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-

High-mass Star Formation in the Outer Scutum–Centaurus Arm
W. P. Armentrout1,2, L. D. Anderson1,2,3, Dana S. Balser4, T. M. Bania5, T. M. Dame6, and Trey V. Wenger4,712Department of Physics and Astronomy, West Virginia University, Morgantown, West Virginia 26505, USA
Center for Gravitational Waves and Cosmology, West Virginia University, Chestnut Ridge Research Building, Morgantown, WV 26505, USA
3
Adjunct Astronomer at the Green Bank Observatory, P.O. Box 2, Green Bank, WV 24944, USA
4
National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903-2475, USA
5
Institute for Astrophysical Research, Department of Astronomy, Boston University, 725 Commonwealth Avenue, Boston, MA 02215, USA
6
Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA
7
Astronomy Department, University of Virginia, P.O. Box 400325, Charlottesville, VA 22904-4325, USA
Received 2017 March 3; revised 2017 April 20; accepted 2017 May 5; published 2017 June 2

Abstract
The Outer Scutum–Centaurus (OSC) spiral arm is the most distant molecular spiral arm in the Milky Way, but until
recently little was known about this structure. Discovered by Dame and Thaddeus, the OSC lies ∼15 kpc from theHigh-mass Star Formation in the Outer Scutum–Centaurus Arm
W. P. Armentrout1,2, L. D. Anderson1,2,3, Dana S. Balser4, T. M. Bania5, T. M. Dame6, and Trey V. Wenger4,712Department of Physics and Astronomy, West Virginia University, Morgantown, West Virginia 26505, USA
Center for Gravitational Waves and Cosmology, West Virginia University, Chestnut Ridge Research Building, Morgantown, WV 26505, USA
3
Adjunct Astronomer at the Green Bank Observatory, P.O. Box 2, Green Bank, WV 24944, USA
4
National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903-2475, USA
5
Institute for Astrophysical Research, Department of Astronomy, Boston University, 725 Commonwealth Avenue, Boston, MA 02215, USA
6
Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA
7
Astronomy Department, University of Virginia, P.O. Box 400325, Charlottesville, VA 22904-4325, USA
Received 2017 March 3; revised 2017 April 20; accepted 2017 May 5; published 2017 June 2

Abstract
The Outer Scutum–Centaurus (OSC) spiral arm is the most distant molecular spiral arm in the Milky Way, but until
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 nearly 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 II 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 II 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 consistent
with that of the OSC. Nearly 60% of the observed sources were detected in radio continuum, and more than 20%
have ammonia or water maser detections. The velocities of these sources mainly place them beyond the Solar orbit.
These very distant high-mass stars have stellar spectral types as early as O4. We associate high-mass star formation at
2 new locations with the OSC, increasing the total number of detected H II regions in the OSC to 12.
Key words: Galaxy: structure – H II regions
Supporting material: extended ﬁgures
1. Introduction
An H II region is an area of ionized hydrogen surrounding
massive stars. Stars of O and early B-type emit enough Lymancontinuum radiation (91.2 n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
with(see
CASA(McMullin
Henrik Beuther2, and Gael Chauvin9,10mJy
Figure1).
1

