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
34
Departmentof Astronomy,
PekingUniversity,
100871,
Beijing,
China
East Asian
Observatory,
660 N. A’ohōkū
Place,
Hilo, Hawaii
96720-2700,
USA
45
Department
Astronomy, Universityof Texas atAustin,Austin,
TX 78712,
USA USA
East AsianofObservatory,
660 N. A’ohōkū
Place,
Hilo,
Hawaii
96720-2700,
6
5
Astronomy
Department,
Universityof California,
Berkeley,
CAAustin,
94720, TX
USA78712, USA
DepartmentofAstronomy,
University
of
Texas
at
Austin,76European Southern
Observatory,Karl-Schwarzschild-Str.2,
D-85748 Garching
München,Astronomy
Department,
University of California,
Berkeley,beiCA
94720, Germany
USA
8
Department of 7Astronomy, Yunnan University, and Key Laboratory of Astroparticle Physics of Yunnan Province, Kunming, 650091, China
EuropeanSouthern
Observatory,Karl-Schwarzschild-Str.2,
D-85748
Garchingbei
München,Germany
9
Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA
8
10
Department of Astronomy, Yunnan
University,and Key Laboratoryof Chile,
Astroparticle
Physicsof Yunnan
Departamentode Astronomía,
Universidad deCasilla 36-D,
Santiago,
Chile Province, Kunming, 650091, China
911Harvard-Smithsonian
Centerfor
Astrophysics,
60
GardenStreet,Cambridge,
MA 02138, USA
Department of Astronomy, Peking University, Beijing 100871, China
1012DepartamentodeAstronomía,
Universidad
deChile,
Casilla36-D,
Santiago,
Chile China
Astronomy Department, University of Science and Technology, Chinese Academy of Sciences, Hefei 210008,
11
13
National Astronomicalof Japan,
2-21-1University,
Osawa, Mitaka,
Tokyo100871,
181-8588,
Japan
DepartmentObservatoryof Astronomy,
PekingBeijingChina
14 12
National
Astronomical
Observatories,
ChineseAcademy andof Science,
A20 Datun
Road,Academy
Chaoyang ofDistrict,
Beijing
100012,China China
Astronomy
Department,
Universityof Science
Technology,
ChineseSciences,
Hefei
210008,1513
Academia
Sinica,InstituteofAstronomy
andAstrophysics,
P.O.
Box
23-141,
Taipei106,
Taiwan16 National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan14
Key Observatories,
Laboratory for Radio
Astronomy,
ChineseAcademyA20
of Sciences,
NanjingChaoyang
210008, China
National Astronomical
ChineseAcademyof Science,
Datun Road,
District, Beijing 100012, China
Received2017 May 13; revised 2017 August 15; accepted 2017 September 15; published 2017 October 26
15
2

Academia Sinica, Institute of Astronomy and Astrophysics, P.O. Box 23-141, Taipei 106, Taiwan
Key Laboratory for Radio Astronomy, Chinese Academy of Sciences, Nanjing 210008, China
Received 2017 May 13; revised 2017 AugustAbstract
15; accepted 2017 September 15; published 2017 October 26
16

