Star Formation News Letter
No. 299 #36‒40, 46-50
楠根貴成（国立天文台）#36 ALMA Reveals Sequential High-mass Star Formation in the G9.62+0.19
Complex#38 A turbulent origin for the complex envelope kinematics in the young lowmass core Per-Bolo 58#40 The Seahorse Nebula: New views of the ﬁlamentary infrared dark cloudG304.74+01.32 from SABOCA, Herschel, and WISE

Reveals
High-massStar
Star
Formation
inG9.62+0.19
the G9.62+0.19
Complex
ALMA
RevealsSequential
Sequential High-mass
Formationin theComplex#36ALMA
7 7
10
55
8
9
Tie1,2,3,4
Liu1,2,3,4, John
, JohnLacy
Pak Shing
Shing Li, Sheng-Li
Qin8Qin, QizhouZhang9Zhang, Kee-TaeKim1 , Guido, Garay10,
Tie Liu
Lacy, ,Pak
Li66, ,Ke
KeWangWang, Sheng-Li, Qizhou, Kee-TaeKim1 Garay, Guido
10
12 12
13
14
11 11, Diego Mardones10
13
13
Yuefang,, Qingfeng
Zhu, Ken’ichi
Tatematsu, Tomoya
Hirota13 Hirota, Zhiyuan
Ren,
Yuefang
WuWu, Diego Mardones
Qingfeng
Zhu,
Ken’ichiTatematsu,
Tomoya,Zhiyuan
Ren14,
15
15
15
14,16
Sheng-Yuan Liu
Chen, Yu-Nung
Su , andLi Di Li14,16
Sheng-Yuan
Liu15 , Huei-Ru, Huei-Ru
Chen15, Yu-Nung
Su15Di, and1Korea Astronomy and Space Science Institute 776, Daedeokdae-ro, Yuseong-gu, Daejeon, Korea (34055); liutiepku@gmail.com
2

1

KoreaofAstronomy
and America
Space Science
Institute776, (CASSACA)
Daedeokdae-ro,
Yuseong-gu,
Daejeon,
Korea (34055);
liutiepku@gmail.com
Chinese Academy
Sciences, South
Center for
Astrophysics
at Cerro
Calán, Camino
El Observatorio#1515, Las
Condes, Santiago, Chile
3 Center for Astrophysics (CASSACA) at Cerro Calán, Camino El Observatorio #1515, Las Condes, Santiago, Chile
Chinese Academy of Sciences, South America
DepartmentofAstronomy,
PekingUniversity,
100871,
Beijing,
China
The
AstrophysicalJournal,849:25(21pp),
2017
November1
Liu et al.
3
4
Departmentof Astronomy,
PekingUniversity,
100871,
Beijing,
China
East Asian
Observatory,
660 N. A’ohōkū
Place,
Hilo, Hawaii
96720-2700,
USA
4
5energetic winds, or supernova explosions. The expansion of the
Department
Astronomy,
Universityof Texas atAustin,Austin,
TX 78712,
USA USA
East AsianofObservatory,
660 N. A’ohōkū
Place,
Hilo,
Hawaii
96720-2700,
shock front (SF) that emerges around massive stars can
65
Astronomy
Department,
Universityof medium,
California,
Berkeley,
CAAustin,
94720,
USA78712, USA
DepartmentofAstronomy,
University
of
Texas
at
Austin,TX
compresstheinterstellar
triggeringstarformationin
7
6
European Southern
Observatory,
Garching
beiCA
München,very Karl-Schwarzschild-Str.2,
dense University
layers (Elmegreen&D-85748
Lada 1977;
WhitworthAstronomy
Department,of California,
Berkeley,
94720, GermanyUSA8
et al.Key
1994a,
1994b). Thisso-called “collectand ofcollapse”
Department of 7Astronomy, Yunnan University, andLaboratoryof Astroparticle
Physics
Yunnan Province, Kunming, 650091, China
EuropeanSouthern
Observatory,Karl-Schwarzschild-Str.2,
D-85748
Garchingbei
München,Germany
9
process
self-propagate60andlead to sequential
star formation
Harvard-Smithsonian Centerfor canAstrophysics,
GardenStreet, Cambridge,
MA 02138, USA
8
10
Department of Astronomy, Yunnan
University,and Key&Laboratoryof Chile,
Astroparticle
Physics(Elmegreen
Lada 1977; Whitworth
et al.
1994a,36-D,
1994b).
Theof Yunnan
Departamentode Astronomía,
UniversidaddeCasillaSantiago,
Chile Province, Kunming, 650091, China
9“collectfor
andAstrophysics,
collapse” process 60
has been
revealed
in the Cambridge,
borders
11
Harvard-Smithsonian
Center
GardenStreet,MA 02138, USA
Department of
Peking evidenced
University,
100871,by Beijing
fragmented
shells China
orof Astronomy,
several H II regions,1012DepartamentodeAstronomía,
Universidad
deChile,
Casilla36-D,
Santiago,
Chile China
Astronomy Department, University of
Sciencestar
and formation
Technology,
ChineseetAcademy
Sciences, Hefei 210008,
sequential(Deharveng
al. 2003, of2005;11
13
National Astronomical
Japan,
2-21-1
Osawa,etMitaka,Tokyo
181-8588,
Japan
Zavagnoet al.of2006,
2007;
Deharveng
al. 2008;
Pomarès
DepartmentObservatoryof Astronomy,
PekingUniversity,
Beijing
100871,
China
14 12
etof
al. Science
2009; Petriella
etTechnology,
al. 2010;
Brand
et al.Road,
2011;Academy
Liu et al. of
National
Astronomical
Observatories,
ChineseAcademyof Science,
A20
Datun
Chaoyang
District,
Beijing
100012,China China
Astronomy
Department,
University
andChineseSciences,
Hefei
210008,1513
2012,
2015a, 2016a).
Thompsonet al. (2012)
estimatedthat theAcademia
Sinica,InstituteofAstronomy
andAstrophysics,
P.O.
Box
23-141,
Taipei106,
TaiwanObservatoryof Japan,
Osawa,of massive
stars in2-21-1
the Milky
Way Mitaka,formed byTokyo 181-8588, Japan
16 National Astronomicalfraction
14
Key Observatories,
Laboratory for Radio
Astronomy,
ChineseAcademyof Sciences,
Nanjing
210008, China
triggering
processes of
could
be between
14%
and Road,
30% byChaoyang District, Beijing 100012, China
National Astronomical
ChineseAcademyScience,
A20
Datun
Received2017 May 13; revised 2017
Augustaccepted
2017bubbles.
September
15; published2017 October 26
15
studyinga large15;
sampleof infrared
However,recent2

1. G9.62クランプ： HII領域(B・C)のPDRに囲まれている
2. ALMA 1.3mm：

高密度コア12個同定
・4 - 87 Msun

・星なしコア - UCHII領域

Academia Sinica, Institutenumericalof Astronomy
and Astrophysics, P.O. Box 23-141, Taipei 106, Taiwan
simulations indicate that the ages and geometrical16
Key Laboratory for Radio
Astronomy,
Chineseof Sciences,distributionof stars relative
to theAcademy
feedback sourceor feedback- Nanjing 210008, China
Abstract
drivenstructure(e.g.,
shells,pillar structures)
might be not
Received
2017
May
13;
revised2017
August15;
accepted
2017
September
15; published 2017 October 26
The Astrophysical Journal, 849:25 (21pp), 2017 November 1
Liu et al.

