HNC (1–0)
CS (2–1)

20

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

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

(3)
(4)
(5)
(6)
The Serpens filament
C18 O (1–0)
109.78217
5.0
55.5%
0.04
12.2
HCO+ (1–0)
89.18852
4.3
56.8%
0.21
61
HCN (1–0)
88.63185
4.3
56.8%
0.21
61
N2 H+ (1–0)
93173.76
4.5
61.9%
0.04
12.2
CS (2–1)
97.98095
7.1
60.6%
0.04
12.2
HNC (1–0)
90.66357
4.4
57.0%
0.04
12.2
CH3 OH (JK =20 –10 A+ )96.74138
7.0
63.4%
0.19
61
CH3 OH (JK =2−1 –1−1 E)
96.73936
12.5
63.4%
0.19
61
Source A: (αJ2000 =18h 28m 47.s 62, δJ2000 =00◦ 50′ 55.′′ 8)
HCN (1–0)
88.63185
4.3
56.8%
0.04
12.2
H13 CO+ (1–0)
86.75429
4.2
56.7%
0.21
61
H13 CN (1–0)
86.34018
4.1
56.7%
0.21
61
HN13 C (1–0)
87.09085
4.2
56.7%
0.21
61
13
CS (2–1)
92.49426
6.7
61.9%
0.20
61
CCS (JN =87 –76 )93.87011
19.9
61.9%
0.19
61
Source B: (αJ2000 =18h 28m 57.s 70, δJ2000 =00◦ 48′ 02.′′ 0)
HCN (1–0)
88.63185
4.3
56.8%
0.04
12.2

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

E-mail contact: ygong 18
at mpifr-bonn.mpg.de+

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

The Serpens filament, as one of the nearest infrared dark clouds, is regarded as a pristine filament at a very early
evolutionary stage of star formation. In order to study its molecular content and dynamical state, we mapped thisfilament 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)

σ
(K)
(7)

obs.Mode

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(8)

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
C18 O (1–0)
N2 H+ (1–0)
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+ )CH3 OH (JK =2−1 –1−1 E)

21

!LSR
(km s−1 )(1)
8.11±0.01
8.06±0.12...
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∆!
(km s−1 )(2)0.53±0.01
0.45±0.12...
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!
T mb d!
(K km s−1 )(3)
1.14±0.06
1.29±0.09<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

Nmol(cm−2 )
(4)(5.9±0.3)×1014(3.1±0.2)×1012...
(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.
Filaments
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.

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 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

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

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

Mikito Kohno1 , Kengo Tachihara1 , Shinji Fujita1 , Yusuke Hattori1 , Kazufumi Torii2 , Atsushi Nishimura1 ,Misaki Hanaoka1 , Satoshi Yoshiike1 , Rei Enokiya1 , Keisuke Hasegawa1 , Akio Ohama1 , Hidetoshi
Sano1,3 , Hiroaki Yamamoto1 and Yasuo Fukui1,31

Department of Physics, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8601, Japan; 2 Nobeyama
Radio Observatory, National Astronomical Observatory of Japan (NAOJ), National Institutes of Natural Sciences(NINS), 462-2, Nobeyama, Minamimaki, Minamisaku, Nagano 384-1305, Japan; 3 Institute for Advanced Research,
Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan

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

the origin of isolated high-mass star(s) and the star-formation process around the bubble formed by the HII region.
In this paper, we report the results of new CO observations (12 CO, 13 CO J =1–0, and 12 CO J =3–2) toward theisolated bubble GAL 334.53+00.83 using the NANTEN2, Mopra, and ASTE radio telescopes. We found two velocity
components in the direction of the bubble, at −84 km s−1 and −79 km s−1 . These two clouds are likely to be physicallyassociated with the bubble, because of the enhanced 12 CO J =3–2/1–0 intensity ratio from a ring-like structure aﬀectedby ultraviolet radiation from embedded high-mass star(s) and from the morphological correspondence between the
8 µm emission and the CO distribution. Assuming a single object, we estimate the spectral type of the embedded
star inside the bubble to be O8.5-9 from the radio-continuum free-free emission. We hypothesize that the two clouds
collided with each other 3 Myr ago, triggering the formation of the isolated high-mass star in GAL 334.53+00.83, as
also occurred with RCW 120 and RCW 79. We argue that this scenario can explain the origin of the isolated O-starinside the bubble.