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, USA
we describe
more detail
Section with
3, we describe
We have
adopted a kn valueof 2.3in cm
g theattarget;
230in GHz
r radiometer), correcting
6
Schoolof Cosmic Physics, Dublin
Institutefor
Advanced
Studies,
31
Fitzwilliams
Place,
Dublin2, Ireland
sr 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 sameasliterature;
inAndrews
et5, al.
a frequency
dependenceof nour(shadowing,
INAF-Osservatorio
AstroﬁsicodiArcetri,
L.go
E.
Fermi
5,
I-50125
Firenze,Italy
thecomparison
with
the
and
in
Sectionwe
present
compare them with the available literature.8
ourconclusions.
Astronomy,
E.C. Stoner
Building, The
of Leeds, Leeds LS2 9JT, UK
for School
Taurus,and9andmore
recently
by Pascucci
etUniversity
al. (2016)), deriving
the bandpass
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Pa
Mo yr ,with
OTS44
from the literatureβ,to8e–12
be compatible
this2. Chile
assumption.
ainty isbut, based
Santiago,
Received2017
February
20;OTS44
revisedis2017
accepted
2017spectral
April
28;
estimatethedisk
dust mass from millimeterdata,
赤外へのモデルはM
the AprilobjectthelatesttypepublishedTdust. in the 2017 May 18
Theremainingstrongassumption
rests
on9;withthechoice
of
med
aØ
more
conservative
dust=0.17M
Eàミリ波が必要。
Chamaeleon
I
(Cha
I)
star-forming
region(M9.5)
witha massat the emission is optically thin andisothermal
at used for Tdust below
is 20or close
K, butet(withal.estimates(2013)A typical
value
to theAndrews
planetary borderfrom 6 to
Abstract
therefore; Luhman etsigniﬁcantlyal. 2005b; Bonnefoy
et al. the2014). First
17MJupscales
dust
showedthat242
thisGHz,
temperature
withwe, andtried
to applyselfØ ALMA
Cycle
3, 224,
226,
240,
1.6”,
9.8
µJy/beam。
evidence
for a disk around OTS44 came from mid- and far-IR
OTS44
is one of of
only thefour free-ﬂoating
planets
known
to havethe
a and
disk.
We have previously shown that it is theluminosity
central excess
object,relation:ﬂux recovery Fbutthe2emissionproposing
detected with Spitzer
Herschel (Luhmann ´ dMcoolestand
least
massiveknown
free-ﬂoating
planet
(∼12
)
with
a
substantial
al. 2005b; Harvey
et al.
2012a,In addition, wedisk that is actively accreting.
Jup 2012b).
However,
thisempirical
relation
wasMnot
good enough. , Tdust = 25 ´ (L* L :)1 4 K . etobserved
dust =The
Astrophysical Journal
Letters, 841:L11 (4pp), 2017 May 20
OTS44
with VLT/SINFONI
and verydetectedstrong,disk-bearing object. The data
We have obtained Band 6 (233 GHz) ALMA
continuum
data of this
young
k
´
(
)
B
T
n
n
dust
Figure 1. Frequency collapsed ALMA Band 6 data of OTS44. The 1
yieldsatemperature
of
5.5
for
OTS44
a
wo spectral windows as
broad,Kand variable
Pa β emission,(assumingwhich is evidence foractiveshow a clear unresolved detection of the source. We obtained disk-mass estimatesvia
empirical correlations
disk accretion in the planetary regime with a relatively high mass-−12−1
derivedyoung,(substellar)
rangeetof
e ﬂux density, d is the distance to
Cha Ifor(160
pc ishigher-mass, central; Joergens
al. values2013). obtained are between 0.07 andaccretion
rate (8×10objects.
M: yrThe2
recently determined
propertiesof withthe diskof OTS44(dust masses). We compare theWepropertiesof this theuniquedisk
those
recently reported around higherMÅabsorption
ittet et al. 1997), kn is the 0.63
mass
(Joergens et al. 2013; Liu et al. 2015) through radiative transfer
mass (brownTdwarfs)
young objects inorder to infer constraints on its mechanism of formation. While extreme
modeling of its spectral energy distribution from the opticald Bn is the Planck function of temperature
dust atseparated as possible to obtain a spectral index, but once again,
assumptions on
dust temperature yieldto disk-massvalues thethatradiative
could slightly
divergetheS/N
generaltrends found
the far-IR applying
transfer code
MC3Dfrom theof the data was not good enough for this purpose.
frequency.
(Wolf
2003)
and
a
Bayesiananalysis.
The
disk
model
that
ﬁtted
for more massive brown dwarfs, a range of sensible values provide disk masses compatibleThewithunique primaryscalingbeam corrected image (naturalﬁnala CLEAN,
the mid- and far-IR data best was that of a highly ﬂared disk
opted a kn value of 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* throughthe substellar domain down to planetary masses.
with a dust mass of 0.17MÅ. However, our far-IR Herschela central reference frequency of 233 GHz, and a frequency
ependence of n 0.4 , the same as in Andrews et al.
measurements(a detection
at 70 μm
and anpre-main
upper limitsequenceatrange covered (not continuously) of 20 GHz. We detected
Key words: brown dwarfs – stars: formation– stars:
low-mass– stars:
urus, and more recently by Pascucci
et al. (2016)
160 μm) are insensitive to millimeter-sized grains, which
OTS44 as a point-like source with a peak ﬂux value
prevented us from concluding about the presence of large
0.101±0.01 mJy (see Figure 1).
r consistency, we have adapted all Mdust values
grains (a maximum grain size of 100 μm was assumed in Liu
ature to be compatible with this assumption.1. Introduction
et al. 2015), with this potentiallyleading tounderestimation
Barradoy anNavascués
et al. 2007; Luhman
et al.
2008; Dust
BayoDisk Mass
4. Results andDiscussion:of the disk dust mass. In this Letter, we report the ﬁrst ALMAing strong assumption rests on the choice of Tdust .
et al. 2012),
far-IR(Herschel;e.g.,Harveyal. 2012a,
The most
direct etquantitythat we 2012b;
can derive from our data is
detectionof thestars
disk of a planetary-mass
object,providingaKeyquestionsetare
unanswered about how
low-mass
Andrews
al.still(2013)
e used for Tdust is 20 K, but
the
dust
mass
of
the
disk.
this section,
Alves
deOliveira
Liu we provide such
more robust estimate of its massand supporting
the ideaetthatal. 2013; Joergens et al. In2013;
come to emerge and gain their masses from
their
natal
estimates
andcompare
them
with
the
available
the value obtained in Liu etet al.
al. 2015)(2015) wasan
this temperature scales signiﬁcantly with theand indeed
single-dishmillimeter continuum photometry literature.
molecular clouds, but when we move toward
the substellar
underestimation.
f the central object, domain
proposing
the relation:(e.g., Klein et al. 2003; Scholz 4.1.etDisk
al.Mass
2006;
Mohanty
via Analytical
Prescription(with masses below the hydrogen-burning mass limit,

