Star Formation Newsletter#294 1-5
麻生 有佑 (ASIAA)

nuscript no. Paper1Finalize (00 )a
0.58
0.61
0.65
0.58
0.49

S ⌫ (Jy)b
0.65
0.19
0.12
0.08
0.21

T kin (K)c
285
160
120
300
275

N(H2 ) (cm 2 )d2.4 ⇥ 1025
6.4 ⇥ 1024
3.3 ⇥ 1024
2.5 ⇥ 1024
1.1 ⇥ 1025

Mass (M ) e
13.0
3.8
2.2
1.4
4.4

SO
H13 CO+
SiO
C34 S
HNCO
HDCO
HDO

1.5
1.5
1.4
1.7
1.3
1.5
1.3

3.6 ⇥ 1013 3.6 ⇥ 1013
1.6 ⇥ 1013 5.3 ⇥ 1012
7.1 ⇥ 1013 7.2 ⇥ 1013
2.8 ⇥ 1015 1.2 ⇥ 1015
2.3 ⇥ 1016 7.5 ⇥ 1016
1.6 ⇥ 1015 2.6 ⇥ 1013
1.8 ⇥ 1018 4.8 ⇥ 1017

1.4
0.8
1.1
1.2
1.0
1.2
0.9

3.7 ⇥ 1017 3.6 ⇥ 1017
8.3 ⇥ 1012 8.2 ⇥ 1012
9.0 ⇥ 1013 8.7 ⇥ 1013
3.4 ⇥ 1014 2.9 ⇥ 1014
1.2 ⇥ 1016 6.9 ⇥ 1015
4.5 ⇥ 1014 1.0 ⇥ 1015
5.6 ⇥ 1017 3.3 ⇥ 1016

1.2
1.0
1.1
1.0
1.0
1.0
0.7

3.7 ⇥ 1016 1.7 ⇥ 1016
3.1 ⇥ 1013 3.1 ⇥ 1013
6.2 ⇥ 1012 6.2 ⇥ 1012
4.6 ⇥ 1014 3.5 ⇥ 1014
2.2 ⇥ 1015 9.4 ⇥ 1014
1.7 ⇥ 1014 2.6 ⇥ 1014
1.8 ⇥ 1017 7.8 ⇥ 1015

1.2
1.5
0.8
1.1
1.1
1.5
1.0

3.7 ⇥ 1016 1.1 ⇥ 1017
6.5 ⇥ 1012 2.8 ⇥ 1013
1.2 ⇥ 1011 2.8 ⇥ 1011
5.3 ⇥ 1014 6.8 ⇥ 1014
2.3 ⇥ 1016 8.4 ⇥ 1015
1.6 ⇥ 1015 1.5 ⇥ 1015
9.2 ⇥ 1017 7.6 ⇥ 1016

Chemical Segregation in Hot Cores With Disk Candidates
An investigation with ALMA

1.3
1.5
1.1
1.5
1.1

2.4 ⇥ 1017 1.1 ⇥ 1017
1.7 ⇥ 1013 2.1 ⇥ 1013
5.7 ⇥ 1013 1.1 ⇥ 1014
8.1 ⇥ 1014 7.1 ⇥ 1014
1.8 ⇥ 1016 7.7 ⇥ 1015
N/A
N/A

4 no. Paper1Final
A&A
manuscript
V. Allen1, 2 , F. F. S. van der Tak1, 2, , Á. Sánchez-Monge3 , R. Cesaroni4 , andM.proofs:T. Beltrán

100 K for all but C17 O, which was modeled at 20 K and thesource size was fixed at the measured extent of the 3 emission.
1
Kapteyn Astronomical Institute, University of Groningen, the Netherlands
0 µm continuum.
Several species were previously demonstrated to have quite exuum.
17 bcde-mail: allen@astro.rug.nl, vdtak@sron.nl
tended emission
O, SiO)
Sánchez-Monge
Continuum
Peak
Right
Ascension
Declination
Size(H(0013)aCO+S, ⌫C(Jy)T kinin(K)N(H2 ) (cm et2 )al.
Mass (M ) e2
ed using RADEX. For details, see § 3.3
V. Allen et al.: Chemical Segregation in Hot Cores With Disk Candidates
SRON, Groningen, the Netherlands
25(2014);
Beltrán
etal.
(2014).
A
summaryoftheresultsforthese
G35.20 A
18:58:12.948+01:40:37.419
0.58
0.65
285
2.4 ⇥ 1013.0
mperature (§ 3.3).
3
I. Physikalisches Institut, Köln, Germany
24
species is in Table
6.
e average kinetic temperatures.
G35.20B1
18:58:13.030+01:40:35.886
0.61
0.19
160
6.4
⇥
10
3.8
4
Table 2.AstrofisicoLine detections
measurements
H2 CS
INAF, Osservatorio
di andArcetri,Firenze,forItaly
G35.20 B2
18:58:13.013+01:40:36.649
0.65(H13 CO+0.12
3.3component⇥ 1024
2.2– Formyl Cation4-3) - only120
the emission
7–3
5 accepted May 2017 G35.20 A
G35.20 B1 B3
G35.20 B2
G35.20 B3
A 0.08G35.20
18:58:13.057+01:40:35.442
0.58G35.03
300 emission
2.5 ⇥shown1024 in
1.4
Received June 2016;
ofthisspecieswasmodeled.
Extendedn- KL (Caselli et al. 1993), W3(OH) and W3(H2 O) (Wyrowski
Transition
Frequency
FWHM
T peakFWHM
T peakFWHM
T peakFWHM
T peakFWHM
T peak
G35.03 (K)A
18:54:00.645+02:01:19.235
0.49 et al. (2014);
0.21 Beltrán
275et al. (2014).
1.1 ⇥ 1025
4.4
s et al. 1999b), and AFGL2591 (Jiménez-Serra et al. 2012).
(MHz)(km/s)(K)(km/s)(km/s)(K)(km/s)(K)(km/s)(K)
Sánchez-Monge
17
H2 CS ⌫=0e
The distance to both sources has been estimated from paral– Carbon
Monoxide(CO 3-2) - at the location of our pixel
a 0.1
101,10 -91,93380835.9 ± 0.1
51.7 ± 0.9 Notes.
2.7 ±27.3 ± 1.0 average
2.4 ± 0.1diameter
28 ± 1of the2.54± 0.0644.3of± 0.9
6.6µm± 0.1continuum.
21.0 ± 0.3: Deconvolved
50%
contourthe 870
ABSTRACTd lax measurements to be 2.2 kpc for G35.20 (Zhang et al. 2009)sources
lot±of
101,9 -91,83485325.8 ± 0.1
59.2 ± 1.3 b
2.6 ± 0.1
31 ± 12.3 ± 0.1
31 ± 1
2.58 ± 0.04
52.1 ± 0.7 there
6.33 ±was0.09 a 21.3
0.3 uncertainty in identifying of this:Integrated flux density
withinthe 10 contour of the 870 µm continuum.
e and 2.32 kpc for G35.03 (Wu et al. 2014). G35.20 has a boloH2 C33
S
line
due
to
severeline
blending
at this frequency. For G35.20
c:Average
based
on± CHline
asrichusing
101,10of-91,9high-mass
335160 star
7.5 formation,± 0.2
3.91 ± hot
0.09 cores
1.6 ±0.5kinetic
0.4 temperature± 0.1 defined
1.5 ± 0.6
0.4
0.2 3 CNchemically
2.5±0.2ratios1.47±calculated
0.08emission
3RADEX. For details, see § 3.3
Context.
areempiricallystageswhere
is< detected
e. metric luminosity of 3.0 ⇥ 104 L (Sánchez-Monge et al.
2014) In the study
34
A
this
could
not
be
modeleddue
to line confusion. Extended
d
H
C
S
2
:Calculatedfromsourcesize, continuum
flux
density,and kinetic
temperature(§ 3.3).
YSO.
It is337125
unknown whether
the physicaloriginof thisemissionis 1.0a disk,innerenvelope,or outflow
cavitywalls, and has been previously studied in Sánchez-Monge et al.toward(2013)a massive 10
blended
1.2 ± 0.7
0.7 ± 0.4
1.5 ± 0.2
± 0.1
1.9 ± 0.1
2.5 ± 0.1
< 3that this species is seen in the surroundinge0,10 -90,9emission
indicates:Sourcesmasscalculatedasin
Sánchez-Mongeetal.
(2014)
using
theaveragekinetic
temperatures.
g and Sánchez-Monge et al. (2014) where they report thedetecandwhether the hotcore
is commonto allstars.
104,6-94,5 stage
337460blended with
CH3massive
OH ⌫=1in abs. feature
1.5 ± 0.4
0.55 ± 0.09
blended with CH3 OH ⌫=1
blended with CH3 OH ⌫=1
cloud,
largersize and a lower temperature were
102,9 -92,83374756.3 ± 0.3
16.0 ± 0.3
1.66 ± 0.08
3.8 ± 0.2
1.7 ± 0.1
3.8 ± 0.2
3.1 ± 0.2
4.9 ± 0.2 so a
blendedwithsource
CH3 OH ⌫=1o- tion of a large (r⇠2500 AU) Keplerian disk around CoreAims.
B and Wea investigatethechemical
makeupofseveralhotmolecularcores
todetermine
physicalandchemicalstructure.
We
use
high
103,8 -93,7337555blended
2.0 ± 0.2
0.78 ± 0.05
1.7 ± 0.5
0.6 ± 0.2
2.03 ± 0.04
2.35
± 0.03<3used.
s tentative one in Core A. The bolometric luminosity of G35.03
is and spatial10resolution
spectralsub-millimeter
observations
how thisfits± intoof a highmass (HDO 3 -4 ) - This transition,
337559blended2.16to± determine
0.09
1.55 ± 0.04
1.3 ± stage
0.1
0.54
0.04 the2.37formation± 0.062.26sequence± 0.03<3
3,7 -93,6
Heavy
Water
massiveas±thetemperaturefor(Deuterated)
en- KLet al. 1993),
3,1 2,2 W3(OH) and W3(H2 O) (Wyrowski
102,8 -92,7337933blended
1.2 ± 0.5young
0.8objects
± 0.2
1.8
0.5 higher
0.7 ± 0.1
2.3 ± 0.1 –allows
2.4 ± 0.1
< 3 (Caselli
y 1.2 ⇥ 104 L and was reported to have a Keplerian disk (r⇠1400star.
deuterated
was (Jiménez-Serra
not clearly de- et al. 2012).
dothermic reactions to take place more
readily. In along
reality,with
it isall other
et al. 1999b),
andspecies,
AFGL2591
32000 AU) around the hot core A in Beltrán et al. (2014).Methods. The sub-millimeter interferometer ALMA (Atacama
Large Millimeter Array) was used to observe
theinG35.20-0.74N
and not modeled there. For the othertected
G35.03,sowaslikelythat
bothformationpaths
arenecessarytoachievetheThe
distancetobothsources
has been estimated from paralrG35.03+0.35 hot cores at 350 GHz in Cycle 0. We analyzed spectra and maps
from2 (seefourFigurescontinuum(A,
B1,
B2 andpositions
B3) fairly extended and the best fit
ing
CASA
1 Highand peaks
2peaks,for spectra
extraction
theemissionwasmolecular
abundancesseenaroundhot
cores.
spatialandlaxmeasurements
to
be
2.2
kpc
for
G35.20 (Zhang et al. 2009)
cFig. 9. The
vibrational
for allof intheG35.03+0.35.
HCcontinuum
3 N transitionsin G35.20-0.74N, separated by 1000-2000
AU,and one diagram
continuum
peak
Wefrommadeall possible
line
identifications
00
andlevelsandtoTable
1 for theJ2000
coordinates
andsourcesizes
were
between
0.6for(atB2) and1.5et00 al.
(at 2014).
B3). G35.20 has a bolospectral
resolution
observations
canwithhelp
usdisentangle
theand2.32 kpc
G35.03(Wu
cG35.20
B3
includinggroundandvibrationallyexcitedstatesJ=37across 8 GHz of spectral windows of molecular emission lines
down to a 3 aline
flux ofof0.5statistics).
K and determinedcolumndensities
andandsummary
The other peaks(B-F
in G35.03
4
13 COMs and theiredi↵erent
spatialdistribution
duringthisphase.
metricluminosity
of
3.0
⇥
10
L
(Sánchez-Mongeet al. 2014)36 and J=38-37. Fluxes for C isotopologues were
multiplied
50 tonot analyzed because they do not show
C-G inG35.20)bywere
temperatures for as many as 35 species
assuming local thermodynamic equilibrium(LTE).
ut
Disks isotope
candidates
been
discovered
in
a
few
HMC
sources,
and
has
been
previously
studiedin
Sánchez-Mongeetal. (2013)
be comparable to galactic
ratios.have
The hot
vibrationaltemperaturechemistry,i.e. little
orfrom COMs.
10 no emission
Results. In comparing the spectra calculatedof the fourcontinuum
peaks, we find each hascorea distinct
chemicalcomposition
expressedin overTheyfor peak B3
is 160 ± 20a Klink between
suggesting
disks
and
HMC
chemistry.
Studying
andSánchez-Mongeetal.
(2014)
where
theyreportthedetecthree continuum
peaksinorganicin G35.20species
B werebutchoseninvestigate
G35.03400 di↵erent
transitions. In G35.20, B1 and B2 contain oxygen- and sulfur-bearingorganic andfew tonitrogeno
the chemistry of such regions
can help
us toacrossunderstandthe
pro- in Sánchez-Mongetion of a large (r⇠2500 AU) Keplerian disk around Core B and athechemicalstructure
the
disk
shown
bearing species whereas A and B3 are strong sources of O-, S-, and N-bearing organic and inorganic species (especially those with theecess of high-mass star formation
as chemicaldi↵erences
acrosstentativein Core A. The bolometric luminosity of G35.03 isal. (2014)
analyzed
B asa singlecore),
theonedisk
CN-bond). Column densities of vibrationallyexcitedstatesare observed to beet equal
to or(whogreaterthan thegroundstate
forwhile
a numbere3.4.3. Sulfur
bearingmolecules
small
physical scales provide
clues
to the⇥ 104 Lwith
and was reported to have a Keplerian disk (r⇠1400in G35.03
A onlyhasdi↵erent
a single10evolutionary
continuum point 1.2
associated
tof species. Deuterated methyl cyanide is clearly detected in A and B3 with D/Hratiosof 8 soandanalysis
13%, respectively,
but is much weaker
thewerehot core,
for this source was fromstages involved.
2000 thisAU)peak.
around the hot core A in Beltrán et al. (2014).
Sulfur bearing
SOin2 G35.03,
and H2 CSmodeledwithabundancese
at B1 and undetected at B2. No deuterated
speciesmolecules
are detectedbutsimilarmoleculartoG35.20were foundG35.20A(Atacama
was analyzed
as Millimeter
the strongestArcontinuum
source inWiththeadvent
of
ALMA
Large
their
detectedisotopologues
coupledtothemainisotopologue).
in other species. We also find co-spatial emission of isocyanic acid (HNCO) andformamide(NHcorein bothandsources
indicating
a at
2 CHO)
the region
with hotchemistry
was also
analyzedyis nowisotope
possibletosingle
makehighlysensitive,
high spec-(listed in Appendix
varying
the isotoperay),ratio.it Sulfur
ratiosinthe
ISM havestrong chemical link between the two
species.
thecontinuum
peak.
Line
parameters
32 34resolution observations
34 33
n
andforspatialof using
lessabundant
molecbeen shown
to N-bearing
be tral
15-35
S/ species
S and and
4-9werefor determined
S/in G35.20
S (Chin10
Conclusions. The chemical segregation
betweenorganic
otherssuggests
theprofiles
presence
ofspectral
multiplelines
B)
Gaussian
fit to
32
34
d3
ular
species.
The
searchcontinues
precursorsof lifeetal.
1996).
Solar
isotoperatios
are
22.6
for
S/
andfor
5.5theforpeak
protostars, surrounded by a disk or torus.
from eachScontinuum
using Cassis, primarily using the34 33
erthe simplest
amino
acid,
glycine(H
S/ S (Anders & like
Grevesse1989). Our
best
fit
isotope
ratio
for
2 NCH
CDMS
(Cologne
Databasefor2 COOH),
Molecularbut
Spectroscopy; Müller
e
32 massive
Key words. stars: formation – stars:
ISM:between
individual
objects:
G35.20-0.74N,
G35.03+0.35– astrochemistrycomplex
upSO
to2 /3312
atoms
already Laboratory; PickSO2 /33 SO–2 was16organicand
100.species
Theetratio
of 32
SOand
al.with(2005))
database(Jet Propulsion
2 JPLhavemettal. (1998))
databasefor10CHto
C2 H5 OH, NH2 CHO,
detected. Theseincludeimportantprecursors
amino
in space has been beenreportedfor 1OrionKL
inet Esplugues
et al.
2 DOH,
w
CH3of
CHO,
and
CH
OH
(⌫=2)
transitions.
acids
like
aminoacetonitrile
(H
NCH
CN),
detectedby
Belloche3(2013),
withvaryingratiosfordi↵erentparts
theregion
rang2
2
y
The
processofCore.
identifying
species present in these spectra
et al. (2008);
thesimplestmonosaccharide
sugarallglycolaldeing from 5.8-125 reportinga ratioof candidate
25
in the
Orion
Hot
few
disks
aroundB-typeprotostars
were known. Sev1. Introduction
consistedofseveralparts.
Brightlines
32
34
B > 5 K) from known
first observed
in2 /a hotcore(T
outThe best fit isotopehyde
ratio(CHfor2 OHCHO),
oureralobservations
ofbeenSO
SO2molecular
adiskshave
detectedthroughthestudyof complex
specieswereidentified
first
(ie.
those
from
Sánchez-Mongeet al.orside
the isotopologue
galactic centerfitbyofBeltrán
et al.made(2009); and formamide
Themain
H CS OH,
was
Studying the formation of high-mass wasstarsaround(> 8 M33.) is
importantsSpecies(2014): 2CH(COMs),
CH3 molecular
OCHO, CH3 species
CN, simple
molecules)
numganic
molecules
bearingcarbonand334(NHgalaxCHO)
studiedby López-Sepulcre
et al.
(2015).
based onof3theirtransitions
wasextensively
modeled bering
with
HaboutS
coupled2and2Cs,because they drive the chemical evolution
host
100
linesforperthesource.
The remaining
bright
lines
(>
at
least
6
atoms,
allowing
detection
of
more
disks
(CesaWith
we haveability
to detect(only the abundance
ratioALMA
was varied).
Thethebest
fit isotopic
ratiohot cores and study
3 Fig. 1. Image of the 870 µm continuum emission from Cycle 0 ALMA
Table 1. Source continuum characteristics

