星形成ゼミ
担当：SFN#349 1-5
2022/02/25
総研大 D2 竹村英晃

SFN#349 1-5
1. Velocity structure of the 50 pc-long NGC 6334 filamentary cloud: Hints ofmultiple compressions and their impact on the cloud properties?
2. Constraining the cosmic-ray ionization rate and their spectrum with NIR
spectroscopy of dense clouds - A test-bed for JWST
3. FEEDBACK from the NGC7538 HII region
4. Gas dynamics in the star forming region G18.148−0.283: Is it amanifestation of two colliding molecular clouds?
5. A likely flyby of binary protostar Z CMa caught in action

Velocity structure of the 50 pc-long NGC 6334 filamentary cloud
Hints of multiple compressions and their impact on the cloud properties?
Doris Arzoumanian, Delphine Russeil, Annie Zavagno et al.

•

フィラメントに周囲の環境（HIIバブル）が与える影響を調べる。

•

NGC 6334 (high-mass star-forming complex)のフィラメントに関する観測的研究。

•

APEX 13CO、C18O (J=2-1)で10x50 pcの範囲をマッピングし、75本のフィラメントを同定。
••

フィラメントに垂直な面内の速度構造（PV図）を調べると、V、Λシェイプが見られた。
••

そのうち47本は長さが > 1 pc (5ビーム)。

フィラメント（ハブ）に対して周囲の物質が流入していると考えられる。

V、Λシェイプが同一の分子雲で見られたことから、複数回ショックを経験していると考えられる。
Doris Arzoumanian et al.: Velocity structure of the NGC 6334 filamentary cloud

Herschel

IFS

MFS
GM24FS•

距離：1.3•

MFS：main-filament system

0.3 kpc•

Mline ~ 500-2000 Msun/pc•~ 10 Msunのコアに分裂している(e.g., Shimajiri et al. 2019)

•

10 pc

IFS：inter-filament system

70 μm、160 μm、250 μm
HII 領域 (Langston et al. 2000)
https://arxiv.org/abs/2201.04267v1

分子輝線の観測結果

Doris Arzoumanian et al.: Velocity structu
A&A proofs: manuscript
no. NGC6334_accepted_arxiv
12COはNANTEN)
積分強度図(

平均したスペクトルFig. 2: Integrated intensity maps, in units of K kms 1 , of the 12 CO(2 1), 13 CO(2 1), and C18 O(2 1) emission, from top to bottom.
The 13 CO(2 1) and C18 O(2 1) maps have a spatial resolution of 30.002 (corresponding to 0.19 pc at the 1.3 kpc distance of thecloud) and the emission is integrated over the LSR velocity range 12 to 4 kms 1 . The 12 CO(2 1) map has a spatial resolution of
9000 and the emission is integrated over the LSR velocity range 25 to 12 kms 1 . The blue contours trace column densities of 1.8
and 5.0 ⇥1022 cm 2 derived from Herschel data (at 36.003) and are the same on all three panels.

•

分子輝線は本体の分子雲に付随している。
•

C18Oはフィラメントをトレースし、12COや13COはより広がった成分をトレースしている。

resolution” NH2 maps at the 18.002 resolution of Herschel/SPIRE
250 µm data. The 18.002 resolution corresponds to 0.11 pc at the
1.3 kpc distance of the cloud. The multi-scale decomposition
method used to derive Herschel column density maps at 18.002
resolution is described in detail in Appendix A of Palmeirim
et al. (2013). We here used the module hires of the getsf extraction code (Men’shchikov 2021) to produce these NH2 and T dust
maps. We also smoothed the 18.002 NH2 map to the resolution of
the APEX CO maps at 30.002. In this paper all the NH2 and T dust•

Fig. 3: Positionally averaged spectra for the observed molecularand atomic emission. The spectra are averaged across the sameobserved region defined by the footprint of the APEX maps (cf.,Fig. 2). The vertical lines are as follow: The red line indicatesthe peak position of the 13 CO(2 1) and C18 O(2 1) emission at 3.3 km s 1 . The solid black line gives the position of
the extended emission at 6 km s 1 , observed in emission and absorption, in 12 CO(2 1) and HI, respectively. The dashed blacklines indicate the extent of the cloud emission identified in the12
CO(2 1) V1 velocity range (cf., Sect. 3.2).

