO formation in the simulations,with APEX. We propose that the observations are consistent with a scenario in which shock excitation gives rise tosynthetic observations are produced.
warm and dense gas close to the The
highestcolumnregionsin the accretion
Musca filament.
filament
edgedensity
is definedby filament
shocks, Using shock models, we findthat the CO observations cansee
be forconsistent
excitationJ-type low-velocity
A qualitative comparison
example with
Fig. 11,which isby
a low-velocity
shock dueshocks.
toof the observed CO spectra withsyntheticonobservations
dynamic
formation
simulations shows a goodmass accretionan interstellar offilament
from filament
a converging
flow
agreement with the signatureinofa amolecularfilamentcloud.
accretion
shock
that forms
a coldand dense filament from a converging
For more
informationon thesesimulations
andsynthetic
observations,
we
refer
to
Clarkeetal.
(2017,
2018).accretion shocks that dissipate
flow. The Musca filament is thus found to be dense molecular post-shock gas. FilamentFig. 12. Smoothed ( = 1.3 pix) cut at z = 0.05 pc through the temperaNo
magnetic
field
isincludedinthesimulations,
which
could role
the supersonic kinetic energy of converging flows in the ISM may thus play a prominent
in the evolution of cold
21
2
have an impact on the shock properties (e.g. Draine et al. 1983; ture cube of the simulation, with the black contours (N = 5 ⇥ 10 cm )and dense filamentary structures.
roughly indicating the high column density filament. Note the local
Lesaffre et al. 2013). For a shock propagating perpendicular to increase in temperature at the sub-filament border due to the accreAccepted by A&A
the magnetic field, this makes the shock wider and decreases tion shocks and the temperature drop in the sub-filaments after thethe peak temperature. However, slow-type shocks, which can fit shock compared to the inflowing mass reservoir. Because of smoothing,https://www.aanda.org/articles/aa/pdf/2020/09/aa37104-19.pdf
the observed emission, tend to resemble non-magnetised shocks the temperature peaks of the shocked gas in the map have decreased.
because the dynamics is driven by gas pressure (Lehmann & The area of the simulation that is covered by this figure is indicated inFig. 11. JHK Adaptive
Wardle 2016).
In the simulations
the warmpost-shock
is not OB2:
A High Angular Resolution
Surveyof Massive
Starsin layer
Cygnusresolved,aspost-shockcoolingofalow-velocity
J-typeshock
Optics Results from the Gemini Near-InfraRed Imager
occurs over small distances (e.g. Lesaffre et al. 2013; Whitworth
The good correspondence with synthetic spectra derived
1
2
3
4,5
6
S.M.
Caballero-Nieves
,
D.R.
Gies
,
E.K.
Baines,A.H.
Bouchez,
R.G.
Dekanyet simulation
al.
&
Jaffa
2018),
implying
that
the
gas
heatedbytheshocksisfromtheis remarkable, see Fig. 11. We observe theFig. 11. Bottom: C18 O(2–1) integrated intensity map of the simulation (Clarke et al. 2018), with
the
black
squareindicatingtheregionthat
isstudied18
smearedout.
Consequently,
thetemperatureoftheheatedgas
isbulk
emissionofthefilament
1
Department
ofCO(4–3)
PhysicsandandSpace spectra
Sciences,
FloridaInstituteof Technology
150 University Blvd, Melbourne,
FLwith the C O(2–1)12line and, morein this figure. The red box indicates the region displayed inFig. 12. Left: 12
C18 O(2–1)
extracted
from thesquare whichshow
underestimated. Nonetheless, it is generally observed in the sim- importantly, a bright blueshifted component in CO(4–3) witha blueshifted 12 CO(4–3) component (blue) in addition 32901,
to the component
related tofor
the Highbulk emissionof Resolution
the filament crest(red). The Department
two velocity of Physics and Astronomy,
USA; 2 Center
AngularAstronomy,
Georgia Stateulations
3D
structure
is confined by a no C18 O emissionthat connects the velocity of the inflowing
3inintervals used for the plot on the right are indicated inblue and red.
physicallocationalongthatthe thelineof densesight offilamentary
the gasL.
thevelocityBonne
et al.:
Dense gasformationNavalin the Musca
filament
due to the dissipation of a supersonic converging flow
University,
P.Right:
O. Box5060,
Atlanta,
GA
30302-5060,
USA;
RemoteSensing
Division,
Research
Laboratory,
gas
layer
that
shows
an
increaseintemperatureasaresultoffilcloud
and
the
dense
gas. This is similar to what is found inintervals, showing that the larger blueshifted velocity interval covers a small region compared to the filament and that it is located at the border of
4555
Overlook
AvenueSW,
Washington,
DC20375,USA
4GMTO
Corporation,