Bayo et al.

A Tale of Three Cities
OmegaCAM discovers multiple sequences in the color-magnitude diagram of theOrion Nebula Cluster:1705.09496v1 [astro-ph.SR] 26 May 2017

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
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
May 29, 2017
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(Affiliations can be found after the references)

Fig.
PMS
of th
CMD
dista
mea

degrees around the Orion Nebula Cluster. Thanks to the high-quality photometry obtained, we discovered three well-separated premain 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.
Key words. Stars: pre-main sequence – open clusters and associations: Orion

1. Introduction
Young stellar clusters are conspicuous components of our
Galaxy. They are the best test beds of the stellar initial massfunction because they are assumed to be entities of a common
origin, i.e. born from the same molecular cloud material, and at
the same time. Observations have shown, however, that the stars
born in one and the same cluster are not as coeval as expected.
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 is

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.

2. Observations and data reduction2

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

The images used in this work were collected with the
wide
field
Articlenumber,page 2 of 8
optical camera OmegaCAM on the 2.6-m VLT Survey Telescope(VST) at Cerro Paranal in Chile. OmegaCAM consists of a mosaic of 32 CCDs and samples a 1 deg2 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
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 with Ice Detections
Informationof the Complete
Source

R.A.

Decl.

Cloud

Lbol

Menv

αIRa

N(CH3OH)