3. Velocity structure of the 50 pc long NGC 6334

cloud
分子雲よりもHIガスの速度が広がっているため、分子雲はそのHIガスが起源だと考えられる。

•

3.1. Velocity integrated intensity maps

HIのスペクトルは分子雲の速度（-3.6km/s）で凹んでいる。
Figure 2 presents the velocity-integrated intensity maps for thethree lines observed towards the NGC 6334 molecular cloudcomplex. For the 13 CO(2 1) and C18 O(2 1) lines the emission is integrated for the local standard of rest (LSR) velocity
1

4 kms 1 , and estimated the mean optical depth of the lines assuming a mean value of the abundance ratio [13 CO]/[C18 O]=5.5(Wilson & Rood 1994) in the local ISM (see details in Ap-

速度構造

A&A proofs: manuscript no. NGC6334_accepted_arxiv

PV図•

largeスケール (>10 pc) でのフィラメント構造
は様々な観測で報告されている (e.g., Ragan etal. 2014; Kohno et al. 2021)。

•

12COでブリッジ構造が見られる。
•

CCCの完全な証拠にはならないが、物理的につながっていることを示す観測結果の一つになる。

km/s付近の成分はこの分子雲とは別のもの。
Fig. 4: Position velocity (PV) diagrams, in units of K(TMB ), for the 12 CO(2 •1), 136
CO(21), and C18 O(2 1) emission, from top
13
18
00
12
to bottom. The CO(2 1) and C O(2 1) maps have a spatial resolution of 30. 2. The CO(2 1) map has a spatial resolutionof 9000 . These PV diagrams are averaged on latitude across the cloud for 0. 4  b  1 . The white contours indicate the C18 O(2 1)intensity at 1 K and are the same for the three panels. On the top panel, the thick white contour corresponds to the 12 CO(2 1)intensity
at 0.6
K. of K(TMB ), for the 12 CO(2 1), 13 CO(2 1), and C18 O(2 1) emission, from top
4: Position velocity (PV)diagrams,
in units

ottom. The 13 CO(2 1) and C18 O(2 1) maps have a spatial resolution of 30.002. The 12 CO(2 1) map has a spatial resolution
000 . These PV diagrams are averaged on latitude across the cloud for 0. 4  b  1 . The white contours indicate the C18 O(2 1)sity at 1 K and are the same for the three panels. On the top panel, the thick white contour corresponds to the 12 CO(2 1)sity at 0.6 K.

チャンネルマップ•

C18Oでも同様の結果が得られた。

フィラメント同定

A&A proofs: manuscript no. NGC6334_accepted_arxiv

CRISPy (Chen et al. 2020b)

線幅

速度勾配

Fig. 6: Integrated intensity map, in units of K kms 1 , of the C18 O(2 1) emission (Same as in Fig. 2). The coloured curves show the
crests of the velocity coherent filaments (VCFs) identified using CRISPy. The crests with total length (L) larger than 10 pixels aretraced in cyan and numbered. The VCF 1, 32, and 47 are identified with red arrows. The dotted purple boxes indicate the regions
from which the averaged radial profiles and the PV maps are derived (see Sects. 6.1 and 6.2). The white crosses indicate the seven
infrared high-mass star-forming regions, which are usually referred to as sources I(N), E, I, II, III, IV, and V, from east to west (Persi& Tapia 2008; Arzoumanian et al. 2021). The source I is indicated with the green arrow.

線幅Fig. 6: Integrated intensity map, in units of K kms 1 , of the C18 O(2 1) emission (Same as in Fig. 2). The coloured curves show the
crests of the velocity coherent filaments (VCFs) identified using CRISPy. The crests with total length (L) larger than 10 pixels aretraced in cyan and numbered. The VCF 1, 32, and 47 are identified with red arrows. The dotted purple boxes indicate the regions
from which the averaged radial profiles and the PV maps are derived (see Sects. 6.1 and 6.2). The white crosses indicate the seven
infrared high-mass star-forming regions, which are usually referred to as sources I(N), E, I, II, III, IV, and V, from east to west (Persi& Tapia 2008; Arzoumanian et al. 2021). The source I is indicated with the green arrow.