Ø 円盤候補 G35.20 (2.2 kpc, 3e4 Lo), G35.03 (2.32 kpc, 1.2e4 Lo)Ø ALMA Cycle 0, 350 GHz, 400以上の輝線。

1

G35.20 A
G35.20 B1
G35.20 B2
G35.20 B3
G35.03 A

2

3

HC3 N

C2 H3 CNC2 H5 CNC2 H5 OHNH2 CHOCH3 CHOCH3 OCH3CH3 OCHO

4

HCOOH

Aに円盤

CH3 CN

Bに円盤

850 µmØ CH OHはCOMを作る高温ガスをダストより反映する。
Ø Bの中ではB3が最もリッチ。
Ø G35.20とG35.03で桁は同じ。

Abundance/CH3 OH

1705.06346v2 [astro-ph.SR] 19 May 2017

Ø 大質量星は銀河の化学進化を駆動。
Ø Hot core: 形成初期の化学リッチな段階。
>10 cm , ~300 K, <0.05 pc, 10 yr.
Ø 円盤候補もあるが輝線(COM)の起源が不明。

Chemical Segregation in Hot Cores With Disk Candidates
An investigation with ALMA
V. Allen1, 2 , F. F. S. van der Tak1, 2, , Á. Sánchez-Monge3 , R. Cesaroni4 , and M. T. Beltrán4
Kapteyn Astronomical Institute, University of Groningen, the Netherlands
Ø Bは軸対称円盤ではなさそう。
e-mail: allen@astro.rug.nl, vdtak@sron.nl
SRON, Groningen, the NetherlandsØ 1000 AU以下の化学セグリゲーションを初検出。
I. Physikalisches Institut, Köln, Germany
Osservatorio
Astrofisico di Arcetri, Firenze, Italy
A&A proofs:
manuscript
no. Paper1Final
1. 円盤分裂, 2. 連星,
3. INAF,
disrupted
disk
1

3

1705.06346v2 [astro-ph.SR] 19 May 20174

Received June 2016; accepted May 2017

Ø HNCOとNH2CHOは空間速度分布が一致。
àHNCOを経てNH2CHO。

4.3. HNCO and Formamide co-spatial emission

It has previously been proposed (Bisschop et al. 2007; Mendoza et al. 2014; López-Sepulcre et al. 2015) based on single
dish observations
that formamide (NH2 CHO) forms through the
ABSTRACThydrogenation of HNCO because there appears to be a constant abundance ratio across a large range of source luminosiContext. In the study of high-mass star formation,
areFigureempiricallywheretieshot
andcoresmasses.
12 shows definedthat these stages
two species
havechemically rich emission is detected
almostthe sameorigin
spatial extent
in G35.20
B and
their
emission
toward a massive YSO. It is unknown whether thephysicalof
thisemissionisadisk,
inner envelope, or outflow cavity wall
are only 0.1500 (or ⇠300 AU) apart in G35.20 B. The sepand whether the hot core stage is common to all peaks
massivestars.
00
aration is less than 0.11 (240 AU) in G35.20 A. The velocity
Aims. We investigate the chemical make up of several
molecularcores
determine
physicalintervalshot
spannedby the line
peaktovelocities
in eachpixel dif-and chemical structure. We use highfer by only 0.5
1 km/s. Our how
modeledvaluesspectral and spatial resolution sub-millimeter observations
to-determine
thisabundancestage fits
intoshow
the formation sequence of a high mass
N(HNCO)/N(NH2 CHO) is between 2 and 8 for HNCO at 50 K
star.
and between 1 and 10 for HNCO modeled at 100 K.
Methods. The sub-millimeter interferometer ALMA
(Atacama
LargeandMillimeter
Array)have
wasa used
In G35.03,
the HNCO
formamide emissions
sep- to observe the G35.20-0.74N and00
G35.03+0.35 hot cores at 350 GHz in Cycle 0.aration
We ofanalyzed
spectrafour
peaks (A, B1, B2 and B3)less than 0.11(255 andAU), maps
with thefrom
velocity
peakcontinuum
dif0.5 and peak
1.0 km/s.
striking physicalin G35.20-0.74N, separated by 1000-2000 AU, ferences
and onebetween
continuumin TheG35.03+0.35.
Weconmade all possible line identifications
nection between these two species makes a strong case for theacross 8 GHz of spectral windows of molecular emission
lines down to a 3 line flux of 0.5 K and determined column densities andformation of formamide predominantly through the hydrogenatemperatures for as many as 35 species assumingtion
local
thermodynamic
equilibrium(LTE).observedof HNCO.
Coutens et al. (2016)has also recently
co-spatial emission
HNCO
Formamidein the lowchemical
mass
Results. In comparing the spectra of the four continuum
peaks,inwefindandeach
has a distinct
composition expressed in overprotobinary system IRAS16293.

400 di↵erent transitions. In G35.20, B1 and B2 contain oxygen- and sulfur-bearing organic and inorganic species but few nitrogen-Fig. 11. G35.20 Core B shows clear evidence for small-scale chemical segregation. On the left are spectra extracted from each continuum peak in
species
whereasA andbeB3seenareinstrong
sourcesof N-bearing
O-, S-, andN-bearing organic and inorganic species (especially those with thecore B (corresponding to the red, blue, and green crosses inbearing
the map to
the right).
It can clearly
the spectrathat thespecies
4.4. Deuterationof Onvibrationallystatesare contours
observed to be equal to or greater than the ground state for a number(HC3 N) is only strong in B3, where the O-bearing species CN-bond).
(C2 H5 OH) isColumn
strong in densities
all 3 regions.
the right, theexcitedintegrated
intensityof species.
Deuterated
cyanideis clearly
detectedin andAdeuterated
andwith D/H
ratiosandonly
13%,Fig.
respectively,
but is much weakerof H2 CS 101,9 -91,8 (0.55, 0.94, 1.34, and 1.73 Jy/beam km/s),
CH3 OCHO
279,18 -269,17 methyl(0.70, 1.28,
1.85, and2.43 Jy/beamkm/s),C2 HB3
We detectsevenspeciesin G35.20,
fourof
of 8
which
5 CN
12. Formamide 162,15 -152,14 (red contours) and HNCO 161,16 -151,15
401,39 -391,38 (0.085, 0.100, 0.115, 0.130, and 0.145 Jy/beamat
km/s)
overlaid on(greyscale)forwithCore
Bdetectedof twoG35.20.
oneorobservedtransitions.
determinedthe deu- abundances
B1 areandshown
undetected
at theB2.continuum
No deuterated
speciesareinWhileG35.03,
butWesimilarmolecular
G35.20
wereoverlaid
found(blue contours) toemissionis shown
on the dust continuum
fractionation of the other three, CH2 DCN, CH2 DOH, and (greyscale) for core B. These N- and O- bearing species are present
the O- and S-bearing organics are distributed across core B, intheotherN-bearing
speciesis only
the southwesternpart.
species.
We
alsofoundfind toward
co-spatial
emissionteriumofisocyanic
acid (HNCO) and formamide (NH CHO) in both sources indicating a

重水素比

n
ce
2)
%
at
es
It
d,
be

Fig. 11. G35.20 Core B shows clear evidence for small-scale chemical segregation. On the left are spectra extracted from each continuum peak incore B (corresponding to the red, blue, and green crosses in the map to the right). It can clearly be seen in the spectra that the N-bearing species(HC3 N) is only strong in B3, where the O-bearing species (C2 H5 OH) is strong in all 3 regions. On the right, the integrated intensity contoursof H2 CS 101,9 -91,8 (0.55, 0.94, 1.34, and 1.73 Jy/beam km/s), CH3 OCHO 279,18 -269,17 (0.70, 1.28, 1.85, and 2.43 Jy/beam km/s), and C2 H5 CN
401,39 -391,38 (0.085, 0.100, 0.115, 0.130, and 0.145 Jy/beam km/s) are shown overlaid on the continuum (greyscale) for Core B of G35.20. While
the O- and S-bearing organics are distributed across core B, the N-bearing species is only found toward the southwestern part.

2

tion in Hot Cores With Disk Candidates

n
3of
d
ed
s.
or

の続き

Ø 重水素比が大小質量より高い。
àCOが凍結している若い段階。

CH3 CHDCN, using rotation diagrams in Cassis for consistency 2 in B3 and B1, but B2 is just outside the outermost contour (indicating 1

Ø 過去研究のN系とO系の違い。
Ø Orion D/H
KL:ratio近傍の別の星へ降着(エンカウント？)。G35.20に兆候なし。
It has previously been proposed (Bisschop et al. 2007; Menin methyl cyanide (CH CN). In its place of first diswords. stars: formation – stars: massive – covery,
ISM:
individual
G35.20-0.74N,– astrochemistry
doza et al. 2014; López-Sepulcre et al. 2015) based Key
on single
Orion KL, theobjects:
D/H ratio is0.4-0.9% (Gerin etG35.03+0.35
al. 1992). of 1.3%
was also reported in Taquet et al. (2014) in low-massØ W3: 片方がHII領域、もう片方が分子流付きYSO。~7000
In a recent paper by Belloche et al. (2016), CH DCN was de- protostar IRAS 16293-2422. Our values for G35.20 areAUスケール
signifdish observations that formamide (NH CHO) forms through thetected in Sgr B2 with a D/H of 0.4%. A D/H for methyl cyanide icantly higher, and the varying deuterium fractionation acrosshydrogenation of HNCO because there appears to be a constant abundance ratio across a large range of source luminosiだが可能性あり。
few candidate disks around B-type protostars were known. Sev1. Introduction
ties and masses. Figure 12 shows that these two
species haveeral disks have been detected through the study of complex oralmost the same spatial extent in G35.20 B and their emission
Ø AFGL2591: S, Nが中心星からのUVで光解離。G35.20ではNが外側。
Studying
peaks are only 0.15 (or ⇠300 AU) apart in G35.20
B. Thethesep-formation of high-mass stars (> 8 M ) is important
4.3. HNCO and Formamide co-spatial emission

200strong chemical link between the two species. (because CH2 DOH was not in the XCLASS database). From ). Red contours are 0.20, 0.33, 0.47, 0.61, and 0.74 Jy/beam km/s andblue contoursthe
are 0.40,
0.75, 1.10,of
1.45,
and 1.80 Jy/beam km/s. B1, B2,
rotation diagrams,
calculatedandthe D/Hvalueson suggests
Conclusions. The chemical segregation betweentheseN-bearingorganicwespecies
othersin based
G35.20presence
multiplethe best-fit column densities obtained using the opacity function and B3 are marked with colored boxes as in Figure 1.
protostars, surrounded by a disk or torus.
in Cassis. Relatively little has previously been written about the3