Abstract(J2000.0)
Me1013 cm−2(J2000.0)Ledd
B1-acobserved toward
03:33:16.67
31:07:55.1
Perseus2.8
1.87(LYSOs).
10.21 [3.24]
Complex organic molecules (COMs) have been
severallow-mass
young1.3stellar
objects
B1-c
03:33:17.89
31:09:31.0
Perseus
3.7d
17.7d
2.66
1.69 [0.51]
Small and heterogeneous samples have so far
precluded
conclusions
on
typicalCOM
abundances,aswell
as theB5 IRS1c
03:47:41.61
32:51:43.8
Perseus
4.7d
4.2d
0.78
1.77 [0.46]ef
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]ddIRAS03235+3004cWe
03:26:37.45
30:15:27.9
Perseus
1.9
2.4
1.44
1.17
[0.08]
I) low-mass protostars using the IRAM 30 m
telescope.
detect CH
CO,
CH
CHO,
CH
OCH
,
CH
OCHO,
2
3
3
3
3
IRAS 03245+3002
03:27:39.03
30:12:59.3
Perseus
7.0d
5.3d
2.70
1.54 [0.29]
13%,
13%,
44%,
81%,
and
75%
of
sources,
respectively.
Median
CH3CN, HNCO, and HC3N toward 67%, 37%,d
IRAS 03254+3050
03:28:34.51
31:00:51.2
PerseusK
0.3
0.90 12 K−2
10−2dcolumn densities derived using survival analysis
range between
6.0×10cm Perseus(CH3CN)cm[0.04]
IRAS 03271+3013
03:30:15.16
30:23:48.8
0.8d and1.22.4×10
2.06
0.42
c
e
04108+2803
K
0.90[0.44](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]
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]drespect to CH3OH are more narrowly distributed,
especially03:25:09.44
for oxygen-bearing
species.
compareL1448 IRS1
30:46:21.7
Perseus17.0dWe 16.3
0.34 observed
0.23 [0.04]
0.32d
0.2g although
0.98
1.46
[0.88]
median abundances with a chemical modelL1455
forIRS3
low-mass 03:28:00.41
protostars30:08:01.2
and ﬁndPerseus
fair agreement,
someL1455 SMM1
03:27:43.25
30:12:28.8
Perseus
3.1d
5.3d
2.41
1.48 [0.76]
abundanceswithrespect
tomodeling work remains to bring abundancesL1489
higherwith respect
to CH
3OH. Median
IRSc
04:04:43.07
26:18:56.4
Taurus
3.7e
0.1h
1.10
0.69 [0.14]ciCH3OH in LYSOs are also found to be generallycomparable
toobserved
abundancesinhotcores,
hot
corinos,andSVS 4-5
18:29:57.59
01:13:00.6
Serpens
38
K
1.26
11.19 [4.29]
massive YSOs. Compared with comets, our sample is comparable for all molecules except HC3N and CH2CO,
Notes. Adaptedfrom Graninger et al. (2016).
which likely become depleted at later evolutionary
stages.
aBergner et al.

N(H2O(ice))a1018 cm−2

XCH3OH (ice) b% H2 OX NH3 (ice) b% H2 O

rms(mK)

10.39 [2.26]
29.55 [5.65]
2.26 [0.28]
2.59 [0.25]
14.48 [2.26]
39.31 [5.65]
3.66 [0.47]
7.69 [1.76]
2.87 [0.4]12.95 [2.26]
7.16 [0.91]
0.47 [0.16]
0.92 [0.37]
18.21 [2.82]
4.26 [0.51]
5.65 [1.13]

<1.9
<7.1
<3.7
<6.7
4.2 [1.2]
<9.8
<4.6
<5.6
<3.5
<3.6
3.1 [0.8]
<14.9
<12.5
<13.5
4.9 [1.5]
25.2 [3.5]3.33 [0.98]
<4.04
<2.09
3.46 [0.90]
4.71 [1.00]<4.40
6.66 [1.37]
6.37 [1.86]
4.29 [1.03]<1.24
5.20 [1.43]<4.15
6.21 [3.51]<8.29
5.42 [0.96]
∼4.3

3.6
5.5
7.0
5.8
4.2
3.7
3.9
4.8
4.0
2.7
2.8
3.7
3.9
4.1
5.4
3.9

Boogert et al. (2008).