ASTE

Accepted by PASJ
http://arxiv.org/pdf/1809.00118.pdf

27First 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

Rolf Kuiper1 and Takashi Hosokawa2
1

Institute of Astronomy and Astrophysics, University of Tübingen, Auf der Morgenstelle 10, 72076, Tübingen, Ger-

-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
25

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

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

24µ=> 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）

8

ν

ν

ν

ν

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？
一方、Source IはmassiveなKeplerian降着円盤を持っている（Hirota et al. 2014; Ginsburg et al. 2018）

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 ESA - European Space Agency, Space Telescope ScienceRadio
Astronomy,Auf
AufdemdemHgelHgel69,69,53121
53121Bonn,
Bonn, Germany;
Germany; 14Radio
Astronomy,
ESA - European Space Agency, Space Telescope Science
15
Institute,
3700
San
MartinDrive,
BaltimoreMD
21218,USA;
Astronomy
Institute, 3700 San Martin Drive, Baltimore MD 21218, USA; 15 Dublin
Dublin Institute
Institutefor
forAdvanced
AdvancedStudies,
Studies,
Astronomy
16
Multiplestarsystems
in
the
Orion
nebula&Astrophysics
Section,31
Fitzwilliam
Place,D02
XF86,
Dublin,Ireland;
16University of Vienna, Universitätsring 1,
Multiplestarsystems
in
the
Orion
nebula& Astrophysics Section, 31 Fitzwilliam Place, D02 XF86, Dublin, Ireland; University of Vienna, Universitätsring 1,
1010
Wien,
Austria1
1 1
1 1
1,2 1,21010
Wien,
Austria
GRAVITY
collaboration:
Martina, Frank, Reinhard
Genzel, ReGRAVITY
collaboration:
MartinaKarl
Karl,1 ,Oliver
OliverPfuhl
Pfuhl, FrankEisenhauer
Eisenhauer, Reinhard
Genzel, Re33
1 1
4 4
4 4
5 5
E-mailcontact:
martina.karl@tum.de
bekkaGrellmann, Maryam Habibi , Roberto Abuter , Matteo Accardo , António Amorim , NarE-mail contact:
martina.karl@tum.debekka Grellmann, Maryam Habibi, Roberto Abuter, Matteo Accardo 7, António Amorim, Nar64
7sireddyAnugu,6 ,anGerardoÁvila,4 ,Myriam
Benisty, 7 ,Jean-Philippe
Berger
, 7Nicolas
Blind
This work
presents
interferometric
studyof the massive-binary
fractionin the Orion
Trapezium
Clusterwiththe8 , 8Henrisireddy
Anugu
GerardoÁvilaMyriamBenisty
Jean-Philippe
Berger,Nicolas
Blind,
This work
presents an interferometricstudy of the massive-binary
fraction in
the Orion Trapezium 1Cluster with the Henri
4 comissioned
9
recentlyGRAVITY
instrument.
We
observe10
a 10
of 16 starsof 4mainly
OB spectral
type. ,We
three
Bonnet,4 ,Pierre
Bourget,9 ,Wolfgang
Brandner,totalRolandBrast, 4Alexander
Buron
Carattio o
1Alessio
BonnetPierreBourgetWolfgang
Brandner,
RolandBrast, AlexanderBuron, findAlessio
Carattirecently 10,15
comissioned GRAVITY instrument.
We 2observe
total
OB spectral
type. We
find11three1
2 of 16 stars of
11 a
11 mainly apreviously
unknowncompanionsfor11θ11
Ori
B,
θ
Ori
B,
and
θ
Ori
C.
We
determineseparation
forthepreviously
Garatti,Frédéric
Chapron,Yann
Clénet,ClaudeCollin,Vincent
Coudé
duForesto,Willem10,15
11
11
11
2
Garatti unknown, Frédéric
Chapron, Yann, Claude, Vincent
Coudé forduthe
Foresto, Willempreviously
companionsfor θ1confirm
