HNC (1–0)
CS (2–1)

20

4.72±4.94
CS (2–1) 8.30±0.14
2.11±4.710.09±0.19
8.21±0.15 0.28±0.10
0.05±0.29 4.49±0.85
0.17±0.13
4.24±0.84
2.11±4.71
8.21±0.15
0.05±0.29
0.17±0.13
4.24±0.84
Y. Source
Gong
Serpens filament: at the onset of slightly supercritical collapse
Aet al.: The
Source A 8.11±0.09
HNC (1–0)
3.83±2.41
0.10±0.13
0.29±0.06
5.56±0.79
HNC (1–0)
3.83±2.41
CS (2–1) 8.11±0.09
3.90±4.690.10±0.13
8.05±0.11 0.29±0.06
0.05±0.16 5.56±0.79
0.21±0.09
1. Observed
parametersof the0.21±0.09
molecular4.56±0.92
lines used in 4.56±0.92
the work.
CS (2–1)Table
3.90±4.69
8.05±0.11
0.05±0.16

The Serpens filament: at the onset of slightly supercritical collapse

Notes. (1) The used transition. (2) The fitted opacity. (3) The fitted systemic LSR velocity. (4) The fitted infall velocity. (5) The fitted velocity
Notes. (1) The dispersion.
used transition.
(2)fitted
The fitted
opacity. (3)The fitted systemic LSR velocity.
infall velocity.
velocity δνLine(4) The fitted
Frequency
Eu /k (5) The
Beﬀ fitted δ!
σobs.Mode(6) Thepeak excitation
temperature.
dispersion. (6) The fitted peak excitation temperature.
(GHz)
(K)
(km s−1 )
(kHz)
(K)

Y. Gong1,2 , G. X. Li3,4 , R. Q. Mao2 , C. Henkel1,5,6 , K. M. Menten1 , M. Fang7 , M. Wang2 and J. X.
Sun2

(1)

C18 O (1–0)
HCO+ (1–0)
HCN (1–0)
N2 H+ (1–0)
CS (2–1)
HNC (1–0)
CH3 OH (JK =20 –10 A+ )CH3 OH (JK =2−1 –1−1 E)

1

Max-Planck Institute für Radioastronomy, Auf dem Hügel 69, 53121 Bonn, Germany; 2 Purple Mountain Observatory & Key Laboratory for Radio Astronomy, Chinese Academy of Sciences, 2 West Beijing Road, 210008 Nanjing,
P.R. China; 3 University Observatory Munich, Scheinerstrasse 1, D-81679 München, Germany; 4 South-Western Institute for Astronomy Research, Yunnan University, Kunming, Yunnan 650500, P.R. China; 5 Astronomy Department,
Faculty of Science, King Abdulaziz University, P.O. Box 80203, Jeddah 21589, Saudi Arabia; 6 Xinjiang Astronomical
Observatory, Chinese Academy of Sciences, 830011 Urumqi, China; 7 Department of Astronomy, University of Arizona,
933 North Cherry Avenue, Tucson, AZ 85721, USA

天体：Serpens ﬁlament (最も近いIRDCsの一つ; d ~440pc)

望遠鏡：Purple Mountain Observatory 13.7 m望遠鏡

HCN (1–0)
H13 CO+ (1–0)
H13 CN (1–0)
HN13 C (1–0)
13
CS (2–1)
CCS (JN =87 –76 )E-mail contact: ygong 18
at mpifr-bonn.mpg.de+

輝線：C O, HCO , HNC, HCN, N2H+, CS, CH3OH

HCN (1–0)

The Serpens filament, as one of the nearest infrared dark clouds, is regarded as a pristine filament at a very early
Y. Gong
The Serpens
filament: at theInonsetof slightlyto
supercriticalevolutionary stage
ofet al.:star
formation.
order
studycollapse
its molecular content and dynamical state,
we mapped thisA&A proofs: manuscript no. absfil
filament in seven species including C18 O, HCO+ , HNC, HCN, N2 H+ , CS, and CH3 OH. Among them, HCO+ , HNC,
HCN, and CS show self-absorption, while C18 O is most sensitive to the filamentary structure. A kinematic analysis
demonstrates that this filament forms a velocity-coherent (trans-)sonic structure, a large part of which is one of the

(2)
(3)
(4)
(5)
(6)
The Serpens filament
109.78217
5.0
55.5%
0.04
12.2
89.18852
4.3
56.8%
0.21
61
88.63185
4.3
56.8%
0.21
61
93173.76
4.5
61.9%
0.04
12.2
97.98095
7.1
60.6%
0.04
12.2
90.66357
4.4
57.0%
0.04
12.2
96.74138
7.0
63.4%
0.19
61
96.73936
12.5
63.4%
0.19
61
Source A: (αJ2000 =18h 28m 47.s 62, δJ2000 =00◦ 50′ 55.′′ 8)88.63185
4.3
56.8%
0.04
12.2
86.75429
4.2
56.7%
0.21
61
86.34018
4.1
56.7%
0.21
61
87.09085
4.2
56.7%
0.21
61
92.49426
6.7
61.9%
0.20
61
93.87011
19.9
61.9%
0.19
61
Source B: (αJ2000 =18h 28m 57.s 70, δJ2000 =00◦ 48′ 02.′′ 0)88.63185
4.3
56.8%
0.04
12.2

(7)

(8)

0.27
0.07
0.07
0.20
0.13
0.16
0.07
0.07

mapping
mapping
mapping
mapping
mapping
mapping
mapping
mapping

0.06
0.02
0.02
0.02
0.02
0.04

pointing
pointing
pointing
pointing
pointing
pointing

0.06

pointing

Notes. (1) The observed transition. (2) The rest frequency of the observed transition. (3) The upper energy of the observed transiti
beam eﬃciency. (5) The channel width in units of km s−1 . (6) The channel width in units of kHz. (7) The rms noise level. (8) The o
Table 2. Observed and physical properties of source A.
Line!LSR Herschel∆!250 µm image
T mb d! of the Serpens
Nmol
Fig. 1. (a) The WISE 11.2 µm image of the Serpens filament which shows up inabsorption. (b) The
−1
−1
(km
s−1 )µm
(km
s−1of
) the
(K
km embedded
s−1 )(cm−2 )
Fig. 1. (a) The filament.
WISE 11.2
imagestartof theSerpens
filament
shows
absorption.
(b)panels,
The Herschel
250
image
thethreeSerpensTheµm
contours
at 0.5
Jy beam, and which
increaseby 0.5upJyinbeam. In boththe threeblue
circles
mark
YSOs,
−1
(1) the(2)(3) B (see Sect.
(4)2.1filament. The contours
at 0.5beam−1, and increaseby 0.5
Jy beam. Inandbothpanels,thegivethreecirclesmarkembedded
YSOs,
emb10, start
emb16,
andJyemb28(Enochet al. 2009),
while
the whitecyan
circles
theblueselected
positionsofthree
SourceA and Source
18
14
C
O
(1–0)
8.11±0.01
0.53±0.01
1.14±0.06(5.9±0.3)×10
emb10, emb16, andand Table
emb281).(Enochet al.size2009),
while inthethewhite
andright
cyanofcircles
give the selected positionsof Source A and Source B (see Sect. 2.1
The beamis shown
lowereach panel.
N2 H+ (1–0)
8.06±0.12
0.45±0.12
1.29±0.09(3.1±0.2)×1012
and Table 1). The beam size is shown in the lower right of each panel.
+!

21

HCO (1–0)
H13 CO+ (1–0)
HCN (1–0)
H13 CN (1–0)
HNC (1–0)
HN13 C (1–0)
CS (2–1)
13
CS (2–1)
CCS (JN =87 –76 )CH3 OH (JK =20 –10 A+ )CHOH
(J
–1−1 E)3
K =2−1
A&A proofs: manuscript no.
absfil

...
8.20±0.21...
8.04±0.21...
8.09±0.21...
8.18±0.20
8.47±0.19
8.28±0.19
8.23±0.19...
0.70±0.20...
0.50±0.21...
0.77±0.21...
0.69±0.20
0.52±0.19
0.57±0.19
0.54±0.19<0.32
0.42±0.01
0.31±0.02
0.11±0.01
1.33±0.05
0.47±0.01
0.57±0.04
0.05±0.01
0.13±0.02
0.26±0.03
0.15±0.03...
(2.5±0.1)×1011>1.1×1012(4.0±0.4)×1011>2.4×1012(1.1±0.2)×1012>2.6×1012(2.5±0.5)×1011(2.0±0.3)×1012(1.5±0.2)×1013(8.8±0.2)×1012

HCO+, HNC, HCN, CS：自己吸収が見られる

Notes. (1) The LSR velocity. (2) The FWHM line width. (3) The integrated intensity. For N2 H+ (1–0), the integrated velocity rang
For HCO+ (1–0), HCN (1–0), HNC (1–0), and CS (2–1), the integrated velocity range is 7–9 km s−1 . 3σ is taken as the upper lim(1–0) integrated intensity. (4) The beam-averaged molecular column density is calculated by assuming optically thin emission atemperature of 10 K. Since HCN (1–0), HNC (1–0), and CS (2–1) suﬀer from self-absorption, their derived column densities canlower limits.

C18O：フィラメント構造をよく示す。

velocity coherentな音速フィラメント。
Table 3. A comparison between the Serpens filament and other filaments in nearby clouds.