柱密度

柱密度

速度勾配

7: Scatter plots of measured parameters for the 47 VCFs. The values are averaged along>theof the VCFs. The 。
data•Fig. C18Oでフィラメントを75本同定し、そのうち47本は長さが1crestspc（5ビーム）

points in red, yellow, and blue indicate the VCFs 1, 32, and 47, respectively. Left: Velocity dispersion versus column density. The

22 cm-2で固定）。
and vertical bars indicate the 1 dispersions of NH and v about their average
value
along the crests. The diagonal•horizontal
フィラメントの柱密度背景の差し引いたもの（背景は100.32
2line shows the best power-law fit v / NH2 . Middle: Velocity gradient Gv (given in absolute value) versus column density. The
bars indicate the 1 dispersion of NH2 (same as the left panel). The vertical bars give the 1 uncertainty of the linear fits
•horizontal
フィラメントの線幅は柱密度と共に増加する傾向にある。
to the velocity fluctuations along the crests. Right: Velocity dispersion versus Gv (given in absolute value).

• Fig.周囲の物質が降着してフィラメントが成長する際の結果と一致(ArzoumanianetTheal. data2013)。
7: Scatter plots of measured parameters for the 47 VCFs. The values are averaged along thecrests of the VCFs.
22 yellow,
0.32
in 10
red,
indicate subtracted
the VCFs 1,column
32, andden47, respectively.
versuscolumndensity.toThe
NHpoints
1⇥
cm 2 isand
the bluebackgroundtion of v Left:/ NHVelocity(Fig.dispersion
7-left). This
relation
is similar
what
2
2

horizontal
and from
verticalbars
indicatethe47に注目していく。
1 dispersions
NH andabout theiraveragevalue
along the supercriticalcrests. The diagonal
•sity
VCF
1、VCF
32、VCF(as derived
Herscheldata) averaged
along theofVCF.
was vderived
for thesampleof thermallyfilaments
0.32

2

The amplitudes of the power spectra are scaled so they can be plotted on the same panel. The red lines show the best linear fit topower spectra and the values of the slopes are indicated on the corresponding panels. The vertical black solid lines indicate theangular resolution of the data equivalent to ⇠ 1.2 arcmin 1 , which is the highest frequency data point used to fit the power spec

フィラメントの柱密度および速度のパワースペクトル•of the gradient along the crest as it is the case for the VCF 32(see Fig. 7-middle and Sect. 6).

フィラメントに沿った（1次元）、柱密度および速度の変動を評価する。

1
𝑃 𝑘 = 𝑌& 𝑘
𝐿•

VCF 1では先行研究と似たべきが得られた(Arzoumanian et al. 2021)。
1
2
P(k) =L|Ỹ(k)| ,
R

(2)

2i⇡kl

where Ỹ(k) = Y(l) exp
dl is the Fourier transform of Y(l),コルモゴロフ則に従う（べき＝‒5/3）円柱状のフィラメントはコアへ分裂
l is the spatial position along the crest, k is the angular frequency,
R

