SFN 305 No. 14-23

2018/06/15

島 和宏 (京都大学)

14

BANYAN. XII. New Members of Nearby Young Associations from Gaia-Tycho Data

15

SMA observations of the polarized dust emission in solar-type Class 0 protostars: the magnetic field properties at envelope scales

16

Intracluster Age Gradients In Numerous Young Stellar Clusters

17

Young Star Clusters In Nearby Molecular Clouds

18

Resolving the polarized dust emission of the disk around the massive star powering the HH 80-81 radio jet

19

Chemistry of the High-Mass Protostellar Molecular Clump IRAS 16562-3959

20

Chemical survey toward young stellar objects in the Perseus molecular cloud complex

21

Modelling the molecular composition and nuclear-spin chemistry of collapsing prestellar sources

22

Mid-infrared Multi-wavelength Imaging of Ophiuchus IRS 48 Transitional Disk

23

Blinded by the light: on the relationship between CO first overtone emission and mass accretion rate in massive young stellar objects

18

Resolving the polarized dust emission of the disk around the massive star powering the
HH 80-81 radio jet
J. M. Girart1,2 , M. Fernández-López3 , Z.-Y. Li4 , H. Yang4 , R. Estalella5,2 , G. Anglada6 , N. ÁñezLópez1 , G. Busquet1,2 , C. Carrasco-González7 , S. Curiel8 , R. Galvan-Madrid7 , J. F. Gómez6 , I. de
Gregorio-Monsalvo9,10, I. Jiménez-Serra11 , R. Krasnopolsky12 , J. Martı́13 , M. Osorio6 , M. Padovani14 ,R. Rao15 , L. F. Rodrı́guez7 , J. M. Torrelles1,21Institut de Ciències de l’Espai (ICE, CSIC), Catalonia; 2 Institut d’Estudis Espacials de de Catalunya (IEEC),
Catalonia; 3 Instituto Argentino de Radioastronomı́a, Argentina; 4 Astronomy Department, University of Virginia,
USA; 5 Dep. de Fı́sica Quàntica i Astrofı́sica, Institut de Ciències del Cosmos, Universitat de Barcelona, Catalonia;
6
Instituto de Astrofı́sica de Andalucı́a (IAA, CSIC), Spain; 7 Instituto de Radioastronomı́a y Astrofı́sica (UNAM),
México; 8 Instituto de Astronomı́a (UNAM), México; 9 European Southern Observatory, Chile; 10 Joint ALMA Observatory, Chile; 11 Queen Mary University of London, UK; 12 Institute of Astronomy & Astrophysics, Academia Sinica,
Taipei, Taiwan; 13 Departamento de Fı́sica (EPSJ), Universidad de Jaén, Spain; 14 INAF-Osservatorio Astrofisico di
Arcetri, Italy; 15 Institute of Astronomy and Astrophysics, Academia Sinica, USA;
E-mail contact: girart at ice.cat
Here we present deep (16 µJy beam−1 ), very high (40 mas) angular resolution 1.14 mm, polarimetric, Atacama Large
Millimeter/submillimeter Array (ALMA) observations towards the massive protostar driving the HH 80-81 radio jet.
The observations clearly resolve the disk oriented perpendicular to the radio jet, with a radius of ≃ 0.17′′ (∼291 au
at 1.7 kpc distance). The continuum brightness temperature, the intensity profile, and the polarization properties
clearly indicate that the disk is optically thick for a radius of R ≤ 170 au. The linear polarization of the dust
emission is detected almost all along the disk and its properties suggest that dust polarization is produced mainly by
self-scattering. However, the polarization pattern presents a clear diﬀerentiation between the inner (optically thick)part of the disk and the outer (optically thin) region of the disk, with a sharp transition that occurs at a radius of∼ 0.1′′ (∼170 au). The polarization characteristics of the inner disk suggest that dust settling has not occurred yetwith a maximum dust grain size between 50 and 500 µm. The outer part of the disk has a clear azimuthal pattern
but with a significantly higher polarization fraction compared to the inner disk. This pattern is broadly consistent
with self-scattering of a radiation field that is beamed radially outward, as expected in the optically thin outer region,
although contribution from non-spherical grains aligned with
15 respect to the radiative flux cannot be excluded.
Accepted by Ap. J. Letters (856, L27)
http://iopscience.iop.org/article/10.3847/2041-8213/aab76b/meta
http://arxiv.org/abs/1803.06165