A&A proofs: manuscript no. absfil
Filaments

Fig. 2. Spatial distributions of diﬀerent molecular species, labeled in the lower right of each panel, over the Serpens filament. (a) The Herschel H2column density image. The contours are H2 column densities of 4×1021 cm−2 and 6×1021 cm−2 . This region is divided by the two white dashedlines into three individual regions which are labelled as NW (northwest), SE (southeast), and EX (extended). (b) The C18 O (1–0) intensity map
integrated from 7.4 to 8.7 km s−1 . The contours start at 0.30 K km s−1 (5σ), and increase by 0.18 K km s−1 (3σ). (c) The HCO+ (1–0) intensity
map integrated from 6.5 to 9.5 km s−1 . The contours start at 0.27 K km s−1 , and increase by 0.27 K km s−1 . (d) The HNC (1–0) intensity map
integrated from 7.0 to 9.0 km s−1 . The contours start at 0.24 K km s−1 , and increase by 0.24 K km s−1 . (e) The HCN (1–0) intensity map integrated
from 0 to 1.6 km s−1 , from 7.0 to 8.6 km s−1 , and from 11.8 to 13.4 km s−1 relative to the frequency of the F=2–1 hyperfine structure component.
Article number, page 10 of 22
The contours start at 0.27 K km s−1 , and increase by 0.27 K km s−1 . (f) The N2 H+ (1–0) intensity map integrated from 6.5 to 9.5 km s−1 . The
contours start at 0.30 K km s−1 , and increase by 0.30 K km s−1 . (g) The CS (2–1) intensity map integrated from 7.0 to 9.5 km s−1 . The contours
Article number, page 10 of 22
start at 0.18 K km s−1 , and increase by 0.18 K km s−1 . (h) The CH3 OH (20 –10 ) intensity map integrated from 7.5 to 8.8 km s−1 . The contours start
−1
−1
h
m
s
◦
′
′′
at 0.12 K km s , and increase by 0.12 K km s . In all panels, the (0, 0) oﬀset corresponds to αJ2000 =18 28 49. 642, δJ2000 =00 50 01. 08, and thethree blue crosses give the positions of the three embedded YSOs (see also Fig. 1). The beam size is shown in the lower right of each panel.Fig. 3. Single-pixel spectra (black lines) of all detected molecules toward Source A. Species are given in the upper left of each panel. In all panels,

The Serpens filament
Serpens South(2)
Musca
TMC-1
filaments in IC5146
F2 in OMC1

length(pc)
1.6±0.1
0.53
6.5
0.6
0.45

width(1)(pc)
0.17±0.01
0.13
0.07
0.12
0.06–0.18
0.02±0.008

Ml(M⊙ pc−1 )
41±5
97
21–31
90
1–152

p
2.2±0.1
1.9±0.2
2.6±0.3
2.27
1.3–2.4
5.1±1

The Plummer profilencr0(cm−4 )
(pc)
(4.0±0.8)×104
0.018±0.003(3.6±2.2)×105
0.004±0.002(5–10)×104
0.016±0.005
7.0×104
0.015
0.004–0.028
0.004±0.001

Ṁ⊥(M⊙ Myr−1 )
∼72
∼ 208

Ṁ∥
(M⊙ Myr−1 )∼10∼45Ṁ∥ /L(M⊙ Myr−1 pc∼20∼90Notes. (1) The FWHM width. (2) Scaled to a distance of 415 pc.

the vertical blue dashed lines represent the systemic velocity obtained from C18 O (1–0). Single-peaked spectra are modeled with a Gaussian fit.
The blue-skewed line profiles of CS (2–1), HCN (1–0), and HNC (1–0) are fitted with the Hill5 model (De Vries & Myers 2005). For H13 CN(1–0) and N2 H+ (1–0), the spectra are fitted with the hyperfine structure fitting subroutine in GILDAS. All fitted results are shown in red lines. The
velocities of the N2 H+ (1–0) hyperfine structure components are indicated by vertical red lines. In the CH3 OH panel where the velocity is given
with respect to the rest frequency (96.74138 GHz) of CH3 OH (20 − 10 A+ ), the CH3 OH triplet around 96.74 GHz is also indicated by three vertical
red lines.

フィラメント：質量~66 Msun（長さ ~1.6 pc）、幅~0.17pc
Radial column density proﬁleは非対称
Article number, page 12 of 22

Article num

0.2 pc以内：Plummer proﬁleに近い>0.2 pc：Power lawで落ちてほぼ一定に
Article number, page 11 of 22

Fig. 10. (a) The H2 column density image of the Serpens filament obtained from the Herschel Gould belt survey. The contours correspond to−222−2
10.21 (a)H212 cm
columndensityof the Serpens
filament
obtainedfrom with
the Herschelcolumn densitiesFig.
of 6×10
cm−2The, 8×10, and 1×10
cmimage. The extracted
crest of theSerpens filament
is marked
the blue line.Gould
The belt survey. The contours correspond to
21
−2
21
−2
22
−2
columndensities
6×10thecm,profile
8×10of, anddensity.
1×10Thecm.blackThecrosses
extracted
crestof theofSerpens
emission within thewhite box
is used of
to derive
radialHcm
threegive thepositionsthe three filament is marked with the blue line. The
2 column
embedded YSOs.emission
The beam size
is shown
the lowerof thisto
panel.
(b) Theradialprofile ofof HH2 2column
densities
withinThe
the white
withinthe inwhiteboxright
is usedderivethemeanradialprofilecolumndensity.
threebox
black crosses give the positions of the three
in Fig. 10a. The oﬀsets increase from east to west. A Gaussian fit is indicated by the red line. (c) The mean radial H2 column density profile onembedded YSOs. The beam size is shown in the lower right of this panel. (b) The mean radial profile of H2 column densities within the white box
the west (yellow) and east (orange) sides of the crest. The red and blue dashed lines represent Plummer-like fits to the east and west (see Fig. 10a)in Fig.
10a.pc,Theoﬀsetsincrease
to west.
A Gaussian radial
fit isprofile
indicatedby the redline. (c) etThe
within a radius rangeof <0.2
while
the cyan
and blackfrom
lines east
represent
the beam-convolvedof Musca-West(Kainulainen
al. mean radial H2 column density profile on
the west
and eteast(orange)sides
theThebeamred size
andisbluelines line.
represent Plummer-like fits to the east and west (see Fig. 10a)South(yellow)
filament (Kirk
al. 2013).
In bothFigs.of10a
andcrest.
10b. The
showndashedby the brown2016) and the Serpens

within a radius range of <0.2 pc, while the cyan and black lines represent the beam-convolved radial profile of Musca-West (Kainulainen et al.
2016) and the Serpens South filament (Kirk et al. 2013). In both Figs. 10a and 10b. The beam size is shown by the brown line.

Filament crestに沿ったCD proﬁle：~0.85 pcと~0.26 pcのfragmentation scaleを示す~0.85 pc：Filamentのfragmentation scale~0.26 pc：thermal Jeans instability or YSOからのfeedback？
Y. Gong et al.: The Serpens filament: at the onset of slightly supercritical collapse

Fig. 11. (a) The LSR velocity map similar to Fig. 4b but overlaid with the H2 column density contours which represent 4×1021 cm−2 and6×1021 cm−2 . Source B is marked with the red circle, and the three black crosses give the positions of the three embedded YSOs, i.e., em10,
em28, and em16. (b) The column density profile along the crest of the Serpens filament indicated by the blue line in Fig. 11a. The spatial resolution is ∼0.08 pc. The oﬀset increases from south to north. The red line represents a sinusoidal fit to the profile within the oﬀset range of 1.0–1.4
pc. A sinusoidal orange line is created to better visualize the variation at a large scale. (c) Similar to Fig. 11b but for the C18 O (1–0) velocity. The
four red arrows correspond to the velocity gradients in Fig. 4b, indicated there by black arrows. (d) Similar to Fig. 11c but for the C18 O (1–0) line
widths. In Figs. 11b–11d, the red dashed lines mark the positions of Source B and the YSO emb28.

Serpens ﬁlamentはわずかにSupercritical（Line mass ~ 36-41 Msun pc-1）
blue-skewed HNC・CNと、HCNのhyperﬁne：(tras-)sonic ﬁlamentでのradial collapseを示唆？
「わずかにSupercriticalなﬁlamentは、collapseする傾向にある」という理論とも合う

Fig. 12. (a) The HNC (1–0) spectrum is averaged over 3×3 pixels centered at an oﬀset of (−40′′ , 40′′ ) in Fig. 2 to increase the signal-to-noise level.
′′′′

HCNとCSのblue-skewed proﬁleから、・radial infall vel. はfree-fall vel. の10%以下
・radila collapseのinfall rateは ~72 Msun Myr-1=> ﬁlamentの質量を２倍にするには~0.9 Myr必要
Class I天体を作る時間と同等

Y. Gong et al.: The Serpens filament: at the onset of slightly supercritical collapse

Fig. 4. Maps of peak intensities (Fig. 4a), LSR velocities (Fig. 4b), line widths (Fig. 4c), and Mach numbers (Fig. 4d) derived from singlecomponent Gaussian fits to our C18 O (1–0) data. The color bars represent main beam brightness temperatures in units of K in Fig. 4a, LSR
velocities in units of km s−1 in Fig. 4b, and line widths in units of km s−1 in Fig. 4c. Velocity gradients along the filament and perpendicular to thefilament are indicated by the black and red arrows in Fig. 4b, respectively. In all panels, the (0, 0) oﬀset corresponds to αJ2000 =18h 28m 49.s 642,
δJ2000 =00◦ 50′ 01.′′ 08, and the three black crosses give the positions of the three embedded YSOs (see Fig. 1). The mean uncertainties in derived
peak intensities, LSR velocities, line widths, and Mach numbers are 0.19 K, 0.02 km s−1 , 0.06 km s−1 , and 0.1, respectively. The beam size isshown in the lower right of each panel.

Fig. 9. (a) The C18 O (1–0) integrated intensity map similar to Fig. 2b but overlaid with a PV cut indicated by the white dashed line. (b) The PV
diagram of C18 O (1–0) along the PV cut in Fig. 9a. The channel width of C18 O (1–0) spectra has been binned to 0.1 km s−1 to achieve a higher
dynamical range. (c) Similar to Fig. 9b but for HNC (1–0). (d) Similar to Fig. 9b but for CS (2–1). In Fig. 9b–d, the color bars represent main
beam brightness temperatures in units of K, and the black contours represent the C18 O (1–0) emission starting at 1.5 K (5σ) with increments of
0.9 K (3σ). The oﬀsets are given with respect to the center of the PV cut (αJ2000 =18h 28m 50.s 865, δJ2000 =00◦ 50′ 21.′′ 799, also indicated by thewhite filled circle in Fig. 9a), and increase from southeast to northwest. The resolution element is shown in the lower right of each panel.