L >10 pc

and L = dl is the total VCF length. Figure 8 shows the power
spectra of NH2 (l) and v(l) of three VCF 1, 32 and 47 (see also
Sect. 6 for the analysis of these three selected VCFs). No charL >20 pc
acteristic
scales
can
be
seen
on
the
power
spectra
of
both
N
H
2
べきが‒ 1.5のフィラメントはコアへ分裂し、その質量分布は大質量側でand v, which are well represented by power laws down to the angular resolution of the data (30.002 or s ⇠ 1.2 arcmin 1 ). The obSalpeterのべきを持つと期待されるserved(Inutsuka
2001)。with a power law function in logpower spectra
are fitted
log space where k = 1.2 arcmin 1 (the smallest resolved scale)
Doris Arzoumanian etal.:highest
Velocity
structureof thefilamentary
cloudis thefrequency
data point
usedNGCfor the6334
fit. Figure
9-top
Fig.
9: Top: Distribution of the power spectrum slopes of theshows the distribution of the ↵NH2 and ↵v slopes of the NH2 (l)分解能
and v(l) power spectra, with mean values of ⇠ 1.9 ± 0.7 and umn density (↵NH2 ) and velocity (↵v ) in purple and blue, res⇠ 2.0 ± 0.9, respectively (see Table 8). Figure 9-bottom shows tively, for the 47 VCFs. The dashed vertical line indicates
5/3 value. Bottom: The difference between the power sthat the statistical difference between the ↵NH2 and ↵v slope valtrum
slopes of the column density and velocity (↵NH2 ↵v ).
ues for the same filaments are close to zero with a mean valueof 0.15 ± 0.99. This difference is 0.07 ± 0.81 and closer to zero solid and dashed histograms are for the 47 VCFs and th
when only the VCFs with length L > 20 pixels are considered. A VCFs with L > 10 pixels and L > 20 pixels, mean and stansub-selection of VCFs with L > 20 pixels (10 beams) ensures a deviation of, 0.15 ± 0.99 and 0.07 ± 0.81, respectively.
statistically larger number of resolution elements to describe thefluctuations along the VCF crests.
6. Properties along and across the crests of
The best fit slope value of the NH2 fluctuation along theselected VCFs
VCF 1 is also similar to the value found by Arzoumanian et al.
(2021) for a longer section of the filament, namely the combined Figure 10 shows the variation of the properties along the ccrests of the VCF 41 and 1, and at higher angular resolution of three VCFs 1, 32, and 47, which are part of the subreg(down to 1400 ). We discuss possible implications of this analy- IFS and MFS, respectively (see Fig. 6). We select these V
sis in Sect. 7 below.
because they are located in different environments, yet pa

する (Misugi et al. 2019)。
•

𝑌& 𝑘 = ( 𝑌 𝑙 exp"!#$%& 𝑑𝑙

In order to quantify the observed column density and velocity
fluctuations, we here present the analysis of the one-dimensional(1D) power spectrum along the crests of the identified VCFs.
The power spectrum P(k) of Y(l) (one of the VCF properties)
is proportional to the square of its Fourier transform and can be
expressed in 1D as
パワースペクトルはべき乗則で近似できる（平均値は~ ‒ 2）。

••!

5.2. Column density and velocity power spectra of the
VCFs

Article number, page 9

異なる環境にあるフィラメントの性質

A&A proofs: manuscript no. NGC6334_accepted_arxiv

ダスト温度

柱密度

Doris Arzoumanian et al.: Velocity structure of the NGC 6334 filamentary cloud
VCF1
VCF 32
VCF 47

VCF 1

F_70 μm

Fig. 6: Integrated intensity map, in units of K kms 1 , of the C18 O(2 1) emission (Same as in Fig. 2). The coloured curves show the
crests of the velocity coherent filaments (VCFs) identified using CRISPy. The crests with total length (L) larger than 10 pixels aretraced in cyan and numbered. The VCF 1, 32, and 47 are identified with red arrows. The dotted purple boxes indicate the regions
from which the averaged radial profiles and the PV maps are derived (see Sects. 6.1 and 6.2). The white crosses indicate the seven
infrared high-mass star-forming regions, which are usually referred to as sources I(N), E, I, II, III, IV, and V, from east to west (Persi& Tapia 2008; Arzoumanian et al. 2021). The source I is indicated with the green arrow.

•

NGC 6334のメインのフィラメント。

•

Source Iに向かうと見られる物質の流れを観測•

質量降着率は1.9 10-3 Msun yr-1

VCF 32•

途中で速度勾配の向きが変化している。

Fig. 7: Scatter plots of measured parameters for the 47 VCFs. The values are averaged along the crests of the VCFs. The data
points in red, yellow, and blue indicate the VCFs 1, 32, and 47, respectively. Left: Velocity dispersion versus column density. The
horizontal and vertical bars indicate the 1 dispersions of NH2 and v about their average value along the crests. The diagonalline shows the best power-law fit v / NH0.32. Middle: Velocity gradient Gv (given in absolute value) versus column density. The
2horizontal bars indicate the 1 dispersion of NH2 (same as the left panel). The vertical bars give the 1 uncertainty of the linear fits
to the velocity fluctuations along the crests. Right: Velocity dispersion versus Gv (given in absolute value).