(背景)・HH 80-81 radio jet についてHerbig-Haro (HH) objects 80 & 81

edge of the L291 cloud(Rodriguez-Kamenetzky et al. 2017ApJ)

in Sagittarius at a distance of 1.7 kpc

powerful protostellar jetshigh luminosity
1.7 x 104 Lsun-> massive (early B-type) protostar

non-thermal electrons(普通は free-free emission from thermal electrons)

jet velocities > 600 km/s
(typical: 100-300 km/s for YSO jets)

Fig. 1.— Radio continuum images of the HH 80-81 jet region. (a) and (b) panels correspond to the
C band image, obtained with the JVLA in D configuration by Carrasco-González et al. (2010), while (c)panel corresponds to our widest bandwidth (L+S+C bands) image taken in B configuration with an angularresolution of ⇠2.3700 ⇥1.4600 (PA = 4 ) (this paper). The whole extension of the HH 80-81 jet is seen inpanel (a), where the HH objects and the source associated with the central protostar (IRAS 18162-2048)
are labeled. The structure of the internal region of the jet (panel b) appears poorly resolved in the VLA-D
configuration image, but our new high angular resolution image (panel c) reveals a highly collimated jet
finishing in two lobe-like structures (see also Fig. 2).

strong shocks-> relativistic energies and synchrotron emission

linearly polarized radiation-> magnetic ﬁelds aligned with the jets

1.14 mm (263.0 GHz) continuum polarimetric ALMA observations(Band 6, TDM, with 37 antennas, 15 m to 6.3 km)

Dust polarization
Girart et al.

early op-

most alle polar% of theh-west ofpolarizans in theich coinn. Thislevel oft brightransition
precisely
aw of thesection).
n , (hereion leveln degreeiation ofogram ofin direcwith theof ⇠ 36 .
adrant ofangle of) has signer disk,
viation ofa nearly
tangent
mission).
ngle segexpected
sk centere 4 showscircumstellar disk polarization の研究
self-scattering by dust grains?
alignment of aspherical dust grains?
alignment with anisotropic radiation?

(inner)minor axis (22.6 )方向に polarization している-> self-scattering from an optically thick disk
(dust settlingはまだ起きていない, Yang et al. 2017)-> maximum grain size: 50 - 500 μm(use model of Kataoka et al. 2016)(outer)azimuthal pattern が卓越-> radially anisotropic radiation による polarization(今までのモデル)
optically thin disks around low mass stars: polarization fraction ~ 2-3%(と違う点)

azimuthal pattern は optically thin に切り替わってから現れる
polarization fraction: 5-7 %(を再現する新しいモデル -> future work)Accepted by ApJS
https://arxiv.org/pdf/1804.08245

21

Modelling the molecular composition and nuclear-spin chemistry of collapsing prestellar
sources
Pierre Hily-Blant1,2 , Alexandre Faure2 , Claire Rist2 , Guillaume Pineau des Forts3,4 and David Flower5
1