Filamentの長軸に沿ったC18Oの速度勾配：Filament内でのGas accretionを示唆（~10 Msun Myr-1）

Article number, page 17 of 22

速度や密度構造から、このaccretion ﬂowは、Filament長軸方向のcollapseが原因
Infall rateもFilamentに沿ったaccretion rateも、他の報告されているFilamentのものよりも低い
collapseが始まったばかりの初期ステージにある or 熱的＆非熱的支えが効果的であること示す26

CO observations toward the isolated mid-infrared bubble GAL 334.53+00.83 (S44):
External triggering of O-star formation by a cloud-cloud collision

Spitzer, blue : 3.6 μm, green : 8.0 μm, red : 24 μm(a)Mikito Kohno1 , Kengo Tachihara1 , Shinji Fujita1 , Yusuke Hattori1 , Kazufumi Torii2 , Atsushi Nishimura1 ,Misaki Hanaoka1 , Satoshi Yoshiike1 , Rei Enokiya1 , Keisuke Hasegawa1 , Akio Ohama1 , Hidetoshi
1,3
Sano1,3 , Hiroaki Yamamoto1 and Yasuo Fukui
Publications of the Astronomical Society of Japan, (2014), Vol. 00, No. 0(b)

OH 334.458+0.877

91Department of Physics, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8601, Japan; 2 Nobeyama
Table 1. Observational properties of data sets.
Radio
Observatory,
National Society
Astronomical
Observatoryof Japan(NAOJ),
National
Sciences
TelescopeLine Institutes
HPBW of Natural
Velocity
RMS 19noise(2)Publicationsof the Astronomicalof Japan, (2014),
Vol. 00, No.
0
Resolution Research,
level(NINS), 462-2, Nobeyama, Minamimaki, Minamisaku, Nagano 384-1305, Japan; 3 Institute for Advanced
12′′−1
CO J = 1–0160
0.16 km s∼ 1.2 K
Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan NANTEN2
12
′′(1)
−1

天体：中間赤外bubble S44
望遠鏡：NANTEN2,
Mopra,We
have performed a multi-wavelength studyof the mid-infrared bubble GAL 334.53+00.83 (S44) to investigate
33±20.088 km s
∼ 0.76 K
33±2′′(1)0.092 km s−1∼ 0.53 K
′′
−1
ASTE
22
0.11 kms 00, No.
∼ 0.3
Publications of the
Astronomical Society of Japan,(2014),
Vol.
0K
Mopra

E-mail contact: mikito at a.phys.nagoya-u.ac.jp
16

CO J = 1–0

13 CO J = 1–0

Pillar

12 CO J = 3–2

Telescope/Survey
Band
Resolution
References
the origin of isolated high-mass star(s) and the star-formation process
around the3.6bubble
formedby [1,2]
the HII region.
Spitzer/GLIMPSEµm∼2′′
Jy/Beam
12 Spitzer/GLIMPSE
13
12 ∼2′′
8.0µm[1,2] toward theIn this paper, we report the results of new CO observations ( CO, CO J =1–0, and CO
J =3–2)
Spitzer/MIPSGAL
24 µm
6′′
[3]
isolated bubble 12
GAL 334.53+00.83
using the NANTEN2, Mopra,and ASTE radio telescopes.
two velocity
0.06
0.09
′′We found
5pc
APEX/ATLASGAL 0.00 870 µm0.03
19[4]
HPBW(MOST) HPBW(ASTE)−1−1′′
components in the direction of the bubble, at −84 km s and −79 km
s . These 843
twoMHzclouds ∼are
MOST/SUMSS
60 likely to[5] be physically

ASTE

Image : MOST 843 MHz
Contours : CO J=3-2

N

20pc
5pc

0.90

0.90

Vlsr: -88.5 - -82.1 km/s
Vlsr:
-82.1 - -75.6 km/s
Referenceintensity: Ladd et al. (2005).
associated withbubble, because of the enhanced 12 CO J =3–2/1–0
ratio from a ring-like structure aﬀected(a)the(b)
The values of the rms noise levels after smoothing the (space and/or velocity) data sets.
Fig. 1. (a) Large-scale three-color composite images of S44. Blue, green, and red show the Spitzer/IRAC 3.6-µm, Spitzer/IRAC 8-µm, and Spitzer/MIPS 24-µm
by ultraviolet radiation from embedded high-mass star(s) and fromthemorphological correspondence between the
References [1] Benjamin et al. (2003), [2] Churchwell et al. (2009), [3] Carey et al. (2009), [4] Schuller et
results. The jagged white line along the Galactic latitude at b ∼ 0.◦ 95 shows the observing limit of Spitzer/MIPS 24-µm. (b) A close-up image of (a). The colorsal. (2009),we[5] Bock
et al. (1999) the spectral type of the embedded
8 µm emission and the CO distribution. Assuming a single object,estimate
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0.85K., Sakai, T., Endo, A., Kohno, K., Asayama,
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Galactic Latitude [degree]2

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13
Fig. 6. (a) Integrated
CO J = 1–0 obtainedby Mopra for the −84 km s−1 cloud (blue contours) and the −79 km s−1 cloud (red contours)
0.85 intensity map of
Ohama, A., et al. 2018a, PASJ, 70, 47
Wilson, T. L., 0.85
& Rood, R., 1994, ARA&A, 32, 191
12superposedonthe
Spitzer
8µm
emission.
The
yellowlines show
integrationin latitude
and longitude. (b) Galactic latitude-velocity diagram
0.00
0.07
0.13dashed
5pc70, 45
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Wilson,T. L., 0.20
Rohlfs,K, & theHüttemeister,S., ranges
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of Radio
HPBW(APEX) HPBW(ASTE)◦
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Mod
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Vlsr: -88.5 - -82.1 km/s
Penzias, A. A., & Burrus,
C. A.,
1973, ARA&A,
11, 51Wu,from
B., Van,J. C.,The& Bruderer,
2015, represent
ApJ, 811, 56the radio- recombination-line velocity (−77 km s−1 ) fromvelocity
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81S.,toTan,0.◦ 84.
dashedS. lines
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Pineda, J. L., Goldsmith,F., Chapman,N., Snell,The
R. spatial
L., Li, D.,
Wu, B.,resolutionTan, J.0.80
C., Nakamura,F., Van,D.
CaswellP. andHaynes (1987).
and velocity
are smoothedtoL.52S.,
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Cambresy, L., &for
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334.55334.50334.45334.55334.50334.45Galactic Longitude[degree]
Galactic Longitude [degree]Zavagno, A., Pomarés, M., Deharveng,
Schuller, F., et al. 2009, A&A, 504, 415
L., Hosokawa,T., Russeil, D., &Contour levels (ASTE) : min 10 K km/s, Step 8 K km/s
Contour levels (ASTE) : min 6 K km/s, Step 4 K km/s
Jy/BeamSevenster,M,
N.,
Chapman,J.
M.,
Habing,H.
J.,
Killeen,N.E.B.,&
Caplan,
J.,
2007,
A&A,
472,
835
Jy/beamImage : MOST 843 MHz
Image : APEX 870 μm
M.,
Zinnecker, H., & Yorke, H. W. 2007,
ARA&A,
45,0.13481 0.20
0.00 Lindqvist,
0.03
0.06 1997b,
0.09 A&AS, 124, 509
Contours : 12CO J=3-2 HPBW(MOST) HPBW(ASTE)
5pc
0.00
0.07
5pc
Contours : 12CO J=3-2
HPBW(APEX) HPBW(ASTE)
Simpson, R, J., et al., 2012, MNRAS, 424,2442
0.90
0.90
0.90
0.90
Vlsr: -88.5 - -82.1 km/s
Vlsr: -82.1 - -75.6 km/s
Vlsr: -82.1 - -75.6 km/s

Accepted by PASJFirst hydrodynamics simulations of radiation forces and photoionization feedback
in massive star formation-84 km s-1の分子雲：Bubbleの外側まで広く分布、南側ではR3-2/1-0は0.6以上

Image : APEX 870 μm
Contours : CO J=3-2

(c)

(d)

Galactic Latitude [degree]-79 km s-1の分子雲：8 µmの放射と形状が一致、R3-2/1-0は0.8以上

(a)

(b)

0.85

AGAL G334.521+00.769
0.80

0.80

N

Galactic Latitude [degree]

0.85(c) Vlsr: -88.5 - -82.1 km/s

(d)

0.80

0.80
Galactic Latitude [degree]

Galactic Latitude [degree]

電離ガス（左）coldダストの画像（右）：Bubbleとの空間的な相関関係を示す

0.85

0.80

0.85

0.80

AGAL G334.521+00.769

0.75

0.75
N
0.75

0.75

N
0.75

0.75

334.55334.50334.45334.55334.50334.45334.55334.50334.45334.55334.50334.45334.55334.50334.45334.55334.50334.45Galactic
Longitude[degree]
Galactic Longitude [degree]
Galactic Longitude[degree] Longitude
Galactic
Fig. 6. (a) Integrated
intensity
mapof 13 CO J = [degree]
1–0Contour
obtainedby Mopra
km s−1 cloud (bluecontours)
the−79 km s−1 cloud (red contours)
Galactic Longitude [degree]
Galacticand
Longitude[degree]levels (ASTE): min 10 Kfor
km/s,theStep−84
8 K km/s
Contour levels (ASTE) : min 6 K km/s, Step 4 K km/s
Contour levels (ASTE) : min 10 K km/s, Step 8 K km/s
Contour levelsContour(ASTE): min: min
106 KKkm/s,
km/s,
levels (ASTE)
Step 4Step
K km/s 8 K km/s
Contour levels (ASTE) : min 6 K km/s, Step 4 K km/s
Jy/beamsuperposedon thein latitude and longitude.12(b) Galactic latitude-velocity diagram
Image : APEX
870Spitzer
μm 8µm emission. The yellow dashed lines show the integration rangesFig.
9. (a), (b) Integrated intensity map of CO J = 3–2 (contours) obtained with ASTE superposed on the MOST 843 MHz continuum image. (c), (d)
◦
12
0.00
0.07
0.13 is with
5pc
: 12CO
J=3-2
Integrated forintensity
ofthe
COMOSTJ = 3–2(contours)
obtainedby ASTEon theAPEXµm continuum image. The blue and red contours
HPBW(APEX)HPBW(ASTE)
Fig.Contours
9. (a),over(b)Integrated
intensity
mapof 12
COtoJ334.
=◦3–2(contours)
obtained
ASTE
superposed
onlongitude
843 ofMHz
continuum
image.
(c),870(d)integrated
thelongitude
range from334.
54
57. The1σ noiselevel∼0.200.004
K degreethemapinterval0.◦ 03. (c)superposed
Galactic
longitude0.90
0.90
represent the −84 km s−1 cloud and the −79 km s−1 cloud, respectively.
◦-82.1 - -75.6◦km/s
Vlsr: -88.5 - -82.1 km/s 12
Integrated
intensity
map ofoverCO= 3–2 range(contours)
obtained
ASTE
the APEXµmrecombination-line
continuum image.velocity
The blueandkm
red
contours
velocity
diagramintegrated
theJlatitude
from0.
81 to 0.by84.
Thesuperposed
dashed lineson
represent
the870radio(−77s−1) from(c)(d) Vlsr:
represent
theHaynes−84 kms−1 cloudand theand−79
km s−1cloud, respectively.
Caswelland(1987).
The spatial
velocity
resolution
are smoothed to 52′′ and 0.18 km s−1 , respectively. The 1σ noise level is ∼ 0.004 K degree
for the latitude interval of 0.◦ 03.
e]

27

0.85

0.85

Te )