2

Article number, page 12 of 67

they drive the chemical evolution of their host galaxaration is less than 0.1100 (240 AU) in G35.20because
A. The velocity

ganic molecules (COMs), molecular species bearing carbon andat least 6 atoms, allowing for the detection of more disks (Cesa-

acility

VLA

GBT

B1.5
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Armentrout, Dana S. Balser,
T.
M. Bania, 841:121
T. M.(13pp),
Dame
,June
and
Trey V. Wenger4,7The
AstrophysicalJournal,
2017
1
Arm
1
Departmentof Physics
and Astronomy,West Virginia
H87α
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NH3 (J, K)=(1, 1)
5
Table 4
Institute for Astrophysical Research, Department of Astronomy, Boston University, 725 Commonwealth Avenue, Boston, MA 02215, USA
6 Figure 1. Outer Scutum–Centaurus Arm as traced by H I emission. The H I LAB survey was integrated over a 14 km s
Single-star H II Region Parameters23.7226
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Harvard-Smithsonian
Centerfor
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USA
3−1
We calculate
two separate
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kinematic
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given
by VLSR
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s−1usingdeg
×& Thaddeus(2011).USA
This clearly shows the Galactic warp bending t
Astronomy
University
ofkm
Virginia,
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Ly
Received
2017
March 3; Hrevised2017 April
20; accepted
May 5; frompublished
JuneCatalog
2
Spectralare our
observed
II region
targets(blue),2017selectedthe2017WISE
of Galactic H II regions near the (ℓ , b ) loc(1993)
Smith
MartinsType
Smith and Reid
Martinset al. (2014). For these rotation curve models,High-mass Star Formation in the Outer Scutum–Centaurus Arm

Ø HII領域は大質量星~zero ageなのでまさに今の情報。
Ø 銀河面第1象限は歪んでいる(~4 ; OSC Arm)ので遠くても見える。しかし、銀河面サーベイから漏れる。
pectralypeØ OSC Armの根本はバーから伸びており、OSCより外に大質量星なし。
we use the velocity of the NH3 (J, K)=(1, 1) inversion transition
Abstract
Figure 1. Outer Scutum–Centaurus
as traced by H emission. The H LAB survey was integrated over a 14 km s wide window following the ce
1.5
46.10
L
O7.5
-1 Armof
to 48.70
determine 48.44
distances.
If no ammonia
transition isavailable,
wekm
line
(RRL)
velocities
withinthe& Thaddeus
longitudeℓ in Dame
given by V 15
=−1.6
km ss deg ×(2011). This clearly shows the Galactic warp bending the arm toward positive latitudes.
1
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49.00
48.63
Scutum–Centaurus(OSC)orspiralarm ispreviously
the most
distantspiraltheWay,
but until
are our
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H region targets(blue), arm
selectedinfrom
the Milky
WISE Catalog
of Galactic
H regions near the (ℓ , b ) locus of the OSC arm.
use peakwater maser velocity
velocities
cataloged
Obse
locus
of
the
OSC,
deﬁnedby
Dame&Ø
WISEカタログ、4000/6000が電波連続波なし、radio
quiet。
ongitude–latitude
b
)
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47.00
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L
48.80
velocity
locus
of
the
OSC,
deﬁnedby
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v)
recently
littlewastheknown
aboutForthiseach
structure.
Discoveredby
Dame and Thaddeus, the OSC lies ∼15 kpc from thein Andersonetal. (2015).
rotationcurve, wedetermine
LAB survey was integrated over a 14 km s wide
window
following
centervelocity−1(RRL) velocities
within 15 km sof the longitudeTable 1
0s clearly shows
47.40
L bendingO6
L
48.96Overplottedthe(2011)
Galactic
warp
the arm
towardpositive
latitudes.
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Center.
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the ×
Galactic
Plane
inbytheﬁrst
Galactic(2011)
as.following
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addition,weℓsourceluminosity
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Ø
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Observation Summary
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deﬁnedDame& Thaddeus(degℓ , v ) locus
Facility#
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9.5
L
47.56
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L
49.11
tint (mg of Galactic H II regions near the (ℓ , b ) locus leavingof the OSCitarm.
II region
spatially
unsampledHbyIImost
Galacticplane thesurveys.
Here
weobserve
H km(2011)as V
=−1.6
s deg candidates
×H
additional
four coincidentℓ . An–1
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Facility# Sources
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49.20
49.26
⎤
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et
al.
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withvelocities
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VLAとGreenBank
Telescope。制動放射でHII領域を同定。θ~10”,
ΔV~0.75
kms。
ular
spectra.
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are spectra
from⎡⎤
D Array
Sint to image-radio
regions fromemission
the WISE Catalog
of Galactic
II Regionswith the OSC usingthecontinuum
from 65
targets Hand
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26Large1] . H II
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ammonia(NH
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have
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consistent
with
the
OSC
(Anderson
velocities
the
OSC(Anderson⎣⎦
Telescopetosearchforammonia
and
water
maser
emissionfrom75targets.
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sample,
drawn
from
the
Wide-ﬁeld
H87α − H⎦⎣within
15
of
the
locus
of
the
OSC
to
our
target
km
s
(
ℓ
,
v
)
m
Jy
Astrophysical Journal, 841:121 (13pp), 2017 June 1
結果の例。
ns. Water maser(top panel)areObservation
Summary
8us
48.50detections
48.29
O3
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49.63
The
AstrophysicalJournal,2017 countJune 1 to 10The
Arme
et al.
2012), bringing
the 841:121
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II region
beforeGBT75
6–36
22.2351
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H II region
the longitude–
Catalogof Galactic
H II Regions,ng the upper and lower ranges of emission Infrared Survey Explorer
etIIﬁrstal.
2012),
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IIII every
regioncountcandidate
to 10 near
beforetherepresents
present
ur
23.6945
NH
(J,
K
Rubin
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exploredtherelationshipbetweenist.
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total,
we
identiﬁed
75
OSC
H
regioncandidates.
sD
V
and6–3pea
Gaussianﬁtuncertainties
for
line
width
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Facility#
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75
t (min)latituden (GHzaser peak velocity. Ammonia detectionsof theOSC.
Coupledwiththeircharacteristic
mid-infraredmorphologies,
detectionofradio(ℓ) , b ) locus the
23.7226
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to below our 0.75 km s spectral resolution. I
σV
present
analysis.
region luminosity
andthe spectral
type of its most luminous
ith
redcalculate
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23.8701
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8–10usingContinuumWe
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Selection of associated ammonia orhese,
65 twocomposedourcandidateliststronglyfortheNationalRadio
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is a bona ﬁde H II region.
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3
to the central peak velocity, intensity, and width,
weoncentral
star.
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Rubin’s
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equationch NH3 (J, K)=(1, 1) hyperﬁne transition
H87α− H93αstancesfromtwodifferent
rotationcurves:
Brand
&
Blitz
parameters for hyperﬁne lines. These hyperﬁne lines a
water
maser
emission
allow
us
to
deriveakinematic
distance
anddetermineifthevelocityoftheregionisconsistent
Targets
for
these
observations
were
taken
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WISE
re
f Table 3.GBT
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22.2351
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コントアVLAII Regions.
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Galactic H in
1993)
and Reidto et0.75
al.km(2014).
rotation
curve
models,
with
that
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sources
detected
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ionizing
numberofphotons(inphotonss
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Andersonetal.
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identiﬁed
HIIregioncandidates
by
their
2.
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Thaddeus(2011) as b=0°. 375+0.075×ℓ . In ad
VLA)
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Mexico.
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10sources
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haveammonia
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maser
detections.
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thembeyondtheSolarorbit.
roundedtothenearest
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NH(J,K)=(2,2)
3
mid-infraredemission,primarily
from
the
12
and
22
μm
bands
each H II region. Only sources with both kinematic and radio
added H II regions from Anderson et al. (2015), withintensityof maser emission often varies with time, bu
determine
distances.
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isobservations
available,
we
These
very
distant
high-massstellarspectraltypes
as earlyas O4. Wemorphology
associate ofhigh-massformation
23.8701
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in therce
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ﬁrstlist
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dded
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candidate
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Targets
for
these
observations
were
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the
WISE
mid-infrared
is a 22 μm
of emission
surroundedby a12.
more
seaspeakor velocities
previously
cataloged
regionsin the
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theOSC, increasing
the total numberof detected
H IIcore
list. In total, we identiﬁed 75 OSC H II region cand
S83waterand maser
has a velocity
large negativeneeddistance
todetermine
luminosity:
than 0.5 km s-1.
diffuse12
μm
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emission(WatsonSE
Byrd
GBT
in etGreenWest
Virginia,
theHfollowing
year.
these, 65 composed our candidate list for the NatioAndersonet al. (2015).
For2015).
eachBank,
rotationcurve,
weGalaxy:determine
II etRegions.
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thiswithin
catalog,CatalogH
We longitude–latitudedetected molecular line emission fromof o(Andersonal.
It Keyal. 2008; Anderson
al. 2011). Searching
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structure – of
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regions(ℓ ,∼20%b )orlo
連続波
à
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à
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(モデル)
g,OSC ØAstronomy
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Ly
of the OSC, deﬁned by Dame & ⎡ Te ⎤longitude–latitude(ℓ , b ) locus
In
total,
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sources
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ource
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we identiﬁed
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Shownin
Figure1,
areoverlaidonH
detection.
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52
(VLA)
in
Socorro,New
Mexico.
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souAndersonetal.
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H
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regioncandidates
eircontinuum´ 10
6.3
emission.
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includes10
watermasers,10NH(J,K
Supporting material:
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Thaddeus (2011) as b=0°. 375+0.075×
In =addition,
we ﬁguresℓN. LyThaddeus(2011)
asb=0
3
candidates
with
this
morphology
in
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WISE
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added to the candidate list for observations with thewater maser
emissionwas
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ds
10
K
GHz
lines,
5(2,
2)
lines,
and4(3,
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6000
targets,∼2000
show
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continuum
emission.
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S
added
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II
regions
fromAndersonetal.
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withvelocities
mid-infrared
the 12 and 22 μm bands source
mission,integrated
along
the
velocity ofemission,
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toThe sourcesfrom
int
Byrd added
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Hin1,Bank,
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withinlocus
km s-temperature
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Figurethesecandidates are overlai
n
⎦
⎣
m
Jy
of
WISE.
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morphologyofHII
regionsinthequiet.” In earlier´ ⎢ 20Of[s ].
(4) searches for H II regions, primarily with theighlight
structureoftheHarm.
redetection).
reobservation
emission,
integrated
the expected
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theof(thℓlist.Upon
Inthetotal,
we identiﬁedof
75 OSCII region
candidates.
s-1 ofvelocity
disk. (GBT
Dame
& Thaddeus
wereﬁrst within
to discover
1. Introduction⎣ 10 W Hz-1 ⎥⎦GreenGalactic
Bank Telescope
HRDS;
Bania et al.(2011)2010) andthe the highlightonthestructure
of
the
arm.
017
January,
S83
exhibitedstrong5.
Results
mid-infrared
is
a
22
μm
core
of
emissionsurrounded
by
a
more
these,
65
composedourcandidate
list
for
the
National
Radio
Rubin
(1968)
ﬁrst
exploredtherelationshipbetweenHII
One sourcein km
particular,
G039.183−01.422,
liessigniﬁArecibo
et al. 2012),
onlythissourceswith warp,a Observatory
large-scale(Bania
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possibly4
total,
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Onelist.
sourceInin aparticular, weG039.183−01.422,
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heis anVeryareaof ionizedhydrogensurroundingAns-H
weassumean electron
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K and
mK detection.
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showingboth infrared
and radio
morphologies.
Astronomy
Karl ofG. itsJanskyLarge
Arraydetected
radio
continuum
emissionwereobserved.
5.1. measured
Detectionsthe velocity of t
gion
luminosity
andObservatory’s
the spectral
type
most
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銀河回転モデルからアンモニアの力学距離。
cantlybelow
theplane.
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symmetric
counterpart
to
the
third
quadrant
Perseus
Arm.
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diffuse12
μm
envelopeofsmall-grain
emission(WatsonInfrared WISE bands w2 (4.6 μm), w3 (12 μm), and w4 (22 μm) are represented
on
antly
below
the
plane.
measured
theofthisLymansource
Since
H II. regions emit thermal bremsstrahlung radiation in themassivestars.
Starsof Oequation
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these,
65
composed
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ser differedfrom
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originalby blue, green, and red, respectively. VLA continuum contours from 4 minute
VLA
candidatesnapshots,
had
detec
calledthisstructuretheOuter Scutum–CentaurusArm,ortheitsOSC.
seradio
regime,WISE
candidates withcoincident
radio
continuum
1
et
al.
2008;
Andersonetal.
2011).
Searching
within8°oftheintegrations
atX-bandin
D-conﬁgurationareoverplotted,
withcontours
at
30%,
OSC
locus,
velocityisconsistent
with
that
of
the
O
added
to
the
candidatelist
for
observations
withtheRobertC.
We
assignspectral
types
using
a
combinationofthestellarE>
13.6
continuum
radiation
(
,
eV)
to
coml
<
91.2
nm
ys
nearly15.
Thedrastic
kmscontinuum
emission at X-band,
giving us a detectio
phom
Condon&theRansom(2016),HRDS,
Equation (4),we calculate
the it lies
Astronomy
Observatory’s
~
3
below
the
of
WISE
and
althoughdetections
weredeemedlikelyﬂux
Hto
II beregions.
is Scutum–Centaurus
50%,70%, and90%
peak continuum
(2.37
mJy
beam here). The image
The
OSC
appearsacontinuationofthen. partsame
longitude.
Greenpletely
Bank,
West Virginia,
followingyear.
nearly 60%. The majority of these targets had no pmodelsfromMartins
et al.
(2005) andthem
Smithal. (2002). Both
-1theearches Byrd
for GBT
onlyin watermaserionize
theinterstellarhydrogensurrounding
foretup−1

High-mass Star Formation in the Outer Scutum–Centaurus Arm
1,2

The Astrophysical Journal, 841:121 (13pp), 2017 June 1

W. P. Armentrout , L. D. Anderson

1,2,3

VLSR
(km s−1)

RGal
(kpc)