251
South
Lake
Avenue,Pasadena,
ament
accretion
shocks.
Figure12showsatemperature
map,
cut
the
Musca
filament.
Inthe simulations, this 12 CO(4–3) comthis filament where the density strongly increases because of a filament accretion
shock.
5
CA 91101,USA; Observatories
ofthe
thesimulation,
Carnegiethat
Institution
813increase
Santa at
BarbaraPasadena,
CA velocity transition and density
out ofillustrates for
thisScience,
temperatureponentStreet,corresponds
to a strong
the borderof the filament,by a temperature
dropPasadena,
into increase
91101, USA; 6 California Instituteof Technology,
1200followed
East California
Boulevard,
CA 91125,from a USA
filament accretion shock of the inflowing mass
the filament.
reservoir, see Fig. 11. This accretion shock is responsible for thefilament. The simulation includes hydrodynamics,
self-gravity,
E-mailcontact: scaballero at fit.edu
and heating and cooling coupled with non-equilibrium chemWesimulations,present results of a high angularsurvey of massive OB stars in the Cygnus OB2 association that we
A17, page resolution
10 of 16
istry. From this self-consistent CO formation in the
conducted
with
the
NIRI
cameraand
ALTAIR
adaptive
optics system of the Gemini North telescope. We observed 74
synthetic observations are produced.
O- andshocks,
early B-type stars in Cyg OB2 in the JHK infrared bands in order to detect binary and multiple companions.
The filament edge is defined by filament accretionsee for example Fig. 11, which is a low-velocityThe
shock
due toobservations
are sensitive to equal-brightness pairs at separations as small as 0.!! 08, and progressively faintermass accretion on an interstellar filament from a converging
floware detectable out to ∆K = 9 mag at a separation of 2!! . This faint contrast limit due to readnoisecompanions
in a molecular cloud. For more information on thesesimulations
continues
out to 10!! near the edge of the detector. We assigned a simple probability of chance alignment to eachand synthetic observations, we refer to Clarke et al.
(2017,
2018).
companion based upon its separation and magnitude difference from the central target star and upon areal star counts
No magnetic field is included in the simulations, which could Fig. 12. Smoothed ( = 1.3 pix) cut at z = 0.05 pc through the tempera21
2ture cubeof thesimulation,
the black contours= 5 ⇥ a10field
cm membership)for etthe
fieldof CygOB2.withCompanion
stars(Nwith
probability of less than 1% arehave an impact on the shock properties (e.g. Draine
al. general
1983; starroughly
indicatingthehighcolumndensityfilament.
Note
the
local
assumed to tobe physical companions. This assessment indicates that 47% of the targets have at least one resolved
Lesaffre et al. 2013). For a shock propagating perpendicularin temperature at the sub-filament border due to the accrethat increaseis probably
gravitationally bound. Including known spectroscopic binaries, our sample includes 27
the magnetic field, this makes the shock wider companionand decreases
tion shocks and the temperature drop in the sub-filaments after the
Fig. 13.
Left: density distributionof the gas
with a sufficient
COhighabundance
be observablein a 12 CO(4–3) excess component. CO is consideredbinary,12
triple,and9systemswithfour massor morecomponents.
These results
confirmstudies ofmasstostars
inthe peak temperature. However, slow-type shocks, which can fit shock compared to the
inflowingreservoir.
Because of smoothing,if morethanhalf ofthe carbon is fraction.
locked in CO.
Notethat theare
density
distribution is relatively bimodal, with the densest already shocked
the observed emission, tend to resemble non-magnetised
shocks the temperatureother environmentsthat find thatstarsdetectableareinbornwitha highmultiplicity
The
results
importantpeaks massiveof the shockedgas
the map
havedecreased.
gas highlighted in red. Right: temperature distribution of all the CO gas in grey, with in red the temperature of the high density gas highlighted
because the dynamics is driven by gas pressure (Lehmann & The area of the simulation that is covered by this figure is indicated inon the left. We find for the dense gas that almost all gas at T = 15–25 K has disappeared, leaving only the cold (<15 K) and warm gas (>25 K).
Wardle 2016). In the simulations the warm post-shock layer is not Fig. 11.
This demonstrates that post-shock gas is either warm or cooled behind the shocked gas layer compared to the temperature of the inflowing mass
resolved, as post-shock cooling of a low-velocity J-type shockreservoir.
20