−1

# $#
$2type of the exciting star(s)! ν "0.1"
3.5! Estimation
Te −0.45 ofSνthe spectralD, exciting star(s) embedded in the bubble from the radio continuum flux.
(5)If we assume the 843
the Jyspectralkpc
type of the
GHz We investigatedK
MHz (36 cm) emission from the bubbleM
to sunbe opticallythin, we can estimate the number of Lyman
continuum photons
from
励起星をO8.5-9（~20）と見積もった（fromSUMSS
843NLyMHz(36 cm)、単一星と仮定）
the 843
MHz radio
continuum flux
Sν by using
following
equation
1968c, etMezgeret al. 1974):of the optical path
lengthfor free-freeemissionfromtheOster(1961)
and(Rubin
Altenhoffal. (1960),
which
# $#
$2
!N "
! ν continuum"0.1 ! T "−0.45∼ 1 (Mezger &Henderson
1967a).
The−1radio
fluxSνSν isDestimatedby drawing contours at
Ly
e
48
∼
4.761
×
10
a(ν,
T
)
,
(5)
e
−1
4 Jy
s
GHz
K
kpc
(∼ 5σ ). If we assume the electron temperature to be Te = 10 K in the H II region (Ward-Thompson &−1
48.08
is thetheassume
optical path
length forfree-free
emission
Oster (1961)
and exciting
Altenhoff et al. (1960), whiche)rs of photons iswhere
NLya(ν,∼ T10
s−1ratio. Ifofwea single
object,thisfigurefrom
suggeststhat thefor most cases is a(ν, Te )−1 ∼ 1 (Mezger &Henderson 1967a). The radio continuum flux Sν is estimated by drawing contours at
e of O8.5-9, which corresponds to an 18–19M⊙ star, from the stellar parameters for4 Galactic O stars
intensities of 0.015 Jy/beam (∼ 5σ ). If we assume the electron temperature to be Te = 10 K in the H II region (Ward-Thompson &. In this paper, Whitworth
we assume
thatthethe
ionizing
O-starisisNLy
embeddedpeakof theobject,radio-continuum−12011),
numbersof photons∼ 1048.08 saround. If wethe
assumea single
this figure suggests that the exciting
star in S44 has a spectral type of O8.5-9, which corresponds to an 18–19M star, from the stellar parameters for Galactic O stars
二つの分子雲は、中間の速度で見られるbridge(Martins et al. 2005, Table 4). In this paper, we assume that the ionizing O-star is embedded around the peak of the radio-continuum⊙

image.
で繋がっている（Bubbleの東側）of the 24 µm sources

3.6２つの分子雲の相互作用によるものと解釈される
Color-color
diagramthe 24µm objects
sourcestoward the 24 µm sources cataloged around
diagram to distinguishbetween
YSOsof andother
We constructed
betweenand othercenter
objects position
toward the at
24 (l,µmb)
sourcesyer (2015). Theyobtained aa color-color
radius ofdiagram
7 pc (to=distinguish5.′ 25) aroundtheYSOs
geometric= cataloged aroundthis bubble by Robert & Heyer (2015). They obtained a radius of 7 pc (=5.′ 25) around the geometric center position at (l, b) =0 shows the resultof ofthe[3.6]-[5.8]versustoward the 24 µm sources. We adopted
Publications
the Astronomical
Societyof Japan,[8.0]-[24](2014), Vol. 00, diagram
No. 0
21(334.◦ 523, 0.◦ 823). Figure 10 shows the result of the [3.6]-[5.8] versus [8.0]-[24] diagram toward the 24 µm sources. We adopted
rolle et al. (2004),
whocarriedthis classification
towardstar-forming
region NGC
the YSO
criteria
fromout
Muzerolle
et al. (2004), whocarriedtheout embedded
this classification
toward the embedded
star-forming region NGC
in the MilkyWay.asWe
identified#1 source
S44 as a Class
YSO
the southernedge of11the c,
bubble (Figures 11 c,
identified the 7129
#1 sourcein S44a Class
II theYSO
at theinsouthernedgeII oftheat bubble(Figuresandd).
Takingaccount
of
its
error
bars,
the
#2
sourcelocatedoutsidethebubblealso
ispossibly
a
Class
II
YSO.
error bars, the #2 source located outside the bubble also is possibly a Class II YSO. The photometric The photometricparameters of these sources (#1 and #2) are summarized in Table 3. Many of the other 24 µm sources are categorized as Class(#1 and #2) are
in ofTable
Manyof theotherµ(bluem contours)
sourcesareas Class
Fig. 6. summarized(a) Integrated intensity map
CO J =3.
1–0 obtainedby Moprafor the −84
km s 24cloud
and the−79 categorized
km s
cloud (red contours)
III/stellar
objects. We will not argue these Class III/stellar objects in this paper, because it is not clear whether they are physicallysuperposed on the Spitzer 8µm emission. The yellow dashed lines show the integration ranges in latitude and longitude. (b) Galactic latitude-velocity diagram
ot argue theseintegrated
Class
objects
this57.paper,
becauseitK isnotclear
whetherthey
are longitudephysicallyoverIII/stellar
longitude
range
from 334. 54in
to 334.
The 1σ noiselevel is ∼ 0.004
degreefor thelongitudeinterval of 0. 03. (c) Galactic
relatedtothethebubble.
13

−1

◦

◦

−1

◦

velocity diagram integrated over the latitude range from 0.◦ 81 to 0.◦ 84. The dashed lines represent the radio- recombination-line velocity (−77 km s−1 ) from
Caswell and Haynes (1987). The spatial and velocity resolution are smoothed to 52′′ and 0.18 km s−1 , respectively. The 1σ noise level is ∼ 0.004 K degree
for the latitude interval of 0.◦ 03.

4 Discussion
4.1 Star formation around the bubble and the origin of the isolated O star(s)Fig. 6. (a) Integrated intensity map of 13 CO J = 1–0 obtained by Mopra for the −84 km s−1 cloud (blue contours) and the −79 km s−1 cloud (red contours)
superposed on the Spitzer 8µm emission. The yellow dashed lines show the integration ranges in latitude and longitude. (b) Galactic latitude-velocity diagram
integrated over the longitude range from 334.◦ 54 to 334.◦ 57. The 1σ noise level is ∼ 0.004 K degree for the longitude interval of 0.◦ 03 . (c) Galactic longitudevelocity diagram integrated over the latitude range from 0.◦ 81 to 0.◦ 84. The dashed lines represent the radio- recombination-line velocity (−77 km s−1 ) from
Caswell and Haynes (1987). The spatial and velocity resolution are smoothed to 52′′ and 0.18 km s−1 , respectively. The 1σ noise level is ∼ 0.004 K degree
for the latitude interval of 0.◦ 03.

From previous studies of bubbles, the C&C and/or RDI processes have been discussed as mechanisms for star formation at the edge

2つの分子雲は3nd the bubble
thecreatedoriginofMyrに衝突し、O型星形成を引き起こし、孤立したBubbleができた、と仮説を立てる
the isolated
O (e.g.,star(s)ofanda bubbleby expandingan H II region
Deharveng et al. 2010, Zavagno et al. 2006, 2007). In the case of S44, we
find a cold-dust condensation at 870 µm at the southern edge of the bubble (AGAL G334.521+00.769). Figure 11a shows the H2bles, the C&C衝突シナリオは２つの分子雲の形状、孤立したO型星の起源を説明できる
and/or RDI processes have been discussed as mechanisms for star formation at the edgecolumn density derived from 13 CO J =1–0, togather with the contours of cold-dust emission from 870 µm. There is clearly goodding an H II region
Deharveng
et al.
2010,
Zavagnoet al.
2006,
case emission,of S44, which
we suggests that star
spatial (e.g.,correspondence
betweenthe high
molecular
columndensities
and2007).
the peaksInofthe
cold-dust
aroundedge
the bubble
is likely
to behappenigG334.521+00.769).
at the southern edge, while
such 11acold anddensethedustHcondensations
are not
n at 870 µm at formation
the southernof thebubble(AGAL
Figureshows
213
detectedatthenorthern
side
of
the
bubble.
These
observational
resultsarecommontootherbubbles(e.g.,
RCW
120,
Deharvenget
CO J =1–0, togather with the contours of cold-dust emission from 870 µm. There is clearly goodal. 2009; Figueira et al. 2017; RCW 79, Zavagno et al. 2006, Liu et al. 2017).
een the high molecularcolumn densities and the peaks of cold-dust emission, which suggests that star
Our observations show two velocity components associated with the bubble at the northern and southern sides of the 8 µm
is likely to beemission
happenig
at theedge,
whilesuchconnecting
cold anddust(Figurescondensations
are not(Figure6a), southern
together witha bridging
featurethedense
two clouds
6b and 6c). Thesesignatures suggest thatthetwocloudsareinteracting
with
each
other
at
the
bridgingfeature,
and
they
are
similartotheproperties
ofof the bubble. These observational results are common to other bubbles (e.g., RCW 120, Deharveng etother bubbles that areformed by cloud-cloud collisions (RCW 120, Torii et al. 2015; RCW 79, Ohama et al.2018b; N4, S.Fujita et al. 2018 submitted).
; RCW 79, Zavagno
et al. 2006, Liu et al. 2017).
Numerical simulations of a cloud-cloud collision reproduce the broad-line bridging feature at the interface between the two clouds
wo velocity components
associatedwith(Haworth
the bubble
the 2015b;
northernandthesouthernof ettheµm based on the modelin the position-velocity
diagram
et al. at2015a,
see also
review bysides
Haworthal. 82017)
r with a bridging
featureconnecting
thetwoclouds(Figures
6b
and
6c).
These
signatures
suggestthatfrom Takahira et al. (2014, 2018) and Shima et al. (2017). From synthetic CO observations, they showed that the bridging feature
Fig. 12. Schematic image of a cloud-cloud collision scenario based on Habe & Ohta (1992) and Torii et al. (2015, 2017a). Stage I : a 3D image of the initialis caused
turbulentthecompressed
layer
theproperties
two
condition
clouds.
Stage II motions: a 2D imagein
ofand
the twoclouds in
the X-Zplane between
at theto
timethewhenthetwocolliding
clouds collidewitheach other.
Stage III : athat
2D
g with each otheratof thethetwobybridging
feature,they
aresimilarofclouds.
otherbubblesareimage of the bubble in the X-Z plane. The Y-axis corresponds to the line of sight. The final panel shows the observational result for the two clouds superposed
Stellar feedback from the exciting star may be an alternative explanation for the bridging feature. If expanding motions dominate
on the 24Toriiµm image.
ions (RCW 120,
et al. 2015; RCW 79, Ohama et al.2018b; N4, S.Fujita et al. 2018 submitted).
the kinematics of the bubble, we expect to observe a ring-like velocity distribution in the position-velocity diagram. However,24

High spectral resolution observations toward Orion BN at 6 µm: no evidence
for hot
7
water.
Table 1. Absorption Line Parameters

Nick Indriolo1 , Jonathan C. Tan2,3 , A. C. A. Boogert4 , C. N.! DeWitt5 , E. J. Montiel6 , D. A. Neufeld7
Transition Wavelength E /k
v
FWHM
τ
τ dv
N
and M. J. Richter6
l

(µm)