G026.417+01.683
G028.320+01.243
G029.138+02.218
G033.007+01.150
G034.133+00.471
G037.419+01.513
G039.183−01.422
G039.536+00.872
G039.801+01.984
G040.954+02.473
G048.589+01.125
G050.900+01.055
G053.580+01.387
G054.093+01.748
G054.490+01.579
G055.114+02.422
G060.592+01.572
G064.151+01.282
G066.607+02.060

42.55−44.0034.71−57.6035.65
42.13−51.00−38.5029.31−52.50−34.25−59.0039.44−85.30−39.94−76.10−49.40−55.93−69.10

5.93
15.25
6.44
17.05
6.63
6.49
13.88
12.05
7.09
13.82
10.99
13.40
7.00
16.99
11.22
15.26
11.76
12.18
13.34

5

6

, Dana S. Balser , T. M. Bania , T. M. Dame , and Trey V. Wenger

1

Name

Armentrout
et al.
4

4,7の続き

Departmentof Physics and Astronomy, West Virginia University, Morgantown, West Virginia 26505, USA
Table 52
Derived Region Parameters
Center for Gravitational
Waves and Cosmology, West Virginia University, Chestnut Ridge Research Building, Morgantown, WV 26505, USA
3
Adjunct Astronomer at the GreenBox 2, Green Bank, WV 24944, USA
Brand
Reid Bank Observatory, P.O.
The Astrophysical Journal, 841:121 (13pp),
2017 June 1
Armentrout et al.
4
National
Road,Charlottesville, VA 22903-2475, USAab Radio Astronomy Observatory, a520 EdgemontbcLog10(NLy)
Spectral
RGal Table 6 d ☉Log10(NLy)
Spectral
Note
d5☉
−1
of
Astronomy,
BostonUniversity,
725 Commonwealth Avenue, Boston, MA 02215, USA(kpc)Institute for(s−1Astrophysical)Type Research,(kpc)OSCDepartment
(kpc)
(s
)
Type
H II Regions
6
Harvard-Smithsonian
Centerfor
Astrophysics,
60
GardenStreet,Cambridge, MA 02138, USA
Reid
3.05/12.18
45.77/46.987
B1.5/B0.5Brand 6.57
2.23/12.99
45.50/47.03
B1.5/B0
Department,
Universityof
Virginia,
P.O.
Box
400325,Charlottesville,
VA 22904-4325, USA
RAstronomy
Log(N)
SpectralR
Log(N)
SpectralNote
Name22.18
V47.97dd 48.02
O8.5
16.43
23.41
O8.5NEW
OSC(km s )
(kpc)
(kpc)
(s2017)Type(kpc)2017 (sApril)
Received
March3;(kpc)revised20;
accepted 2017 May 5; published 2017 June 2
2.48/12.36
KK
7.15
1.59/13.26
K
K TypeLSR−1G026.610−00.212
23.54
G028.320+01.243
2.44/11.63
G031.727+00.698
G032.928+00.606
2.83/10.68
G033.007+01.150
19.39
G039.183−01.422
17.32
G040.954+02.473
G041.304+01.997
1.99/11.07
G041.755+01.451d
19.07
dG041.804+01.503
14.57
G054.093+01.748
G055.114+02.422
17.03

Gal

☉

−35.7020.84
48.18 13.77
O8−44.00
15.25
22.18
K
K
−39.2013.26
19.71−38.3012.89 B1.5/B0.5
19.16
45.77/46.92−57.6017.05
23.54
48.28 13.88
O8−51.0019.39
47.33 13.82
B0−52.5019.07−53.7013.95 B1.5/B1
19.16
44.91/46.40−54.80
14.04
19.19
K
K
−52.60
13.69
18.80
46.93
B0.5
−85.3016.99
20.52−76.1018.43
47.78 15.26
O9

10 Ly
−1

a

K
18.31
47.97
K 7.36
K 7.20
48.18
15.01
48.28
13.10
K
K 7.86
K
14.95
K
11.99
48.06
49.28
14.52

b

Gal

K
24.84 14.90
O8.5
16.43
1.44/12.64
K
14.37
K
13.98
1.73/11.78
O8
18.31
20.61 15.01
O8
K 18.49 14.95
K
15.08
0.85/12.21
K
15.18
20.29
K
14.82
15.78
O8.5
18.25
O4 18.30 16.44

☉

10 Ly
−1

22.00
K
48.23
23.41
48.02
K
20.89
K
20.32
K
45.34/47.01
24.84
48.23
48.33 48.33
20.61
47.39
20.29
K
20.39
K
44.18/46.48
20.43
K
K
20.03
K
47.00
21.89
48.11
19.75
49.35
47.84

a

b

c

O8 K
W,RRL
OSC
O8.5
VLA, H2O
K K
RRL
K
RRL
B1.5/B0O8
RRL, VLA
O7.5O7.5
W,RRL,OSC
VLA, H2O
B0 K
H2O
K
RRL
B1.5/B1
K
RRL
K K
OSC
RRL
B0.5 O8
RRL, VLA
O4
RRL,
VLA, H2O
O9
3.56/6.53
KK
7.77
1.37/8.72
K
K
Notes. All known OSC H II regions to date. Sources with data blanked by “K” in the NLy and Spectral Types columns have measured ammonia or maser velocities
48.06
O8.5
18.25
21.89
48.11
O8
W, OSC
from 20.52
our GBT pointings, but
no detected radio continuum.
aLog13.77
photons
through Equation (4).
10 of the number of Lyman-continuum
47.83
O9emitted per second
12.23is determined
15.03
47.91
O8.5
b
Spectral type is assigned based on a combination of the Martins et al. (2005) and Smith et al. (2002) models of Lyman-continuum emission from high-mass stars to
18.43
49.28
O4
16.44
19.75
49.35
O4
W, OSCII
give the ﬁnest gridding of spectral types and cover B1.5 to O3 type stars, as described in Section 5.3.
c
13.31
48.21
O8
12.80
48.29VLA radio continuum
O7.5 emission,
Wand water maser
Sourcesare labeled by RRL,
VLA, and H2O, indicating
detectedemission from 14.62
radio recombination lines,
emission,
respectively. Two H
and 13.24
G040.954+02.473,
were discovered to beK
part of the OSC asK
part of this work and only have
13.19
KII regions, G028.320+01.243
K
14.52
detected water maser emission.
14.20
K
K
14.45
15.54
K
K
d
II
The H II regions G041.755+01.451 and G041.804+01.503 are part of the same complex but have distinct morphologies.

AbstractØ 60%で連続波、20%で分子輝線。
à外縁は金属量と星形成率が小さいため。
Ø O4までいることがわかった。
Ø WISE radio quietで60%も連続波を検出。

The Outer Scutum–Centaurus (OSC) spiral arm is the most distant molecular spiral arm in the Milky Way, but until
à他の象限でも受かるだろう。
recently little was known about this structure. Discovered by Dame and Thaddeus, the OSC lies ∼15 kpc from the
Galactic Center. Due to the Galactic warp, it rises to nearlyNEW
4° above the Galactic Plane in the ﬁrst Galactic quadrant,
leaving it unsampled by most Galactic plane surveys. Here we observe H II region candidates spatially coincident
with the OSC using the Very Large Array to image radio continuum emission from 65 targets and the Green Bank
Telescope to search for ammonia and water maser emission from 75 targets. This sample, drawn from the Wide-ﬁeld
Infrared Survey Explorer Catalog of Galactic H Regions, represents every H II region candidate near the longitude–
latitude (ℓ , b ) locus of the OSC. Coupled with their characteristic mid-infrared morphologies, detection of radio
continuum emission strongly suggests that a target is a bona ﬁde H region. Detections of associated ammonia or
water maser emission allow us to derive a kinematic distance and determine if the velocity of the region is consistentNotes. Sources within the Solar circle have two values for the Distance (d ☉ ), NLy, and Spectral Type columns, since we did not resolve the kinematic distancewiththecolumns
OSC.
60% ofthe velocities
observed
sourceswerein radio continuum, and more than 20%
ambiguity. Sources with data blanked by “K” in the N
Spectralof
Types
haveNearlymeasured ammonia
or maserfrom ourGBT pointings,
but detectedno
Ly and thatHI
emission
detected radio continuum.
have ammonia or water maser detections. The velocities of these sources mainly place them beyond the Solar orbit.
a
Log10 of the number of Lyman-continuum photons emitted per second is determined through Equation (4).
HI emissionb
very
distant
high-mass
havedescribedstellarspectral
momofThese0 fromSpectral type is assigned based on a combination
modelsMartins
et al. (2005)
and Smith stars
et al. (2002),
in Section
5.3. types as early as O4. We associate high-mass star formation atc
Sources whose velocity places them within the Outer2Scutum–Centaurus
Arm areindicated“OSC” in increasing
the note column. Two
II regions, G028.320+01.243 andII regionsmodel)
in the OSC to 12.
new locations
withtheby OSC,
theHtotal
number of detected H(Brand
G040.954+02.473, were discovered to be part of the OSC as part of this work. Additionally, sources previously identiﬁed as H II regions via RRLs in the WISE
catalog are marked by a “W.”
Key words: Galaxy: structure – H II regions+: WISE HII+: 連続波なし
x: 今回観測されなかったHII

The Astrophysical Journal, 841:121 (13pp), 2017 June 1

x: 既知HII+: 連続波なし
点線: 距離が2解

Supporting
material: While
extendedﬁguresrate for molecular line emission was
known as the “kinematic distance ambiguity,”or KDA, in which
our detection
one velocity corresponds to two potential distances. Here, we
rather low (20%), this could be due to both decreasing
analyze both near and far distances, not resolving the KDA.
metallicity and decreasing star formation efﬁciency at highSpectral types for near versus far distances never differ by more
Galactocentric radii. Metallicity decreases with distance fromthan one spectral type. Sources within the Solar circle have1. Introduction
the Galactic Center, which might mean we are simplyGalactic
running disk. Dame & Thaddeus (2011) were the ﬁrst to discovervalues for both distances, given in the same column of Table 5
out of observable tracer molecules in these most distant
H IIa large-scale
structure within this distant warp, possibly a
regionan arearegions.
of ionizedhydrogensurrounding
H IIinclude
regionswith near parameters reported ﬁrst. An
We also
H II isAdditionally,studies ofexternal galaxies have found asymmetric counterpart to the third quadrant Perseus Arm. They
without detected radio continuum
but withstars.
kinematic
informain emitstar formation
massiveStarsof O andrapid
earlydecline
B-typeenough efﬁciency
Lyman- with increasingtion; for these sources, we assign
no Lyman photon
ﬂux.
Galactocentric(Bigielal. com2010). Thus called
our lowthis structure the Outer Scutum–Centaurus Arm, or OSC.
> 13.6
continuum
radiation(l < 91.2eV)et tonm , E radius
detection rate phfor molecular gas emission is perhapsThe
notOSC appears to be a continuation of the Scutum–Centaurus
pletely ionize the interstellar hydrogen surrounding them for up

A

Figure 5. Face-on map of H II regions in the ﬁrst Galactic quadrant. The Solar circle and tangent points are marked by solid and dashed lines, respectively. B

CLEAN,
primary windows
beam corrected image (natural
Four spectral2
s a beam
1 6×1
6,Firstan rmsMillimeterof 9.8 μJy/beam,Fn ´ daround
Detection
of
the
Disk
a Young, Isolated, Planetary-mass Object
GHz
andofeach
one withM=,
dust
rence frequency of 233 GHz, and a frequency
kn ´ Bn (T4dust )be collapsed in a single Bayo1, Viki Joergens2, Yao Liu2,3, Robert
Brauer , Johan Olofsson1,2, Javier Arancibia1, Paola Pinilla5, Sebastian Wolf4,d (not continuously) Ameliaof 20 GHz. We detected
42
6,7JanﬂuxPhilipp
Ruge, ThomasHenning, Antonella
Natta, Katharine
G. isJohnston8, Mickael Bonnefoy9,
point-like source with a peak
value
F
where
is
the
ﬂux
density,disthedistance
to
Cha
I
(160
pc
n
2
9,10
with(see
CASA(McMullin
The AstrophysicalJournalLetters,(4pp), 2017 May 20
HenrikBeuther, and
Gael841:L11
ChauvinmJy
Figure1).
1Bayo et al.