OriB,fourθ2Clénet
Ori
B, andθfor
OriC.CollinWeθdetermine
a separation
previously
1914suspected
companion
ofde
NUZeeuw
Ori. We1,12companions
θ11 Ori A,
Ori C, θ1 1Ori D, and4 ,θ24RoderickOriA, all with
Jan
de
Wit
,9 , Tim, ,CaseyDeen, 1 ,Franoise
Delplancke-Ströbele
Dembet
, 4,
1,12
1
2
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
estimates.
We
refine
the
orbit
of
the
eccentric
high-mass
4
1 and photometric mass
7
10
3,13
4
Frédéric
Derie
,
Jason
Dexter,GillesDuvert,MonicaEbert,
AndreasEckart,MichaelEsselborn, 4,
4
1 photometric mass
7 estimates.
10
substantially
improved
astrometry
We refinethe orbitEckartof the 3,13
eccentric
high-mass
1
Frédéric, Jason, GillesDuvert, Monica
Ebert, Andreas, Michael
Esselbornbinary1θ1 Derie
Ori
C and
we
areDexter
able 4toand
derive
a new
orbit
11
6,9 for θ 1 Ori D. We find a system mass4of 21.7 M⊙ and a period
10,15
PierreFédou,Gert
Finger,Paulo
Garcia,Cesar
Enrique
GarciaDabo,
RebecaGarciaLopez,
11 we are able to 4derive a new orbit6,9
4
10,15
binaryOri C
andθ Ori D.
Weinfinda systemDabo
massof, 21.7
M⊙ anda period
PierreFédou, Gert Finger, Paulo Garcia for, Cesar
Enrique
GarciaRebecaGarciaof 53θdays.
seen
spectroscopy
or direct
imaging,
elevenofLopez10 ,1 Together with other11 previously detected companions
1
4
5
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
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
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
1,13
10,14
4
Jocou , Andreas4 Kaufer9 , Stefan
Kellner,
Sarah
Kendrew,
Lothar
Kern,
PierreKervella
,
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
Lacour,11 of mass
7
11
10
companions
follow a standard
power
lawdeclines
initial7mass
function.
Again,Le
thisBouquin
is inthecontrasttoearlier
findingsof flatthatmassThe
observed
distribution
ratioswith mass,
andlikedirectstar
counts,indicates
ourVincent
Lapeyrère, Bernard
Lazareﬀ,7steeply
Jean-Baptiste, 7Pierre
Léna,11Rainer
Lenzen,10
11
Vincent
LapeyrèreBernard, Jean-Baptiste
Bouquin, mechanism
PierreLéna, ofRainer
Lenzen,ratio distributionsin Chien-Cheng
OB, associations.
We10exclude
collision asLippaa dominant
but findnoflat
clear
1Le
7
4
companions
follow a4 ,standard
power lawLazareﬀ
initialfunction.
Again,
thisis formationin contrast
to earlier
findings
mass
SamuelLévêqueLin, massMagdalena, 1 Yves
Magnard, 7Leander
Mehrgan, 4An4
10
SamuelLévêque, Chien-Cheng
Linexclude, Magdalena
Lippa, Yves, Leander, Anpreference
for 4coreinaccretionor competitive
accretion.
ratio
distributions
OB
associations.
collisionasadominant
formationmechanism
but
no
clear
7 We
4
10 Magnard
10 findMehrgan
4toine Mérand ,4 Thibaut Moulin ,7 Eric Müller , 4Friedrich Müller ,10Udo Neumann ,10Sylvain Oberti , 4
toine
Mérand,accretion
Thibaut
MoulinMüller , FriedrichMüller , Udo Neumann , Sylvain Oberti ,preferencefororcompetitive
accretion.
1A&A
9 , Eric
Acceptedby coreThomasOtt,1 Laurent
Pallanca,9 Johana
Panduro10 10, Luca Pasquini4 , 4Thibaut Paumard11 ,11Isabelle
ThomasOtt,
Laurent
Pallanca,
JohanaPanduro,Luca
Pasquini , Thibaut Paumard , Isabelle
4
7
11
Accepted
by ,A&A