温度

ﬁlament

積分強度

視線方向の
密度分布

• 高密度のガスは低温の領域 (< 15 K)か温かい領域 (> 25 K)に集中している。
• 断続的に流入するconverging ﬂowは
ﬁlamentの冷却に重要• シールディングとCOの冷却率の増加

密度

温度

1

http://arxiv.org/pdf/2008.00010

A Novel Survey for Young Substellar Objects with the W-band Filter. I. Filter Design
and New Discoveries in Ophiuchus and Perseus
K.N. Allers1,2 and Michael C. Liu3
Department of Physics and Astronomy, Bucknell University, Lewisburg, PA 17837, USA; 2 Visiting Astronomer at
the Infrared Telescope Facility, which is operated by the University of Hawaii under contract NNH14CK55B with the
National Aeronautics and Space Administration; 3 Institute for Astronomy, University of Hawai’i, 2680 Woodlawn
Drive, Honolulu, HI 96822, USA
1E-mail contact: mliu at ifa.hawaii.edu
We present the design and implementation of a medium-band near-IR filter tailored for detecting low-mass stars andbrown dwarfs from the summit of Maunakea. The W-band filter is centered at 1.45 µm with a bandpass width of 6%,
designed to measure the depth of the H2 O water absorption prominent in objects with spectral types of M6 and later.
When combined with standard J- and H-band photometry, the W-band filter is designed to determine spectral types
to ≈1.4 subtypes for late-M and L dwarfs, largely independent of surface gravity and reddening. This filter’s primary
application is completing the census of young substellar objects in star-forming regions, using W-band selection to
greatly reduce contamination by reddened background stars that impede broad-band imaging surveys. We deployed
the filter on the UH 88-inch telescope to survey ≈3 sq. deg. of the NGC 1333, IC 348, and rho Ophiuchus star-forming
regions. Our spectroscopic followup of W-band selected candidates resulted in the confirmation of 48 ultracool dwarfs
with a success rate of 89%, demonstrating the efficacy of this new filter and selection method.
Accepted by PASP
http://arxiv.org/pdf/2008.00010

Selected aspects of the analysis of molecular line observation of edge-on circumbinary
disks
Roman Avramenko1 , Sebastian Wolf1 , Tobias F. Illenseer1 and Stig Rehberg1
1

University of Kiel, Institute of Theoretical Physics and Astrophysics, Leibnizstrasse 15, 24118 Kiel, Germany

E-mail contact: ravramenko at astrophysik.uni-kiel.deContext: Inner cavities, accretion arms and density waves are characteristic structures in the density distribution of
circumbinary disks. They are the result of the tidal interaction of the non-axisymmetric gravitational forces of thecentral binary with the surrounding disk and are most prominent in the inner region, where the asymmetry is mostpronounced.
Aims: The goal of this study is to test the feasibility of reconstructing the gas density distribution and quantifying
properties of structures in the inner regions of edge-on circumbinary disks using multiple molecular line observations.

3

https://arxiv.org/pdf/2009.03861

On the Nature of the T Tauri Triple System
Tracy L. Beck1 , G. H. Schaefer2 , S. Guilloteau3 , M. Simon4 , A. Dutrey3 , E. Di Folco3 and E. Chapillon3,5
The Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA; 2 The CHARA Array ofGeorgia State University, Mount Wilson Observatory, Mount Wilson, CA 91023, USA; 3 Laboratoire dAstrophysiquede Bordeaux, Universit de Bordeaux, CNRS, B18N, Alle Geoffroy Saint-Hilaire, 33615 Pessac, France; 4 Departmentof Physics and Astronomy, Stony Brook University, Stony Brook, NY 11794, USA; 5 IRAM, 300 Rue de la Piscine,
38406 Saint Martin dHres Cedex, France
1