Institut Universitaire de France; 2 Université Grenoble Alpes, CNRS, IPAG, F-38000 Grenoble, France; 3 IAS (UMR
8617 du CNRS), Bâtiment 121, Université de Paris Sud, F-91405 Orsay, France; 4 LERMA (UMR 8112 du CNRS),
Observatoire de Paris, 61 Avenue de l’Observatoire, F-75014 Paris, France; 5 Physics Department, The University,
Durham DH1 3LE, UK
E-mail contact: pierre.hily-blant at univ-grenoble-alpes.fr
We study the gravitational collapse of prestellar sources and the associated evolution of their chemical composition. We
use the University of Grenoble Alpes Astrochemical Network (UGAN), which includes reactions involving the diﬀerent
nuclear–spin states of H2 , H+
3 , and of the hydrides of carbon, nitrogen, oxygen, and sulfur, for reactions involving up
to seven protons. In addition, species-to-species rate coeﬃcients are provided for the ortho/para interconversion of
the H+
3 + H2 system and isotopic variants. The composition of the medium is followed from an initial steady statethrough the early phase of isothermal gravitational collapse. Both the freeze–out of the molecules on to grains andthe coagulation of the grains were incorporated in the model. The predicted abundances and column densities of thespin isomers of ammonia and its deuterated forms are compared with those measured recently towards the prestellar
cores H-MM1, L16293E, and Barnard B1. We find that gas–phase processes alone account satisfactorily for theobservations, without recourse to grain-surface reactions. In particular, our model reproduces both the isotopologue
abundance ratios and the ortho:para ratios of NH2 D and NHD2 within observational uncertainties. More accurate
observations are necessary to distinguish between full scrambling processes—as assumed in our gas-phase network—anddirect nucleus- or atom-exchange reactions.
Accepted by MNRAS
https://arxiv.org/pdf/1804.01354

Multi-wavelength Imaging of Ophiuchus IRS 48 Transitional Disk
22 Mid-infrared+
Mitsuhiko Honda, Kazushi Okada , Takashi Miyata , Gijs D. Mulders , Jeremy R. Swearingen ,H
Hのスピン
2 Kamizuka
3
Takashi, Ryou Ohsawa , Takuya Fujiyoshi , Hideaki Fujiwara , Mizuho Uchiyama , Takuya(新しい点)

1

2<latexit sha1_base64="MPXThhwqGNR/hq0lqkJgdbFdwD8=">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</latexit>

22も考慮した重力収縮する protstellar core の化学進化を計算
2

5

3

5

4

6

<latexit sha1_base64="UBdK70SvRdJaRyxbCKKu8Nk4xVA=">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</latexit>

Yamashita6 And Takashi Onaka7
1

Department of Physics, Kurume University School of Medicine, 67 Asahi-machi, Kurume, Fukuoka, 830-0011, Japan;

0.97 0.73
0.97 (背景)0.73
0.97 0.73
0.97 0.73
0.95 0.60
0.97 0.60

0.040
0.043
0.043
0.043
0.057
0.057

227
195
178
178
594
557

86
75
75
75
97
108

0.021
0.019
0.019
0.019
0.043
0.038

アンモニア: most useful probes of the dense cores

AMstarless and prestellar cores

0.95 0.81
0.068
166
15
0.080
0.94 0.79
0.053
22
0.098
H-MM1 249
in Ophiuchus
0.93 0.72
0.038
310
22
0.137
b
(Harjuet al. 2017A&A)
h, ENBW). On the T MB scale at the original spectral
resolution.
F. Daniel et al.: N2 H+ , NH3 , CN, HCN and HNC isotopologues in B1

structure are
ak main-beam
VLSR , the line
knesses, ⌧sum ,o gives an esthe spectrum
approximatedming that they, the two lasts, Ntotal , of theng the H2 col. The derived
e from ⇠ 1 tocally thin, andity is propor-

d line widths
es, and consethod have relNH2 D, whichcolumn denX and IRAM
Table 2) andcount. In conN2 D+ (2 1)by a factor of+(2 1) specsolved hyperects rotational
an J = 3 andobtained from+

Fig. 4. NH3 (1, 1), (2, 2), and (3, 3) inversion line spectra observed with
the GBT towards the centre of H-MM1. The spectra are on the T MB
scale. Fits to the (1, 1) and (2, 2) hyperfine structures are indicated withorange curves. The origin of the absorption feature seen in the (3, 3)
spectrum (at 23869.6 MHz) is unkown to us.