kn is theassumed;Whittet Facultad
et al.de1997),
mass Av.
absorption
steps starting from the Institutode Física y Astronomía,
Ciencias, Universidad
de Valparaíso,
Gran Bretaña 1111, Valparaíso, Chile; ameia.bayo@uv.cl
and OTS44 (~12MJup ; Joergens et al. 2013), with central object
2
Max
PlanckInstitutfürAstronomie,
Königstuhl
17,
D-69117
Heidelberg, Germany
coefﬁcient,and Bn is the Planckof hastemperatureof theof3 Purple
massesfunction
well below what
been studied withT
ALMA
until now.
dust atsults
andDiscussion: Dust
Disk
MassObservatory,
Mountainand Key Laboratory forInRadio
Astronomy,
ChineseAcademyof
Sciences,
2 West Beijing Road, Nanjing 210008, China
Ø performance
substellarの形成過程は不明。星形成物理量とM*の関係が基本。
this Letter, we present the ﬁrst millimeter detection of one
4
the observedd or useless data (using
Institutefrequency.
of Theoretical Physicsofand
Astrophysics,
UniversityofKiel,
Leibnizstr.
15,
Kiel, Germany
these four extremely
objects, OTS44. In SectionD-24118
2,5
2 low-mass−1of Arizona,
irect
quantity
that
we
can
derive
from
our
data
is
Ø
BDは最近やられている。小さいスペクトル指数はダスト成長を示唆。
DepartmentofAstronomy/Steward
Observatory,
The
University
933
North
CherryAvenue,Tucson, AZ 85721,
USAdust mass of the disk of OTS44 de
we describe
more detailin GHzSection3, we
describe determinations
kn value
We have
adopted2.aIllustrationof
2.3infourcm
g theattarget;230
withr radiometer), correcting
FigureofInstitutethe(ﬁve-pointredstars)
possibleof the6
Schoolof Cosmic Physics, Dublin
forAdvanced
Studies,
31
Fitzwilliams
Place,
Dublin2,
Irelandsr ofﬂagging
the disk.
In
thissection,we
providesuch
0.4observations; in Section 4, we present our disk estimate and7àsubstellarだとradial
driftで成長できないという説と反対。
, the
same
in
Andrews
et5,substellaral.
a frequency
dependenceof nour(shadowing,M
diagram,along
withcomparisons
with
other
reported in the literature. In each panel, we outline
INAF-Osservatorio
AstroﬁsicodiArcetri,
L.go
E.
Fermi
5, I-50125
Firenze,objects
Italy
the
comparison
with
theas
literature;andin Section
we present*–Mdiskcompare them with the available literature.8
ourconclusions.
Astronomy,
E.C. Stoner
Building, The
of Leeds, Leeds LS2 9JT, UK
for School
Taurus,andmorerecently
by Pascucci
etUniversity
al. (2016)), deriving
the bandpass
assumedfor9and
OTS44.
Ø OTS44:
Cha I, M9.5,(2013)
M*=6-17
MJ,of Physics
Univ. Grenoble Alpes, CNRS, IPAG, F-38000
Grenoble,
Mdust
for Internacional
Cha I. For
consistency,
we have
adaptedall andvaluesFrance
ating
the cubefrom the10–1
UnidadMixta
Franco-ChilenadeAstronomía,
CNRS/INSU
UMI
3386
Departamentode Astronomía, Universidad de Chile, Casilla 36-D,
Disk Massvia
Analytical
Prescription
Ø∼8%,
Spitzer/Herschelで円盤、VLTでPaβ,to8e–12
Mo yr ,with
2. Chile
OTS44
from the literaturebecompatible
thisassumption.
ainty isbut, based
Santiago,
luminosityof 20;0.0024
L April; Joergens
etAprilal.28;
2013), which iswould fall in the lower enve
Received2017
February
revisedis2017
accepted
2017spectral
estimatethedisk
dust mass from millimeterdata,
赤外へのモデルはM
OTS44
the e
objectthelatesttypepublished. in the 2017 May 18
Theremainingstrongassumption
rests
on9;withthechoiceof Tdust
med
aØ
more
conservative
dust=0.17M
Eàミリ波が必要。
Chamaeleon
I (Cha I) star-forming
region (M9.5) reportedwith a mass merely by
unrealistic
given
theK,higher
temperatures
drawn by the literature dataat the emission is optically thin andisothermal
at used for T
is 20
et(withal.estimates(2013)A typical
value
dust below
or close but
to theAndrews
planetary borderfrom 6 to
Abstract
therefore
unrealistic value for the dus
due to theinterstellar
ﬁeld
Draine 2011).
; Luhman etsigniﬁcantly
al. radiation
2005b; Bonnefoy
et al. (IRF;
2014). First
17MJupdust
showedthatheating
thisGHz,
temperaturescaleswiththewe, andtried
to applyselfØ ALMA
Cycle
3, 224,
226,
240,
242
1.6”,
9.8
µJy/beam。
evidence
for a disk around OTS44 came from mid- and far-IR
ALMA
230
GHz
OTS44
is one ofVery
only thefourrecently,
free-ﬂoating
planets
known
to
have
a and
disk.
We
have
previously shown that it isthesethevery
low-mass
central o
van
der
Plas
etthe
al.relation:(2016)
luminosityofcentral excess
object,proposingﬂux recovery Fbutthe2emission
detected
with Spitzer
Herschel(Luhmanrevised this´dnMcoolestand
least
massiveknown
free-ﬂoating
planet
(∼12
)
with
a
substantial
disk
that
is
activelyaccreting.
0.16
al. 2005b;
Harveyal.
2012a,
InKaddition,
we
JupL 2012b).
However,
relation
wasMnot
good enough. , Tdust = 25 ´dependence(L* L :)1 4 Kas. etobserved
than those around low-mas,youngwhich
TALMA=continuum
22this´et The(empirical
Ldata
)and
dust =
AstrophysicalJournalLetters,
841:L11 (4pp), translates
2017 May 20
Bayo et al.
dust OTS44:thiswith VLT/SINFONI
detectedstrong,disk-bearing object. The dataWe
haveobtained
Band
6
(233
GHz)
of
very
*
k
´
(
)
B
T
n
n
dust
Figure 1.
ALMA
Band 6 data of OTS44.
1 6×1
yieldstemperatureof of5.5
for8.4
OTS44(assuminga activewo spectral windows as
broad,KvariablePa K
β emission,
which is evidence
forexample,by TheLiu
et 6al. (2015to a dust
temperatureoffor OTS44(withthe same
LFrequency
e as collapsedshow
a cleara unresolved
detection
theandsource.
Weobtained
disk-massestimates
via
empirical
correlations
disk accretion in the planetary regime with a relatively high mass-

beam is displayed in the lower left corner. Solid-line white contours highlightregions
3, 5, 7, and 10
timesOntherms ofthe dataother(9.8 μJy/beam).
Dashed- values b−12−1
derivedyoung,(substellar)
rangeetof
arewithbetween
0.07
ande ﬂux density, d is the distance to
Cha Ifor(160
pcbefore).
ishigher-mass, central
the
hand,
; Joergens
al. values2013). obtained
accretion
rate (8×10objects.
M: yrTheline white contours highlight -3´ rms and -5´ rms regions, and there are no2
recently determinedthepropertiesof withthe diskof OTS44(dust masses).
compare theWepropertiesof thisuniquedisk
those
recently
reportedaround0.63
at the −7 and−10 rms higherlevels.
MÅabsorption
kn2 g
ittet et Øal. κ=2.3
1997),cm
is–1themass(β=0.4)、温度は光度でスケールすると5.5
K,masses compatible with t
ForWe completenesshavefour data
different(Joergens et al.we
2013; Liuet al. 2015)consideredthrough radiative transfer
mass(browndwarfs)young
objects
in
order
to
infer
constraints
onitsmechanismofformation.
While
extrememodelingof its spectral20
energydistribution
the opticald Bn is the Planck
function of temperature
Tdusttemperatures:atseparated as possible to obtaina spectral index,
but once
again,
literaturedata(although5.5
the“classical”
theslightly
8.4from
Kdiverge
obtained
assuming
星間輻射は7.5
K, スケール修正版(vanderPlas+’16)だとassumptions
on dust temperature yieldvalues thethatK,
could
theS/N
generaltrends foundto disk-mass
the far-IR applying
radiative
transfer code
MC3Dfrom theof the data was not good enough for this purpose.
frequency.
(Wolf
and
a BayesianThe
diskthat compatible
ﬁtted that The
for more massivethebrown
dwarfs, a rangeof2003)sensiblevaluesprovidemasseswitha CLEAN,unique primaryscaling
to thethat
an I
relationshipfromvander analysis.
Plasetdiskal.model(2016),
ofIRF
ﬁnal
beam factcorrected
imageincluding(natural
8.4 K,of小質量星の典型は20
K, それぞれthe mid- and far-IR data best was that of a highly ﬂared disk
opted a kn value
2.3 cm2 g−1relation
at 230between
GHz withweighting)
has
a
beam
of
1
6×1
6,
an
rms
of
9.8
μJy/beam,
Mdust and M* throughthesubstellar
domaindown
planetary
masses.
M*–Mdisk coK),ofpushing2011),
and
the
5.5
K to
derivedfollowing
the frequency
ourfar-IR Herschelwitha dust massof 0.17
MÅ. However,
0.4 =0.07, 0.27, 0.33, 0.63 M
a central reference
233 GHz, andthe
a frequency
Ø ofMndust, the same as in Andrews et (7.5
al.E。K, Draine measurements
ependence(adetection
at
70
μm
and
an
upper
limit
at
range covered (not continuously)of 20 GHz. We detected
Key words: browndwarfs – stars:fromformation– stars: low-mass –(2013).
stars: pre-main
sequence
the planetary-mass
domain.
relationshipAndrews
Thewhichcorresponding
urus, andrecently by Pascucci
et al. (2016)
160 μm)are insensitiveetto al.
millimeter-sized grains,
OTS44 as a point-like source with a peak ﬂux valueØmore
大きい側のM
dust-M*関係に矛盾しない。 prevented us from concluding about the presence of large
0.101±0.01
r consistency, we have adapted all Mdust values
estimates for the
dust
mass of the disk of OTS44 are:0.07,mJy (see Figure 1).
grains(a maximum grain size of 100 μm was assumed in LiuØ
しかし、ダストの性質に依存するのでBand
3でも観測する。
ature to be compatible with this assumption.1. Introduction
al. 2015),M
with,thispotentiallyleading tounderestimation
Barradoy anNavascués
et al. 2007; Luhman
et al.
2008; Dust
BayoDisk Mass
0.27, 0.33, andetof0.63
4. Results andDiscussion:Å respectively.
the disk dust mass. In this Letter, we report the ﬁrst ALMA
5. Co
ing strong assumption rests on the choice of Tdust .
et al. 2012),
far-IR(Herschel;Harveyal. 2012a,
The most
direct etquantitythat we 2012b;
can derive from our data is
detectionof thestars
disk
of a planetary-mass
object,providinga of e.g.,
In
Figure
2,
we
show
how
our
four
estimates
the
dust
Key
questionsarestillunanswered
about
how
low-masse used for Tdust is 20 K, but Andrews et al. (2013)
the dustJoergens
mass of theetdisk.
this section,
Alves
de Oliveiraal. In2013;
Liu we provide such
more robust estimate of its massand supporting
the ideaetthatal. 2013;
come to emerge and gain
theirmasses
from
their
natal
mass
in
the
disk
aroundOTS44
comparetoliterature
valuesforestimates
andcompare
them
with
the
available
literature.
We
have
the ﬁrs
the value obtained in Liu etet al.
al. 2015)(2015) wasan κは文献から変えて揃えている。
this temperature scales signiﬁcantly with theand indeed
single-dishmillimeter continuum photometry presented
molecular clouds, but when we move toward
the substellar
underestimation.
stellar and substellar objects in(e.g.,
the Klein
literature
Pascucci
disk
aroundan isolated pla
f the central object, domain
proposing
the relation:
et al. from2003; Scholz
etDiskal.Mass
2006;
Mohanty
4.1.
via
Analytical
Prescription(with masses below the hydrogen-burning mass limit,

A Tale of Three Cities
OmegaCAM discovers multiple sequences in the color-magnitude diagram of theOrion Nebula Cluster
G. Beccari1 , M.G. Petr-Gotzens1 , H.M.J. Boffin1 , M. Romaniello1, 12 , D. Fedele2 , G. Carraro3 , G. De Marchi4 ,W.-J. de Wit5 , J.E. Drew6 , V.M. Kalari7 , C.F. Manara4 , E.L. Martin8 , S. Mieske5 , N. Panagia9 , L. Testi1 , J.S. Vink10 ,J.R. Walsh1 , and N.J. Wright6, 11
A&A proofs: manuscript no. msONC:1705.09496v1 [astro-ph.SR] 26 May 2017

Ø 星団の年齢幅は連続的な星形成か、降着の違いか。
(Affiliations can be found after the references)
May 29, 2017
Ø ONCは年齢幅~3 Myr。距離414 pc。

Fig. 1. Panel a: The (r-i),r colormagnitude diagram of a region of 1. 5
radius centered on the ONC. The arrow represents a reddening vector for
Av = 1.8 (typical for Orion; Schlafly
et al. 2014) and extinction curve with
Rv = 3.1 (Cardelli et al. 1989). The photometric errors (magnitudes and colors)
ABSTRACT
are indicated by black crosses; Panel b
the same CMD shown in panel (a) after
unsharp masking.
As part of the Accretion Discs in H↵ with OmegaCAM (ADHOC) survey, we imaged in r, i and H↵ a region of 12 ⇥ 8 square

Fig.
PMS
of th
CMD
dista
mea

等級

Ø チリの2.6 m VST, FoV=1 deg2 , 0.21”pix–1, r, i bandとHα。
degrees around the Orion Nebula Cluster. Thanks to the high-quality photometry obtained, we discovered three well-separated preØ Accretion Discs in Hα with
OmegaCAM survey。
main sequences in the color-magnitude diagram. The populations are all concentrated towards the cluster’s center. Although several

explanations can be invoked to explain these sequences we are left with two competitive, but intriguing, scenarios: a populationof unresolved binaries with an exotic mass ratio distribution or three populations with di↵erent ages. Independent high-resolution
spectroscopy supports the presence of discrete episodes of star formation, each separated by about a million years. The stars fromthe two putative youngest populations rotate faster than the older ones, in agreement with the evolution of stellar rotation observed in
pre-main sequence stars younger than 4 Myr in several star forming regions. Whatever the final explanation, our results prompt for arevised look at the formation mode and early evolution of stars in clusters.

Ø 色等級図に３つPMSｓを検出、Hartigans’ dip test。
赤化ベクトルに沿うので赤化のせいではない。

色

Key words. Stars: pre-main sequence – open clusters and associations: Orion

1. Introduction

A&A proofs: manuscript no. msONC
Fig. 2. (a) Portion of the CMD zoomed on the
PMS. The black line shows the mean ridge lineof the blue population; (b) Rectification of the
CMDmetricallyshown in andpanela; (c) Histogramof the single band catalogs
photometricallycalibrated
distancein the(r-i)VST
colorarchiveof the PMS
stars2 .fromfromat CASU
Starsthelying in the overlap remeangion
ridgebetween
line of thebluest population.
adjacent
fields were used to adjust residual photometric o↵sets. The photometric calibration of the final bandmerged catalog covering the entire area was checked against aof multiple sequences in the observed optical color-magnitude
diagram of the ONC.