連続的な星形成を示唆

substantially helpful in distinguishing triggered star formation

Stellar feedback from high-mass starsfrom(e.g.,H II regions)inﬂuence
the surrounding interstellar
spontaneousstar formationcan(Dalestrongly
et al. 2015). In
addition,in mostprevious
studies,observations
the fragmented shells
surroundingthe
medium and regulate star formation. Ournew
ALMA
revealsequential
high-mass star formation
Abstract
enough to form a new generation of
H II regions are not dense
Figure 1. Spitzer/IRAC three-color composite image (8 μm in red, 4.5 μm intaking place within one subvirial ﬁlamentary
clump
(the
G9.62starclump)G9.62+0.19
Theof 12dense complex. The Spitzer/IRAC
green,complex.
and 3.6 μm in blue)
the G9.62+0.19
high-mass
stars. Can
high-mass
formationinbe thetriggered?
Toemissionis alsoshownby phase
the red contours.
The contour levels are (0.1,
Stellarfrom detected
high-mass
starsanswer(e.g.,H IIdifferent
regions)canstrongly
inﬂuencethesurrounding
thisdetailed studies
of massive
clumps(thecoresfeedback(MM1–MM12)
by ALMAareat question,very
evolutionary
stages,from80.2,μm
thestarlesscore
tointerstellar
0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9)×2550 MJy/sr. The JCMT/SCUBA
birth places of high-mass stars) near feedback sources (H II
450μm emission
from the G9.62
is shown
by the white contours. The
mediumstar Threeformation.
Our
new
ALMA
observations
sequential
high-mass
star
formation
region phase.
dense cores(MM6,
MM7/G,
MM8/F) arereveal
associatedwith
outﬂows.
Theclump
mass–
the UCand
H IIregulate
regions or supernova remnants) are urgently needed.
contour levels are (0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9)×96 Jy/beam. A, B, and C
velocityoutﬂows associated
with
MM7/G
MM8/F
can bebybrokenpower
laws. Theare thethree evolved
H II regions.
takingplacediagrams
within ofonethesubvirial
ﬁlamentary
clump(theand
G9.62
clump)
inwell-ﬁt
the G9.62+0.19
complex.
The 12 dense
mass–velocity
diagramoftheSiO
outﬂow
associated
with
MM8/F
breaksmuch
earlierthanother
outﬂow
tracers
The
G9.62+0.19
Complexcores (MM1–MM12) detected by ALMA are at very different evolutionary stages,
fromthe Itstarlessphase(parsec-scale)tois very clearcorethat large-scaleevolvedH II region.
SO, CS,phase.
HCN), Threesuggesting
thatcores
SiO traces
newly
gas,et whilethemolecular
lines(e.g.,
CO,
Locatedat a distanceof shocked
5.2 kpc (Sannaal. 2009),
theothersequential
high-mass
star
formationis Thetaking placefrom west to
II region
dense
(MM6,
MM7/G,
MM8/F)
areassociatedwith
outﬂows.
mass–
the (e.g.,
UC HCO,
G9.62+0.19
complex containsentrained
a cluster of byradiooutﬂow
continuumjets. eastin theG9.62+0.19
complex(e.g., Liu et al. 2011).
SO, CS, HCN) mainly trace the ambient
gas continuously
Five
cores
(MM1,
MM3,
sources (denoted
from
A–I), whichand
are atMM8/F
different evolutionary
velocity
diagramsoftheoutﬂows
associated
with
MM7/G
can
be
well-ﬁtbybrokenpower
laws. TheIn this work,
we study theinteraction
the evolved
MM5, MM9, MM10) are massive starless
whose
are estimatedbe larger
25 “C”)
M☉, andbetween“A,”masses
cometary-shaped
H II
stagescore(e.g., candidates
extended H II region(“A,” than“B,” andthe G9.62 clump.
H IItoregions
mass–velocity
diagramoftheSiO
outﬂow
associated
with
MM8/F
breaksmuch
earlierthanother
outﬂow
tracers
regionshocks“B,” compact
H IItheregion“C,” ultracompact
II regions (“B”
Particularly,
investigate
and “C”)wetothoroughly
the west
may the fragmentation andassuming a dust temperature of 20 K. The
from
expanding
H II Hregions“D andE,” and
hot molecularcore shocked“F”; Garay et al.
1993;while
Testi theoutﬂows
in theG9.62 clump lines
from high-resolution
and high(e.g.,
CO,
SO,
CS,
HCN),
suggestingthat
SiO
traces
newly
gas,
other
molecular
have a great impact on the G9.62 clumpetbyal.compressing
into aSequential
ﬁlamenthigh-mass
and inducing
core
collapse successively, (e.g., CO,
2000; Liu et al.it 2011).
starsensitivity ALMA observations.
Figure 2. 1.3SO,
mm continuum
fromobservations.
Theformation.
red ellipses
dense
cores
identiﬁed
fromtheGaussianﬁt.complex
The blackﬁlled
ellipseformation
is takingplace
inthatthe 2D
G9.62+0.19(Hofner
CS, HCN)
mainlytrace
the represent
ambient
gas
continuously
entrainedby
outﬂow
jets. Fivecores (MM1,MM3,
may enhancetheleading
toALMA
sequential
starOurtheﬁndings
suggeststellarfeedback
from
H II regions
represents the beam. The vertical red line represents a spatial scale of 0.1 pc. The positionof radiois marked
et al.
1994,source
1996,“C”
2001;
Testibyetan
al.arrow.
2000;Left
Liupanel:
et al.observed2011). image;The theformation
efﬁciency
low-mass
formation
inclumpadjacentpre-existing
massive toclumps.
MM5,
MM9,are70,andmassivestarlesscore
candidates
areestimatedbe 2.larger
than 25 M☉,
contours are (−3,3,star5, 7, 10,15, 20, 25,MM10)30, 35,40, 50, 60,
80, 90,suppress
100, 110)×0.8
mJy/beam.
Asstardepictedbythe yellow
dashedcurve,
the northernof theyoungest
sourcesarelocatedin awhose
to masses
theeastof parttheObservations(“B”
and2.1.“C”)
the west may
assuming
a dustH temperatureof 20K.+0.19
The
shocksfromkinematics
the expanding
H regions
ALMAtoObservations
regions – ISM:
jets andoutﬂows– ISM:and dynamics– stars:formation
Key words:
complex is an ideal target to study the effect of stellar
on new generations itof high-massstar formation.and inducing
have a great impact on the G9.62 clumpfeedback
by compressing
into a ﬁlamentcore collapse
successively,
The observations(Project ID: 2013.1.00957.S)of the G9.62
R  ab and presented in the ninth column of Table 1. The
areFigureshown1 inside
parentheses
in the10th column
shows theSpitzer/IRAC
three-color(8 μm ofin Tablered, 1. +0.19 complex were conducted with ALMA on 2015 April 27
mayenhancethein the 12
sequential
starformation.
Ourﬁndings
suggeststellarfeedback
H II regions∼20 K become
about
The
core
derivedwithinorathat
Td ofcomposite
radii oftheleading
dense corestorange
from 3000 au
to 10,000
au.
3.
うち３つでOutﬂowを検出
in
SiO
CO
(2-1)：
MM7/G,
MM8/F
4.5 μminmasses
green,(5-4)
and
3.6 μm
blue)
image
of
the twofrom
in its MM6,
compact
conﬁguration
with a totalof 39 antennas
Therefore,
theTurbulentCore
Accretion
model
predicts
the1.
Introduction
of
∼35
K.
times
larger
than
the
core
massesderivedwithaT
G9.62+0.19
complex.
The
redcontours
represent
theSpitzer/
The masses
of
the
dense
cores
can
be
derivedwithmarray,
on
2015
May
24
in
its
extended
conﬁguration
with adstar formation efﬁciency and suppress IRAC
low-massstar formation in adjacentpre-existing
massive clumps.
8 μm polycyclic aromatic hydrocarbon (PAH) emission,
total of 34 antennas in the 12 m array, and on 2015 May 4 with
ﬁtted image;the contours
5, 7,
10, 15,Therefore,
20, 25, 30, 35,
50, 60, 70,
G9.62 clump is very likely bent by the compression of the H II region “C.” Middle panel:(Liuareet(3,al.
2011).
the40,
G9.62
evolvedH II regionsII80, 90, 100, 110)×0.8 mJy/beam. Right: residual
image; the contours are (−3, 3, 5)×0.8 mJy/beam.
II

Equations (8) and (9) in Appendix A. The uncertainties ofexistence of massive starless cores that will form high-massFlow Velocity Intervals(km s−1)(15, 21)R2

a or γAccretion rate
3.9 x 10-4

Blueshifted SiO Outﬂows of MM6a(5, 14)MM6：

若く(~8.5 x 103 yr)、collimateしたoutﬂow(5, 25)

MM7/G：

inclinationが非常に小さい

MM8/F：

100km s-1と非常に活発
a or γR

2

Blueshifted SiO Outﬂows of MM6
0.11±0.01(6, 12)(12, 22)0.98(5, 15)(15, 21)0.14±0.01
0.07±0.01(5, 12)(12, 22)0.06±0.01

0.99

0.97
0.99

Blueshifted SiO Outﬂows of MM7/Gb0.75±0.08
2.19±0.10

2.2 x 10-3 Msun yr-1
0.75±0.08
2.19±0.10

0.44±0.05
3.36±0.17

0.25±0.02
3.38±0.13b0.51±0.06
2.26±0.19(12,31)(31, 70)

1.53±0.03
3.10±0.03

0.87
0.96

0.44±0.05
3.36±0.17

0.91
0.97

Redshifted SiO Outﬂows of MM8/Fb
0.25±0.02
3.38±0.13

0.91
0.98

Blueshifted CO Outﬂows of MM8/Fb(12,31)(31, 70)

The Astrophysical Journal, 849:25 (21pp), 2017 November 1

Notes.
aLinear ﬁt: M(v) ∝ –a×V.
b
Power law ﬁt: M (v ) r V H .

0.91
0.97

projection effect, which prevetion of possible ﬂow velocitie(iii) The slope of the mass–velocity
age and energy in the ﬂow (Det al. 2000; Arce et al. 2007)
velocity (Vflow  12 kms−1
with MM7/G is ∼2.2, whichof the high-velocity SiO outﬂ
F, indicating that the outﬂoyounger than the outﬂows
Ray 1999).
(iv) The mass–velocity diagram
associated with MM8/F break(12–18 km s−1) than those(31–33 km s−1). In addition, tof the outﬂows traced by SO
HCN (4–3) do not seem to
25 kms−1 (Liu et al. 2011). W

0.91
0.98

1.53±0.03
3.10±0.03

0.99
1.00

projection effect, which prevents an accurate determination of possible ﬂow velocities.
(iii) The slope of the mass–velocity diagram may steepen withage and energy in the ﬂow (Downes & Ray 1999; Richer
et al. 2000; Arce et al. 2007). The slope γ of the highvelocity (Vflow  12 kms−1) SiO outﬂows associatedwith MM7/G is ∼2.2, which is smaller than the γ (∼3.4)of the high-velocity SiO outﬂows associated with MM8/
F, indicatingthat
Liu etal. the outﬂows of MM7/G may be
younger than the outﬂows of MM8/F (Downes &Ray 1999).
(iv) The mass–velocity diagrams of the SiO outﬂows
associated with MM8/F break at much smaller velocities(12–18 km s−1) than those of the CO outﬂows(31–33 km s−1). In addition, the mass–velocity diagramsof the outﬂows traced by SO (87  77), CS (7–6), andHCN (4–3) do not seem to break at velocities up to
25 kms−1 (Liu et al. 2011). Why do SiO outﬂows break=> HII領域からのfeedbackが星形成効率を上昇・低質量星形成を抑制
0.99
1.00

Redshifted CO Outﬂows of MM8/Fb(22, 33)
1.86±0.04
1.00(33, 70)
4.42±0.08
0.99
Figure 11. Mass–velocity diagrams of outﬂows associated with MM6 (panel(a)), MM7/G (panel (b)), and MM8/F (panel (c)). The outﬂow masses derived
Notes.
afrom CO (2–1) or SiO (5–4) are normalized. The mass–velocity diagrams ofLinearﬁt: M(v)∝ –a×V.
theoutﬂowsof MM6
were ﬁtted with linear functions, while the outﬂows ofb
H .
Power law
M (v ) r V
MM7/G
andﬁt:MM8/F
werebetter ﬁtted with broken power laws. The
parameters of the ﬁts are summarized in Table 5.

projection effect, which prevents an accurate determination of possible ﬂow velocities.
(iii) The slope of the mass–velocity diagram may steepen with 16
age and energy in the ﬂow (Downes & Ray 1999; Richer
et al. 2000; Arce et al. 2007). The slope γ of the highvelocity (Vflow  12 kms−1) SiO outﬂows associatedwith MM7/G is ∼2.2, which is smaller than the γ (∼3.4)of the high-velocity SiO outﬂows associated with MM8/
F, indicating that the outﬂows of MM7/G may be
younger than the outﬂows of MM8/F (Downes &

1
4

0.87
0.96

(22, 33)
1.86±0.04
1.00(33, 70)
4.42±0.08
0.99
Figure 11. Mass–velocity diagrams of outﬂows associated with MM6 (panel(a)), MM7/G (panel (b)), and MM8/F (panel (c)). The outﬂow masses derived
Notes.
a from CO (2–1) or SiO (5–4) are normalized. The mass–velocity diagrams ofLinear ﬁt: M(v) ∝ –a×V. ﬁtted with linear functions, while the outﬂows ofb the outﬂows of MM6 wereH.
Power
law andﬁt: MMM8/F(v ) r V were
MM7/G
better ﬁtted with broken power laws. The
parameters of the ﬁts are summarized in Table 5.

7. 他のMassiveクランプよりも、高い星形成効率・ガスの枯渇時間が短い
G6.92には低質量星がほとんどない(6, 18)(18, 35)(22, 33)(33, 70)b0.51±0.06
2.26±0.19

1
3

Redshifted CO Outﬂow

0.95
0.98

Redshifted CO Outﬂows of MM8/Fb
0.95
0.98

Blueshifted SiO Outﬂows of MM8/Fb(5, 12)(12, 22)(12,31)(31, 70)

Blueshifted CO Outﬂows of MM8/Fb

0.14±0.01
0.07±0.01

Redshifted SiO Outﬂows of MM7/G(6, 18)(18, 35)

0
3Blueshifted CO Outﬂow

0.97
0.99

Redshifted SiO Outﬂows of MM8/Fb

Blueshifted CO Outﬂows of MM6a(5, 15)(15, 21)5.7 x 10-5

Blueshifted SiO Outﬂows of MM8/Fb

Redshifted SiO Outﬂows of MM6a(6, 12)(12, 22)

0.99

Redshifted SiO Outﬂows of MM7/G

a(12, 15)(15, 21)(6, 18)(18, 35)

Blueshifted SiO Outﬂows of MM7/Gb

Table 5The Slopes of the Outﬂow Mass–Velocity Relation(5, 25)0.06±0.01

03

Redshifted SiO Outﬂow

Redshifted SiO Outﬂows of MM6aBlueshifted CO Outﬂows of MM6(12, 15)(15, 21)

Liu et al.