速度•

VCF 1など周囲のフィラメントと合体をしているかもしれない (Arzoumanian et al. 2021)。

NH2 1 ⇥ 1022 cm 2 is the background subtracted column density (as derived from Herschel data) averaged along the VCF.
The background value ⇠ 1 ⇥ 1022 cm 2 is the mean NH2 towards
the regions of the molecular cloud not traced by C18 O (see also
the discussion about the similar background value estimated inthis region by Arzoumanian et al. 2021).
Figure 7-left shows the mean velocity dispersions of the
VCFs as a function of their mean column density. The mean
velocity dispersion corresponds to the mean value of the fitted
velocity dispersions (i.e., line width) of the corresponding velocity component at each position along the VCF. The mean velocity dispersions of the VCFs show an increasing trend as afunction of their mean column density with a best fit linear rela-

速度分散

VCF 47•星形成が起きている（複数の70 μm源が存在）。

•

局所的な速度勾配が存在•

フィラメントに沿った位置

tion of v / NH0.32(Fig. 7-left). This relation is similar to what2
was derived for the sample of thermally supercritical filaments
presented in Arzoumanian et al. (2013) and was interpreted as
resulting from the evolution of the filaments by accretion ofsurrounding matter. We measure a wealth of velocity gradientsalong the VCF crests. We quantify the velocity gradients withlinear 1D fits of the observed velocity along the crests (see figure 10-middle). We find a large scatter in the measured velocity
gradients for filaments with NH2 . 5 ⇥ 1022 cm 2 and a tentative
increasing trend for filaments with NH2 & 5 ⇥ 1022 cm 2 (Fig. 7middle). The filaments with larger velocity gradients tend to also
show larger velocity dispersions. We note, however, that the observed velocities are line-of-sight projected velocities and small
velocity gradients may be due to 1) the orientation of the filament close to the plane-of-the-sky or 2) the variation of the sign

分裂とinfallか？→速度勾配と高密度領域はmass of a 0.1 pc wide filament with non-Gaussian wings beyond the
0.1 pc inner width.

Fig. 10: Properties along the VCF crests 1, 32, and 47, from left to right. The zero offsets correspond to the most western-southern end of thecrests (as seen on Fig. 6). Rows from top to bottom are: (1) Column density as derived from Herschel data. (2) LOS averaged dust temperature Article
asnumber, page 8 of 21
derived from Herschel data. The horizontal blue lines indicate the mean background temperature around the VFCs of ⇠ 17.9 ± 0.2 K. (3) PACS
70 µm flux. The horizontal blue line indicates the mean background emission of ⇠ 146 ± 23 MJy/sr. (4) Velocity. The black vertical lines on eachdata points show the velocity dispersion (same as the values shown in row 5). The black lines show a linear fit to these data points. The velocity
resolution of 0.3 km s 1 is indicated by the vertical blue lines. For the VCF 1, a linear fit to the velocity > 2.8 km s 1 over a length of 0.7 pc isindicated in red and corresponds to the crest crossing the young star cluster identified as source I (see, e.g., Persi & Tapia 2008). The position ofsource I is indicated with the vertical dashed green line (see also the green arrow on Fig. 6). (5) Velocity dispersion. The velocity resolution of•

一致していない (Chen et al. 2020b)。

VCF 1とは違い、深いポテンシャルを持つ場所がないため、全体的な速度勾配はない。

A&A proofs:
no. NGC6334_accepted_arxiv
Fig. 11: Radial profiles across the MFS-warm, MFS-cold, and IFS regions, from left to right (see boxes
inmanuscript
Fig. 6).
The column
density, the PACS 70 µm emission, and the dust temperature are shown in solid black, blue dashed, and red dotted dashed lines,
respectively. The scaling of the different curves is indicated in the caption of each panel. The r > 0 values correspond to the Galactic
north.

各フィラメントのPV図•

V（Λ）型のPV図は、磁化したシートがショック
MFS
MFS
warm

Filament

IFS

cold

North

Extended sheet-likestructureによって圧縮されてフィラメントが形成されるシナ

South

Fig. 11: Radial profiles across the
MFS-warm, MFS-cold, and IFS regions,HII region
from left to right (see boxes in Fig. 6). The column
HII region
リオと整合的(e.g.,70InoueetFeedback?
al.and2018)。temperature are shown in Feedback?
density, the PACS
µm emission,
the dust
solid black, blue dashed, and red dotted dashed lines,
HII region
respectively.Feedback?
The scaling of the different curves is indicated in the caption of each panel. The r > 0 values correspond to the Galactic
north.
MFS
warm