1

(K)

b

LSR

(km s−1 )0(km s−1 )l(km s−1 )(1015 cm−2 )2Space Telescope Science
Institute,
21218,0.84±0.02
USA; 4.78±0.19
Department
1 –0
6.116331Baltimore,
0
7.5 MD5.3±0.2
2.35±0.09 of Space, Earth & Environment,
3 –3
6.113771
196.8
8.2
4.3±0.3
0.21±0.01 0.95±0.10
1.67±0.17
3Chalmers University of Technology,
SE-41293
Gothenburg,
Sweden;Departmentof Astronomy, University of Vir3 –3
6.075447249.4
7.8
4.8±0.4
0.06±0.01 0.31±0.05
0.51±0.08–06.116331
00.4 for 13.3±0.8
0.27±0.01
3.76±0.25
1.85±0.12
ginia, Charlottesville, VA,1 22904,
USA; 4 Institute
Astronomy,
Universityof Hawaii at Manoa, Honolulu, HI, 96822,
3 –3
6.113771
196.8
0.7
14.7±1.1
0.13±0.01 2.17±0.19
3.82±0.33
5USA;
USRA, SOFIA,BN
NASA
Ames
CenterMS 232-11,
Moﬀett 1.67±0.20
Field, CA 94035, USA; 6 Department of
3 –3
6.075447 Research
249.4
0.6
14.0±1.3
0.07±0.01 1.00±0.11
天体：Orion
71–06.1163310−178.0±0.2
0.63±0.01
5.42±0.16
2.66±0.08
Physics, University of California Davis, Davis, CA, 95616, USA; Department of Physics & Astronomy, Johns Hopkins
Note—Transition properties, parameters for the gaussian fits shown in Figure 2, and derived column
University, Baltimore, MD
21218, USAdensities.
1,1

0,0

1,2

0,3

2,1

1,2

1,1

0,0

1,2

0,3

2,1

1,2

1,1

0,0

観測：6.7 µm, 6.1 µm, 5.7 µm。SOFIAに積まれたEchelon-Cross-Echelle Spectrograph (EXES)

E-mail contact: nindriolo at stsci.edu

The Becklin–Neugebauer (BN) object in Orion has a large proper motion and radial velocity with respect to the gas
and other stars in the region where it is presumed to have formed. Multiple dynamical interaction scenarios havebeen proposed to explain this motion. In one case BN is thought to have interacted with stars in the
Trapezium
手前の冷たい（~70K）高密度分子雲でcluster, while in another it is thought to have interacted with source I while deeply embedded in molecular gas. If
there is dense gas that has been retained in close proximity to BN, it may be evidence that the latter
scenario is 2Oからの吸収を検出
で起こるH
favored. We observed BN at high spectral resolution in three windows near 6 µm using the Echelon-Cross-Echelle
Spectrograph on board the Stratospheric Observatory for Infrared Astronomy targeting the ν2 vibrational band of
H2 O. Absorption from only three transitions of H2 O is detected, and through kinematic analysis is associated withcool, dense foreground gas, not BN itself. We find no evidence for H2 O absorption or emission at the systemic
velocity
水とCOの存在比N(H2O)/N(CO)=5 10-3、of BN.

水蒸気と氷の存在比

Accepted by ApJLN(H2O)/N(H2Oice)~0.04

https://arxiv.org/pdf/1809.08155

solid form

24µ

Figure 1. Spectra of Orion BN over the full wavelength range covered by our SOFIA/EXES observations. Each spectrum
corresponds to a separate observation at a diﬀerent grating setting. Oscillations in the noise level result from the cross-dispersed
nature of the instrument, with higher noise regions coming from the edges of the individual echelle orders. Gaps in the spectra
correspond to regions where telluric water vapor lines reduce transmission levels to near zero. The water absorption lines
discussed herein are all from the spectrum in the middle panel.

=> PDR環境を示す（薄い光脱離層中で、ice mantleからH2Oが放出される）

7

8
ν

Table 1. Absorption Line ParametersνTransition

Wavelength

El /kb

vLSR

FWHM

!

τ0

τ dv

Nl
ν

ν

ν

11,1 –00,0
31,2 –30,3
32,1 –31,2
11,1 –00,0
31,2 –30,3
32,1 –31,2
11,1 –00,0

(µm)

(K)

(km s−1 )(km s−1 )6.116331
6.113771
6.075447
6.116331
6.113771
6.075447
6.116331

0
196.8
249.4
0
196.8
249.4
0

7.5
8.2
7.8
0.4
0.7
0.6
−17

5.3±0.2
4.3±0.3
4.8±0.4
13.3±0.8
14.7±1.1
14.0±1.3
8.0±0.2

0.84±0.02
0.21±0.01
0.06±0.01
0.27±0.01
0.13±0.01
0.07±0.01
0.63±0.01(km s−1 )(1015 cm−2 )4.78±0.19
0.95±0.10
0.31±0.05
3.76±0.25
2.17±0.19
1.00±0.115.42±0.16

2.35±0.09
1.67±0.17
0.51±0.08
1.85±0.12
3.82±0.33
1.67±0.20
2.66±0.08

Figure 2. Spectra showing the water absorption lines observed toward Orion BN. Fits to the components at 8 km s−1 ,km s , and −17
s ,gaussian
are shown byfits
blue,shown
cyan, andingreen
curves,2,respectively,
and the column
sum of all components is shown as
Note—Transition properties, 0.5
parameters
forkm
the
Figureand derived
a red, dashed curve. The top spectrum shows a non-detection of the transition predicted to have the strongest absorption after
densities.
−1−1

the detected transitions in the observed wavelength range (ν2 31,2 –22,1 at 6.1068262 µm). Spectra have been shifted verticallyfor clarity.

νFigure 2. Spectra showing the water absorption lines observed toward Orion BN. Fits to the components at 8 km s−1 ,0.5 km s−1 , and −17 km s−1 , are shown by blue, cyan, and green curves, respectively, and the sum of all components is shown asa red, dashed curve. The top spectrum shows a non-detection of the transition predicted to have the strongest absorption after
the detected transitions in the observed wavelength range (ν2 31,2 –22,1 at 6.1068262 µm). Spectra have been shifted verticallyfor clarity.

Figure 3. Rotation diagrams for the 8 km s−1 component (blue) and 0.5 km s−1 component (cyan). Color coding corresponds
to the gaussian fits shown in Figure 2.

H2Oの吸収も放射も、BNの系速度では検出されず
BNの近傍でのH2Oの非検出は、現在の状況に新たな情報を与える => 力学的放出モデル？
例えば、BNがejection直前のprotostellar phaseにあったとすると、高密度ガスの全てが剥ぎ取られたor星へ降着？
µFigure 1. Spectra of Orion BN over the full wavelengthetrange
by our Ginsburg
SOFIA/EXES observations.
Each spectrum
一方、Source IはmassiveなKeplerian降着円盤を持っている（Hirota
al.covered2014;
et al. 2018）
corresponds to a separate observation at a diﬀerent grating setting. Oscillations in the noise level result from the cross-dispersed
nature of the instrument, with higher noise regions coming from the edges of the individual echelle orders. Gaps in the spectra
correspond to regions where telluric water vapor lines reduce transmission levels to near zero. The water absorption lines

Figure 3. Rotation diagrams for the 8 km s−1 component (blue) and 0.5 km s−1 component (cyan). Color coding corresponds
discussed herein are all from the spectrum in the middle panel.
to the gaussian fits shown in Figure 2.

Orion分子雲中の冷たい高密度ガスによる近赤波長域での分子吸収の研究への役立つ？
天球面での分子雲構造の研究も徐々に可能になるかも。BNが速い固有運動を持っているので異なる時期
での視線方向に沿って観測される手前のガスが変わる。