(5, 14)(5, 12)(12, 22)

0.98

a

The Astrophysical Journal, 849:25 (21pp), 2017 November 1

Flow Velocity Intervals(km s−1)

0.11±0.01

2

Blueshifted SiO Outﬂow

16

#38 AATurbulent
TurbulentOrigin
Originfor
forthetheComplex
ComplexEnvelope
EnvelopeKinematics
KinematicsininthetheYoung
YoungLow-mass
Low-massCore
CorePer-bolo
Per-bolo58
58
1 1
1
2 2
33
44
María
José
Maureira, Héctor
G.G.
Arce
S.S.R.R.Offner, Michael
M.M.Dunham, JaimeE.E.Pineda
,,
María
José
Maureira, Héctor
Arce1 , Stella, Stella
Offner,MichaelDunham,Jaime
Pineda5 5
6 6
77
ManuelFernández-López
ManuelFernández-López, Xuepeng, XuepengChen
Chen, and
, andDiego
DiegoMardones
Mardones
1 1

Astronomy
Department,
Yale
University,
New
Haven,
CT06511,
USA;
mariajose.maureira@yale.edu,
hector.arce@yale.edu
The AstrophysicalJournal, 849:89 (14pp), 2017 November
10
Astronomy
Department,
Yale
University,
New
Haven,
CT06511,
USA;
mariajose.maureira@yale.edu,
hector.arce@yale.edu
2 2
DepartmentofAstronomy,
The
University
of
Texas
at
Austin,Austin,TX
78712,
USA
Department of Astronomy, The University of Texas
at Austin,
Austin,producedby rotation
and/or TX
infall.78712,
RotationUSA
can produce
3 3Department
of ofPhysics,
State
University
of of
New
York
at at
Fredonia,
Fredonia,USAvelocity
gradients along
the majorNY
axis
of 14063,
a ﬂattenedenvelope,
Department
Physics,
State
University
New
York
Fredonia,
Fredonia,
NY14063,USA
4 4perpendicular to1,
theD-85748
outﬂow axis.
Some examplesof young
Max-Planck
Institutefor
Extraterrestrial
Physics,
Giessenbachstrasse
Garching,
Germany
Max-Planck Institute for Extraterrestrial Physics, Giessenbachstrasse
Garching,
Germany
5 5sources that show 1,
thisD-85748
type of velocity
distribution
can beInstituto
Argentinode deRadioastronoma(CCT-La
Plata,CONICET;CICPBA),
No.
5,TobinElisa,
Instituto
Argentino
Radioastronoma(CCT-La
Plata,CONICET;CICPBA),No.
5,1894,Villa
1894,Villa
Elisa,Argentina
foundin BellocheC.C.
et C.C.
al. (2002),
et al. (2011),
Tanner&Argentina
6 6PurpleMountainObservatory,
ChineseAcademyof of
Sciences,
2 WestBeijingRoad,
Nanjing
210008,China
Arce(2011),
Yen
et al. (2013),
Oya
etal. (2016),
and Maureira
PurpleMountainObservatory,
ChineseAcademySciences,2
West
BeijingRoad,
Nanjing
210008,China
7 7
et al. (2017).
On 36-D,the otherSantiago,
hand, velocity
gradients along the
Departamentode deAstronoma,
Universidad
dede
Chile,
CasillaChile
Departamento
Astronoma,
Universidad
Chile,
36-D,
Santiago,
Chile
minor
axisCasillaof ﬂattenedenvelopes,
viewed close
to edge-on, canReceived
2017
June
2; 2;
revised2017
September
18;18;
accepted
2017
October4; 4;published
arise
from
infall motions(Torrelles 2017et2017
al. November
1995;
Ohashi6 6
Received2017
June
revised2017
September
accepted
2017
October
published
November

目的：

Maureira et al.

深く埋もれたﬁrst core候補Per-bolo 58周辺のenvelopeの構造や力学を調べる

et al. 1999; Caselli et al. 2002b; Yen et al. 2010). In addition,
if the envelope is ﬁlamentary, as are those produced bysimulation that include turbulence, a velocity gradient along the
major axis can be also produced by infall rather than rotationalmotions (Tobin +et al.
+ 2012). + +2 Infallcan also be detected using optically thick
2 and2rotation2+
molecular lines such
HCN (1–0), HCO(1–0),and (14pp),
CS
TheasAstrophysicalJournal,849:892017 November 10(2–1). In this case, the shape of the emission line will dependon changes in the kinetic temperature and density (excitation−1−1
temperature), as well as velocity along the line of sight. A twopeak proﬁle with a more intense blueshifted peak (also known
as blue asymmetric proﬁle) is expected to arise
from etinfall
The Astrophysical Journal, 849:89 (14pp), 2017 November 10
Maureiraal.
motions in isolated spherically symmetric envelopes in which
Figure 1. Herschel 250 μm map of the NGC 1333 region in Perseus. The white
the density increases toward the center (Evans 1999; Tomisaka: :arrow indicates the position of the dense core Per-bolo 58.
& Tomida 2011). On the other hand, simulations of cores
formed in a turbulent environment show a more complex++
Tomisaka 2006; Matsumoto & Hanawa 2011; Joos et al. 2012;
picture due to the asymmetries
in density and the disordered
2 2
Tomida et al. 2013; Bate et al. 2014; Tomida et al. 2015).
velocity ﬁeld, leading
to highly variable proﬁles for the same
Per-bolo 58 was identiﬁed as a ﬁrst core candidate by Enochcore as seen along different lines of sight. Smith et al. (2012)
et al. (2010) based on its SED, which shows that the central
simulated optically thick and thin tracers toward the center ofsource has a very low luminosity (L int _ 0.012 L :), lower
dense cores embedded in ﬁlaments, which were in turn formed
than the typical Class 0 object and even very low luminosity+ +out of a turbulent molecular cloud. They showed that evenobjects (VeLLOs). Using this same criterion, past studies have
2 2though the gas motions were dominated by infall, opticallyreported about nine other ﬁrst core candidates (e.g., Belloche
thick tracers can show both blue and red asymmetries in
et al. 2006; Chen et al. 2010; Enoch et al. 2010; Dunham
their double-peak proﬁle,dependingontheinclination
and−1
et al. 2011; Pineda et al. 2011; Chen et al. 2012; Pezzuto et al.
Figure 2. Integrated intensity maps of different species toward Per-bolo 58. The integration velocityazimuthal
range is angle[7, 8.1]usedkms. This velocity
rangeRed-asymmetric
was chosen tofor observing
the core.
2012; Schnee et al. 2012; Huang & Hirano 2013; Murillo &T and increase
3
T
7
T
in
steps
of
for
CS
(2–1)
and
for
the
rest.
include the main spectral components among the hyperﬁne line components. Black contours start at 3proﬁlesappeared in these turbulent collapsing cores, due to
Lai 2013).
White contours show the 3 mm continuum at 2σ and 3σ (see Table 1). The blue and red arrows show thedirectionandextent
of
the
blue
and
red
lobe
outﬂowemission
either the contribution of a ﬁlamentary envelope or accretion
The central source in Per-bolo 58 is driving a bipolarin Dunham et al. (2011).
occurring from only one side.
outﬂow, which was detected using SMA CO (2–1) observaIn this work we present Combined Array for Research intions with a resolution of 2 7 (Dunham et al. 2011). The
Millimeter-wave4.Astronomy
ratios, using the more intense peak among the two velocity
Analysis(CARMA) molecular line obseroutﬂow is slow, with a characteristic velocity of 2.9 kms−1,
vations
at
1000
au
scales
of
the
young
dense
core
Per-bolo58,
and shows a compact morphology with an opening semi-angle
components in each hyperﬁne, results in estimates of the total
The double-peakedof Per-bolo
58regioncannotbe welllocated north linesof the NGC
1333 cluster
in Perseus,
at aof about 8° for both lobes. This is only partially consistent withline opacity of about 5, 4, and 9 for NH2 D (11,1  10,1 ), N2H+
distanceof 230Gaussianpc (Hirotaﬁt.
et Thus,al. 2008).
1 shows
thereproduced bya single
to Figurequantify
centralseveral simulations of outﬂows launched by ﬁrst cores, which(1–0), and HCN (1–0), respectively. We can do a similarof Per-boloin aspectra
250 μmwith
Herschelmap, which
are typically low in velocity (110 kms−1) but also poorly
velocities andlocationline widths,
we ﬁt58thesetwo Gaussiansshows that the dense core is embedded in a large-scale
analysis by ﬁtting a single Gaussian to the double-peak proﬁle.
collimated (Matsumoto & Hanawa 2011; Tomida et al. 2013,
wherever theline
presentedadouble-peakstructure.
Toﬁlamentary structure. We study Per-bolo 58’s kinematics using
2015; Bate et al. 2014; Machida 2014). In addition, theThe total line opacity estimate obtained this way is about 4, 5,+
disentangle opticallythe emissionfrom(NHthe
blue and red
thin andcoming
thick tracers
2 D (11,1  10,1 ), N2Hdynamical time inferred from these outﬂow observations is+and 6 for NH2 D (11,1  10,1 ), N2H+ (1–0), and HCN (1–0),
components,
we
use
the
integrated
intensities(1–0),
HCN(1–0),
HCO(1–0), andCS (2–1)).deﬁned in
104 yr, which is close to the upper limit of the lifetime of ﬁrst
respectively. For N2H+ (1–0) and HCN (1–0), the opacity ofPer-bolo
58
is
an
ideal
sourceforstudyingtheconditions
inSection 3 (see also Figure 5). We ﬁt a Gaussian to the blue
cores, derived in simulations (Tomida et al. 2010). Althoughwhichiftheis transported
the core centerin threeyoung
the outﬂow morphology and its estimated lifetime could lead tothe isolated and weakest hyperﬁne components, respectively, is(red) component
thegasintegrated
blue toward(red) intensity
is oversources; the spectral energy distribution (SED) of this source
the straightforward conclusion that Per-bolo 58 is a protostar
about 0.1 of the total line opacity (Ahrens et al. 2002; Pagani
times the rmssuggests
at thatthat
particular
position.
Thus,asingleGaussianthe compact source at the center is not a protostar(and not a ﬁrst core), studies of the outﬂow launching
et al. 2009). Hence, these hyperﬁne components in these two
is ﬁt at positions
were only one
integrated
emission,blue
or ared,yet, corresponding
insteadto a theoreticalobjectcalledﬁrst
mechanism in ﬁrst cores and very young protostars havespecies (which are shown in Figure 3) are very likely optically
A ﬁrst hydrostatic(FHSC, oris over three hydrostatic
times the corerms,(seeandbelow).
two Gaussians
are ﬁtcore
at positions
shown that outﬂow collimation depends on the interplay