Stellar feedback from high-mass stars (e.g., H II regions) can strongly inﬂuence the surrounding interstellar
medium and regulate star formation. Our new ALMAAbstractobservations reveal sequential high-mass star formation
taking place within one subvirial ﬁlamentary clump (the G9.62 clump) in the G9.62+0.19 complex. The 12 dense
Stellarfrom detected
high-mass
stars are(e.g.,H IIdifferent
regions)
can strongly
the surrounding
coresfeedback(MM1–MM12)
by ALMAat very
evolutionary
stages,inﬂuence
from the starlesscore phase tointerstellar
mediumstar Threeformation.
Our new
ALMA
observations
sequential
high-mass
star formation
region phase.
dense cores(MM6,
MM7/G,
MM8/F) arereveal
associatedwith outﬂows.
The mass–
the UCand
H IIregulate
velocity
diagramsoftheoutﬂows
associated
with
MM7/G
and
MM8/F
can
be
well-ﬁtbybrokenpower
laws.
taking place within one subvirial ﬁlamentary clump (the G9.62 clump) in the G9.62+0.19 complex. The
The 12 dense
mass–velocity
diagramoftheSiO
outﬂow
associated
with
MM8/F
breaksmuch
earlierthanother
outﬂow
tracers
cores (MM1–MM12) detected by ALMA are at very different evolutionary stages, from the starless core phase to
SO, CS,phase.
HCN), Threesuggesting
thatcores
SiO traces
newly
shocked MM8/F)
gas, while themolecular
lines(e.g., CO,The mass–
II region
dense
(MM6,
MM7/G,
areotherassociatedwith
outﬂows.
the (e.g.,
UC HCO,
SO, CS, HCN) mainly trace the ambient gas continuously entrained by outﬂow jets. Five cores (MM1, MM3,
velocity
diagrams of the outﬂows associated with MM7/G and MM8/F can be well-ﬁt by broken power laws. The
MM5, MM9, MM10) are massive starless core candidates whose masses are estimated to be larger than 25 M☉,
mass–velocity
diagramof theofSiO
associatedwith
MM8/FH breaks
much
other
tracers
II regions(“B” earlierand “C”)than
to thewestoutﬂow
may
assuming a dust
temperature20outﬂow
K. The shocks
from theexpanding(e.g.,
CO,
SO, CS,HCN),
SiO traces newly
while theothermolecularlines (e.g., CO,have
a great
impacton thesuggestingG9.62 clumpthat
by compressing
it into ashockedﬁlament gas,
and inducing
core
collapse
successively,SO,leading
CS, HCN)
mainlystar
trace
the ambient
gas continuously
entrained
byfromoutﬂow
jets. Fivecores (MM1,MM3,
may enhancetheto sequential
formation.
Our ﬁndings
suggest that stellar
feedback
H II regions
star MM9,
formation
efﬁciency
suppress
low-mass
formation whose
in adjacentpre-existing
massive toclumps.
MM5,
MM10)
are andmassivestarless
corestarcandidates
massesare estimatedbe larger than 25 M☉,(“B”
and “C”) to the west may
assuming
a dustH temperatureof 20K. Theshocksfromkinematics
the expanding
H II regions
II regions – ISM:
jets andoutﬂows– ISM:and dynamics– stars:formation
Key words:
have a great impact on the G9.62 clump by compressing it into a ﬁlament and inducing core collapse successively,
leading to sequential star formation. Our ﬁndings suggest that stellar feedback from H II regions may enhance the
Therefore,inthe
TurbulentCore Accretion
model
predicts the
1. Introduction
star formation efﬁciency
and suppress low-mass star formationadjacentpre-existing
massiveclumps.
existence of massive starless cores that will form high-mass

MM6：

若く(~8.5 x 103 yr)、collimateしたoutﬂow

Accretion rate
3.9 x 10-4

MM7/G：

inclinationが非常に小さい

5.7 x 10-5

MM8/F：

100km s-1と非常に活発

2.2 x 10-3 Msun yr-1

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

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, indicating that the outﬂows of MM7/G may be
younger than the outﬂows of MM8/F (Downes &Liu et al.

#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 as HCN (1–0), HCO+ (1–0), and CS(2–1). In this case, the shape of the emission line will dependon changes in the kinetic temperature and density (excitation
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 infall
motions in isolated spherically symmetric envelopes in which
the density increases toward the center (Evans 1999; Tomisaka& Tomida 2011). On the other hand, simulations of cores
formed in a turbulent environment show a more complex++
picture due to the asymmetries
in density and the disordered
2 2velocity ﬁeld, leading
to highly variable proﬁles for the same
core as seen along different lines of sight. Smith et al. (2012)
simulated optically thick and thin tracers toward the center ofdense cores embedded in ﬁlaments, which were in turn formedout of a turbulent molecular cloud. They showed that eventhough the gas motions were dominated by infall, opticallythick tracers can show both blue and red asymmetries intheir double-peak proﬁle, depending on the inclination andazimuthal angle used for observing the core. Red-asymmetricproﬁles appeared in these turbulent collapsing cores, due toeither the contribution of a ﬁlamentary envelope or accretionoccurring from only one side.
In this work we present Combined Array for Research inMillimeter-wave4.Astronomy
Analysis(CARMA) molecular line observations at 1000 au scales of the young dense core Per-bolo 58,
The double-peakedof Per-bolo
58regioncannotbe welllocated north linesof the NGC
1333 cluster
in Perseus,
at adistanceof 230Gaussianpc (Hirotaﬁt.
et Thus,al. 2008).
1 shows
thereproduced bya single
to Figurequantify
centralof Per-boloin aspectra
250 μmwith
Herschelmap, which
velocities andlocationline widths,
we ﬁt58thesetwo Gaussiansshows that the dense core is embedded in a large-scale
wherever theline presented
double-peakToﬁlamentary
structure. Weastudy
Per-bolo 58’sstructure.
kinematics using+
disentangle opticallythe emissionfrom(NHthe
blue
and
red
D
(
1