PercheronKarine Perraut , Guy Perrin 11, Andreas Pflüger1 , 1Thanh Phan Duc4 , 4Philipp M. Plewa1 , 1
http://arxiv.org/pdf/1809.10376
Percheron4 ,4 Karine Perraut7 , Guy
Perrin , Andreas
Pflüger , 10Thanh Phan Duc, Philipp M. Plewa ,1
9Dan
Popovic , Sebastian Rabien , Andrés Ramı́rez , 9Jose Ramos ,10Christian Rau1 , 1Miguel Riquelme9, 9
http://arxiv.org/pdf/1809.10376
Dan Popovic4 , Sebastian11Rabien1 , Andrés Ramı́rez, Jose Ramos , 1Christian Rau , MiguelRiquelme ,10
Gustavo Rodrı́guez-Coira 11, Ralf-Rainer Rohloﬀ 10, Alejandra Rosales , 1Gérard Rousset11 ,11Joel Sanchez
VISION- Vienna survey
Orion.
III.
Young
objectsin Orion
A Rousset , Joel
Gustavo
Rodrı́guez-Coira, in
Ralf-Rainer
Rohloﬀ, stellar
Alejandra
Rosales, Gérard
Sanchez
9,10
10
4
9Bermudez 9,10
, Silvia 1Scheithauer, Markus Schöller, 4 Nicolas 4 Schuhler , 9Jason
Spyromilio4 ,6 4Odele
1 10 , Markus Schöller
1,2,3
Bermudez, Silvia
Scheithauer, Nicolas
Schuhler, 1,5,6
Jason
Spyromilio
Josefa
,
João
Alves
Teixeira
HervéBouy,
Jan
Forbrich,
CharlesJ.
Lada
11E. -Großschedl
3, Paula S.
1 ,stellar
4
9 , , Odele
VISION
ViennasurveyinOrion.
III.
Young
objectsin
Orion
A
Straub 11, ChristianStraubmeier,3 Eckhard Sturm, 1 Marcos Suarez, Konrad R.W.
Tristram , 19Noel
11,7
8
1Suarez4 , Konrad R.W.
1
Straub, Christian, Eckhard
Tristram
Stefan Meingast, Álvaro
Hacar
Ascenso, Christine
Ackerl, 4Birgit Hasenberger, Rainer
Köhler ,, Noel
1 Straubmeier
1 , Joana
1,2,3 , Marcos
11
1 Sturm
3Bouy
1 1,5,6 , Charles
Josefa E.7 ,Großschedl
,
João
Alves
,
Paula
S.
Teixeira,
Hervé
,Jan
Forbrich
J. Lada6 , 1 , 1
VenturaFrédéric
Vincent,
Idel
Waisberg
,
Imke
Wank
,
Felix
Widmann,
Ekkehard
Wieprecht
109
7 Kubiak1 , Irati Larreina
11 1 , Lorenz Linhardt
1 9 , Marco Lombardi
3
1
Karolina, TorstenMöller
Ventura,Frédéric
Vincent,
Idel
Waisberg,
Felix
Widmann,
Ekkehard
Wieprecht,
1
1,7
8 , Imke Wank
1
1
1
3
1
4
4
4
Stefan Meingast, Joana
AscensoWittkowski, Christine Ackerl, Birgit
Hasenberger, Rainer
Köhler,
MichaelWiest ,3, Álvaro
Erich Hacar
Wiezorrek,1 Markus, 4 Julien
Woillez, 4Burkhard
Wolﬀ, Senol
12MichaelWiest
Erich
Wiezorrek, 9 Markus
Wittkowski, Julien, Univ.
Burkhard
Wolﬀ4 , Senol
1 ,Institut
1
9
10 Woillez
9de Barcelona
Universität
Wien,
für
Astrophysik,Türkenschanzstrasse
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Karolina,
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Yazici, Denis
Zins(IEEC-UB),
Martı́ Ziegler
Franquès 1,, 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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Max Planck
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85741
Garching,
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Max
PlanckInstituteforextraterrestrial
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Giessenbachstr.,
Garching,
Germany;
Department
385741(IEEC-UB),
Martı́
Franquès
1,
E-08028
Barcelona;
SUPA,
SchoolofPhysics
andAstronomy,
Univ.
of
St.
Andrews,
5of Physics,
Le Conte
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UniversityofCalifornia,
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Harvard-Smithsonian