Ø 空間分布は青がまばらに見える。
Young stellar clusters are conspicuous components of our
Galaxy. They are the best test beds of the stellar initial mass
Ø Minimal Spanning Tree:
中心は同じでなくて良いが、function
because they are assumed to be entities of a common 2. Observations and data reduction
origin, i.e. born from the same molecular cloud material, and at The images used in this work were collected with the wide fieldcompletenessは同じと仮定。
the same time. Observations have shown, however, that the stars optical camera OmegaCAM on the 2.6-m VLT Survey Telescopeborn
in one and the same cluster are not as coeval as expected. (VST) at Cerro Paranal in Chile. OmegaCAM consists of a moØ MSTblue/MSTgreen=1.16,
5σレベルで青の方がまばら。
2
In fact, stellar age spreads up to several million years have been
postulated for several clusters from fitting isochronal ages to theposition of cluster member stars in the Hertzsprung-Russell diagram (HRD; e.g. Cargile & James 2010; Cignoni et al. 2010;
Reggiani et al. 2011; Bell et al. 2013; Balog et al. 2016). But, if
this observation is a consequence of a continuous star formation
process lasting over several dynamical time scales, or rather is2

http://casu.ast.cam.ac.uk/vstsp/

Article number, page 2 of 8

saic of 32 CCDs and samples a 1 deg Field of View (FoV)
with a pixel sampling of 0.21 arcsec pixel 1 . Orion was sampledthrough the r, i broad band filters and the H↵ narrow band as partof the Accretion Discs in H↵ with OmegaCAM (ADHOC) survey (PI: Beccari). Each target region is sampled in groups of 3
overlapping fields, and in each group the fields are contiguouswith a footprint close to 3 ⇥ 1 deg2 . For each position in sky wecatalog of stars from theused as secondary standto homogeneously samp
12 ⇥ 8 size in Orion dotained withby
our theMontespectroscopic
Carlo simulations
provided
analysis of Da Rio et al. (2016).
(black, heavy lines) and as observed(red).
right panels explanation
show the corAn The
alternative
for the presence of the green andresponding assumed distribution of theredmasssequences
could
be
a
PMS
population
located more than 100
ratios of all the binaries in our sim2
sample.
Thetheofforegroundeach solution is of the blue sequence, respectively.
andulated
200
pc
in
also indicated in the left panels. Both top
OmegaCAM discovers multiple
sequencesinthatthediagram of the
Alves
Bouy
(2012)
thecolor-magnitude
population of PMS
panels&correspondto thecanonicalsuggested
cases
of 40% multiplicity and a uniform massaround◆Oribelongstotheassociation
NGC
1980
and
repreratio distribution.
Orion Nebula Cluster
sents a population of 4-5 Myr old stars located at ⇠ 30 pc in theforeground of Orion
A (Bouy et al. 2014).
their detailed
1, 12In D.
2 ,specG. Beccari1 , M.G. Petr-Gotzens1troscopic, H.M.J.analysis
Boffin1Da, M.
FedeleG. Carraro3 , G. De Marchi4 ,RioRomanielloet al. (2016) rule, out
this hypothesis
5
6
7
4
8
5
G. Beccari et al.: OmegaCAM
discoversin the ONC
findingthat thecandidateforegroundis kinematicallyW.-J.
demultiple
Wit sequences, J.E. Drew
, V.M. Kalari, C.F.
Manara, E.L.
Martinpopulation, S. Mieske, N. Panagia9 , L. Testi1 , J.S. Vink10 ,1 , the6, 11 conclude that theindistinguishable
fromone. They
J.R. Walsh
andOrion
N.J.A’s
Wrightold population studied by Bouy et al. (2014) witnesses the earliest (i.e. oldest) episode of star formation in the ONC. The three(Affiliations
can be foundafterinthe
Fig. 4. The leftdistinct
panelsshow
the hisPMS
populations
found
ourreferences)
CMD and their spatial
tograms of the distancein the (r-i)arecolornot compatible with the presence of a old foredistributionof the PMS stars from the mean ridge
May 29, 2017
groundpopulationline of the bluest
population,
as ob- of PMS stars. Fang et al. (2017) performed
and Carlo
extensive
spectroscopic analysis of 691 “foreground” stars
tained with our Montesimulations(black, heavy lines)
andOrionas observedin theA regionABSTRACT
and confirm that NGC 1980 is not a fore(red). The right panels show the corFig. 6. Distribution of the logarithm of the spectroscopically deterA&A proofs: manuscript
no. msONCthat the candidate foregroundgroundpopulation.
Considering
responding assumed distribution of themined ages for stars from the three populations, old (in blue), young
population
studiedby Bouy etsurvey,al. (2014)
is located
than
mass
ratiosall thebinaries
in oursimof thebe AccretionDiscs
ininofFig.
H↵
OmegaCAM(ADHOC)we imaged
in morer, i andH↵ a(inregion
12very⇥ 8young
squarealso higher total binary fractions, As
up topart
65% would
feasiblegreen),ofand(in red) with the best Gaussian fits indicated.
Moreover,ulated
as shown
5 withwe2 haveverifiedthat isthe stars
sample.
Theof eachsolution
1
deg
south
with
respect
to
the
peaks
of
the
densitymapsoftheaccording to our simulation. In thisdegrees
case, however,the blue
popfromthe threeNebulasequencesCluster.
have approximately
thetosame
distriaround
the
Orion
Thanksthehigh-quality
photometry
obtained,we
discovered
three
well-separated
prealsoindicated
in
the
left
panels.
Bothtopulation would contain a large number of unresolved low bution
q sys- of visual extinction AV . To
this aim
we adopted theshownAV
three
populations
in areFig.all3 concentrated
we think thattowards
it is unlikely
tomain sequences
inobthe color-magnitude
diagram.
the cluster’scenter.
Althoughofseveral
panelscorrespondtotheofcanonicaltems. Such specific mass ratio distributions
are at odds with
providedby thespectroscopic
analysis
Da RioTheet casesal. populations(2016).
Table
1. Properties
the three populations.
berelated.
of40%
multiplicity
anda
uniformmass
servations. We are thus led to the conclusion
that
in
order
for
the
explanations can beAninvoked
to explain
thesesequences
we are left with two competitive, but intriguing, scenarios: a population
alternative explanation
for thepresenceof the green andratio
distribution.
binary hypothesis to be valid, one would need to postulate reda verysequencescould
a PMS population
locateddistribution
more than 100 or three populations with di↵erent ages. Independent high-resolution
withanbeexotic
mass ratio
distinct mass-ratio distribution. of unresolved binaries
old
young
very young
and 200 pc in the foreground of the blue sequence, respectively.
spectroscopyof discrete
episodesof star formation, each separated by about a million years. The stars fromIn the same vein, the reddest sequence
we find in supports
the Alves
CMD & theBouypresence(2012) suggested
that the populationof PMS
Mean
Log
age
(yr)
6.46±0.06
6.27±0.09
6.09±0.07
would be even more difficult to explain,
as it would
requirearound
triple ◆ Ori belongs
to the association
NGC 1980
and therepre6. Three
discrete
episodesstar formation
the twoputative
youngest
populations
rotatefasterthanolder
ones, inof
agreementwith the evolution of stellar rotation observed insystems, where, the mass ratio distributions would have also
Mean age (Myr)
2.87
1.88
1.24
sentstoa population of 4-5 Myr old stars located at ⇠ 30 pc in the
pre-mainsequencestars ofyoungerthanet4al.Myr
severalstar
forming regions. Whatever the final explanation, our results prompt for abe quite tailored, i.e. the mass ratiosof both secondaries
andforeground
Orion A (Bouy
2014).inIn theirdetailed
spec1ageinterval(Myr)
2.51–3.28
1.55–2.29
1.08–1.53
Intheprevious
sections
we
show
that
di↵erential
extinctionor
tertiaries would need to be strongly
peaked lookto q > at
0.8theandbe analysis Da
troscopic
Rio etandal. (2016)
out this hypothesis
revisedformationmode
earlyrule
evolutionof stars in clusters.
2.30–3.58 1.37–2.60
1.04–1.63
exactly similar.
finding that the candidate foregroundpopulation
is kinematicallydistanceo↵setsare very unlikely to explain the discovered fea- 5–95% interval (Myr)+6+25from the Orion A’s one. They conclude that the
Although formally we cannot exclude the presence of indistinguishable
a popRotational
velocity(km/s)
1425
35+36
Key words. Stars:
pre-main sequence –al.open
clusters
andassociations:in theCMD.
The
presence ofOrionunresolved binary and tertiary
4
12
16
population studied by Bouy ettures(2014)
witnesses
the earliulation of binaries with an unusual f (q), the fact that no oldyoung
est (i.e. oldest) episode of star formationin the ONC.
The three the CMD morphology only if the underbinary population in any star forming region has shown indicapopulations
reproduce
tions of such an usual f (q), casts some doubts on binariesdistinct
as the PMS populations found in our CMD and their spatial
lying mass ratio distribution is rather unusual (Fig. 4).
distribution
are not compatible with the presence of a old foreorigin for the observed multiple sequences. On the other hand,if
In Fig. 6 we show the distributions of the ages derived
byground population of PMS stars. Fanget al.
(2017)explore
performedthe possibility that the age is the origin ofconfirmed this fact would certainly challenge many of the studies
We
here
G. Beccari et al.: OmegaCAM discovers mu
1. Introductionof multiple sequences in the observed
opticalcolor-magnitude
and extensive spectroscopic analysis of 691 “foreground” stars
published so far on the stellar
population in the ONC wheneverD16 ofthe stars
in the three samples. These age histograms inthe
discreetness
of
the
color
distribution
of
the
PMS
in
the
ONC.
in theetOrion A region and confirm that NGC 1980 is not a foresuch stars were considered as single objects (e.g. Hillenbrand
the
ONC.
Fig. 5. Distribution of the visual extinction, Av , for the stars
fromever, tFig.
6. diagram
Distributionof ofthe logarithmof the aspectroscopicallyground population.
Considering We
that thecandidateforegroundverifiedthat
the distancein magnitude
between
1 Myr anddeter-dicate that the three sequences that we discovered in the photoal. 2013; Da Rio et al. 2016).
the three populations, old (in blue), young (in green), and verymined
youngages for stars from the three populations, old (in blue), young
Herbs
Young stellar clusters
areconspicuouscomponentsofourpopulation
studied
by
Bouy
et
al.
(2014)
islocatedmore
thanmetric study have distinct ages, with the bluer population being(in red). The inset showsthenormalized
cumulative
fraction.
The anda3
Myr
PMS
isochrone
Bressan
et
in
the
r,
r
i
(infromgreen),
very young(inal.
red)(2012)
with the bestGaussianfits
indicated.
In
1 deg southwith respect to thetestpeaks
of thethat
densitymaps of the of the old
Kolmogorov-Smirnov
indicates
the Ainitial
v distribution
Galaxy. They are the
best
test
beds
of
the
stellarmass
rotatiotheoldest.
We
havefittedthe
distributions
with
Gaussians,usingisthatindeed⇠the0.75,
i.e. equal
to the the shift inluminosity
three populations
shown in Fig.population
3CMD
we think
it is fromunlikely
to parental
and intermediate-youngareextracted
same
5. Differential AV and distances scenario
2.
Observations
anddata
reduction
Table
1.
Properties
of
the
three
populations.
2
shown
be related.
with more
5entities
significance.
The a
very
young
populationThis unfortunate fact is at the root ofa -minimization technique, to derive the mean and standard
function because they
are distribution
assumedto thanbedueofcommonto unresolved
binaries.
eff
ing scAny e↵ect of di↵erential extinction can be rejected by the fact shows hints of a slightly higher Av distribution but is a↵ected by low
deviation( with). Asthethese
are field
distributions of the logarithm of theaccret
old
young
very
young
origin,
i.e.
born
from
the
same
molecular
cloudmaterial,
and
at
why
it
is
hard
to
distinguishbetweenthebinaryhypothesis
andthat the reddening vector as shown on the CMD of Fig. 1a runs number statistics.
The
images
used
in
this
work
were
collected
wide
et al. i
Mean Log age (yr)6.46±0.06 6.27±0.09
6.09±0.07 ages, we then estimated the corresponding distributions of the5parallel to the PMSs.
6. Three discreteofstarformation
multiple
population
scenarios.
the same time. Observations
have episodes
shown,thehowever,thatthe stars
cameraon
Mean ageoptical(Myr)
2.87OmegaCAM
1.88
1.24 the 2.6-m VLT Survey Telescopeages
andcomputedtherespective
1and
5–95%
intervals.
Ouralso higher total binary fractions, up to 65% would be feasible
1-5 ofage
2.51–3.28 1.55–2.29
1.08–1.53
number,8 interval
the previous
sections
show asthatIndi↵erential
extinction
orpageages
orderArticle
to expected.
assigntothe(Myr)stars
belongingto thethree OmegaCAM consists of a moborn in one and the Insame
clusterarewenotcoevalas(VST)at Cerro
Paranalin Chile.
2.30–3.58 1.37–2.60
1.04–1.63 results are shown in Table 1.
7. Co
according to our simulation. In this case, however, the blue popdistance o↵sets are very unlikely to explain the discovered fea- 5–95% interval (Myr)distinct
PMS
populations,
we
use
the
measurements
2+6+25presentedIn
fact,
stellarage
spreadsuptoseveralmillion
years
have
been
velocity
14 4
25 12samples
35+36
tures in the CMD. The presence of unresolved binary and tertiary Rotational
saic
of(km/s)
32 CCDs
andField
ofisView(FoV)
16 a 1 deg
ulation would contain a large number of unresolved low q sysWe haThisfinding
consistentwiththehypothesis
that
theforDa Rio
etifagesal.
(2016,
performed a specreproduce
CMD bymorphology
only
the under1
postulated
for severalpopulations
clusters
fromthefitting
isochronalto theD16 hereafter).
tems. Such specific mass ratio distributions are at odds withobulationa pixelD16
sampling
of 0.21 arcsec
pixel of
. the
Orion
was sampledlying mass ratio distribution is rather
unusual (Fig.
4). of the youngwith
mationpopulation
of
PMS
stars
in
the
ONC
that
was
troscopic
study
stellarpopulation
of
the
Orion
A
presenservations. We are thus led to the conclusion that in orderposition
for theof cluster member
the Hertzsprung-Russell
6 we show
the r,
distributions
ofbandthe agesderived andby the H↵ narrow band as partWe herestars
explore in
the possibility
that the age is the origin of di- In Fig.
throughtheibroad
filters
The dmolecular
cloud
with
the
In theirwork in-thought to be the outcome of a single episode extended overbinary hypothesis to be valid, one would need to postulate a very
D16APOGEEof the stars in spectrograph.
the three samples. Theseage histograms
the discreetnessof the color2010;
distributionof the PMS
in the
ONC.
agram
(HRD;
e.g.
Cargile&James
Cignoni
et
al.
2010;
15.5 <
ofthe
theAccretion
in H↵
with
(ADHOC)
sur- by 3 discrete and sequential
that
three
sequencesthat,Discs
we
discoveredin thephoto-3OmegaCAM
Myr is instead
best described
distinct mass-ratio distribution.
We verified that the distance in magnitude
between a 1 accurate
Myr and dicate
they measured
stellarparameters(T
logg,
vsini)
ande↵
We inv
metricstudy have distinct ages, with the bluer population being
Reggiani
et
al.
2011;
Bell
et
al.
2013;
Balog
et
al.
2016).
But,
if
a
3
Myr
PMS
isochronefromBressanetal.
(2012)
in
the
r,
r
i
In the same vein, the reddest sequence we find in the CMD
vey(PI:fitted
Beccari).
targetregionis sampled in groups of 3
servedextinctions
concludethatstarin Eachthewith
ONC
prothe oldest.
We
haveformation
the distributions
Gaussians,
usingepisodes of star formation over the same time span.
CMD is indeed ⇠ 0.75, i.e. equal
to the the shift andin luminosity
2
would be even more difficult to explain, as it would require
triplethisobservation is a consequenceof aThis
continuous
formationW-minimization
technique,to derivethehavemean
andstandard
overlapping
fields,andin crosseachgroupD16
the provide
fields are
alsocontiguous
stellar rotational velocities. However, specdue to unresolved binaries.
unfortunate
factstaris an
at theroot of a period
ceededover
extended
of
⇠
3
Myr
age.
We
velocisystems, where, the mass ratio distributions would haveprocess
also to lasting over why( ). As these are distributions of the logarithm of the2
it is harddynamical
to distinguish between
thescales,binary hypothesis
and deviation
severaltimeorratheris
only
providesinv sky
sin i,wewhere
i is the unknown
inclination
withaoffootprintclose todistributions
3(includ⇥ 1 deg. For eachposition
our stars withages,
thewecatalogstellarparameters
Fig. 7. Distributionof the logarithmof the rotational velocity of the for co5then estimatedthe correspondingof thetroscopy
be quite tailored, i.e. the mass ratios of both secondaries andthe multiple population scenarioscorrelated.