Abstract
観測：CARMAを使用。3 mmAbstract
連続光、NH2D(11,1-10,1)、

WeWe
useuseCARMACARMA3 mm
3 mmcontinuum
continuumand
andmolecularmolecularlines
lines(NH(NHD,D,NNHH, HCO, HCO, ,HCN,
HCN,andandCS)CS)atat∼1000∼1000auau2++
resolution
characterize
thethestructureandkinematics
surrounding
N H to(1-0)、HCN(1-0)、HCO(1-0)の分子輝線マップ@
resolution
tocharacterize
structureandkinematicsof
ofthetheenvelope
envelope
surroundingthe
thedeeply
deeplyembedded
embeddedﬁrst
ﬁrstcorecore
candidatePer-bolo
58.
The
line
proﬁleoftheobserved
speciesshows
twodistinct
peaks
separatedcandidate Per-bolo 58. The line proﬁle of the observed species shows two distinct peaks separated byby
, which0.4–0.6kms, whichmost
most
likelyarise
arisefromfromtwotwodifferent
differentoptically
opticallythin
thinvelocity
velocitycomponents
componentsrather
ratherthan
thanthethe0.4–0.6kms~1000
分解能
aulikely
product
productof ofself-absorption
self-absorptionin inananoptically
opticallythick
thickline.
line.The
Thetwotwovelocity
velocitycomponents,
components,eacheachwith
witha amassmassofof,
overlap
spatiallyatthepositionofthecontinuum
emissionandproduceageneralgradient
along∼0.5–0.6Mthe∼0.5–0.6 M , overlap spatially at the position of the continuum emission and produce a general gradient alongthe
outﬂow
outﬂowdirection.
direction.WeWeinvestigate
investigatewhether
whetherthese
theseobservations
observationsareareconsistentconsistentwith
withinfall
infallinina aturbulent
turbulentand
andmagnetizedenvelope.
WeWe
comparethethemorphology(1–0)withwithsynthetic
syntheticobservations
observationsofof
magnetizedenvelope.
comparemorphologyand
andspectra
spectraofofthetheNNHH (1–0)
an an
MHD
simulation
thatconsidersthethecollapse
ofofananisolated
MHD
simulation
thatconsiderscollapseisolatedcore
corethatthatis isinitially
initiallyperturbed
perturbedwith
witha aturbulent
turbulentﬁeld.
ﬁeld.
The
proposedThe
proposedmodel
modelmatches
matchesthethedata
datain inthetheproduction
productionofoftwo
twovelocity
velocitycomponents,
components,traced
tracedbybythe
theisolated
isolated
H H (1–0)
spectra,hyperﬁneline
of ofthetheNN(1–0)
spectra,and
andshows
showsa ageneralgeneralagreementagreementininmorphology
morphologyand
andvelocity
velocityﬁeld.
ﬁeld.WeWe
hyperﬁneline
also
useuse
large
maps
of of
thetheregionto tocompare
also
large
maps
regioncomparethethekinematics
kinematicsofofthethecorecorewith
withthatthatofofthe
thesurrounding
surroundinglarge-scalelarge-scaleﬁlamentary
structure
and
ﬁnd
that
accretionfromthelarge-scaleﬁlament
could
also
explaintheﬁlamentary structure and ﬁnd that accretion from the large-scale ﬁlament could also explain thecomplex
complexkinematics
exhibited
byby
this
young
dense
kinematics
exhibited
this
young
densecore.
core.
Key
words:
ISM:
individual
objects(Per-bolo
Keywords:
ISM:
individual
objects(Per-bolo58)58)– –stars:
stars:formation
formation– –stars:
stars:kinematics
kinematicsand
anddynamics
dynamics– –stars:
stars:
low-mass– stars:
protostars
low-mass– stars:
protostars

1. ラインプロファイル：
Introduction
1. 1.
Introduction

directionofofﬁeld
ﬁeldlines
linesatat1000
1000auauscales
scalescancanbebedifferent
differentfrom
fromdirection
initialﬁeld
ﬁelddirection
direction atat larger
larger scales
scales (Matsumoto(Matsumoto &&thetheinitial
Low-mass
protostars
form
from
gravitational
collapseofof
Low-mass
protostars
form
from
thethegravitational
collapse
２つのピークを持ち、0.4-0.6km
s-1離れている
Hanawa2011).
2011).Turbulence
Turbulencecan
canalsoalsoimprint
imprintbulk
bulkrotation
rotationinin
Hanawadense
cores
insidemolecular
clouds(Benson(Benson& &Myers
Myers1989;
1989;
nse
cores
insidemolecular
clouds
the
gas,
in
which
case
the
rotation
axis
can
be
misaligned
with
the
gas,
in
which
case
the
rotation
axis
can
be
misaligned
withCaselli
2002a;
Larson1969;
Shu1987).
Accordingselli et etal.al.
2002a;
Larson
1969;
Shu
et et
al.al.
1987).
Accordingmagneticﬁeld
ﬁelddirection.
direction.InInthis
thislast
lastscenario,
scenario,more
moremassive
massivethethemagnetic
totheory,
theory,thethedetails
detailsof ofthis
thisprocessprocessvary
varywith
withthetheinitial
initialdisksareareallowed
allowedtotoform,
form,asaswellwellasasoutﬂows
outﬂowsthat
thatarearenotnotdisks
conditions
core
such
presencemagneticﬁelds,
ﬁelds,
nditions
in in
thethe
core
such
as as
thethepresenceofof
magnetic
34

3. N2H+の形状・スペクトルをMHDシミュレーションの結果と比較

Figure 7. Simulation column density maps for the core at three different times, viewed edge-on. The sink particle location, after it forms, is marked in the right panel.
The magnetic ﬁeld is mainly along the horizontal direction.

N2H+ (1–0) cube. The two velocity components remained
detectable in the synthetic cubes.

collapse開始から0.13と0.15 Mry＠edge on
プロファイルは2つの速度成分を持つ
5.1.4. Comparison with Observations

The Astrophysical Journal, 849:89 (14pp), 2017 November 10

Maureira et al.

Figure 8 shows N2H+ (1–0) spectra at different positions andat two different time steps in the simulation viewed edge-on,
along with the spectra from the CARMA observations of Perbolo 58. The two different time steps show two velocity
components (although sometimes they are blended owing to
the limited resolution) in some locations. In other locations thesimulation shows spectra with one dominant (blue or red)
spectral component, similar to the observed N2H+ (1–0)
spectral map of Per-bolo 58.
Figure 9 shows the N2H+ (1–0) integrated intensity map forthe blue and red velocity components for these same simulation
outputs and for Per-bolo 58. We selected the ranges for
Figure 8. N2H+ (1–0) spectra at different offsets (in arcseconds) from theintegration following the same procedure described for thecontinuum
peak position (Per-bolo 58; black) and center position (simulations;observations (see Section 3). Similar to the observations, thegreen). The simulated spectra correspond to the edge-on view data cube in
two velocity components show spatial overlap. The blue andFigure 7, where light green and dark green correspond to the time steps 0.13
red integrated intensity peaks are close to each other in both ofand 0.15 Myr, respectively.
the simulation time steps in Figure 9, resembling most of
the emission distribution seen for both components in most of
velocities appear on the side of the red outﬂow lobe is also
the observed molecular line maps (see Figure 5). The moreconsistent with a system that is close to edge-on.
compact contours in the simulation follow the elongated dense
Figure 10 shows N2H+ (1–0) maps of velocity andstructure that forms during the collapse. This structure isnonthermal-to-thermal line width ratio for the view and time
perpendicular to the direction of the magnetic ﬁeld. The later
steps previously shown. We also show Per-bolo 58 forstage shows a more compact integrated emission in bothcomparison.
components in comparison
with both our observations and theThe(right)
collapsea N2more
Figure 10. Simulation and Per-bolo 58 central velocity (left) and line width
maps for theat
blue0.13
and redMyrpeak in shows
the spectra of
H+ (1–0).complex
Values in theseandmaps
earlier simulation output. Thisis a result
the evolutionof theincreasingof 0.05 kms
. Contours
thewere obtained
from a of
double-Gaussianﬁt. Contours
for the velocity
maps are drawn
from 7.1 ﬁeld
kms−1, thandisorderedvelocity
thein steps
collapse
at −1
0.15
Myr.for In
nonthermal-to-thermal line width ratio maps are drawn from 1, increasing in steps of 0.5. The blue and red arrows represent the outﬂow as in Figure 2.
denser regions in the envelope,which become more ﬂattenedcomparison,thevelocityﬁeldinPer-bolo
58
shows
less
with time. Thus, morphologically Per-bolo 58 N2H+ (1–0)
substructure than the simulated collapse at both stages. The
emission agrees better with the earlier evolutionary stages inabsolute velocity difference between the blue- and redshifted
the simulations (i.e., t _ 0.13 Myr) and/or with a system that isvelocities increases from the early to the later simulation. This
viewed close to, but not exactly, edge-on. Dunham et al. (2011)
can also be seen in Figure 11, which compares p–v diagrams ofconcluded, using the outﬂow morphology, that extreme edgethe simulated collapse at both time steps with Per-bolo 58
on or pole-on inclinations are ruled out, and thus an inclination
observations. The later stage shows a concentration of bluedifferent from exactly edge-on is expected. Given the close
shifted and redshifted velocities close to the center, which
spatial overlap between the blue and red components (seeresults from the turbulent conditions of the gas in the envelope.
Figure 9), inclinations closer to edge-on rather than pole-on
This velocity distribution is similar to what is seen in Figure 6
are in better agreement with Per-bolo 58. Indeed, the samefor Per-bolo 58. The value of the nonthermal line width for thesimulation viewed pole-on shows little spatial overlap between
simulation at 0.15 Myr is 1.5–2 times the sound speed at 10 K.
the components, as expected if the emission arises from a
A mix of both narrow and broad line widths are present inﬂattened infalling envelope. Similarly, as mentioned inboth the simulation and observations. However, line widths are
Section 5, a velocity gradient where the blueshifted velocities
higher in the simulation at both stages, as compared toappear on the side of the Figure
blue 11.
outﬂowlobe
and the maps
redshifted
The nonthermal contribution is up to ∼3 and ∼4
N2H+ (1–0)
position–velocity
for the simulationsobservations.
at 0.13 and

観測結果と一致
2つの速度成分：

非対称ガス分布のエンベロープで生じている↑この非対称性は乱流起因 in シミュレーション
turbulent&magnetized collapse：

コアの観測的特徴の解釈として妥当

4. large scale (>0.1pc)フィラメント降着による、1000auスケールでのガスの非対称性についても議論
N2H+のemission：

C18Oのフィラメント構造の中にあり、コアスケールでの２つの速度成分と一致する。
2つの速度成分はフィラメントスケールからの降着の結果の可能性もある

0.15 Myr. For comparison, Per-bolo 58 position–velocity maps for N2H+ (1–0)
are also shown. For the simulations, the top and bottom panels are cut
9perpendicular and parallel to the B-ﬁeld direction, respectively.
For theobservations the top and bottom rows correspond to a cut in a direction
perpendicular and parallel to the outﬂow lobe direction, respectively. Black

Figure 12. C18O (1–0) and N2H+ (1–0) integrated intensity contours over theNew#40viewsof the filamentary infrared dark
The Seahorse Nebula: New views of the⋆filamentary infrared dark
2 from SABOCA,
Herschel,from
andSABOCA,
WISE Herschel, and WISE ⋆cloud G304.74+01.32
O. Miettinen1, 2, 3
1
2

O. Miettinen1, 2, 3

Avarea Oy, Rautatieläisenkatu 6, FI-00520 Helsinki, Finland

rXiv:1710.07791v1 [astro-ph.GA] 21 Oct 2017

Helsinki, Finland 3 Department of Physics, Faculty of Science, University of Zagreb, Bijenička cesta 32, HR-10000 Zagreb, Croatia
Physics, P.O. Box 64, FI-00014 University of Helsinki,階層的なfragmentationを経て、
Finland
UniversityFilamentaryof Zagreb,Department
Bijeničkaofcloud（例：IRDCs）：
cesta
32, HR-10000 Zagreb, Croatia
Received ;Finland
accepted
14 University of Helsinki,