by Punanova et al. (2016) (3.8 ± 0.9 1012 cm 2 , beamsize 3200 )towards a position lying 1300 o↵ from our centre position.
Assuming that ortho and para NH3 have equal abun-

New conversion rates for H+
3 +H(A new chemicalvariantsnetwork)
2.2.1(1D free-falling core model)
spherically-symmetric, isothermal, non-rotating gas and dust
initial number density: 104 /cc
initial mass = Jeans mass ~ 7 Msun (at 10 K)
cosmic ray ionization rate: 3 x 10-17 /s
grain size: 0.1 μm

nuclear-spin state species+reaction+ ne
An2 importanttothepH2 oNHaddition
pNH
oH
oH
pH
3
3
3
3 etc.
<latexit sha1_base64="X8MRfHsKUBtJWfx6CVpVf0Pmq4k=">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</latexit><latexit sha1_base64="4VXwhU+PfPs9kJWo/Wt0KDCuPzI=">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</latexit><latexit sha1_base64="SsA2VliLBPPgOeYkv/PqAJWdYHw=">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</latexit><latexit sha1_base64="0Ra4azK2gUrrs0jqh7NCvCf3anQ=">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</latexit>

gic proton–exchange reaction<latexit sha1_base64="KHxyARULtbNij9Bs6a9zbWVuMLw=">AAACdHichVHLSsNAFD2Nr1ofrboRdCGWiiCUGxUUV6Ibl9paFXyUJI5taF4k00It/oA/4MKVooj4GW78ARd+grhUdOPC2zQgKuoNkzlz5p47Z+bqnmUGkughprS1d3R2xbsTPb19/cnUwOBG4FZ9QxQM13L9LV0LhGU6oiBNaYktzxearVtiU68sN/c3a8IPTNdZl3VP7NpayTEPTEOTTBVTyR1bk2XfbrgrR8WZvaliKk1ZCmPsJ1AjkEYUq27qCjvYhwsDVdgQcCAZW9AQ8LcNFQSPuV00mPMZmeG+wBESrK1yluAMjdkK/0u82o5Yh9fNmkGoNvgUi4fPyjFk6J6u6Znu6IYe6f3XWo2wRtNLnWe9pRVeMXk8nH/7V2XzLFH+VP3pWeIA86FXk717IdO8hdHS1w5PnvMLuUxjgs7pif2f0QPd8g2c2otxuSZyp0hwA9Tvz/0TbExnVcqqa7PpxaWoFXGMYByT/N5zWMQKVlEIe3KKC1zGXpVRJa1kWqlKLNIM4Uso2Q8ilI/s</latexit><latexit sha1_base64="1BdDU37Ci5bYXtRAQjMT+cowpjc=">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</latexit>

ortho/para interconversion

+
oH+
+
oH
!
pH
3
2
3 + oH2 etc.

whichprestellar
was sources
excluded
from the reaction
Chemical models of collapsing
9
結果(実線)が観測(斜線)とよく一致

grounds that the change of proton spin
+
H+
ion
must
be
accompanied
by
oH
3
3 +o
yielding para-H2 . However, both forms osented by the combinations of the “spinMNRAS 000, 1–?? (2017)
H-MM1: core density
1.2 x 106 /cc (Harju et al. 2017)

B1: core density
3 x 106 /cc (Daniel et al. 2013)
I16293E: core density
1.4 x 107 /cc (Bacman et al. 2016)
Figure 5. Column densities of ammonia and its deuterated forms, as predicted from our “Larson-Penston” collapse model (full lines)
and from observations (hashed regions) of the I16293E, Barnard-B1, and H-MM1 prestellar cores (Daniel et al. 2016; Harju et al. 2017)(see Table 6). The initial parameters are those of Table 1.