Filament/hubs
SouthExtended sheet-like structure

North

MFS
cold

South

Extended sheet-likestructure

Filament

Fig. 6: Integrated
the C18 O(2 1) emission(Same as in Fig. 2). The coloured curves show the
IFS intensity map, in units of K kms 1 , ofFilament
North
Northof the velocity coherent filaments
crests(VCFs)
Extended
sheet-like identified using CRISPy. The crests with total length (L) larger than 10 pixels are
structuretraced in cyan and numbered. The VCF 1, 32, and 47 are identified with red arrows. The dotted purple boxes indicate the regions
from which the averaged radial profiles and the PV maps are derived (see Sects. 6.1 and 6.2). The white crosses indicate the sevenSouthinfrared high-mass star-forming
regions, which are usually referred to as sources I(N), E, I, II, III, IV, and V, from east to west (Persi& Tapia 2008; Arzoumanian et al. 2021). The source I is indicated with the green arrow.

Fig. 12: Position velocity (PV)HIIdiagrams
perpendicular to and averaged along
the main axes of the MFS-warm, MFS-cold, andregionHII region
Feedback?
Feedback?
IFS regions, from left to right (seeboxes in Fig. 6). The PV maps are in unitsof K(TMB ) and correspond to the 13 CO(2 1) andHII region
C18 O(2 Feedback?
1) emission on the top and bottom, respectively. The white contours indicate the C18 O(2 1) intensity and are the samefor the two panels of the same filament system. The magenta contours on the left panel correspond to the 13 CO(2 1) intensity. The
zero offset position (in the x-axes) corresponds to the Galactic South side of the filament systems. At the distance of this cloud 100
corresponds to 3.8 pc. The
position of the filaments Extended
are indicatedwith a dark blue circle and the velocity gradients induced by theFilament/hubs
sheet-like
Filament
structure
South
South arrows
Extended sheet-likestructure
North
North
compression
areshown as converging
red dashedtowards the filament.
Longitudinal PV diagrams along the crest of VCF 32
of the MFS-cold region are shown in Fig. C.1.

Fig. 7: Scatterplots of axes
measured
for the 47 VCFs.MFS-cold,
The values are averaged
Fig. 12: Position velocity (PV) diagrams perpendicular to and averaged along
the mainofparameters
the MFS-warm,
and along the crests of the VCFs. The data
points in red, yellow, and blue indicate the VCFs 1, 32, and 47,
13 respectively. Left: Velocity dispersion versus column density. The
IFS regions, from left to right (see boxes in Fig. 6). The PV maps are in unitsof K(T
andindicate
correspondto theandMB ) bars
horizontal
and verticalthe 1 dispersionsof NH CO(2and v about1)
theiraverage value along the crests. The diagonal
0.32
line shows
the bestthe
power-law
fit v / N1)
Middle: Velocity
Gv (givenin absolute value) versus column density. The
C18 O(2 1) emission on the top and bottom, respectively. The white contours
indicate
C18 O(2andgradient
are thesame
H .intensity
horizontal bars indicate the 1 dispersion of N13
H (same as the left panel). The vertical bars give the 1 uncertainty of the linear fits
for the two panels of the same filament system. The magenta contours on thetoleft
panelfluctuations
correspondtheRight:
CO(21) intensity.
Thein absolute value).
the velocity
along theto
crests.
Velocity dispersion
versus Gv (given
zero offset position (in the x-axes) corresponds to the Galactic South side of the filament systems. At the distance of this cloud 100
221 ⇥ 10cm 2 andis the backgroundsubtracted
column den- induced
tion of v /by
NH0.32
corresponds to 3.8 pc. The position of the filaments are indicated with a darkNH blue
circlethe velocity
gradients
the(Fig. 7-left). This relation is similar to whatsity (as derived from Herschel data) averaged along the VCF. was derived for the sample of thermally supercritical filaments
22
2compression are shown as converging red dashed arrows towards the filament.
along
the crestof VCF
32
TheLongitudinalbackground value ⇠ PV
1 ⇥ 10diagrams
cm is the mean
NH towards
presented
in Arzoumanian
et al. (2013) and was interpreted as
the regions of the molecular cloud not traced by C18 O (see also resulting from the evolution of the filaments by accretion ofof the MFS-cold region are shown in Fig. C.1.
the discussion about the similar background value estimated in surrounding matter. We measure a wealth of velocity gradients
2