21
21

14
suspected
companion
of
NU
Ori.
We
confirm
fourcompanionsfor θ--European
Ori A, θ SpaceOri C,
θ Ori Space
D,
andTelescope
θTelescope
Ori A,Scienceallwith
14 ESARadio
Astronomy,
Aufdem
dem
Hgel
69,
53121
Bonn,
Germany;
Agency,Radio
Astronomy,
Auf
Hgel
69,
53121
Bonn,
Germany;
ESA
EuropeanSpace
Agency,Space
Science15
substantially
improved
astrometry
andphotometricmassestimates.
We
refine
the
orbit
of
the
eccentric
high-mass
15 Dublin
Institute,
3700
San
MartinDrive,
BaltimoreMD
21218,
USA;
Institutefor
Advanced
Studies,
Astronomy
Institute, 3700
San Martin Drive, Baltimore MD 21218, USA;
Dublin 16
Institute for Advanced Studies, Astronomy
binaryθ1 Ori
CSection,
andwe31
areFitzwilliamable
derive
a new
orbit
for
θ1 Ori D. We finda system mass of 21.7
M⊙ and a period
Multiplestarsystems
inintotheOrion&
Astrophysics
Place,
D02 nebula
XF86,
Dublin,1, 1,
star
systemstheOrion
nebula&Multiple
Astrophysics
Section,
31 Fitzwilliam
Place,D02
XF86,
Dublin, Ireland;
Ireland; 16University
UniversityofofVienna,
Vienna,Universitätsring
Universitätsringof 53Wien,
days. Austria
Together with other previously detectedcompanions
seenin
spectroscopyordirectimaging,
eleven of
1010
1 1
1 1
1 1
1,2 1,21010
Wien,
Austria
GRAVITY
collaboration:
MartinaKarl
Eisenhauer , Reinhard
Genzel, ReGRAVITY
collaboration:
Martina
Karl, ,Oliver
OliverPfuhl
Pfuhl, Frank, Frank, Reinhard
Genzel, Rethe 16 high-massstars
are multiple
systems.
of 22Eisenhauercompanions
33
1 1 We obtain a total 4number
4 4with separations up to
5 5
E-mailcontact:
martina.karl@tum.de4
bekka
Grellmann,
MaryamHabibi,RobertoAbuter,MatteoAccardo,António
Amorim,NarE-mailcontact:
martina.karl@tum.de
bekkaGrellmann,
MaryamHabibi,RobertoAbuter,MatteoAccardo,António
Amorim,Nar600 AU. The companion
fraction of theearly B and O stars 7in our sample is about 2, significantly
higher than8in
6
4
7
sireddyAnugu,6mostly
GerardoÁvila,4 ,Myriam
Benisty, 7 ,Jean-Philippe
Berger
, 7Nicolas
Blind
This
work
presents
aninterferometric
studyof themassive-binary
fraction
intowards
the Orion
Trapezium
Clusterwiththe , 8HenriearlierstudiesofOB
associations.
The
separation
distributionhintsabimodality.
Suchabimodality
sireddy
Anugu,
GerardoÁvilaMyriamBenisty
Jean-Philippe
Berger,Nicolas
Blind
,
Henri
This work
presents an interferometricstudy of the massive-binary
fraction in
the Orion Trapezium 1Cluster with the
4 comissioned
9
10 total of 16
4mainly
recentlyGRAVITY
instrument.
We
observe
starsofOB
spectral
type.
three
Bonnet,4 ,Pierre
Bourget,binaries,
Roland
Brast
,to
Buron
,We
Carattio o4Alexander
1Alessiohas been
previously
found in,9 ,Wolfgang
Astars, but Brandner
rarelyin OBaa 10
which
up
point
have
been
to
beCaratti
BonnetPierreBourgetWolfgang
Brandner,
RolandBrast, thisAlexanderBuron, findAlessiorecently
comissioned
GRAVITY
instrument.
We
observe
total
of
16
stars
of
mainlyOB
spectraltype.assumed
We
find11three
1
2
2
10,15unknown companions for11θ Ori B, θ Ori B,
11 and θ Ori C. We determine
11
previouslyaseparation
forthepreviously
Garatti,Frédéric
Chapron,Yann
Clénet,ClaudeCollin,Vincent
Coudé
duForesto,Willem10,15
11
11
11
11
mostly compact
witha tailof widercompanions.
WeB,
also
findC.Collina We
substantial
populationof equal-mass
binaries.
2
Garatti, Frédéric
Chapron, Yann,doClaude, Vincent
Coudé
duthe
Foresto, Willempreviously
unknowncompanionsforθ1confirm
OriB,fourθ2Clénet
Ori
and
θnot
Ori
determinea separationforpreviously
914suspected
companion
ofde
NUof
Ori.
We1,12companionsforθ11 Oriθ11theOri direct
C, θ1 1OriD,
and4 ,θ24indicatesOriA, allwithTheobserved
mass
ratiosdeclines
steeply
with
mass,
andA,
like
star
counts,
that
our
Jan
de
Wit
,9distribution
Tim
Zeeuw
, ,CaseyDeen, 1 ,Franoise
Delplancke-Ströbele
Roderick
Dembet, 4,
1,122
suspected
companion
of
NU
Ori.
We
confirm
fourcompanions
for
θ
Ori
A,
θ
Ori
C,
θ
Ori
D,
and
θ
Ori
A,
all
with
Jan
de
Wit
,
Tim
de
Zeeuw
Casey
Deen
Franoise
Delplancke-Ströbele,
Roderick
Dembetsubstantially
improved
astrometry
photometricmassestimates.
We
refine
the
orbit
of
the
eccentric
high-mass
4
1 and7function.
10
3,13
4
companions
followastandard
power
law
initialmass
Again,
thisisincontrasttoearlier
findings
of
flat
mass
Frédéric
Derie
,
Jason
Dexter,GillesDuvert,MonicaEbert,
AndreasEckart,MichaelEsselborn, 4,
4
1 photometric mass
7 estimates.
10
substantially
improved
astrometryrefinethe orbitof the 3,13
eccentricFrédéric, Jason, GillesDuvertEbert
AndreasEckart, Michael
Esselbornbinaryθ1 Derie
Ori
C and
we
areDexter
able 4toand
derivea new
orbit
for, Monica
θ11 Ori
D.
WeWe
find
a,formation
systemmass
ahigh-mass
period⊙ and116,9collision
4of 21.7 Mbut
10,15
ratio Fédou
distributions
inOB
associations.
We
excludeasadominant
mechanism
find
no
clear
1
Pierre,Gert
Finger,Paulo
Garcia,Cesar
Enrique
GarciaDabo,
RebecaGarciaLopez,
11 we are able to 4derive a new orbit6,9
4
10,15
binaryOri C
andfor, Cesar
θ Ori D.
Weinfinda systemDabo
massof, 21.7
M⊙ anda period
PierreFédou, Gert, Paulo accretion.
Garcia companions
Enrique
GarciaRebecaGarciaof
53θdays.
Together
withFinger
other
previously
detectedseen
spectroscopy
or direct
imaging,
elevenofLopez10 ,1 for11competitive
1
4
5
preferencecore
accretion
or
Feng
Gao
,Together,previously
StefanGillessen, 1a,Frédéric
Gonté
, 4companions
Paulo
Gordo
,imaging,Grözinger,10 ,1 Éric Gendron
11
5Ulrich elevenofFeng53 days.
withotherdetected
companions
seen
inofspectroscopyordirectofthe16high-massstars
aremultiplesystems.
We
obtaintotal
number22
withseparations
up
to
Gao
, Éric
Gendron,StefanGillessenFrédéric
Gonté
,
Paulo
Gordo
,
UlrichGrözinger
9
7
4
1
9
Acceptedby
A&A
Patricia
Guajardo,
Sylvain
Guieu,
PierreHaguenauer,
OliverHans,
XavierHaubois,Marcus
7 We
4 ofis22
1 with separations
the
16 AU.
high-mass
stars 9are
multipleofsystems.
obtaina totalnumbercompanions
600
The
companion
fraction
the early
andO stars
in oursampleabout
2, significantly
higherthanupin9toPatricia
Guajardo, Sylvain
Guieu, BPierre
Haguenauer, 10
OliverHans, Xavier
Haubois, Marcus
1,4
1
3
10
Haug
,studies,1 Thomas
Henning, stars
StefanHippler,10
Horrobin, bimodality
600
AU.
The
companion
fractionof the earlyBand 10O10
in oursampleisMatthewabout
2, significantly
thanHuberin
1,4
3ArminearlierofHaumannmostlyOB associations.
The
separation
distribution
hints towards
a bimodality.
Such ahigher
http://arxiv.org/pdf/1809.10376
Haug,FrankFrank
Haumann,
ThomasHenning,
StefanHippler,Matthew
Horrobin,
Armin
Huber,10 ,
11
4
4
4
4
earlierstudiesof mostly
OB inassociations.
separation
distribution
towardsa bimodality.
a bimodality
ZoltanHubert, ,Norbert
Hubin
,4The
A.A.
Hummel,hints, 4Lieselotte
Jochum, 4Laurent
has been
previously
foundAstars, butrarelyin OBbinaries,which
to Jakob
this
point
have
beenSuchassumed
to be
11
4Gerd
ZoltanHubertNorbertHubin,Christian
Christian
Hummel
,up
Gerd
Jakob
, Lieselotte
Jochum, Laurent
7 compact
1,13
10,14
4
11
hasmostly
been
found
stars,
butrarelyinOBbinaries,
which
up
to
this
point
have
been
assumedtobewitha tailinof9A
companions.
We
also
do
not
find
a
substantial
populationofequal-mass
binaries.
Jocou,7 previously
AndreasKaufer,widerStefanKellner,
Sarah
Kendrew,
Lothar
Kern,
PierreKervella
,11
9
1,13
10,14
4
Jocou
,
AndreasKaufer,StefanKellner,
Sarah
Kendrew,
Lothar
Kern,
PierreKervella,
VISION
ViennasurveyinOrion.
III.
Young
stellarobjects
in
Orion
A
4
10
10,16
9
10
11
mostlycompactwith a,4tailof widercompanions.
We alsowith
do10,16notfind
a substantial
populationofequal-mass
binaries.
The observed
distribution
mass
ratiosdeclines Köhler
steeply
mass,
and
like
the ,directstar
counts,indicates
that
our
Mario
Kiekebusch
Ralf
Klein
,10Rainer, Johan
Kolb
MartinKulas,
Sylvestre
Lacour
,11
9
10
Mario
Kiekebusch
,
Ralf
Klein
,
RainerKöhler
,
Johan
Kolb
,
MartinKulas,
Sylvestre
Lacour1 declines
4 direct
1,5,6
11 1of7mass
7companions
follow a standard
power
law
function.
Again,
thisBouquin
is inthecontrasttoearlier
findingsof flatthatmassThe
observed
distribution
mass
ratiossteeply
with1,2,3
mass,
and
like
star
counts,indicates
our6 , 10 ,10 ,JosefaE. Großschedl, JoãoAlves,initial
Paula
Teixeira, HervéBouy, Jan
Forbrich,11
CharlesJ.
Lada
Vincent
Lapeyrère, Bernard
Lazareﬀ,7S.
Jean-BaptisteLe, 7Pierre
Léna,11Rainer
Lenzen11
Vincent
LapeyrèreBernard
Lazareﬀ, Jean-Baptiste
Bouquin, mechanism
PierreLéna, ofRainer
Lenzen
,
1
1,7
8
ratio
distributions
in, Chien-Cheng
OB, associations.
We
excludecollision
asLippaa dominantbut1 ,findnoflat
clear
10
1Le
7
4 1,
companions
follow a4 ,standard
power
function.
Again,
thisis formation
in1 ,contrast
to earlier
findings
mass
StefanMeingastÁlvaroHacarlaw,initial
Joana
Ascenso, Christine
AckerlBirgitHasenberger
RainerKöhlerSamuelLévêqueLin, massMagdalena, 1 Yves
Magnard, 7Leander
Mehrgan, 4An4110
9 as Lippa
9 findMehrgan
SamuelLévêque,, Irati
Chien-Cheng
Lin, Magdalena, Yves, Leander, Anpreferenceforcoreinaccretionor competitive
accretion.
ratio
distributions
OB
associations.
excludecollisionadominant
formationmechanism
but
no
clear
4
71 ,We4
10 10Magnard
10
4
Karolina
KubiakLarreina
LorenzLinhardt,
Marco
Lombardi,
TorstenMöller
toine Mérand ,4 Thibaut Moulin ,7 Eric Müller , 4Friedrich Müller ,10Udo Neumann ,10Sylvain Oberti , 4
toine
Mérand,accretion
Thibaut
Moulin9 , Eric
Müller , FriedrichMüller , Udo
Oberti ,preferenceforaccretion.
1
2 Neumann , Sylvain
1A&A
4
11
Acceptedby coreUniversität
Wien,
Institut orfürcompetitive
Astrophysik,Türkenschanzstrasse
1180 Wien,
Austria;
ICCUB, Univ.
de Barcelona
ThomasOtt,1 Laurent
Pallanca,9 Johana
Panduro10 10
,17,
Luca
Pasquini, 4Thibaut
Paumard,11Isabelle
ThomasOtt,
Laurent
Pallanca,
JohanaPasquini,
Thibaut
Paumard,Isabelle
3 Panduro , Luca
4
7
11
1
4
(IEEC-UB),
Martı́ Franquès 1, E-08028 Barcelona;, Andreas
SUPA, Schoolof Physics
and Astronomy,
Univ.
of St. Andrews,
Accepted
by ,A&A
Percheron
Pflüger, 1Thanh
Phan Duc, 4Philipp
M. Plewa1 , 1
http://arxiv.org/pdf/1809.10376
4 Karine Perraut ,7 Guy Perrin 11
Percheron,4 Karine
Perraut, Guy
Perrind’Astrophysique, Andreas
Pflüger, 10Thanh
Phan
Duc
PhilippM. Plewa,
4
1Laboratoire
9
1 , Allée
North
Haugh,
Fife
KY16
9SS,
UK;
de
Bordeaux,Univ.
deBordeaux,
GeoﬀroyDan
Popovic ,4 Sebastian Rabien ,1Andrés Ramı́rez, 9Jose Ramos ,10Christian Rau , 1Miguel Riquelme9, 9
http://arxiv.org/pdf/1809.10376
5
Dan
PopovicCS, Sebastian,CEDEX,