1
)
thin andcoming
thick tracers
,
N
2
1,1
0,1
2H
+
components,(1–0),
we HCNuse (1–0),
the HCOintegrated
intensities(1–0), andCS (2–1)).deﬁned in
58 is an5).
idealsourcestudying thetoconditions
Section 3 (seePer-bolo
also FigureWeﬁt fora Gaussian
the bluein
which
the
gas
is
transported
towardthecorecenterin threeyoung(red) component if the integrated blue (red) intensity is oversources; the spectral energy distribution (SED) of this source
times the rmssuggests
at thatthat
particular
position.
Thus,asingleGaussianthe compact source at the center is not a protostar
is ﬁt at positions
were only one
integrated
emission,blue
or ared,yet, corresponding
insteadto a theoreticalobjectcalledﬁrst
A ﬁrst hydrostatic(FHSC, oris over three hydrostatic
times the corerms,(seeandbelow).
two Gaussians
are ﬁtcore
at positions

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
−1−1
, 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
Figure1. Herschel
250 μm map of the NGC 1333 region in Perseus. The white,
overlap
spatiallyatthepositionofthecontinuum
emissionandproduceageneralgradient
along∼0.5–0.6
Malongthethe∼0.5–0.6 :M:, overlap spatially at the position of the continuum emission and produce a general gradient
arrow indicates the position of the dense core Per-bolo 58.
outﬂow
outﬂowdirection.
direction.WeWeinvestigate
investigatewhether
whetherthese
theseobservations
observationsareareconsistentconsistentwith
withinfall
infallinina aturbulent
turbulentand
andTomisaka 2006; Matsumoto & Hanawa 2011; Joos et al. 2012;
H
(1–0)
with
synthetic
observations
ofof Bate et al. 2014; Tomida et al. 2015).
magnetizedenvelope.
We
comparethemorphology
andspectraoftheN
magnetized envelope. We compare the morphology and spectra of the N H (1–0) with synthetic observations
Tomida et al. 2013;
Per-bolo58
was identiﬁed as a ﬁrst core candidate by Enoch
an an
MHD
simulation
thatconsidersthethecollapse
ofofananisolated
ﬁeld.
MHD
simulation
thatconsiderscollapseisolatedcore
corethatthatis isinitially
initiallyperturbed
perturbedwith
witha aturbulent
turbulent
ﬁeld.
et al. (2010) based on its SED, which shows that the central
sourcehas a very low luminosity (L int _ 0.012 L :), lower
The
proposedThe
proposedmodel
modelmatches
matchesthethedata
datain inthetheproduction
productionofoftwo
twovelocity
velocitycomponents,
components,traced
tracedbybythe
theisolated
isolatedthan the typical Class 0 object and even very low luminosity+ +H2H (1–0)
spectra,ﬁeld.
Wehyperﬁneline
of ofthetheN2N(1–0)
spectra,and
andshows
showsa ageneralgeneralagreementagreementininmorphology
morphologyand
andvelocity
velocityﬁeld.
WeUsing this same criterion, past studies havehyperﬁneline
objects(VeLLOs).
reported about nine other ﬁrst core candidates (e.g., Belloche
also
useuse
large
maps
of of
thetheregionto tocompare
also
large
maps
regioncomparethethekinematics
kinematicsofofthethecorecorewith
withthatthatofofthe
thesurrounding
surroundinglarge-scale
et large-scale
al. 2006; Chen et al. 2010; Enoch et al. 2010; Dunham
et al.
2011;
Pineda et al. 2011; Chen et al. 2012; Pezzuto et al.
ﬁlamentary
structure
and
ﬁnd
that
accretionfromthelarge-scaleﬁlament
could
also
explainthecomplexﬁlamentary structure and ﬁnd that accretion from the large-scale ﬁlament could also explain thecomplex2012; Schnee et al. 2012; Huang & Hirano 2013; Murillo &kinematics
exhibited
byby
this
young
dense
kinematics
exhibited
this
young
densecore.
core.
Lai 2013).
The central source in Per-bolo 58 is driving a bipolar
outﬂow,
which was detected using SMA CO (2–1) observaKeywords:
ISM:
individual
objects(Per-bolo– –stars:
Key
words:
ISM:
individual
objects(Per-bolo58)58)– –stars:
stars:formation
formation– –stars:
stars:kinematics
kinematicsand
anddynamics
dynamics
stars:
tions with a resolution of 2 7 (Dunham et al. 2011). The
ratios,
using
the
more
intense
peak
among
the
two
velocity
low-mass– stars:
protostars
low-mass– stars:
protostars
outﬂow is slow, with a characteristic velocity of 2.9 kms ,components in each hyperﬁne, results in estimates of the totalline opacity of about 5, 4, and 9 for NH2 D (11,1  10,1 ), N2H+
(1–0), and HCN (1–0), respectively. We can do a similar
Introduction
1. 1.
Introduction
analysis by ﬁtting
a single
Gaussian to the double-peak proﬁle.
The total line opacity estimate obtained this way is about 4, 5,+
Low-mass
gravitational
collapse
Low-mass
protostars
gravitational
collapse(11,1 from from10,1 )theandprotostars
6 for NHform, Nthe(1–0), and HCN(1–0), ofof
2 D form
2H+
respectively.
For
N
H
(1–0)
and
HCN
(1–0),
opacityof 1989;
2
dense
cores
insidemolecular
clouds(Benson(Benson&MyersMyers1989;
nse
cores
insidemolecular
clouds&thethe isolated and weakest hyperﬁne components, respectively, isCaselli
2002a;
1969;
Shu1987).
Accordingselli et etal.al.
2002a;Shu
et etal.al.
1987).
Accordingabout
0.1 Larsonof Larson
the total1969;
line
opacity(Ahrens
et
al.
2002;
Paganitotheory,
theory,theetthe
detailsof
thisprocessvary
withinitialal.
2009). Hence,theseprocess
hyperﬁne components
in thesetwodetailsof thisvary withthetheinitialspecies(whichareshownin
Figure3)
areverylikelyoptically
conditions
core
such
presencemagneticﬁelds,
ﬁelds,
nditions
in in
thethe
core
such
as as
thethepresenceofof
magnetic