2

2

2

2

2

this region by Arzoumanian et al. 2021).
Figure 7-left shows the mean velocity dispersions of the
VCFs as a function of their mean column density. The mean
velocity dispersion corresponds to the mean value of the fitted
velocity dispersions (i.e., line width) of the corresponding velocity component at each position along the VCF. The mean velocity dispersions of the VCFs show an increasing trend as afunction of their mean column density with a best fit linear relamass of a 0.1 pc wide filament with non-Gaussian wings beyond the

•
•
•
•

along the VCF crests. We quantify the velocity gradients withlinear 1D fits of the observed velocity along the crests (see figure 10-middle). We find a large scatter in the measured velocity
gradients for filaments with NH2 . 5 ⇥ 1022 cm 2 and a tentative
increasing trend for filaments with NH2 & 5 ⇥ 1022 cm 2 (Fig. 7middle). The filaments with larger velocity gradients tend to also
show larger velocity dispersions. We note, however, that the observed velocities are line-of-sight projected velocities and small
velocity gradients may be due to 1) the orientation of the filament close to the plane-of-the-sky or 2) the variation of the sign

0.1 pc inner width.
Fig. 13: Schematic view of the suggested scenario where propagating extended
gas structures interact with the NGC 6334 complex,
V型とΛ型のPV図が見られており、それぞれ別のショックによって形成されたと考えられる。
Article number, page
8 of 21
resulting in the formation or altering the properties of the filament systems MFS-warm,
MFS-cold,and IFS from left to right. Thesesketches are in the PP space perpendicular to the filament along axes. The velocities of the different structures are indicated in the
MFS領域ではフィラメントの周囲にもCOが分布しており、これからフィラメントへ降着できる物質が多い。
LSR frame according to the PV diagrams (Fig. 12). The shock front is indicated in the post-shock configuration. The << and >>symboles refer to more blueshifted and more redshifted velocities, respectively, with respect to the velocity of the extended sheet
VCF 1およびハブに向かうフィラメントの速度勾配が質量流入をトレースしていると考えられる。
like structures. The velocity of the sheet like structure is connected to the filament velocity through a velocity gradient. The ambient
B-field (indicated by the black lines) is parallel to the shock front.

IFSではCOが広がっておらず、元のシートに物質がほとんど降着したと考えられる。

A likely flyby of binary protostar Z CMa caught in action
Ruobing Dong, Hauyu Baobab Liu, Nicolas Cuello et al.

•連星（Z CMa）とそれに付随するstreamerをALMA、JVLT（＋すばる Hバンド）で観測。

•

SPHシミュレーション＋模擬観測を行い、観測結果と比較した結果、 streamerは近傍を天体が通過したことによって形成されたと考えられる。

•

典型的な星団内でフライバイが起こるタイムスケールと、 Z Cmaがフライバイを経験したことは整合的。

Z CMa (Canis Major R1 accociation)•

距離 ~ 1125 pc•

連星系はface-onの円軌道を持ち、5 M◉ (EXor)と1 M◉ (FUor)の原始星からなる。

すばる Hバンド（偏光） ALMA 1.3 mm
       






JVLA 9 mm  ! "#








$%  "#








"



    



Ø

A、B
•
連星系、~20 auほどの円盤をもつØC（perturber、YSOか？）•
サイズ：40-50 au•
Mdust = 28 1 MØD（streamerの形成には寄与しない）



&'(

&'(





•

Ø
































  


















Mdust = 22

1M

streamer•

Mdust： 119 24 M

http://arxiv.org/abs/2201.05617v1

SPHシミュレーション、輻射輸送計算モデル•

連星とperturberの質量比は0.3（6 M◉と1.8 M◉）。

•

perturberは円盤から45度傾いた平面内で放物線を描く。
•

1''@1125pc

1''@1125pc•

近日点での連星とperturberの距離は3000 au。
•

近日点通過から14 kyr後シミュレーション結果
シミュレーション結果（zx平面の柱密度）log(Gas Column Density)（xy平面の柱密度）log(Gas Column Density)
0