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EuropeanSouthern
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EuropeanSouthern
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LeidenObservatory,
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Dr.
RobertoFrias,
P-4200-465,
Physics,
via
Celoria16,
I-20133
Milan;CENTRA– Centrode Astrofı́sica
e Gravitação,
IST,
Universidade
de Lisboa,
P-1049-001
Lisboa,Portugal;
7deEngenharia,
Universidade
Porto,
Rua Dr.
RobertoFrias,29/S6,
4200-465
Porto,
Portugal;
GrenobleFaculdade
Alpes,
9
10
7 Milan, Dept. ofPorto;
Univ. Wien,
Fakultät dofür
Informatik,Währinger
StraßeA-1090Wien;
Univ. ofUniv.
deEngenharia,
Universidade
doPorto,Dr.
RobertoFrias,
4200-465
Porto,
Portugal;
Univ.
Grenoble1290
Alpes,
8 Rua
E-mailcontact:
josefa.elisabeth.grossschedl
atunivie.ac.at
CNRS,
IPAG,
38000
Grenoble,
France;ObservatoiredeGenève,
UniversitédeGenève,51
Ch.
desMaillettes,
Physics,
via
Celoria
16,9Grenoble,
I-20133 Milan;
8
CNRS,
IPAG,
38000
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-Planck910
E-mailcontact:
josefa.elisabeth.grossschedl
at univie.ac.at
Versoix,
Switzerland;
EuropeanObservatory,
Casilla19001,
Santiago
19, Chile;
massivestar-forming
regionto Earth. Southern
This updated
catalog is driven
by thelarge spatial
coverage(18.3 deg2 ,MPIA∼950 pc-2 Max-Planck),22′′
limited), andsensitivitymag) ofthe ESO-VISTA
near-infrared
surveycloud,of the theOrion
A
Weseeing
extendand resolution
refine the(∼0.7
existing
young
stellar (Kobject(YSO)
catalogs
for the Orion
A molecularclosests < 192
cloud (VISION).
Combinedarchival
to far-infrared
data,
data
allowcoverage
for a refinedandmorerobustmassivestar-forming
region towith
Earth.
Thismidupdated
catalog is 22
driventhe
byVISTAthe large
spatial(18.3
deg, ∼950pc2 ),
sourceselection.
We estimate
amongpreviously
known
protostars
and pre-main-sequencestarssurvey
with disks,seeinglimitedresolution(∼0.7′′that), andsensitivity(Ks <19 mag)of the ESO-VISTA
near-infraredof thesource
Orion A
22
contaminationlevels(falsepositives)
are
at
least
∼7%
and
∼2.5%
respectively,
mostlydue
tobackgroundgalaxiesandcloud (VISION). Combined with archival mid- to far-infrared data, the VISTA data allow for a refined and more robust
nebulosities.
identify
274thatnewamong
YSO candidates
VISTA/Spitzer
based
selections withinstars
previously
analyzed
sourceselection.WeWe
estimatepreviouslyusing
known
protostars andpre-main-sequencewith disks,sourceregions, and VISTA/WISE
based selections
to addsourcesin the respectively,
surroundings,mostly
beyonddue
previously
analyzed
regions.
contaminationlevels (false positives)
are at least∼7%
and ∼2.5%
to backgroundgalaxies
and
The
WISE
selection
methodrecovers
about
59%
of
the
known
YSOs
in
Orion
A’s
low-massstar-forming
part
nebulosities. We identify 274 new YSO candidates using VISTA/Spitzer based selections within previously L1641,
analyzed
which andshows
what can be achieved by the all-sky WISE survey in combination with deep near-infrared data in regions
regions,
VISTA/

23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