クランプやコア、星へとなる。

目的：

ABSTRACT

Context. Filamentary molecular clouds, such as many of the infrared dark clouds (IRDCs), can undergo hierarchical fragmentation
・IRDC
intoG304.74+01.32のクランプ中での、コアへのfragmentationを見つける
substructures (clumps and cores) that can eventually collapse to form stars.
ABSTRACT

Aims. We aim to determine the occurrence of fragmentation into cores in the clumps of the filamentary IRDC G304.74+01.32(hereafter, G304.74). We also aim to determine the basic physical characteristics (e.g. mass, density, and young stellar object (YSO)
content)of theclouds
clumps andcores in G304.74.
as many of the infrared
dark(IRDCs),can undergo hierarchical fragmentation
Methods.
We
mappedtheG304.74
filament
at 350 µm using the SABOCA bolometer. The new SABOCA data have a factor of 2.2
eventually collapse to form stars.
times higher resolution than our previous LABOCA 870 µm map of the cloud (9′′ versus 19′′. 86). We also employed the Herschelof fragmentation into
cores (IR)in theclumps of thefilamentary
IRDC
far-infraredand submillimetre,and Wide-field
Infrared
SurveyG304.74+01.32
Explorer (WISE) IR imaging data available for G304.74. The
data allowed us(e.g.
to trace
the IRdensity,
emission of
the young
YSOs associatedthe cloud.
e the basic physicalWISE
characteristics
mass,
and
stellar with
object(YSO)
Results. The SABOCA 350 µm data show that G304.74 is composed of a dense filamentary structure with a mean width of only
0.18 ± 0.05 pc. The percentage of LABOCA clumps that are found to be fragmented into SABOCA cores is 36% ± 16%, but
350 µm using the the
SABOCAbolometer.
The ofnew
SABOCAhavea factorof 2.2
irregular morphology
of somethe coressuggests datathat thismultiplicity
fraction
could be higher. The WISE data suggest that′′ A&A proofs: manuscript′′
no. AA_2017_31704
18%cloudof the SABOCA
cores19
host
YSOs.
Thealsomeanemployed
dust temperature
the clumps, derived by comparing the Herschel 250,
BOCA 870 µm map65%
of±the(9 versus. 86).
We
the ofHerschel
350, Explorer
and 500 µm flux
densities,
found todata
be 15.0± 0.8 K. The
mass, beam-averaged
H2 column density, and H2 number-field Infrared Survey(WISE)
IR wasimagingavailable
formean
G304.74.
The
density of the LABOCA clumps are estimated to be 55± 10 M⊙ , (2.0 ± 0.2) × 1022 cm−2 , and (3.1 ± 0.2) × 104 cm−3 . The correspondingof the YSOs associatedcloud.
values withfor thethe
SABOCA
cores are 29 ± 3 M⊙ , (2.9 ± 0.3) × 1022 cm−2 , and (7.9 ± 1.2) × 104 cm−3 . The G304.74 filament is estimated tobe thermallyby a factor of !
3.5 on the scaleby LABOCA,
by a factor of ! 1.5 for the SABOCA filament.
at G304.74 is composedof asupercriticaldense filamentary
structure
withprobeda meanwidth ofandonly
Conclusions.
Our
datastronglysuggest
that
the
IRDC
G304.74has
undergone
hierarchicalA clumps that are found to be fragmented into SABOCA cores is 36% ± 16%, but fragmentation. On the scale where theclumps have fragmented into cores, the process can be explained in terms of gravitational Jeans instability. Besides the filaments suggests that this being
multiplicity
be higher.
The
WISE
data itssuggestfragmented,fraction
the findingcouldof embedded
YSOs in
G304.74
indicates
thermallythat
supercritical state, although the potential nonthermal (turbulent)motions
can render
the cloudvirial equilibriumon scale
traced by LABOCA. The IRDC G304.74 has as. The mean dust temperatureof theclumps,derivedbyacomparing
thesystem
Herschel250,
seahorse-likemorphology
in the Herschel H
images,and the filament appears to be attached by elongated, perpendicular striations. Thisbe 15.0 ± 0.8 K. The
mean mass,
beam-averaged
2 column density, and H2 number
is potentially evidence
thatG304.74isstillaccreting
mass
from
22
4
−3 the surrounding medium, and the accretion process can contribute toto be 55± 10 M⊙ , (2.00.2) × 10
cm−2
and
(3.1
± 0.2)One
× 10
cm
. The
correspondingthe ±dynamical
evolutionof ,themain
filament.
of theclumpsin G304.74,
IRAS 13039-6108, is already known to be associated
22
−2
4
−3
high-mass
formation,
clumps andcores inis
thisfilament might
2.9 ± 0.3) × 10 cmwith, and(7.9 ±star1.2)
× 10 butcmthe .remaining
The G304.74
filament
estimated
to preferentially form low and intermediatemass
stars
owing
to
their
mass
reservoirs
andsizes.
Besidesthepresenceofperpendicularly
oriented, dusty striations and potential
on the scale probed by LABOCA, and by a factor of ! 1.5 for the SABOCA filament.
embedded intermediate-mass YSOs, G304.74 is a relatively nearby (d ∼ 2.5 kpc) IRDC, which makes it a useful target for future star
he IRDC G304.74 formation
has undergone
hierarchicalfragmentation.
On thethat
scale
where
studies. Owing
to its observed
morphology, we propose
G304.74
couldthebe nicknamed the Seahorse Nebula.

・クランプやコアの物理量も求めたい
観測：

SABOCA bolometerを使った350μmのマッピング（分解能~9ʼʼ）+ Herschel & WISELABOCAクランプの36%：
SABOCAコアへと分裂

WISEデータから：

SABACOコアの65%にYSOが付随（残りはprestellar core候補天体）

ess can be explainedin terms of gravitational Jeans instability. Besides the filament
Key words. Stars: formation - ISM: clouds - ISM: individual objects: IRDC G304.74+01.32 - Infrared: ISM - Submillimetre: ISM
Fig. 1. SABOCA
350 µm (left)
LABOCA 870 µm(right) images of G304.74.
In bothalthoughpanels, the colourthe
scale islinear. The contours
levels
SOs in G304.74
indicates
its andthermally
supercriticalstate,
potential
nonstart from 3σ, and progress in steps of 1σ. The dashed contours show the negative features at the −3σ level. The identified clumps are labelledonthe
LABOCA
map,
where
the
numbers
refer
to
the
SMM
IDs
(e.g.
1
means
SMM
1),
while
the
sources
I13037,I13039,andI13042areud a virial equilibrium
system on scale traced by LABOCA. The IRDC G304.74 has athe
three IRAS sources in the filament. The white circles indicate the LABOCA peak positions of the clumps (see Sect. 3.1). The identified SABOCA
sources
not labelled
for legibility
purposes(see Sect. 3.2),
but they
are indicated in thezoom-in images in Fig.Wilcock
4.striations.
A scale baretof al.
1 pcThisprojected
ges, and the filament
appears
to beattachedbyelongated,
perpendicular2012). Observational studies of IRDCs have
1. areIntroduction
length, and the eﬀective beam size (9 for SABOCA, 19 . 86 for LABOCA) are shown in the bottom left corner.
demonstrated
that
reting mass from the surrounding medium, and the accretion process cancontributeto some of the clouds are able to give birth′′′′OCA, Herschel, and WISE views of G304.74+01.32

2015; see also035.39-00.33).
the collision of
into a chain ofd magnetic perThe clumps repnd the physicalonal instabilitym.

p, plus the three
SABOCA map
associated witha (two sources
entage of staremaining seven
IR images, andwever, owing tois possible thatmbedded, lowion limit of thehickness in therender the em012). For comf their 18 cores
ed with Spitzerr percentage of016) found thath the Atacamaat 3 mm in thealso consistentertainties. Simheir sample ofws, which sugmong the cores.
CA clumps andadii. These valass star forma5. Considering
A clumps, only
aforementioned
sive star(s). On
ear to fulfil theertainties in the, some of them
We note, howgated from thewould imply aurce would also
oint to the right
independent of

SABOCAコア

LABOCAクランプ

平均質量

29 Msun

55 Msun

H2柱密度2.9 x 1022 cm-2

2.0 x 1022 cm-2

H2個数密度

7.9 x 104 cm-3

3.1 x 104 cm-3

be B1 (they adopted a distance of 2.4 kpc for IRAS 13039).
Hence, the IRAS 13039 region appears to be associated withhigh-mass star formation, although the corresponding LABOCA
clump or the SABOCA core IRAS 13039a do not fulfil the
KP10 threshold (not even within the error bars plotted in Fig. 5).
The IRAS 13039 region is surrounded by an extended, diﬀuse
arc-like emission feature in the WISE 12 µm and 22 µm images (Fig. 3). This could be an indication of a photodissociation
region (PDR) surrounding the associated H ii region, that is aboundary between the fully ionised region and the surrounding
neutral gas. The PDRs are expected to be extended and strong
emitters at 12 µm. Alternatively (or additionally), the observed
features in the WISE 12 µm and 22 µm images could be related
to the shocks driven by stellar winds (Peri et al. 2012). Hence,the star formation activity in IRAS 13039 can have some feedback eﬀect on the nearby clumps (e.g. SMM 8) that can be either
negative or positive in terms of star formation, that is it can either
prevent or slow down the clump collapse to YSOs, or trigger starformation.
Apart from IRAS 13039, it is unclear whether the otherclumps or cores in G304.74 are forming high-mass stars, or
low to intermediate-mass stars. Construction and analysis of
the SEDs of the detected SABOCA sources associated with the
WISE detected YSOs would help to answer this question. For example, although the SMM 4 clump lies above the KP10 threshold for high-mass star formation, the clump is strongly fragmented (Fig. 4), which might prefer the formation of a clusterof lower mass stars. However, competitive accretion in such asystem could eventually lead to the formation of a high-mass star
(Bonnell et al. 2001; Bonnell & Bate 2006). Also, the aforementioned case of IRAS 13039 demonstrates that clump fragmentation does not necessarily prevent the formation of massive stars.
Finally, if the clump or core can accrete more mass from thesurrounding medium, for example via the filamentary striations
seen in the Herschel/SPIRE images towards G304.74 (Fig. 2),
the central YSO embedded in the source can grow to become ahigh-mass star (e.g. Wang et al. 2011; Ohashi et al. 2016).

5. Herschel画像：

18 GHz andd that there is
RAS 13039 ine south-east of
The authors didowards the H ii
y-stage Type 1
ecause only 8%th H ii regions).
s concluded toMiettinen: SABOCA, Herschel, and WISE views of

G304.74は伸びたstriationが付随している=> 周辺からのmass accretionが続いている=> 周辺媒体の圧力がフィラメントの力学的進化に重要な役割を果たしているかも

LABOCAクランプの１つだけがFig. 5. Masses of the LABOCA clumps and SABOCA cores in G304.74
plotted as a function of their eﬀective radii. The upper size limits areindicated by left pointing arrows. The blue dashed curve represents the
mass-radius threshold for high-mass star formation proposed by KP10,
that is M(R) = 870 M⊙ × (R/pc)1.33 .

Article number, page 13 of 16大質量星形成を示す

Fig. 2. Herschel/SPIRE images of G304.74 and its surroundings. The
images are displayed in logarithmic colour-scale to improve the appearance of the low surface brightness features. The overlaid black contours
show the SABOCA 350 µm dust continuum emission as in Fig. 1. A
scale bar of 3 pc projected length is shown in the bottom left corner of
each panel. The two obvious striations are labelled in the middle panel(striation 1 and striation 2).