AndrésF;Ramı́rez
Jose Ramos, 1ChristianRau, Miguel
Riquelme ,Saint-Hilaire,
50023,
33615
PESSAC
CentreResearch,
SchoolofPhysics,
Astronomy
11Rabien
10 for, Astrophysics
11
Gustavo Rodrı́guez-Coira 11, Ralf-Rainer Rohloﬀ 10, Alejandra Rosales 6, 1Gérard Rousset ,11Joel Sanchez
VISION- Vienna
Orion.
III.
Young
in Harvard-SmithsonianOrion
A RoussetCenter
Gustavo
Rodrı́guez-Coira, in
Ralf-Rainer
Rohloﬀ, stellar
Alejandra
Rosales, Gérard, Joel Sanchez
and Mathematics,
Univ.surveyof Hertfordshire,
Lane,
Hatfield
9AB,
UK;
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10 College
4 AL10objects
9
Bermudez,
SilviaScheithauer,
MarkusSchöller
Spyromilio4for, 4Odele
9,10
10
7 , 4 Nicolas 4 Schuhler , 9 Jason
1
1
1,2,3
Astrophysics,
60
GardenStreet,Cambridge,
02138,
USA;
LeidenObservatory,
Niels
Bohrweg
2,2333
CA
Leiden,Bermudez, Silvia
Scheithauer, MA
MarkusSchöller, Nicolas
Schuhler, 1,5,6
Jason
Spyromilio
Odele
Josefa
,
João
Alves
S.
Teixeira
HervéBouy,
Jan
Forbrich,
CharlesJ.
Lada96,, , Noel
11E. -Großschedl
3, Paula
1 ,stellar
4
VISION
ViennasurveyinOrion.
III.
Young
objectsin
Orion
A
Straub8 11, ChristianStraubmeier,
EckhardSturm,
MarcosSuarez,KonradR.W.
Tristram
3
1
1
1,7
8
1Suarez1
NL; Univ.
do Porto,
de11Engenharia
Fı́sicada1 Faculdade
Engenharia,
Rua4Hasenberger
RobertoP-4200-465,
Straub, ChristianStraubmeier, Eckhard
Sturm
Marcos,Dr.Konrad
R.W.
Tristram
StefanMeingast, Álvaro
Hacar
Ascenso, Christine
Ackerl, 4Birgit, Rainer
Köhler196,, Noel
1 Dept.
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JosefaE.9,Großschedl, João Alves
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Widmann, 1Ekkehard
Wieprecht
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1 Vincent
1, Paula
9 Straße
9Charles7Univ.
11
Porto;
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Fakultätfür
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A-1090Univ.
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Milan,
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StefanMeingast
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Erich
Wiezorrek,1 Markus, 4 Julien
Woillez, 4Burkhard
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Celoria16, I-20133
Milan;
1Physics, via
2MichaelWiest
Erich
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9
10 Woillez
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für
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11
Karolina, IratiLarreina, Lorenz
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1,3contact: josefa.elisabeth.grossschedl
3E-mailat 9univie.ac.at
Yazici, Denis
Zins(IEEC-UB),
Martı́ Ziegler
Franquès111,, Gérard
E-08028 Barcelona;
SUPA, School of Physics and Astronomy,
Univ. of St. Andrews,
2
11 Universität Wien, Institut für Astrophysik,2Türkenschanzstrasse
17,de1180
Wien, Austria;
ICCUB,
Univ.
deGeoﬀroy
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4
MPE
Max
PlanckInstituteforextraterrestrial
Physics,
Giessenbachstr.,
85741
Garching,
Germany;
Department
North
Haugh,
Fife
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9SS,
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Bordeaux,Allée1 We extend and refine the existing young stellar object
2(YSO)
catalogs
for
the
Orion
molecular
cloud,
theclosest3
MPE
Max
PlanckInstituteforextraterrestrial
Physics,
Giessenbachstr.,
Garching,
Germany;
Department
385741(IEEC-UB),
Martı́
Franquès
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E-08028
Barcelona;
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SchoolofPhysics
andAstronomy,
Univ.
of
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2
of Physics,
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massivestar-forming
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Haugh,
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Lane,
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AL10
9AB,
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ZlpicherStr.
50937
Köln,
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EuropeanSouthern
Observatory,Karl-Schwarzschild-Str.
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(K
<
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60
GardenStreet,Cambridge,
MA02138,
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Bohrweg
2,2333
CA
Leiden,85748
Garching,
Germany;
CENTRA–
CentrodeAstrofı́sicaeGravitação,
IST,
UniversidadedeLisboa,P-1049cloud(VISION).
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midto
far-infrared
data,
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VISTA
data
allow
for
a
refinedandmorerobust6
5
8 Garching, Univ.
and
Mathematics,of Hertfordshire,College
Lane,
Hatfield
AL10
9AB, UK;
Harvard-Smithsonian
Centerfor P-104985748
Germany;
CENTRA–
CentrodeAstrofı́sicaeGravitação,
IST,
UniversidadedeLisboa,
6
NL;
Univ.
do
Porto,Dept.
deEngenharia
Fı́sicadaFaculdadedeEngenharia,
Rua
Dr.
RobertoFrias,
P-4200-465,
001source
Lisboa,Portugal;
Universidade
de Lisboa- Faculdade
Grande,1749-016
Portugal; 6
selection.
We estimatethat among
previously
known protostars
and Campo
pre-main-sequencestars withLisboa,
disks, source
7de Ciências,
910
Astrophysics,
60 Wien,
GardenFakultätStreet, Cambridge,
MAWähringer
02138,
USA;
LeidenObservatory,
Niels
Bohrweg
2333 CA
Leiden,Porto;
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für eInformatik,
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of2,Milan,
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of
001
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Ciências,
CampoGrande,1749-016
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contaminationlevelspositives)
areleast ∼7%and∼2.5%
respectively,
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and
CENTRA– Centrode (false
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de Engenharia
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Milan;CENTRA–
CentrodeAstrofı́sicaeGravitação,
UniversidadedeLisboa,P-1049-001
Lisboa,7 Frias, Portugal;
nebulosities.
We
identify
274
new
YSO
candidates
using
VISTA/Spitzer
based
selections
withinpreviously
analyzeddeEngenharia,
Universidade
doPorto,
Rua Dr.
RobertoFrias,29/S6,
4200-465
Porto,
Portugal;
GrenobleFaculdade
Alpes,
9
10
7 Milan, Dept. ofPorto;Univ.
Wien,
FakultätbasedfürInformatik,Währinger
StraßeA-1090Wien;
Univ. ofUniv.
deEngenharia,
Universidade
doPorto,Dr.
RobertoFrias,
4200-465
Porto,
Portugal;
Univ.
Grenoble1290
Alpes,
8 Rua
regions,and
VISTA/WISE
selectionstoaddsourcesinthesurroundings,
beyondpreviously
analyzed
regions.
E-mailcontact:
josefa.elisabeth.grossschedl
atunivie.ac.at
CNRS,
IPAG,
38000
Grenoble,
France;ObservatoiredeGenève,
UniversitédeGenève,51
Ch.
desMaillettes,
Physics,
via
Celoria
16,9method
I-20133recovers
Milan;
8 59% of the known YSOs in Orion A’s low-mass star-forming part L1641,
The
WISE
selection
about
CNRS,
IPAG,
38000
Grenoble,
France;ObservatoiredeGenève,
UniversitédeGenève,51
Ch.
desMaillettes,
1290
10
We extend
and refine theexisting youngstellarobject (YSO)
catalogs
for theOrion A 19,
molecular
the closest
Versoix,
Switzerland;
EuropeanSouthern
Observatory,
Casilla19001,
Santiago
Chile; cloud,
MPIA- Max-Planck9be achieved by the all-sky
102
whichcontact:
shows
what
can
WISE
surveyin combination
with
deep
near-infrared
in regions
E-mailjosefa.elisabeth.grossschedl
at univie.ac.at
Versoix,
Switzerland;
EuropeanObservatory,
Casilla19001,
Santiago
19, Chile;
massivestar-forming
regionto Earth. Southern
This updated
catalog
is drivenby thelarge spatial
coverage(18.3 degdata
,MPIA
∼950
pc-2 Max-Planck),′′withoutthemassivestars.
The new
contains
2978
which
classified
basedon
limitedresolution), andsensitivity
(K
< 19
mag)
of
the ESO-VISTA
near-infrared
surveycloud,of theOrion
Athe
Weseeing
extendandinfluencerefine theof(∼0.7
existing
young
stellarobject(YSO)
catalogs
forYSOs,
the Orion
A weremoleculartheclosests catalog
22de-reddened
mid-infrared
spectralindex
into to188
protostars,
184theflat-spectrum
sources,and2606
pre-main-sequence
cloud(VISION).
Combinedwitharchival
far-infrared
data,
VISTA
data
allow
for
a
refinedandmorerobustmassivestar-forming
region to
Earth.
Thismidupdated
catalogisdrivenbythelarge
spatialcoverage
(18.3
deg
,
∼950
pc
),
2322
′′thatstars
withcircumstellar
disks.
Wefindastatisticallysignificant
diﬀerenceinthespatialdistribution
of
the
three
sourceselection.
Weestimate
among
previously
known
protostars
andpre-main-sequence
stars
with
disks,
sourceseeing limited resolution (∼0.7 ), and sensitivity (Ks < 19 mag)22of the ESO-VISTA near-infrared survey of the Orion A
evolutionary
with respect
to areregions
oftohigh
confirming
thatforsources
arecontaminationlevels(falsepositives)at least∼7%dustand column-density,∼2.5%
mostlydue
toflat-spectrum
backgroundgalaxiesand atcloud(VISION).classes
Combinedwitharchival
midfar-infrareddata,respectively,
the VISTA
data allowa refined andmore robust
a younger
evolutionary
phase
comparedtoClass IIs,
andVISTA/Spitzer
arenot a sub-sample
seen at particular
viewing
angles.
nebulosities.
We
identify
274thatnew
YSO candidates
using
based
selections
withinstars
previously
analyzed
sourceselection.
Weestimate
among
previously
known
protostars
andpre-main-sequencewith disks,sourceregions,andselections
to addsourcesin the respectively,
surroundings,mostly
beyonddue
previously
analyzed
regions.
contaminationlevels(false positives)
are at least∼7%
and ∼2.5%
to backgroundgalaxiesandAccepted
byVISTA/WISE
Astronomy& basedAstrophysics
The
WISE
selection
methodrecovers
about
59%
of
the
known
YSOs
in
Orion
A’s
low-massstar-forming
part
L1641,
nebulosities.
We
identify
274
new
YSO
candidates
using
VISTA/Spitzer
based
selections
withinpreviously
analyzed
https://arxiv.org/pdf/1810.00878
which
shows
what can be achievedby the all-sky
WISE
surveywithbeyond
deep near-infrared
data in regions
regions,and
VISTA/WISE
based selections
to addsourcesin inthecombination
surroundings,
previously analyzed
regions.
The
WISE
selection
methodrecovers
about
59%
of
the
known
YSOs
in
Orion
A’s
low-massstar-forming
part
L1641,
H2 CO ortho-to-para ratio in the protoplanetary disk HD 163296
which shows what 1can be achievedbythe
all-sky
WISE
surveyincombination
with
deep
near-infrareddata
inregions
23
V.V. Guzmán , K.I. Öberg2 , J. Carpenter1 , R. Le Gal2 , C. Qi2 , and J. Pagues2