1. ラインプロファイル：−1

and shows a compact morphology with an opening semi-angleof about 8° for both lobes. This is only partially consistent withseveral simulations of outﬂows launched by ﬁrst cores, which
are typically low in velocity (110 kms−1) but also poorly
collimated (Matsumoto & Hanawa 2011; Tomida et al. 2013,2015; Bate et al. 2014; Machida 2014). In addition, thedynamical time inferred from these outﬂow observations is
104 yr, which is close to the upper limit of the lifetime of ﬁrst
cores, derived in simulations (Tomida et al. 2010). Although
the outﬂow morphology and its estimated lifetime could lead tothe straightforward conclusion that Per-bolo 58 is a protostar(and not a ﬁrst core), studies of the outﬂow launchingmechanism in ﬁrst cores and very young protostars haveshown that outﬂow collimation depends on the interplay

directionofofﬁeld
ﬁeldlines
linesatat1000
1000auauscales
scalescancanbebedifferent
differentfrom
fromdirection
theinitial
initialﬁeld
ﬁelddirection
direction atat larger
larger scales
scales (Matsumoto(Matsumoto &&２つのピークを持ち、0.4-0.6thekm
s-1離れている
Hanawa2011).
2011).Turbulence
Turbulencecan
canalsoalsoimprint
imprintbulk
bulkrotation
rotationinin
Hanawagas,ininwhich
whichcasecasethetherotation
rotationaxis
axiscancanbebemisaligned
misalignedwith
withthethegas,
magneticﬁeld
ﬁelddirection.
direction.InInthis
thislast
lastscenario,
scenario,more
moremassive
massivethethemagnetic
disksareareallowed
allowedtotoform,
form,asaswellwellasasoutﬂows
outﬂowsthat
thatarearenot
not
disks
3

4

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
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