BLOBCAT does
tative analysis.
The identifi
Owing to the s
opposed to the
LABOCA clum
were resolved icall these cores
cal tags follow
The LABOCA
detected in ouremission was reter sources wer
it to the resolut
responding 1σ
Considerinflux density ofmass estimatesthe emission ismaps (Sect. 2.1
sity of the G30
350 µm map su
brightness 350
present SABOC
estimate only bpresent study hscale. Similarly
LABOCA 870
dust emission mavailable throu
To take the freq
the Planck databy assuming th
responds to a Gservations (Platimate that abo
been filtered ou
sion should bephysical proper
A quantitat
the SABOCA
tained throughe.g. Weiß et alhttp://adsabs.harvard.edu/pdf/2017ApJ...849...25L
Academia Sinica Institute of Astronomy and Astrophysics, 11F of AS/NTU Astronomy-Mathematics Building,#37

No.1, Sec. 4, Roosevelt Rd, Taipei 10617, Taiwan
14
Department of Physics and Astronomy, The University of Western Ontario, 1151 Richmond Street, London, ON,
The
Transient Survey: Identifying Submillimetre Continuum Variability over
N6AJCMT
3K7, Canada
15
SeveralYear
Using Archival
JCMT
Gould
SurveyObservations
SUPA, SchoolTimescalesof Physics & Astronomy,
North Haugh,
St Andrews,
KY16Belt
9SS, United
Kingdom16
1,2 Observatory, Alonso
2 Vitacura, Santiago,
Joint
ALMA
Cordova
3107,
Chile S. Bell3 , Sarah Graves3 , Gregory
Steve
Mairs
, Doug Johnstone1,2de, Helen
Kirk, James Lane1 , Graham
17
NationalofJapan,
2-21-1
Osawa,
Mitaka,Tokyo
181-8588,
4 Astronomical Observatory
5
6
J. 18
Herczeg , Peter Scicluna , Geoﬀrey C. Bower , Huei-Ru Vivien
Chen7Japan, Jennifer Hatchell8 , Yuri
Departmentof Astronomy10and Space Science,
Yuseong-gu, Daejeon
9
11 Chungnam National
11 University, 99 Daehak-ro,
Aikawa , Wen-Ping Chen , Miju Kang , Sung-Ju Kang , Jeong-Eun Lee12 , Oscar
Morata13 , Andy
34134,
Republic of Korea
14
15
16,17
12,18

Pon , Aleks Scholz , Satoko Takahashi
1and Hyunju Yoo

E-mail contact: s.mairs at eaobservatory.org

Department of Physics and Astronomy, University of Victoria, Victoria, BC, V8P 1A1, Canada
Investigating
at andthe earliest
stages 5071
of low-massstar formation
is fundamental
understanding
NRC
Herzbergvariability
Astronomy
Astrophysics,
West Saanich
Rd, Victoria,
BC, V9Ein2E7,Canada how a
3 protostar assembles mass. While many simulations of protostellar disks predict non-steady accretion onto protostars,
East Asian Observatory, 660 North Aohoku Place, University Park, Hilo, Hawaii 96720, USA
4 deeper investigation requires robust observational constraints on the frequency and amplitude of variability events
Kavli Institute for Astronomy and Astrophysics, Peking University, Yiheyuan 5, Haidian Qu, 100871 Beijing, Peoples
characterised across the observable SED. In this study, we develop methods to robustly analyse repeated observations
Republic of China
5 of an area of the sky for submillimetre variability in order to determine constraints on the magnitude and frequency
Academia
Sinica Institute of Astronomy and Astrophysics, P. O. Box 23-141, Taipei 10617, Taiwan
of deeply embedded protostars. We compare 850 µm JCMT Transient Survey data with archival JCMT Gould Belt
6
Academia
SinicaInstitute ofvariability
Astronomy
645 N.
HI 96720,
USA sources
Survey data
to investigate
overand
2-4Astrophysics,
year timescales.
OutAohoku
of 175 Place,bright, Hilo,
independent
emission
7 in morphology and velocity field. We also use large maps of the region to compare the kinematics of the core with
DepartmentofPhysics
andInstituteofAstronomy,
National
Tsing
Hua
University,
Taiwanidentified
the overlapping
fields, wefind 7 variablecandidates,
5thatof which
we classify
as large-scale
Strong andfilament
the remainingof andtheinsurrounding
filamentary
structureandfindaccretion
from
the
could
8 inthatmorphology
andlarge-scale
velocity
field.
We
also
use
large
maps
ofUK
the
regionto compare
Physics
Astronomy,
UniversityofExeter,
StockerRoad,
Exeter
EX4
4QL,
2also
as explain
Extendedtoindicatethelatterareassociatedwithlarger-scale
structure.
For
the
Strongvariablecandidates, the kinematics of the core withthe complex kinematics exhibited by this young dense core. −1
9−1
Departmentof surrounding
Astronomy,of Tokyo,Tokyo,
Japan
we findaveragefractionalUniversity
peakbrightnesschangeper yearof |4.0|%
yr witha standard
deviationof 2.7% yrfrom.
thatof anthelarge-scalefilamentary
structureandfind that
accretion
the large-scale filament could
10 Accepted by ApJ
Graduate
Instituteof Astronomy,
National
Road,
Zhongli,Taoyuan,TaiwanIn total, 7%of the protostars
associated
withCentral
850 µm University,
emission in 300
our Jhongda
sample show
signsof variability.
Fourof the11also explain the complex kinematics exhibited by this young dense core.
Korea
Astronomy
Space Science
776 Daedeokdae-ro,
Yuseong-gu,
34055, Republic
of an
Korea
five
Strongsources andare associatedwith Institute,a known protostar.
The remaining
source is Daejeon
a good follow-up
target for
http://arxiv.org/pdf/1710.02506
12 object that is anticipated to contain an enshrouded, deeply embedded protostar. In addition, we estimate the 850 µm
SchoolofSpace
Research,
Kyung
Hee
University,
1732,
Deogyeong-Daero,
Giheung-gu
Yongin-shi,
Gyunggi-do
Acceptedby ApJ
periodicity
17104,
Korea of the submillimetre variable source, EC 53, to be 567 ± 32 days based on the archival Gould Belt Survey
2Forming spectroscopic massive proto-binaries by disk fragmentation

data.
http://arxiv.org/pdf/1710.02506
1
1
1

D.M.-A. by
Meyer, R. Kuiper Journal, W. Kley , K.G. Johnston2 and E. Vorobyov3,4,5
Accepted
The Astrophysical1
Institut für Astronomie und Astrophysik, Universität Tübingen,
Auf der Morgenstelle 10, 72076 Tübingen, Germany
https://arxiv.org/pdf/1710.03761
26
2
School of Physics and Astronomy, E.C. Stoner Building, The University of Leeds, Leeds LS2 9JT, UK
3
Institute of Fluid Mechanics and Heat Transfer, TU Wien, Vienna, 1060, Austria
4
Departmentof Astrophysics,
Vienna,A-1180, Austria
A
turbulent
origintheUniversity
complexenvelope
kinematics
in the 2young low-mass core 3,4,5
1 for The
1 of Vienna,
D.M.-A.
Meyer, R. Kuiper, W.
Kley1Stachki, K.G.
and E.
Vorobyov5
Research Instituteof Physics,
Southern Federal
University,
194, Johnston
Rostov-on-Don, 344090,
RussiaPer-Bolo
58
1
1
1 MariaE-mailcontact:
dominique.meyer
atG.
uni-tuebingen.de
Josefür
Maureira, Hectorund
Arce, Stella S. R.UniversitätOﬀner2 , Michael
M. Dunham
Jaime
E. Pineda4 , 10, 72076 Tübingen, Germany
Institut
Astronomie
Astrophysik,Tübingen,Auf3 , derMorgenstelle
5
6
7
Fernandez-Lopez, Xuepeng
Chen and
Diego Mardones
2 Manuel
The surroundingsof massive protostars
constitutean accretion
disc which has numerically been shown to be subject#39 Forming spectroscopic massive proto-binaries by disk fragmentation

School of Physics and Astronomy, E.C. Stoner Building, The University of Leeds, Leeds LS2 9JT, UK

1

fragmentation
and responsible
for luminous
outbursts.
Department,
Yale University,
Newaccretion-driven
Haven, CT 06511,
USA Moreover, it is suspected to produce close
3 toAstronomy
Institute
of
Fluid
and
TU
Wien,
Vienna,1060, Austria
2binarycompanions
which Mechanics
willThelaterUniversity
strongly
influencestar’s future
evolutionin theHertzsprung-Russel
diagram.
Departmentof Astronomy,of Heat
Texas theatTransfer,
Austin,Austin,
TX,
78712
4 3We
present three-dimensional
simulationsof USA100
M⊙ pre-stellar
cores.
Departmentof Physics,
Stategravitation-radiation-hydrodynamic
UniversityTheof New
York at Fredonia,
Fredonia,NY14063,
Departmentof Astrophysics,
University
ofnumerical
Vienna,Vienna,A-1180,Austria
find that accretion
young massivePhysics,
stars violently
fragment without
preventing
the (highlyvariable) accretion
Max-Planck
Institutediscs
for ofExtraterrestrial
Giessenbachstrasse
1, 85748
Garching,
Germany
5 4We
Research
Instituteofprotostars.
Physics,
Southern
Federal
University,
Stachki
194,
Rostov-on-Don,
344090, Russia
5ofInstituto
gaseous clumps
ontodetheWhileacquiring
theCONICET;
characteristics
of a nascent
low-masscompanion,some
Argentino
Radioastronoma(CCT-La
Plata,CICPBA),
C.C. No.
5, 1894,Villa
Elisa,
Ardisc fragments migrate onto the central massive protostar with dynamical properties showing that its final Keplerian
gentinaE-mailcontact:
dominique.meyer
at uni-tuebingen.de
6
orbit
is closeenoughto constitutea closeAcademy
massive of
proto-binary
havingRoad,
a younghigh-mass
anda low-mass
PurpleMountainObservatory,
ChineseSciences, 2 system,
West Beijing
Nanjing
210008,China
7component.
We deconcludeon theUniversidad
viability of detheChile,
disc fragmentation
channel forthe formation of such short-period
Departamento
Astronoma,
Casilla36-D,
Santiago,
Chile
The
surroundings of massive protostars constitute an accretion disc which has numerically been shown to be subject
binaries, and that both processes -close massive binary formation and accretion bursts- may happen at the same time.
E-mailcontact: mariajose.maureiraat yale.edu
toFU-Orionis-type
fragmentation
foryoung
luminous
outbursts.
Moreover,bursts,andsuch responsible
as observed in thehigh-massaccretion-driven
star S255IR-NIRS3, may
not only indicate
ongoing it is suspected to produce close
+
+
We
use
CARMA
3mm
continuumandmolecular
lines
(NH
D,
N
H
,
HCO
,
HCN
and
CS)
at
∼1000
au
resolution
disc fragmentation,
but also
be considered
as a tracer
for theformationof theclose massive
the the Hertzsprung-Russel diagram.
2 influence2
binarycompanions
which
will laterstrongly
star’s binaries
future- progenitors
evolutionof intocharacterize
the spectroscopic
structure andbinaries
kinematicsof thethe high-massenvelope surrounding
core candidate
subsequentmassive- oncecomponent ofthe
thedeeply
systemembedded
will enter firstthe main-sequenceWe
present
three-dimensional
gravitation-radiation-hydrodynamicof 100 M⊙ pre-stellar cores.
Per-Bolo
58.evolution.
The
lineFinally,
profile weof theobserved
shows two distinct
separated numericalby 0.4-0.6 kmsimulations
s−1 , mostphaseof itsinvestigate
thespecies
ALMA-observabilityof thepeaks
disc fragments.
likelyarising
fromtwo
diﬀerent
opticallythinvelocity
components
ratherthan
theproductofself-absorption
inanWefind that
accretion discs of young massive stars violently fragment without preventing the (highly variable) accretion
Acceptedby MNRAS
optically thick line. The two velocity components, each with a mass of ∼0.5-0.6 M⊙ , overlap spatially at the position
ofhttp://arxiv.org/pdf/1710.01162
gaseous clumps onto the protostars. While acquiring the characteristics of a nascent low-mass companion, some2
http://arxiv.org/pdf/1710.06450
Laboratoire d’Astrophysique de Bordeaux, Univ. Bordeaux, CNRS, F-33615 Pessac, France
3#46

Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 91023 USA
Astronomy Department,
Universityof Michigan,
Ann Arbor, MI 48109,
USA dust growth in the Taurus,
Far-infrared
to millimeterdataof protoplanetarydisks:
5
Institute forSpaceChamaeleon
Imaging Science, IDepartmentof Physics& Astronomy, University of Lethbridge, Canada
Ophiuchus,andstar-forming
regions
6
Inst. de Ciencia de Materiales de Madrid. Calle Sor Juana Inés de la Cruz 3, E-28049 Cantoblanco, Madrid, Spain
1
1
2
3
7
ÁlvaroRibas1 ,theCatherine
C.InstituteEspaillat, Enrique
Macı́as
Hervé
BouyDwingeloo,, Sean Andrews, Nuria Calvet4 ,ASTRON,
Netherlands
for Radio
Astronomy,
PO ,Box2, 7990AA
The Netherlands
4David
A. Naylor5 , Pablo Riviere-Marichalar6 , Matthijs H.D. van der Wiel5,7, and David Wilner3
E-mail contact: aribas at bu.edu
1

Department
Astronomy,
BostonUniversity,
Boston,MA
USA
Far-infraredofand(sub)millimeter
fluxescan be used
to study
dust02215,
in protoplanetarydisks, the building blocks of planets.
Laboratoired’AstrophysiquedeBordeaux,
Univ.
Bordeaux,
CNRS,
F-33615
FranceHere, we combine observations from the Herschel Space Observatory with ancillaryPessac,
data of 284
protoplanetary disks in3
Harvard-Smithsonian
CenterforOphiuchus
Astrophysics,
Cambridge,
91023fromUSA
the Taurus, Chamaeleon
I, andstar-forming
regions,MAcovering
the optical to mm/cm wavelengths. We
4Astronomy
Department,
Universityof Michigan,
Ann Arbor,
MI 48109,
USA
analyze theirspectral indicesas a functionof wavelengthand determine
their(sub)millimeter slopes when possible.
5
Most disks
displayImaging
observational
evidenceof grainofgrowth,
withUniversity
previous studies.
No correlation
Institutefor Space
Science,
Department
Physicsin&agreement
Astronomy,of Lethbridge,
Canadais
6
found
betweenother
tracersof
disk
evolutionandthemillimeter
spectralindices.
A
simple
disk
model
is
used
to fit Spain
Inst. de Ciencia de Materiales de Madrid. Calle Sor Juana Inés de la Cruz 3, E-28049 Cantoblanco, Madrid,
7
these sources,
and we deriveInstituteposteriorfor
distributions
for the opticaldepth2,at7990AA
1.3 mm Dwingeloo,
and 10 au, thedisktemperature
ASTRON,
the Netherlands
Radio Astronomy,
PO BoxThe
Netherlands
2

at this same radius, and the dust opacity spectral index. We find the fluxes at 70 µm to correlate strongly withA
Studyof thefrom
Interstellar
IRAS05506+2414
E-mailcontact:
aribasatat10bu.edu
diskMolecular-Linetemperatures
au, as derived
these simple Bullet
models. Engine
We find tentative
evidence for spectral indices
1

2

3

4

5

in Chamaeleon
I being, steeper
thanLeethoseof useddiskstoinSánchez
Taurus/Ophiuchus,
althoughmore
millimeter
observations
Raghvendra
Sahai
Chin-Fei
CarmenContreras, Nimesh
Patel
Mark
Morrisand
Far-infraredand (sub)millimeter
fluxescan, bestudy
dust
in protoplanetarydisks,
the,building
blocks ofare
planets.
6
neededtoconfirm
this
trend
and
identify
itspossibleorigin.
Additionally,
wedeterminethemedianspectralenergyMark
ClaussenHere, we combine observations from the Herschel Space Observatory with ancillary data of 284 protoplanetary disks inof each region and find them to be similar across the entire wavelength range studied, possibly due to the
1distribution
the Taurus,
Chamaeleon
I, and Ophiuchus
regions,
coveringfrom the optical to mm/cm wavelengths. We
Jet Propulsion
Laboratory,
MS 183-900,star-forming
Caltech, Pasadena,CA
91109, USA
2large scatter in disk properties and morphologies.
Academia
SinicaInstituteofAstronomy
andAstrophysics,
P.O.
Box
23-141,106, Taiwan slopes when possible.
analyze their spectral indices as a function of wavelength and determine theirTaipei(sub)millimeter
3Accepted by ApJ
Astrofı́sica
Molecularevidence
e Infraroja,de Estructurade la Materia-CSIC,
Serrano121, Madrid,
Spain isMost Dpto.
disks dedisplayobservationalof Instituto
grain growth,in agreementwith previous
studies.
No correlation
4
Harvard-Smithsonian
Centerfor
Astrophysics,
Cambridge,
USA
http://arxiv.org/pdf/1710.08426
between other tracers
diskevolutionand the Bullet
millimeter
spectralindices. A simple disk model is used to fit
Molecular-Line
Studyof oftheInterstellar
EngineIRAS05506+2414
5#47 AfoundDivisionofAstronomy&
Astrophysics,
UCLA,
Los
Angeles,CA
90095-1547,
USA
these6 sources, and we
derive posterior
distributions for the optical depth
at 1.3mm andtemperature1
3
4 10 au, the disk
Raghvendra
Sahai,Astronomy
Chin-Fei Observatory,
Lee2 , Carmen
SánchezContreras, Nimesh
Patel, Mark Morris5 andNational
Radio
1003
LopezvilleRoad,
Socorro,NM
87801,
USAat thisClaussen
same radius,
and the dust opacity spectral index.
6
32 We find the fluxes at 70 µm to correlate strongly withMark
E-mailcontact:sahai
atjpl.nasa.gov
disk temperatures at 10 au, as derived from these simple models. We find tentative evidence for spectral indices1
Propulsion Laboratory,
MS 183-900,
Caltech,Pasadena,
CA 91109, USA although more millimeter observations are
inJet
Chamaeleon
I being steeper
thoseof disks
inlineTaurus/Ophiuchus,
We presentinterferometric
andthansingle-dishobservationsof the Taipei
interstellar
source IRAS05506+2414,
2
Academia
SinicaInstitute of Astronomy
andmolecular
Astrophysics,
P.O. Box 23-141,
106, bullet-outflow
Taiwanneededtoconfirm
this
trend
and
identify
itspossibleorigin.
Additionally,
wedeterminethemedianspectralenergywhose
wide-angle
bulletspray
issimilar
to
the
Orion
BN/KL
explosive
outflowandlikelyarisesfromanentirely
diﬀer3
Dpto. de Astrofı́sica Molecular e Infraroja, Instituto de Estructura de la Materia-CSIC, Serrano 121, Madrid, Spainof eachthan
regionand findaccretion-disk-driven
them to be similar bipolar
across the
wavelength
range The
studied,possibly due
to theent mechanism
the classicalflowsentire
in young
stellar objects.
bullet-outflow
source4distribution
Harvard-Smithsonian Center for Astrophysics, Cambridge, USA
associatedwith properties
a large pseudo-disk
and three molecular outflows – a high-velocity outflow (HVO), a medium-velocity
in diskand morphologies.
5largeisscatter
Division of Astronomy& Astrophysics,
UCLA, Los Angeles, CA 90095-1547, USA

outflow (MVO), and a slow, extended outflow (SEO). The size (mass) of the pseudo-disk is 10,350 AU×6,400 AU (0.64–
0.17 M⊙ ); from a model-fit assuming infall and rotation we derive a central stellar mass of 8–19 M⊙ . The HVO (MVO)
E-mailsahaisize
at jpl.nasa.gov
http://arxiv.org/pdf/1710.08426
hascontact:
an angular∼ 5180 (∼ 3330) AU, and a projected outflow velocity of ∼ 140 km s−1 (∼ 30 km s−1 ). The
SEO size(outflow speed)is ∼ 0.9 pc molecular(∼ 6 km s−1). observations
The HVO’s axis
aligned with(orthogonalsourceto) thatof the SEO
We presentinterferometricand single-dishlineof theisinterstellar
bullet-outflow
IRAS05506+2414,(pseudo-disk).
The
velocity
structure
of
the
MVO
is
unresolved.
The
scalarmomenta
in
the
HVO
and
SEO
are verywhose wide-angle bullet spray is similar to the Orion BN/KL explosive outflow and likely arises from an entirely diﬀer32
similar, suggestingthat the accretion-disk-driven
SEO has resulted fromthe flows
HVO ininteracting
withobjects.
ambientThecloudmaterial. The
bulletent mechanism
than the classicalbipolaryoung stellar
bullet-outflow
sourcespray
sharesacommon
axis
with
the
pseudo-disk,
and
has
an
age
comparable
to
that
of
MVO
(few
hundredyears),
is associated with a large pseudo-disk and three molecular outflows – a high-velocity outflow (HVO), a medium-velocity
suggesting
structures
intimately
linkedtogether.
We discuss several
for theoutflow(MVO), thatand atheseslow,threeextendedoutfloware(SEO).
The size(mass)of the pseudo-disk
is 10,350models
AU×6,400
AUoutflows(0.64– in
IRAS
05506+2414(including
dynamical
decay
of
a
stellarcluster,chanceencounterofarunawaystar
witha dense0.17 M⊙ ); from a model-fit assuming infall and rotation we derive a central stellar mass of 8–19 M⊙ . The HVO (MVO)−1−1
cloud,and sizeclose∼passageof 3330)
two protostars),
concludethat 2nd-epoch
to sderiveof thehas anangular5180 (∼
AU, and aandprojected
outflow
velocity ofimaging∼ 140 km(∼proper30 km smotions). The−1bullets
andnearby
stars
can
help
to
discriminate
betweenthem.
SEO size (outflow speed) is ∼ 0.9 pc (∼ 6 km s ). The HVO’s axis is aligned with (orthogonal to) that of the SEO
6National Radio
Astronomy Observatory, 1003 Lopezville Road, Socorro, NM 87801, USA
Acceptedby ApJ

Slingshot Mechanism for Clusters: Gas Density Regulates Star Density in the Orion
http://arxiv.org/pdf/1710.03311
Nebula Cluster (M42)

Amelia M.
Stutz
Mechanism
for Clusters: Gas Density Regulates Star Density in the Orion#48 Slingshot
1
1

NebulaCluster(M42) Universidad de Concepci?on, Casilla 160-C, Concepcio?n, Chile
Departmentode Astronom?a,1
AmeliaStutzastutz
E-mailM.
contact:
at astro-udec.cl
1