b
Bottinelli
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

Ceccarelli 2012). Once temperatures reach 100–300 K, large
low-mass star-forming regions, molecular outﬂows, and prestellar
2. Observations
protostars with hot molecules
envelopes andno ice andabsorption.
desorbreact Moreover,in the gas phase to form “secondcores (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
representativerole 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, CH3OH,
followed byin thegas were selected from the Spitzer c2d ice
abundances,
stages of star formation can become incorporated intoBecause
proto-of uncertainties in “typical” LYSO COM
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
The sources were observed with the IRAM 30 m telescope using
planetesimals and planets, seeding nascent planets withthatcomplex
LYSOs are moreenhanced inbetween
COMs thanCOMs
MYSOsand(Bottinelli
connection
the original
ice
composition.
Ice and the Fourier Transform Spectrothe EMIR 90 GHz receiverorganic 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
CH
OH
ice
abundances(Öbergetal.
2011a).
Furthermore,
the and SVS 4-5 were observed on 2013
+2803,
IRAS
03235+3004,
3stars host most planetary systems, and so the (Bisschop
molecularet al. 2008; Öberg et al. 2011b). A better estimate ofJune 12–16
at 93–101
chemistry may depend on the stellar radiation
ﬁeld
and GHzthe and 109–117 GHz. All other sources25pp), 2017 June 1

Bergner et al.

Garrod et al. (2017); however, for the molecules of interest
here, the differences between the work of Garrod (2013) andmore recent implementations are very minor. The model
considers both the gas-phase and grain-surface/ice-mantle
formation and destruction of molecules. COMs are largely
assumed to have only dust-grain-related formation mechanin the absenceof other information.
od et al. (2017); however, for theisms,
moleculesof interest
WeGarrod
run themodel
the differences between the work of(2013)and multiple times using a selection ofphysicalconditions
that are representative of values at a range
e recent implementations are very
minor.
The modelof radial distances from the core center. We use results fromiders both the gas-phase and grain-surface/ice-mantle
this gridof chemical
models to produce a composite, spatiallyation and destruction of molecules.
COMs
are largely
dependent
pictureof the chemistry in the LYSO.
med to have only dust-grain-related
formationmechan, in the absence of other information.We begin with a spherically symmetric physical model of awith aofpower-law temperature proﬁle adapted
e run the model multiple timesgenericusing LYSO,
a selection
fromofChandler
Richer (2000):
ical conditions that are representativevalues at&a range
bolometricluminosity.
Upper
adial
distancesfromthe limits
core center. We use results fromq 2⎛⎞-q ⎛ L bol ⎞ngrid
correlation
coefﬁcients
are
shown
r
of chemical models to produce a composite,spatially⎟
T (r ) = 60 ⎜
(4 )
⎟ K,
⎜
⎝ 2 ´ 1015 m ⎠ ⎝ 10 5 L : ⎠ndent picture of the chemistry in the LYSO.
e begin with a spherically symmetric physical model of aØ モデル。
ric LYSO,
with a power-law temperature
adaptedwhere weproﬁleassumeq=2/5 and Lbol is either 1 or 10 Le. For the
Chandler& Richerproﬁle,we assumeØ q=2/5,
n1000(2000):=1e6 cm–3density, α=1.5,
T=10-250
K。 the power law:⎛⎞-q ⎛ L bol ⎞r⎟
T (r ) = 60 ⎜⎟⎜⎝ 2 ´ 1015 m ⎠ ⎝ 10 5 L : ⎠

q 2

⎛
⎞-a
r
⎜
⎟
.
K, nH (r ) (=4) n1000 au ⎝⎠1000 au(5 )Based1 ontheLemedianvalues determined from radiative transfer
re we assume q=2/5 and Lbol is either
or 10. For theØ HNCO以外は桁では観測と同じ。
modeling of low-mass protostars in Jørgensen et al. (2002), we
ity proﬁle, we assume the power law:
Ø HNCOの反応率を上げるべき(Belloche+’17)。
assume n1000 au=106 cm−3 and α=1.5. We also assume an⎛⎞-a radius where T=250 K, again following Jørgensen et al.
rinnerØ CHn3HOHが系統的に高いのは外側でoveractive⎟(r ) = n1000 au ⎜(5 ).
⎝ 1000 au⎠(2002),
and
an
outer
radiuswhere T=10 K. In the Lbol=10 Le
chemical desorption(?)。
case, a temperature of 250 K is achieved at a radius of 3.8 au, with