A Tale of Three Citiesの続き:1705.09496v1 [astro-ph.SR] 26 May 2017

観測、モデル 連星率

Ø 連星が単星として数えられる可能性。
Ø 光度LàM-L関係àMà質量比f(q)を与えるàqMを加えて色等級図に戻す。
Ø ほとんどq>0.6なら合うが、過去の研究に合わない。

年齢Av

Ø 赤(very young)は低Avが少ないà一番遠い。
Ø Da Rio+’16 (T , log g, V sin i)による分光年齢を見ると、
3 Myrの年齢幅を説明できる。
Ø さらに青(old)は回転速度が遅い。
àdisk-lockingか。今後、降着との関連も調べる。

回転速度

Complex Organic Molecules toward Embedded Low-mass Protostars∗
Jennifer B. Bergner1, Karin I. Öberg2, Robin T. Garrod3, and Dawn M. Graninger2
1

Harvard University Department of Chemistry and Chemical Biology, Cambridge, MA 02138, USA
The Astrophysical Journal, 841:120 (25pp), 2017 June 1
Bergner et al.
2
Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138, USA
3
University of Virginia Departments of Chemistry and Astronomy, Charlottesville, VA 22904, USA
Table 1
Received 2017 February 7; revised 2017 May 8; accepted Source
2017 May
12; published201716-object
June 2 c2d Embedded Protostar Sample
Informationof the Completewith Ice Detections
The Astrophysical Journal, 841:120 (25pp), 2017 June 1

Ø 小質量星のCOM (水素リッチ 6原子以上)は生命の起源。
X
X
Source
R.A.
Decl.
Cloud
L
M
α
N(CH OH)N(H O )rms
Ø ダスト表面で小さい飽和分子 (第0世代)
Abstract(J2000.0)
M
10 cm
10 cm
%HO
%HO
(mK)
(J2000.0)LØ 光解離でラジカル Complex organic molecules (COMs) have been
B1-a observed toward
03:33:16.67
31:07:55.1
Perseus1.87(LYSOs).
10.21 [3.24]
10.39 [2.26]<1.9
3.33 [0.98]
3.6
severallow-mass
young1.3stellar2.8objects
B1-c
03:33:17.89
31:09:31.0
Perseus
3.7
17.7
2.66
1.69 [0.51]
29.55 [5.65]
<7.1
<4.04
5.5
Small
and
heterogeneous
sampleshavesofar
precluded
conclusions
on
typicalCOM
abundances,
as
well
as
the
B5 IRS1
03:47:41.61
32:51:43.8
Perseus
4.7
4.2
0.78
1.77 [0.46]
2.26 [0.28]
<3.7
<2.09
7.0
Ø >30 Kで第1世代
origin(s) of abundance variations between sources.
observations
toward16 deeply0/
HH 300 We present
04:26:56.30
24:43:35.3
Taurus1.27 embedded
0.03
0.79 (Class
0.24 [0.10]
2.59 [0.25]<6.7
3.46 [0.90]
5.8
IRAS03235+3004 We
03:26:37.45
30:15:27.9
Perseus
1.9
2.4
1.44
1.17
[0.08]
14.48[2.26]
4.2
[1.2]
4.71
[1.00]
4.2I) low-mass
protostars using the IRAM 30 m
telescope.
detect CH
CO,
CH
CHO,
CH
OCH
,
CH
OCHO,
Ø à 100-300 Kでガス反応(第2世代)
2
3
3
3
3
IRAS 03245+3002
03:27:39.03
30:12:59.3
Perseus
7.0
5.3
2.70
1.54 [0.29]
39.31 [5.65]
<9.8
<4.40
3.7
13%,
13%,
44%,
81%,
and
75%
of
sources,
respectively.
Median
CH3CN, HNCO, and HC3N toward 67%, 37%,
IRAS 03254+3050
03:28:34.51
31:00:51.2
PerseusK
0.3
0.90 12 K−2
3.66 [0.47]<4.6
6.66 [1.37]
3.9
10
−2
column densities
derived using survival analysis
range between
6.0×10cm Perseus(CH3CN)cm[0.04] 7.69 [1.76] <5.6
Ø これまで14天体だがprestellar
coreから水氷がIRAS 03271+3013
03:30:15.16
30:23:48.8
0.8 and1.22.4×10
2.06
0.42
6.37 [1.86]
4.804108+2803
K
0.90[0.44]
2.87 [0.4]<3.5
4.29 [1.03]
4.0(CH3OCH3), and median abundances range IRAS
between
0.48% 04:13:54.72(CH3CN) 28:11:32.9
and 16% Taurus(HNCO)0.62
with respect
to CH1.04
3OH.
IRAS 23238+7401
23:25:46.65
74:17:37.2
CB244
K
K
0.95
2.19 [1.01]
12.95 [2.26]
<3.6
<1.24
2.7
溶ける段階まで。
Column densities for each molecule vary byL1014
about
one
order
of
magnitudeacrossthesample.
Abundances
with
IRS
21:24:07.51
49:59:09.0
L1014
K
K
1.28
0.88 [0.56]
7.16 [0.91]
3.1 [0.8]
5.20 [1.43]
2.8
respect to CH3OH are more narrowly distributed,
especially03:25:09.44
for oxygen-bearing
species.
compareL1448 IRS1
30:46:21.7
Perseus17.0 We 16.3
0.34 observed
0.23 [0.04]
0.47 [0.16]
<14.9
<4.15
3.7
Ø 大質量星より多い、少ない両方の予想。
0.32
0.2 although
0.98
1.46
[0.88]
0.92 [0.37]<12.5
6.21 [3.51]
3.9
median abundances with a chemical modelL1455
forIRS3
low-mass 03:28:00.41
protostars30:08:01.2
and ﬁndPerseus
fair agreement,
some
c

c

bol

env

e

e

d

d

d

d

d

13

3

−2

2
18

a
(ice)
−2

CH3OH (ice)2bNH3 (ice)

b

2

d

e

c

a
IR

f

d

d

d

d
d

d

c

d

e

d

d

d

g

SMM1
03:27:43.25
30:12:28.8
Perseus
3.1d
5.3d
2.41
1.48 [0.76][2.82]
<13.5
<8.29
4.1
abundanceswithrespect
to 18.21
modeling work remains to bring abundancesL1455
higherwith respect
to CH
3OH. Median
L1489 IRSc
04:04:43.07
26:18:56.4
Taurus
3.7e
0.1h
1.10
0.69 [0.14]
4.26[0.51] column densities
4.9 [1.5]
5.42 [0.96]
5.4with res
Figure4.
(a)Observedforeachmolecule.
(b)Abundancesc
CH3OH in LYSOs are also found to be generallycomparable
to observed
abundances
corinos,
SVS 4-5
18:29:57.59
01:13:00.6
Serpensin hot
38i cores,
K hot 1.26
11.19and[4.29]
5.65blue.
[1.13]
25.2 sources[3.5] are ordered∼4.3 alphabetically: B1-a,
3.9 B1-c, B
limits in light
For each molecule,Ø おもしろい天体だけでなくClass
16個を選んだ。
massive YSOs.0/I
Comparedwith comets, our sample is comparable for all molecules except HC3N and CH2CO,
Notes. Adaptedfrom Graninger et al. (2016).
which
likelybecomedepletedat later evolutionary
stages.
Ø 北半球、氷吸収、IRAM 30 m, 27”-21”
Boogert et al. (2008).
The Astrophysical Journal, 841:120 (25pp), 2017 June 1

Bergner et al.

23238, L1014 IRS, L1448 IRS1, L1455 IRS3, L1455 SMM1, L1489 IRS, SVS 4-5.

abBottinelli
et al.
(2010).
Key words: astrochemistry – ISM: molecules– stars:
protostarsc

Sources were observed by Öberg et al. (2014).
Hatchell et al. (2007).
e
Furlan et al. (2008).
f
1. Introduction
Arce et al. (2008). produces the same types of molecules that are commonlyg
Enoch et al. (2009). observed in YSOs, although some COMs are still underhComplex organic molecules (COMs), hydrogen-rich molecules
Brinch et al. (2007).
produced in models compared to observations (Caselli &Pontoppidanwith six or more atoms, have been observed toward ihighand et al. (2004).
d

検出だけ
survivalØ 光学的に薄いLTEで柱密度。CH3OHの柱密度は文献から。
Ø 上限値を使わず、検出値だけだと過大評価
Ceccarelli 2012). Once temperatures reach 100–300 K, large
low-mass star-forming regions, molecular outﬂows, and prestellar
2. Observations
protostars
withhotenvelopes andno ice andabsorption.
molecules
desorbreact Moreover,in the gas phase to form “secondØ àsurvival analysis
cores (e.g., Blake et al. 1987; Bottinelli et al. 2004b, 2007;
Arce size is small (∼14 objects), and objects that were
the sample
generation” molecules. Gas-phase reactions
mayselection
also playa
Sourceand observation
strategy are described in detail
et al. 2008; Öberg et al. 2010; Bacmann et al. 2012; Cernicharo
chosen for hosting interestingchemistry may not bechemistry
representative
Ø Kaplan-Meier推定（経過観察の中断など）・・・
role in ﬁrst-generation
via thein desorptionof(2016).
smallBrieﬂy, 16 Class 0/I YSOs, identiﬁed
Graninger et al.
et al. 2012; Fayolle et al. 2015). COMs formed at theseof the earlytrue sample distribution.
by reaction
their IR spectral
indices,
molecules,
namely,followed byin thegas were selected from the Spitzer c2d ice
3OH,of uncertainties
in “typical”
LYSOCHCOM
abundances,
stages of star formation can become incorporated intoBecause
proto全てを昇順にして、検出に挟まれた上限は小さ
柱密度（上）、CH3OHとの比%（下）
samplepresented
in
Boogertphase rather than on grain surfaces (e.g., Balucani et al. 2015). et al. (2008) based on their location
it is unclear
planetary disks (Visser et al. 2009, 2011) and further
into how LYSOs compare with their massive counterpartsin the northern hemisphere and their ice abundances (Table 1).
(MYSOs)in terms of chemicalrichness.
It hasbeen claimed
both scenarios
Both theice andgas-phasechemistry
predict a close
い方の検出値とする(検出に上限で重み付け)。
検出、上限
The sources were observed with the IRAM 30 m telescope using
planetesimals and planets, seeding nascent planets withthatcomplex
LYSOs are more enhanced in COMs than MYSOs (Bottinelli
Figure 4. (a) Observed column densities for each molecule. (b) Abundances with respect to CH3OH. For both panels, detections are shown in dark blue and upper
limits in light blue. For each molecule, sources are ordered alphabetically: B1-a, B1-c, B5 IRS1, HH 300, IRAS 03235, IRAS 03245, IRAS 03271, IRAS 04108, IRAS
23238, L1014 IRS, L1448 IRS1, L1455 IRS3, L1455 SMM1, L1489 IRS, SVS 4-5.

03254, we omit this source from comparison. Once normalized to
CH3OH, B1-a and SVS 4-5 molecule abundances are consistentor underabundant compared with other sources, suggesting that
their high column densities do notthesignifya distinct
EMIR
90chemistry.
GHz receiver and the Fourier Transform Spectro-

connection between COMs and the original ice composition. Ice
organic material. COM abundances around protostars are
thus2007;of Herbst & van Dishoeck 2009) and that LYSO
et al.
composition is known to vary betweenmetersources,
especially(FTS) backend.
B1-a, B5 IRS1, L1489 IRS, IRAS 04108
abundances are comparable to or smaller than MYSO abundancesconsiderable interest for the study of origins of life. Low-mass
3.3.2. Median
ColumnDensities
andFurthermore,
Abundances
CH
OH
ice
abundances(Öbergetal.
2011a).
the and SVS 4-5 were observed on 2013
+2803,
IRAS
03235+3004,
3
estimateofstars host most planetary systems, and so the (Bisschop
molecularet al. 2008; Öberg et al. 2011b). A better
abundances were ﬁrst calculatedusing detections
only;5. (a)June 12–16
at 93–101
GHzand
109–117GHz.
All othersourcesFigureMediancolumndensities ofeach molecule,calculatedusingchemistry may depend Medianon thestellar radiation
ﬁeld
and
the

25pp), 2017 June 1

Bergner et al.