-2

-4

0

-2

-4

log column density [g/cm2]

円盤半径は840 au（円盤内を通過しない）。

•

streamerやCの位置は観測結果に似ている。

•

これが観測結果を説明し得る唯一のモデルではな

log column density [g/cm2]

1

2

2

3

3

角運動量ベクトルのなす角が45度。

-2

-2

2

1

0 -1 -2

-3

3


 









  










2






1

0

-1

-2



1125 AU















 









•




•



   



-3

     

Z CMa のstreamerはCが円盤の近傍を通過したことによる潮汐作用で形成されたのではないか。

-3

-3

3

輻射輸送計算     

（Hバンドの偏光） 



•

-1

-1

0

0

1

い（当たりをつけて計算したモデルのひとつ）。



観測結果と合わない点もある。
•

モデルの方がstreamerが長く暗い。

•

モデルにのみ北側にもう一つのarmがある。

perturberの軌道や円盤サイズ、観測する角度、ダストの散乱に関する性質が異なる可能性がある。

 

すばる


      （Hバンドの偏光）

 

分子輝線観測、天体Cについて

















 



 

 















天体Cは1.3 mm連続波、Hバンドの偏光に加え、13COや



C18Oでも観測された。
一方、可視光や赤外線（SDSS、Gaia、2MASS、

WISE）では観測されていない。

•



Hバンドの等級の上限は21.9 mag（Keckの観測より）•

年齢が数Myrの惑星質量天体•~10 mag程度の減光を受けた太陽質量のYSO









 


  








別のシミュレーションより、中心星とperturberの質量比が0.1以下の場合はstreamerを形成しづらい。

サイズが200 au程度あるはずなのに加え、envelopeがフライバイの影響を受けた跡がない。

























  









  ↑moment-0







•

 

12
13
Figure2: Integrated
intensity0) maps of the(2-1),CO (2-1),
C18O (2-1),     (moment

CO

  
 
00
00
andSO 3 ⌃
6(5)-5(4)transitions.
) is 
marked at the Thebeam size (0.19 ⇥ 0.18 ; P.A.=88
 lower
left corner. The Robust = 0 weighted 224 GHz continuum image (beam size 000 .075 ⇥ 000 .047;
1)   
 50

P.A.=65
is shown
in green
contours at 0.13 and 1.3 mJy beamlevels (5 and⇥ the root mean!
  
 squarenoises)to highlightthe four compact continuum
sources.
The !ALMA/JVLA
source C islabeled.


7







フライバイ以前からもともと円盤を持っていClass 0のYSOか？→違うと思われる。

   



•





フライバイによって連星周囲の円盤から物質た（edge-on）。







を剥ぎ取った。
•

 





減光を受けたYSOの説が濃厚
•







•





 

•





•








•






 









 












 









 










 

double burster nature

















 













•

Z CMaは“double burster”である (Audard et al. 2014)。

•

孤立した0.1 ‒ 40 M◉ の原始星は寿命の1-10%の期間



accretion outburstを起こしている。
•

連星でoutburstが独立に起こる場合、“doubleburster”を観測できる確率は < 1%。







 









 





 





 


•

天体Cの通過により、質量降着が誘発されて“double

回転の周期の10分の1程度の時間でoutburstがピークとなり、数千年続く。

  

perturberが近日点を通過後、その点でのケプラー















 





burster”となったと考えられる。
•
















このイベントはどのくらいの頻度で起こるのか•   

moment-1

Extended data figure 2: Moment-1 maps (intensity-weighted mean velocity) of the ga
servations. The Robust = 0 weighted 224 GHz continuum image (beam size 000 .075 ⇥ 000
P.A.=65 ) is shown in white contours at 0.13 and 1.3 mJy beam 1 levels (5 and 50 ⇥ the root msquare noises). The systematic velocity is ⇠ 14 km/s 91 . The ALMA/VLA source C is labele

ある星が経験するフライバイ イベントの間隔は以下の通り計算でき、Z CMaの年齢とconsistent。
21•

Z CMa周囲の環境は不明だが、~ 1 pcのフィラメントの中心付近に位置し、ρcluster が高いと期待できる。
•

この計算結果も、Z CMaのstreamerが天体Cのフライバイで形成されたことを支持している。