E-mail contact: tbeck at stsci.edu
We present a multi-wavelength analysis to reveal the nature of the enigmatic T Tauri triple star system. New opticaland infrared measurements are coupled with archival X-ray, UV and mm datasets to show morphologies of disk
material and outflow kinematics. A dark lane of obscuring material is seen in silhouette in several emission lines andin model-subtracted ALMA mm continuum dust residuals near the position of T Tau Sa+Sb, revealing the attenuating
circumbinary ring around T Tau S. The flux variability of T Tau S is linked in part to the binary orbit; T Tau Sb
brightens near orbital apastron as it emerges from behind circumbinary material. Outflow diagnostics confirm thatT Tau N powers the blue-shifted western outflow, and the T Tau S binary drives the northwest-southeastern flow.
Analysis of the southern outflow shows periodic arcs ejected from the T Tau system. Correlation of these arc locations
and tangential kinematics with the orbit timing suggests that launch of the last four southern outflow ejections iscontemporaneous with, and perhaps triggered by, the T Tau Sa+Sb binary periastron passage. We present a geometryof the T Tau triple that has the southern components foreground to T Tau N, obscured by a circumbinary ring, with misaligned disks and interacting outflows. Particularly, a wind from T Tauri Sa that is perpendicular to its circumstellar
disk might interact with the circumbinary material, which may explain conflicting high contrast measurements of thesystem outflows in the literature. T Tauri is an important laboratory to understand early dynamical processes inyoung multiple systems. We discuss the historical and future characteristics of the system in this context.
Accepted by The Astrophysical Journal
https://arxiv.org/pdf/2009.03861

Spectroscopic characterization of the known O-star population in Cygnus OB2. Evidence of multiple star-forming bursts
S.R. Berlanas1,2,3 , A. Herrero2,3 , F. Comerón4 , S. Simón-Díaz2,3 , D.J. Lennon2 et al.
Departamento de Física Aplicada, Universidad de Alicante, 03690 San Vicente del Raspeig, Alicante, Spain; 2
Instituto de Astrofísica de Canarias, 38200 La Laguna, Tenerife, Spain; 3 Departamento de Astrofísica, Universidad
de La Laguna, Tenerife, Spain; 4 ESO, Karl-Schwarzschild-Strasse 2, 85748 Garching bei München, Germany
1E-mail contact: sara.rb at ua.es

6

7

http://arxiv.org/pdf/2008.00064
http://arxiv.org/pdf/2008.09826

The observational impact of dust trapping in self-gravitating discs
James Cadman1,2 , Cassandra Hall3,4,5 , Ken Rice1,2 , Tim J. Harries6 and Pamela D. Klaassen7
SUPA, Institute for Astronomy, University of Edinburgh, Blackford Hill, Edinburgh, EH9 3HJ, Scotland, UK; 2
Centre for Exoplanet Science, University of Edinburgh, Edinburgh, UK; 3 Department of Physics and Astronomy,
University of Leicester, University Road, Leicester, LE1 7RH, UK; 4 Department of Physics and Astronomy, The
University of Georgia, Athens, GA 30602, USA; 5 Center for Simulational Physics, The University of Georgia, Athens,
GA 30602, USA; 6 Department of Physics and Astronomy, University of Exeter, Stocker Road, Exeter, EX4 4QL, UK;7
UK Astronomy Technology Center, Royal Observatory Edinburgh, Blackford Hill, Edinburgh, EH9 3HJ, UK
1E-mail contact: cadman at roe.ac.uk
We present a 3D semi-analytic model of self-gravitating discs, and include a prescription for dust trapping in the discspiral arms. Using Monte-Carlo radiative transfer we produce synthetic ALMA observations of these discs. In doing so
we demonstrate that our model is capable of producing observational predictions, and able to model real image data ofpotentially self-gravitating discs. For a disc to generate spiral structure that would be observable with ALMA requiresthat the disc’s dust mass budget is dominated by millimetre and centimetre-sized grains. Discs in which grains havegrown to the grain fragmentation threshold may satisfy this criterion, thus we predict that signatures of gravitational
instability may be detectable in discs of lower mass than has previously been suggested. For example, we find thatdiscs with disc-to-star mass ratios as low as 0.10 are capable of driving observable spiral arms. Substructure becomeschallenging to detect in discs where no grain growth has occurred or in which grain growth has proceeded well beyond
the grain fragmentation threshold. We demonstrate how we can use our model to retrieve information about dust
trapping and grain growth through multi-wavelength observations of discs, and using estimates of the opacity spectral
index. Applying our disc model to the Elias 27, WaOph 6 and IM Lup systems we find gravitational instability to bea plausible explanation for the observed substructure in all 3 discs, if sufficient grain growth has indeed occurred.
Accepted by MNRAS
http://arxiv.org/pdf/2008.09826

Colliding in the shadows of giants: Planetesimal collisions during the growth and migration of gas giants
Philip J. Carter1 and Sarah T. Stewart1
Department of Earth and Planetary Sciences, University of California, Davis, One Shields Avenue, Davis, CA 95616,
USA
1

E-mail contact: pjcarter at ucdavis.edu
Giant planet migration is an important phenomenon in the evolution of planetary systems. Recent works have shown