Complex Organic Molecules toward Embedded Low-mass Protostars∗の続き

Garrod et al. (2017); however,for the moleculesof interest
2
3
Jennifer B. Bergner1, Karin I. Öberg
,AstrophysicalRobin T. Garrod, and Dawn M. Graninger2
The
Journal,and
841:120 (25pp), 2017 June 1
Bergner e1here, the differences
betweentheworkofGarrod(2013)The Astrophysical Journal, 841:120 (25pp), 2017 June 1
Harvard University Department of Chemistry and Chemical Biology, Cambridge, MA 02138, USA
2
Harvard-Smithsonian
Center for
Astrophysics,
Cambridge,
MA 02138, USA(dark blue) temperature proﬁles. Triangles representsabundances
results fr
more recent implementations
are veryminor.
The
model
Figure 7. Column densities (cm−2) of each molecule plotted against one3 University
another. Detections
areDepartments
shown as black
circles andand
upper
limits are Charlottesville,
shown as gray arrows.
of Virginiaof Chemistry
Astronomy,
VA 22904, USA
temperatures
the ﬁducial temperature proﬁles, and error bars show
the resu
both Received
the gas-phaseandgrain-surface/ice-mantleØcorrelation
Menvとの相関。HC
cold envelopeで反応。
Pearsoncoefﬁcients are listed in brackets.
2017 February 7;
revised2017 May 8; accepted 2017 May 12; published 2017 June 2
3N:considers
for temperature proﬁles 10% higher and 10% lower.et al. 2016),
while the maformationand destructionofmolecules. COMs are largely
Apart from HNCO, the model abundances are within
an ofor
the trend
CH3CN: 高温反応、HNCO:
両温度。CHOH:
ダスト反応。
3 no COMs are detected despite
Bergneretal.
ofmagnitudeoftheobservations.
Agreement
within
an
order
The
high
being oneof the most massive and
Abstract
assumed to have only dust-grain-related formation
mechanis a resultino
magnitude is very reasonable given modeling uncertainties
luminousof
oursample.
Massivesourcesare morelikelyyoung
to be stellar objects (LYSOs).
by H atoms
isms,
in
the
absenceof
otherinformation.
Complexorganic
molecules(COMs)
havebeen
observed
towardseverallow-mass
reactionrates,
aswell
asobservational
uncertainties
inod et al. (2017); however, for the molecules of interestyoung sources (e.g., Hatchell et al. 2007), so its unusual
Chemical ddifferent
excitation
properties
ofthemolecules
being
comparedSmall
andheterogeneous
sampleshavesofar
precluded
conclusions
on
typicalCOM
abundances,
as
well
as
the
We
run
the
model
multiple
times
using
a
selectionofcases, as dethe differences between the work origin(s)of Garrod(2013) andcharacteristics
be related
to an observations
early evolutionary
stage.
particular,
using an efofabundance
variations
betweencould
sources.
Wevalues
present
16 deeply embedded (Class
0/ the systematic underestimation of most molecules
physicalconditions
thatarerepresentativeof
at detected
a rangeintoward
the
model
in the moAllsourcesinthesample
have
been
water
ice
and
e recent implementations are veryI) low-mass
minor. protostars
The modelusing the IRAM 30 m telescope. We detect CH2CO, CH3CHO, CH3OCH3, CH3OCHO, may be due in part to an excess of CH3OHhydrogenati
sufﬁcientlyatlarge
radii,
causedbyoveractive
chemicaldesorptionofradialdistances
from
the
core
center.
We
use
results
from
CH3OH,
and respectively. Medianat least67%,
one ofthe 13%,minor13%,ice constituents
while the to37%,44%, 81%,NHand3,75%of sources,
CH3CN, HNCO, and HC3Nintoward
iders both the gas-phase and grain-surface/ice-mantle
methanol
HNCOs
10
−2
12
−2 at cold temperatures. The underproduction ofrelatively
CH
(see
Table
1).
In
the
context
ofCOM
formation,
it
is
this
grid
of
chemicalmodelstoproduceacomposite,spatiallycolumndensities
cm orders of magnitude is likely a result of an overestima
ation and destruction of molecules.
COMs
are derived
largelyusing4 survival analysis range between 6.0×10 cm (CH3CN) and 2.4×10 several
grains is com
especiallyinteresting
test0.48%
whether
relative
abundances
ofwith respect to CH(CHformation
andmechanmedianabundances
range(CHtheand 16%(HNCO)
barrier
for the grain-surface process of NH + COboth directio
HNC
dependent
pictureof thechemistry
inbetween
thetoLYSO.
3OCH3),
3CN)
3OH.
med to have only dust-grain-related
these proceswhich
impedes
efﬁcient
grain-surface
formation
of
HNCO
in
Oand
N-bearingCOMs
arerelatedtotherelative
ice
Columndensitiesforeachmolecule
vary
by
about
one
order
of
magnitudeacrossthesample.
Abundanceswith
We begin with a spherically symmetric physical model of aformed met, in the absence of other information.
model. While there are no strong constraints on thisboth
barrierfr
abundances
CH3OH (thetheoreticalstarting point ofspecies.
O-rich We compare observed
respect to CH3OH are morenarrowly of
distributed,
especiallyfor oxygen-bearing
its form
LYSO,
with
a
power-lawtemperature
proﬁleadaptedlaboratory work, recent modeling work by Bellochedesorption,
et al. (20e run the model multiple timesgenericusingaselectionofmedian abundances with aCOM
chemicalmodel andfor low-mass
and ﬁndcarrier
fair agreement,
although somechemistry)
NH3 (theprotostars
main observedofadditiotested several values ranging from 1000 to 2500 K, the In
latterva
from&a range
Richer(2000):
大質量星
OH.
Medianabundanceswith respect
to one used in our present study. They foundmodeling
workatremains
to nitrogenbring
abundanceshigherrespect
to CH
ical conditions that are representativeofChandler
valuesice abundan
in interstellar
iceswith(Öberget al.
2011a);
N
is
also
a
3
2
being thethat
in LYSOs
also possible
found to reservoir
be generallycomparable
to observed
abundancesin hot cores, hot corinos,
andis required to be no greater than ∼1500 Kabsorbanceof nitrogenin icesbut cannot
be observed
3OHusebarrierin orderbolometricluminosity.
Upper
adial
distancesfromthe limits
core center.CHWe
resultsarefrommaterial
rat
q
2
-qour
⎞
⎛
massive
YSOs.
Comparedwith
comets,sampleiscomparableforallmolecules
except
HC
N
and
CH
CO,
producesufﬁcient
HNCO
toexplainobserved
abundances
observedice⎛⎞
directly).
The
numberofsources
with
both
CH
OH
and
NH
3
2
ngrid
correlation
coefﬁcients
are
shown
r
L
3
3
bol
of chemical models to produce a composite,spatiallyeach icemo
spe
CH3NCO. The value of around 2500 K used in the present
T (r )become
K, only 10 sources(4 )= 60 ⎜depleted⎟ small:⎜ 5 stages.
which likely
at15later⎟
evolutionary
detectionsisunfortunately
have
both
maximum⎝ 2 ´ 10 m ⎠ ⎝ 10 L : ⎠Figure was
14. Model
results showing
the fraction
molecule’swhen
total column
ndent picture of the chemistry in the LYSO.
adoptedby Garrod
et ofal.each(2008),
this reaction
was rﬁwith the me
density that comes from different temperature ranges. For each molecule, the ydetections,or one –detection
and one low upper limit, forKeywords:
astrochemistry–
ISM:
molecules
stars:
protostars
into thenetwork,
and was based on the barrier
scale is introducedtheØsame as反応温度分布。
is indicatedfor CHOH.
8. Column
plotted againstenvelope mass.
Upper limits
due to of adensities fou
on
eFigurebegin
with densities
a sphericallysymmetric
physicalmodel
CH3OH and NH3 ice columns. Of this, only a subset are rich in
HCO. Reducing
for the analogous reaction H + CO
values of 10
molecule
nondetections
are
shown
in
blue.
Pearsoncorrelation
coefﬁcients
are
Ø
モデル。
ric
LYSO,
with
power-law
adaptedwhere weproﬁleassumeq=2/5
andwhich
Lbol islimits
eitherthe1 or
10 Le. For oftheany correlation
few detectedlines,
so of
it is2500
difﬁcult
to assesshow K
seriousthese K,
respect
to wa
current
value
K to
the CH3OH~81500
recommended
by Belloc
COMs,
conclusiveness
cf.,
回転温度
shown
in brackets
in thea lower
right corner.temperatureof a few of
constraints
are.
They
seem toimprove
rule out, agreement
however, thatthe our observatio
et
al.
may
therefore
with
Chandler& Richer
the withsamerespecttypes ofthat arecommonly
1. Introduction
studies.
abundances
to molecules emission
proﬁle,we assume
theFigurepower10(a)law:shows theproduces
is coming
exclusively from the hot material asØ q=2/5,
n1000(2000):=1e6 cm–3density, α=1.5,
T=10-250
K。
data
in futuremodelK,
iterations.
CH
CO~8
CH CHO~8 K, 19% are som
3

In the mopredicted
theHC3N, HNCO, CH
2 model.
32CO, and CH3CN
observed
YSOs,against
althoughareby still
underno single molecule stands out as particularly
correlatedwith(COMs),
CHhydrogen-richnitrogen-bearing
species,inplotted
the some COMs
3OH gas for theComplexwellorganic
molecules
molecules
Figure by
14temperatures
shows thecolder
fractionof Keach
total colu
outsideof th
are all dominatedthan 50in themolecule’s
model.
q2aqmodels HC
compared
to observations(Caselli& different
Lbol. This suggests
not driven⎞areatoms,⎛sixLorOH ricehighratio
the samein sources.
to K,
6 au modin th⎞ andtoward produced
The available
rotationaltemperatures(14 K,K for
HC3N and27rangesK
3/CH⎛
3toward3N/
densitycomingfromtemperatureinthe⎛ that rthe weak⎞withcorrelationsCH
OCHO~16
CH
CN~27
more
have been NH
observed
3
3
bol
⎜
⎟
much smalle⎜ rather excess ⎟excitationfor 100–300
CH
fully
consistent withThus, therotationalmodel
nH (rmolecular
) (=
n1000
(5) Once.are clearly
Ceccarelli2012).
temperaturesreach3CN) are(r ) = 60but4)CH
au gas-phaseby Tchemistry,and⎟ice K,
desorption⎜ 5star-forming
which
canK,
be large
compared
withthis.
measuredtemperatur
ratiosnot correlatedwith NH
3OH
3/
彗星
low-massregions,
outﬂows,
andprestellar
ic
15
⎝
⎠
successfully
reproducestheenvelope-dominated,
low-temper⎝⎠
auOtherwise, there2 ´ 10aroundm hotterL : ⎠ The most⎝ 10 protostars.
HC
N~14
K,observed
HNCO~14
K。 therefore
We
note
that
if theLYSOs,
transitions
notsamein LT
molecules
desorb andrelationreact in the gas phaseform“secondra(affecting all molecules)
CHet
ice1000
ratios.
are no conclusive
3seen
aturetochemistryin these
withoutline
the needfor hot- are the3OH
cores (e.g.,
Blake et al. 1987; Bottinellial. 2004b,
2007;
Arce
then themeasuredrotational
will underestim
observed ga
core maychemistry.
This
is true evenfor CH3CN,temperatures
which is typicallygeneration”
molecules.
Gas-phasereactions
also
play
a
ships
betweentheabundance
of
NH
ice
and
nitrogen-bearing
obvious outlier in Figures 8 and 9etisal.
L1448
IRS1,
toward
which
3
2008;
Öberg
etthe
al. 2010;
Bacmann
2012; Cernicharo
N以外はnonLTE。
a 3
hot-coremolecule. To
The assess
gas-phasetheHCkinetic
howpathway
much this molecules
impacts tho
Basedon
medianvalueset al.
determinedfrom radiativerole intransferﬁrst-generation chemistry via the considered
desorption
oftemperature.
small
ice composi
re we assume q=2/5 and Lboliseither
1
or
10
L
.
For
the
described
inSection5.1
ismainlyresponsibleforthislukewarmeFigure 13. COM abundances with respect to CH3OH across different types of
et al. 2012; Fayolle et al. 2015). COMs formed at these earlyobservations, we run RADEX models for moleculeswith bØ HNCO以外は桁では観測と同じ。
and inner ein theinmodel
andgasis driven by an enhancement of gasmolecules,
namely,CHstars.
followedby formation
reactiontheobjects.et
For allpanels,
LYSOs areshown as pink
Scatterpoints
represent
3OH,
9 protostars
modelingof low-massin Jørgensenal.
(2002),
wecollisional
constants
androtationaltemperatures(HC
ity proﬁle, we assume the powerstages law:ofstar formation
can become
incorporated
into protoproﬁlesare3Ø
大質量星とはおよそ同じ。
phase HCN. This in turn is due to either sublimation of HCN
median values, phaseand error rather
bars span thanthe ﬁrston
and grain
third quartiles.
(a) Comparison
surfaces(e.g.,
Balucanietal.
2015).
6
−3
CH
CN,
and
CH
OH;
van
der
Tak
et
al.
2007)
using
sublimation
3 in warmer regimes
3(∼40 K) or purely gas-phaseØ HNCOの反応率を上げるべき(Belloche+’17)。
the protostellar
warm-up model described in Section 4 from grains
planetarydisks (Visser
al. 2009,
further with
into
assumen1000 auet=10
cm 2011)andandα=1.5.
Weabundances
also fromassumeantemperatures
column sublimation
densities
ice blue)
andproﬁles.
gas-phasechemistry
scenarios
predictin rotational
acoolerclose
HCN measured
formation
regimes.
The observedandrotational-ablue)Bothand 10theLe (dark
Error bars
span the resultsfor 1 ØLe (light
彗星とも同じなので太陽は典型的。
⎛⎞
tion to ices
planetesimals
andplanets,seeding
nascent
planets
withcomplexrtemperature
of
27K
is
consistent
with
some
combinationof
innerradiuswhereT=250K,
again
following
Jørgensenetal.
inputsandassuming
thedensityandtemperature
proﬁlesfortemperature
proﬁles10%higher
and
10%
lower
than
the
ﬁducialrun.
(b)Ø CHn3HOHが系統的に高いのは外側でoveractive
connection
between
COMs
and
the
original
ice
composition.
Ice⎟
observed ga(r ) = n1000 au ⎜ organic material.
(5around). COM abundancesintermediate-temperature
production
of CH
3CN.
Comparisonof different star formation environments. Hot corinos (van low- andprotostars are thusofØ HC
Section
4.1.
We
ﬁnd
that
CH
CN
and
HC
N
observations
3
3
NとCH
COは後期になくなるかも。
⎝ 1000 au⎠
composition
known
toin vary
betweenespecially
CH3CHO is foundentirely at warm temperatures (50–100 K) in
3 =10
2is2003)(2002),
andforanthe
outerradius
where
K.Dishoeck
In theet al.L
1995;
Cazaux etLal.
are showndark pink,
MYSOs sources,bolewell due
reproduced
byoftheconsiderable
interest
study
of originsof T=10
life. Low-masschemical desorption(?)。
to desorption
CH3simulated
CHO formedRADEX
on grain emission wh(Fayolle et al. 2015)
inOH
light ice
blue, abundancesand hot cores (Bisschop
et al. et2007)
in 2011a).
dark the model,CH(Öbergal.
Furthermore,the3
5.3. Ma
CH
OH
is
not.
Therefore,
forsomemolecules (especia
surfaces;
this
is
much
higherthanits
observed
8
K
rotationalcase,atemperature
of
250
K
is
achievedataradius
of
3.8
au,
with
3
stars host most planetary systems, and so the molecular
blue. (c) Comparison with observations of solar system comets (Crovisierchemistry may depend on the stellar radiation ﬁeld and the