Departmentode Astronom?a,
Universidad
Concepci?on,
160-C, Concepcio?n,
We characterize
the stellar andgas volume dedensity,potential,Casillaand gravitational
field profilesChilein the central ∼ 0.5 pc

of the Orion Nebula Cluster (ONC), the nearest embedded star cluster (or rather, proto-cluster) hosting massive starE-mailcontact: astutz at astro-udec.cl

formation available for detailed observational scrutiny. We find that the stellar volume density is well characterized by
2 −5/2
We acharacterize
the stellar
andgas volume
and agravitationalfield
the central∼ 0.5 pc
Plummer profileρstars (r)= 5755M⊙ pc−3density,(1+(r/a)potential,), where= 0.36 pc. The
gasprofiles
densityin
follows
a cylindrical3−1.775of theOrion
NebulaCluster(ONC),
thenearestembeddedstarcluster(orrather,proto-cluster)
hosting
massive
power law ρgas (R) = 25.9 M⊙ /pc (R/pc). The stellar density profile dominates over the gas density profilestar
formation
detailed
observational
scrutiny. We findthat
thebutstellardensity
is wellcharacterized
inside ravailable∼ 1 pc. forThegravitational
field is gas-dominatedat allradii,
the volume
contribution
to thetotal
field by the by
−3
2
−5/2
stars is nearlyof ther ∼ a. Thisfact
alonea demonstrates
thatgasthedensity
proto-clusterbea Plummer
profileequalρstarsto(r)that= 5755M⊙gas
pc at (1+(r/a)), where= 0.36 pc. The
follows cannot
a cylindrical
3a virialized−1.775consideredagas-freesystemorsystemdominated
by
its
own
gravity.
The
stellarproto-cluster
core
ispower law ρgas (R) = 25.9 M⊙ /pc (R/pc). The stellar density profile dominates over the gas density profile−1
dynamicallyan age of field∼ 2-3isMyr,a 1D velocity
2.6 km s , anda crossing
timebyof theinsider ∼ 1 pc.young,
The with
gravitational
gas-dominatedatdispersion
all radii, of
butσobs
the=contribution
to thetotal field
∼
0.55
Myr.
This
timescaleisalmostidentical
to
the
gas
filament
oscillation
timescaleestimatedrecently
by
Stutz
& be
stars is nearly equal to that of the gas at r ∼ a. This fact alone demonstrates that the proto-cluster cannot
Gould (2016).
Thissystemprovidesevidencethat theproto-cluster
structureis regulated
the gasfilament. The
considereda gas-freeorstronga virialized
systemdominatedby itsown gravity.
The bystellarproto-cluster
core isproto-cluster
structure
may
be
set
by
tidal
forcesduetotheoscillating
filamentarygaspotential.
Suchforcescould−1
dynamically young, with an age of ∼ 2-3 Myr, a 1D velocity dispersion of σobs = 2.6 km s , and a crossing time ofnaturally suppress low density stellar structures on scales >analysis presented here leads to a new suggestion∼ a. Theoscillation∼ 0.55 Myr. This timescale is almost identical to the gas filament
timescale estimated recently by Stutz &that clusters form by an analog of the ”slingshot mechanism” previously proposed for stars.

#49

Gould
(2016). This
provides strongthat
the proto-cluster
Monitoring
observations
ofevidence
6.7 GHzmethanolmasersstructure is regulated by the gas filament. The
Acceptedby
MNRAS
1
1 set by tidal 1forces due to1
proto-cluster
structurebethe oscillating
filamentarygas potential. Such forces could
M. Szymczak, M. may
Olech, R. Sarniak , P. Wolak1 and
A. Bartkiewicz
naturally
suppress low density stellar structures on scales >a. The analysis presented here leads to a new suggestion
1http://arxiv.org/pdf/1705.05838∼Informatics,
Centre for Astronomy,
Faculty of Physics,
Astronomy
andNicolaus Copernicus University, Grudziadzka
Monitoring
observations
of
6.7
GHz
methanolthat clusters form by an analog of the ”slingshot mechanism” previouslymasers
proposed for stars.
5, 87-100 Torun, Poland

1
M.E-mailSzymczak, M. Olech1 , R. Sarniak1 , P. Wolak1 and A. Bartkiewicz1
Acceptedby MNRAS
contact: msz at astro.umk.pl
1
http://arxiv.org/pdf/1705.05838
Centreforresults
Astronomy,
Physics,
Astronomy
and Informatics,
University, Grudziadzka
We reportof 6.7 GHzFaculty
methanolofmaser
monitoringof33139 star-forming
sites withNicolaus
the Torun Copernicus
32 m radio telescopeJune2009 toPoland
February 2013. The targets were observed at least once a month, with higher cadences of 2-4
5, from87-100
Torun,
measurements per week for circumpolar objects. Nearly 80 per cent of the sources display variability greater thanE-mailat astro.umk.pl
10 per contact:cent on a msz
time-scale
between a week and a few years but about three quarters of the sample have only 133

spectral results
features ofwhichvary significantly.
Irregular
intensity fluctuationis the dominant
type
of variability
and32 m radio telescope
We3 report
6.7 GHzmethanol maser
monitoringof 139 star-forming
sites
with
the Torun
only nine objects show evidence for cyclic variations with periods of 120 to 416 d. Synchronised and anti-correlatedfrom
June 2009 to February 2013. The targets were observed at least once a month, with higher cadences of 2-4
variations of maser features are detected in four sources with a disc-like morphology. Rapid and high amplitude bursts
measurements
per week
foroncircumpolar
Nearly80 perof thelastingsources
display
variability greater thanof individual featuresare seen
3-5 occasions inobjects.
five sources.
Long (>50
d tocent
20 months)
burstsare observedfor individual
or groups offeatures insourcessourceexperienced
a remarkableglobal10mostly
per cent
on a time-scale
betweena 19
weekandanda only
fewoneyears
but
about threequartersof flare.
the A
sample have only 1few
flaringfeaturesdisplayastronganti-correlation
betweenintensityandline-widththatisexpectedforunsaturated
3 spectral features which vary significantly. Irregular intensity fluctuation is the dominant type of variability andamplification. There is a weak anti-correlation between the maser feature luminosity and variability measure, i.e.
onlynine objects show evidence for cyclic variations with periods of 120 to 416 d. Synchronised and anti-correlated
maser features with low luminosity tend to be more variable than those with high luminosity. The analysis of thevariationsof maserfeaturesdetectedin emission
four sourcesmorphology.
Rapid increases
and high amplitude bursts
spectral energy
distribution
andarecontinuum
radio
revealswiththat athedisc-likevariabilityof the maser featuresof whenindividualfeaturesare seenandonLyman
3-5 occasions
five sources.
Long (>50
d to 20months)lastingofbursts are observed
the bolometricluminosity
flux of thein
exciting
object decreases.
Our results
supportthe concept
a majorfor infraredorpumping
in triggeringof maseremission.experienced a remarkable global flare. A
mostlyforroleindividual
groupsphotonsof features
in 19 outburst
sources activity
and only
one source
MNRASdisplay a strong anti-correlation between intensity and line-width that is expected for unsaturated
fewAccepted
flaringby
featuresKei E. I. Tanaka , Jonathan C. Tan , Jan E. Staﬀ and Yichen Zhang
1#50

University of Florida, USA
University of Virgin Islands,HIIUSVI regions.
Outflow-Confined
3
RIKEN, Japan2

II. The Early Break-Out PhaseKei
E. I. Tanaka1 , Jonathan C. Tan1 , Jan E. Staﬀ2 and Yichen Zhang3E-mail contact: ktanaka at ufl.edu
1of Florida,
USA
InUniversity
this series of papers,
we modelthe formation and evolution of the photoionized region and its observational signatures

2during massive star formation. Here we focus on the early break out of the photoionized region into the outflow cavity.

University of Virgin Islands, USVIRIKEN, Japan

3Using results of 3-D magnetohydrodynamic-outflow simulations and protostellar evolution calculations, we perform

post-processing radiative-transfer. The photoionized region first appears at a protostellar mass of m∗ = 10M⊙ in ourE-mailcontact:
fiducial model,
and ktanaka
is confinedattoufl.edu
within 10–100 AU by the dense inner outflow, similar to some observed very small
hyper compact HII regions. Since the ionizing luminosity of the massive protostar increases dramatically as KelvinIn
this series of papers, we model the formation and evolution of the photoionized region and its observationalsignature
Helmholz (KH) contraction proceeds, the photoionized region breaks out to the entire outflow region in <10,000yr.
∼duringmassive
starfree-freeformation.
Here
we focuson theinearly
breakInoutof the photoionized
into the outflow cavity
Accordingly,
the radioemissionbrightens
significantly
this stage.
our fiducial
model, the radioregion
luminosity
at 10 GHzchangesmJy kpc2 at m∗ = 11M⊙ to 100 mJy
kpc2 at m∗ =and
16Mprotostellar
luminosity
Using
results
of from
3-D 0.1
magnetohydrodynamic-outflow
simulations
evolution
calculations, we perform⊙ , while the infrared
increases
by
less
than
a
factor
of
two.
The
radio
spectralindex
alsochangesinthebreak-out
phase
from
the
optically
post-processing radiative-transfer. The photoionized region first appears at a protostellar mass of m∗ = 10M⊙ in ou
thick value of ∼ 2 to the partially optically thin value of ∼ 0.6. Additionally, we demonstrate that short-timescale
fiducial
model, and is confined to within 10–100 AU by the dense inner outflow, similar to some observed very smal
variation in free-free flux would be induced by an accretion burst. The outflow density is enhanced in the accretion
hyper
compact
Since
theregion
ionizing
luminosity
the massive
protostarincreases
dramatically as Kelvinburst phase,
whichHII
leadsregions.
to a smaller
ionizedand weaker
free-freeofemission.
The radio
luminosity
may decrease
Helmholz(KH)
contraction
proceeds,
thewhile
photoionized
breaksout lessto theentireoutflowyr
by one orderof magnitude
duringsuch bursts,
the infraredregion
luminosity
is muchaﬀected,sinceinternalregion in <10,000∼
protostellar luminosity
dominates
accretion
luminositysignificantly
after KH contraction
starts. In
Such
may be the radio luminosity
Accordingly,
the radio
free-freeover
emissionbrightensin this stage.
ourvariability
fiducial model,
2if accretion bursts are driven by disk instabilities.
2
observableontimescalesasshort
10–100yr,
at 10 GHz changes from 0.1 mJy kpc at m = 11M to 100 mJy kpc at m = 16M , while the infrared luminosity
∗

⊙

∗

⊙

Accepted byincreases
byApJ
less than a factor of two. The radio spectral index also changes in the break-out phase from the optically

https://arxiv.org/pdf/1706.07444.pdf
thickvalue of ∼ 2 to the partially optically thin value of ∼ 0.6. Additionally, we demonstrate that short-timescal
variation in free-free flux would be induced by an accretion burst. The outflow density is enhanced in the accretion
burst phase, which leads to a smaller ionized region and weaker free-free emission. The radio luminosity may decreas
by one order of magnitude during such bursts, while the infrared luminosity is much less aﬀected, since interna
protostellar luminosity dominates over accretion
34 luminosity after KH contraction starts. Such variability may beobservable on timescales as short 10–100 yr, if accretion bursts are driven by disk instabilities.

Accepted by ApJ
https://arxiv.org/pdf/1706.07444.pdf

34