22

22
22

23

1

Joint ALMA Observatory (JAO), Alonso de Córdova 3107 Vitacura, Santiago de Chile, Chile; 2 Harvard-Smithsonianhttps://arxiv.org/pdf/1810.00878

H2 CO ortho-to-para ratio in the protoplanetary disk HD 163296

23 V.V. Guzmán , K.I. Öberg , J. Carpenter , R. Le Gal , C. Qi , and J. Pagues
1

2

1

2

2

2

1

Joint ALMA Observatory (JAO), Alonso de Córdova 3107 Vitacura, Santiago de Chile, Chile; 2 Harvard-Smithsonian
Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA
E-mail contact: viviana.guzman at alma.cl
Ortho-to-para (o/p) ratios of species like water, ammonia and formaldehyde (H2 CO) are believed to encode information
about the formation history of the molecule. Measurements of o/p ratios in protoplanetary disks could thus be used
to constrain their physical and chemical histories. We present the first measurement of the H2 CO o/p ratio in a
protoplanetary disk, using three ortho and two para lines observed with the Sub-millimeter Array (SMA) combinedwith one highly resolved measurement of a single H2 CO line with ALMA toward the disk around Herbig Ae star HD
163296. We find a disk-averaged H2 CO o/p ratio of 1.8–2.8 (depending on the assumed disk structure), corresponding
to a spin temperature of 11–22 K. We also derive a rotational temperature of 24 K from the flux ratio of the threeortho lines. The observed spatial distribution, as seen by ALMA, as well as the rotational temperature and the o/p
ratio, at the large scales the SMA is most sensitive to, are consistent with a low-temperature formation pathway, most
likely grain surface chemistry, of H2 CO in this disk.
Accepted by ApJ
http://arxiv.org/pdf/1809.01705

High spectral resolution observations toward Orion BN at 6 µm: no evidence for hot

water.
24 Capture
and, Jonathan
Escape: C.
Theof Radiation
ForcesNick Indriolo
TanDependence, A. C. A. Boogert, C. N. DeWitt, E.onJ. Clumping
Montiel , D. in
A. Dusty
Neufeld Envelopes
and
M.
J.
Richter
25
1

2,3

4

5

6

7

6

1
1
1
Peter
JumperScience
and Christopher
D. Matzner
SpaceH.Telescope
Institute, Baltimore,
MD 21218, USA; 2 Department of Space, Earth & Environment,
1Chalmers University of Technology, SE-412 93 Gothenburg, Sweden; 3 Department of Astronomy, University of VirDepartment of Astronomy and Astrophysics,
University of Toronto, 50 St. George Street, Toronto, Ontario, M5S
ginia,Canada
Charlottesville, VA, 22904, USA; 4 Institute for Astronomy, University of Hawaii at Manoa, Honolulu, HI, 96822,
3H4,
USA; 5 USRA, SOFIA, NASA Ames Research Center MS 232-11, Moﬀett Field, CA 94035, USA; 6 Department ofE-mailjumperat astro.utoronto.ca
Physics,contact:
Universityof California
Davis, Davis, CA, 95616, USA; 7 Department of Physics & Astronomy, Johns Hopkins
University,
Baltimore,MD
21218,
Dust barriers eﬀectively capture USA
the photon momentum of a central light source, but low-density channels, alongwith
re-emission
at longeratwavelengths,
enhance its escape. We use Monte Carlo simulations to study the eﬀects ofE-mailcontact: nindriolo
stsci.edu
inhomogeneity on radiation forces imparted to a dust envelope around a central star. We survey the strength and
The Becklin–Neugebauer (BN) object in Orion has a large proper motion and radial velocity with respect to the gas
scale of an inhomogeneous perturbation field, as well as the optical depth of its spherical reference state. We run atand other stars in the region where it is presumed to have formed. Multiple dynamical interaction scenarios havemoderatenumerical resolution, relying on our previous resolution study for calibration of the associated error. We
been proposed to explain this motion. In one case BN is thought to have interacted with stars in the Trapezium
find
that
inhomogeneities
mosttowhen
scale exceeds
the characteristic
free path.
As expected,
cluster, while in another itmatteris thought
havetheir
interactedwith source
I while deeplymean
embeddedin moleculargas. Ifthey
tend
toreducethenetradiation
force
andextendits
range;
however,there
issignificant
variance
amongrealizations.
there is dense gas that has been retained in close proximity to BN, it may be evidence that the latter scenario is
Withinforce
correlatewith theinemergent
spectralenergygiven a specified set offavored.our
Wemodels,
observed
BN integrals
at high spectral
resolution
three windowsnear
6 µmdistribution,using the Echelon-Cross-Echelle
dust
properties.
criticalis the choiceof integralof the radiation
force:
strong deviations
Spectrograph
on A
board
the issue
Stratospheric
Observatory
for measures
Infrared Astronomy
targetingthe forν2 vibrationalband offrom
spherical
symmetry
theonly
relevant
assessforcesrelative
to
the
cloud
centreofmass.
Ofthese,
wewithfind theH2 O. Absorption
fromthreemeasurestransitionsof HradialOisdetected,andthroughkinematic
analysisisassociated2virialterm dueto radiation
to BN
be theleastof several
integralmeasures in the presence of inhomogeneities.
cool, dense
foregroundgas, notitself.
Westochastic
find no evidence
for H
2 O absorption or emission at the systemic velocityof BN. by MNRAS
Accepted
Accepted by ApJL
https://arxiv.org/pdf/1806.05686.pdf

https://arxiv.org/pdf/1809.08155

26

CO observations toward the isolated mid-infrared bubble GAL 334.53+00.83 (S44):
External triggering of O-star formation by a cloud-cloud collision
Mikito Kohno1 , Kengo Tachihara1 , Shinji Fujita1 , 24
Yusuke Hattori1 , Kazufumi Torii2 , Atsushi Nishimura1 ,1
1
Misaki Hanaoka , Satoshi Yoshiike , Rei Enokiya1 , Keisuke Hasegawa1 , Akio Ohama1 , Hidetoshi

27First hydrodynamics simulations of radiation forces and photoionization feedback
in massive star formation2

Departmentof Physics, Kyoto University,
Kyoto, 606-8502, Japan1
Rolfmany;
Kuiperand Takashi
Hosokawa2
1

E-mail contact: rolf.kuiper at uni-tuebingen.deInstitute of Astronomy and Astrophysics, University of Tübingen, Auf der Morgenstelle 10, 72076, Tübingen, GerAims: We present the first simulations of the formation and feedback of massive stars which account for radiation
forces as well as photoionization feedback (along with protostellar outflows). In two diﬀerent accretion scenarios modeled, we determine the relative strength of these feedback components and derive the size of the reservoir from which25
the forming stars gained their masses.
Method: We performed direct hydrodynamics simulations of the gravitational collapse of high-density mass reservoirs
toward the formation of massive stars including self-gravity, stellar evolution, protostellar outflows, continuum radiation transport, photoionization, and the potential impact of ram pressure from large-scale gravitational infall. For
direct comparison, we executed these simulations with and without the individual feedback components.
Results: Protostellar outflows alone limit the stellar mass growth only in an accretion scenario with a finite mass
reservoir; when including accretion and ram pressure from large scales (> 0.1 pc), protostellar outflows do not limit
stellar mass growth at all. Photoionization and HII regions dominate the feedback ladder only at later times, after thestar has already contracted down to the zero-age main sequence, and only on large scales. Specifically, photoionization
yields a broadening of the bipolar outflow cavities and a reduction of the gravitational infall momentum by about 50%,
but does not limit the stellar mass accretion. On the other hand, we find radiation forces restrain the gravitational
infall toward the circumstellar disk, impact the gravito-centrifugal equilibrium at the outer edge of the disk, andeventually shut down stellar accretion completely. The most massive star formed in the simulations accreted 95 M⊙
before disk destruction; this mass was drawn-in from an accretion reservoir of ≈ 240 M⊙ and ≈ 0.24 pc in radius.
Conclusion: In the regime of very massive stars, the final mass of these stars is controlled by their own radiation force
feedback.
Accepted by A&A
http://adsabs.harvard.edu/pdf/2018A%26A...616A.101K
http://arxiv.org/pdf/1804.10211

High-resolution ALMA Study of the Proto-Brown-Dwarf Candidate L328-IRS

28

Chang Won Lee1,2 , Gwanjeong Kim1,2,3 , Philip C. Myers4 , Masao Saito5 , Shinyoung Kim1,2 , Woojin
Kwon1,2 , A-Ran Lyo1 , Archana Soam1 , and Mi-Ryang Kim1
1

Korea Astronomy & Space Science Institute, 776 Daedeokdae-ro, Yuseong-gu, Daejeon, Republic of Korea; 2 Korea
University of Science & Technology, 217 Gajungro, Yuseong-gu, Daejeon, 305-333, Republic of Korea; 3 Nobeyama
Radio Observatory, National Astronomical Observatory of Japan, National Institutes of Natural Sciences, Nobeyama,
Minamimaki, Minamisaku, Nagano 384-1305, Japan; 4 Harvard-Smithsonian Center for Astrophysics, 60 Garden
Street, Cambridge, MA 02138, USA; 5 National Astronomical Observatory of Japan, National Institutes of Natural
Sciences, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan
E-mail contact: cwl at kasi.re.kr
This paper presents our observational attempts to precisely measure the central mass of a proto-brown dwarf candidate,L328-IRS, in order to investigate whether L328-IRS is in the substellar mass regime. Observations were made for thecentral region of L328-IRS with the dust continuum and CO isotopologue line emission at ALMA band 6, discovering
the detailed outflow activities and a deconvolved disk structure of a size of ∼87 AU × 37 AU. We investigated therotational velocities as a function of the disk radius, finding that its motions between 130 AU and 60 AU are partiallyfitted with a Keplerian orbit by a stellar object of ∼0.30 M⊙ , while the motions within 60 AU do not follow any
Keplerian orbit at all. This makes it diﬃcult to lead a reliable estimation of the mass of L328-IRS. Nonetheless, our
ALMA observations were useful enough to well constrain the inclination angle of the outflow cavity of L328-IRS as∼66◦ , enabling us to better determine the mass accretion rate of ∼8.9 × 10−7 M⊙ yr−1 . From assumptions that theinternal luminosity of L328-IRS is mostly due to this mass accretion process in the disk, or that L328-IRS has mostly
accumulated the mass through this constant accretion rate during its outflow activity, its mass was estimated to be