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
integration following the same procedure described for theobservations (see Section 3). Similar to the observations, thetwo velocity components show spatial overlap. The blue andred integrated intensity peaks are close to each other in both of
the simulation time steps in Figure 9, resembling most of
the emission distribution seen for both components in most of
the observed molecular line maps (see Figure 5). The morecompact contours in the simulation follow the elongated dense
structure that forms during the collapse. This structure isperpendicular to the direction of the magnetic ﬁeld. The laterstage shows a more compact integrated emission in bothcomponents in comparison with both our observations and theearlier simulation output. This is a result of the evolution of thedenser regions in the envelope, which become more ﬂattenedwith time. Thus, morphologically Per-bolo 58 N2H+ (1–0)
emission agrees better with the earlier evolutionary stages inthe simulations (i.e., t _ 0.13 Myr) and/or with a system that isviewed close to, but not exactly, edge-on. Dunham et al. (2011)concluded, using the outﬂow morphology, that extreme edgeon or pole-on inclinations are ruled out, and thus an inclinationdifferent from exactly edge-on is expected. Given the close
spatial overlap between the blue and red components (seeFigure 9), inclinations closer to edge-on rather than pole-on
are in better agreement with Per-bolo 58. Indeed, the same
simulation viewed pole-on shows little spatial overlap between
the components, as expected if the emission arises from aﬂattened infalling envelope. Similarly, as mentioned in
Section 5, a velocity gradient where the blueshifted velocities
appear on the side of the blue outﬂow lobe and the redshifted

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：

velocities appear on the side of the red outﬂow lobe is also
consistent with a system that is close to edge-on.
Figure 10 shows N2H+ (1–0) maps of velocity andnonthermal-to-thermal line width ratio for the view and time
steps previously shown. We also show Per-bolo 58 forcomparison.
The collapse at 0.13 Myr shows a more complex anddisordered velocity ﬁeld than the collapse at 0.15 Myr. In
comparison, the velocity ﬁeld in Per-bolo 58 shows lesssubstructure than the simulated collapse at both stages. The
absolute velocity difference between the blue- and redshiftedvelocities increases from the early to the later simulation. Thiscan also be seen in Figure 11, which compares p–v diagrams of
the simulated collapse at both time steps with Per-bolo 58
observations. The later stage shows a concentration of blueshifted and redshifted velocities close to the center, which

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

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,
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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 with

E-mailaribasatat10bu.edu
diskcontact:
temperatures
au, as derived from these simple models. We find tentative evidence for spectral indicesin
ChamaeleonI
being
steeperthan thoseof useddiskstoinstudy
Taurus/Ophiuchus,
although more
observations
Far-infrared and (sub)millimeter fluxes
can bedust in protoplanetarydisks,millimeterthe building
blocks ofare
planets.
neededtoconfirm
this
trend
and
identify
itspossibleorigin.
Additionally,
wedeterminethemedianspectralenergyHere, we combine observations from the Herschel Space Observatory with ancillary data of 284 protoplanetary disks in
distribution of each region and find them to be similar across the entire wavelength range studied, possibly due to thethe Taurus,
Chamaeleon I, and Ophiuchus star-forming regions, covering from the optical to mm/cm wavelengths. We
large scatter in disk properties and morphologies.
analyze their spectral indices as a function of wavelength and determine their (sub)millimeter slopes when possible.
by ApJobservational evidence of grain growth, in agreement with previous studies. No correlation is
MostAccepteddisks display
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#47 Afoundthese sources, and we derive posterior distributions for the optical depth at 1.3 mm and 10 au, the disk temperature
Raghvendra Sahai1 , Chin-Fei Lee2 , Carmen Sánchez Contreras3 , Nimesh Patel4 , Mark Morris5 andat thisClaussen
same radius,
and the dust opacity spectral index.
6
32 We find the fluxes at 70 µm to correlate strongly withMark
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
than thoseof disks
in Taurus/Ophiuchus,
2
Academia Sinica Institute of Astronomy and Astrophysics, P.O. Box 23-141, (26409.96264O)-5.9(.)-325.2(B)(a)-518.962(ia264005.9(3)-4(5.2(M)06
needed to confirm this trend and identify its possible origin. Additionally, we determine the median spectral energy
distribution of each region and find them to be similar across the entire wavelength range studied, possibly due to thelarge scatter in disk properties and morphologies.
Accepted by ApJ
http://arxiv.org/pdf/1710.08426
32

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