Accepted by PASJ
http://arxiv.org/pdf/1804.02145

23

Blinded by the light: on the relationship between CO first overtone emission and massaccretion rate in massive young stellar objects
J. D. Ilee1 , R. D. Oudmaijer2 , H. E. Wheelwright3 and R. Pomohaci2
1

Institute of Astronomy, Madingley Road, Cambridge CB3 0HA, UK; 2 School of Physics and Astronomy, EC Stoner
Building, University of Leeds, Leeds, LS2 9JT, UK; 3 Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69,
53121, Bonn, Germany
E-mail contact: jdilee at ast.cam.ac.uk
To date, there is no explanation as to why disc-tracing CO first overtone (or ‘bandhead’) emission is not a ubiquitousfeature in low- to medium-resolution spectra of massive young stellar objects, but instead is only detected toward
approximately 25 per cent of their spectra. In this paper, we investigate the hypothesis that only certain massaccretion rates result in detectable bandhead emission in the near infrared spectra of MYSOs. Using an analytic disc−4
−1
model combined with an LTE model of the CO emission, we find that high accretion rates (>∼10 M⊙ yr ) result inlarge dust sublimation radii, a larger contribution to the K-band continuum from hot dust at the dust sublimation
radius, and therefore correspondingly lower CO emission with respect to the continuum. On the other hand, low−6−1
accretion rates (<∼10 M⊙ yr ) result in smaller dust sublimation radii, a correspondingly smaller emitting area ofCO, and thus also lower CO emission with respect to the continuum. In general, moderate accretion rates produce
the most prominent, and therefore detectable, CO first overtone emission. We compare our findings to a recent
near-infrared spectroscopic survey of MYSOs, finding results consistent with our hypothesis. We conclude that thedetection rate of CO bandhead emission in the spectra of MYSOs could be the result of MYSOs exhibiting a rangeof mass accretion rates, perhaps due to the variable accretion suggested by recent multi-epoch observations of theseobjects.
Accepted by MNRAS
https://arxiv.org/pdf/1804.01934(新しい点)

24

bandheademissionの inaccretion
rate Emission
依存性の理論計算
Signaturesof Young
Planets
the Continuum
From Protostellar Disks
Andrea Isella1 and Neal J. Turner2
1

Department of Physics and Astronomy, Rice University, USA; 2 Jet Propulsion Laboratory, California Institute ofTechnology, USA
E-mail contact: neal.turner at jpl.nasa.gov

(背景)MYSOs周辺のディスクの内側を直接見るのは難しい-> CO is an ideal tracer
bandhead emission(appear in bands in low-resolution spectra)
the ﬁrst overtone11

ν=2-0, 2.3 μm, T = 2500-5000 K, n > 10/cc ~ inner accreting disc conditions

CO bandhead emission of MYSOs(Ilee et al. 2013MNRAS)

IRAS 08576−4334

Normalised Flux

2.0

3

3 MODELLING THE EMISSION−1[km s ]
−100 0 100
1.0

1.5

0.5
0.0
−0.0015 0.0000 0.0015
Wavelength (µm)

1.0
0.5
0.0
2.295

2.300
2.305
Wavelength (µm)

Figure 1. Spectrum of the first overtone bandhead emission of IRAS
08576−4334 (solid black). The gap in the data is due to the spacing between
chips three (left) and four (right) of the detector. The best fitting model isshown above (dashed red) and has been shifted upwards for clarity. The
theoretical wavelengths of the transitions that make up the bandhead aremarked on the abscissa, and have been shifted to account for relative motion. The panel shows the line shape of the J = 51-50 transition that was
adopted for the best fitting model.

To determine whether the CO emission originates from circumstellar discs and to constrain the physical properties of the emitting
region, we compare the observations to a model of emission from
ただし、bandhead
emissionは普遍的ではない
a disc. There are several ways in which the physical parameters
within the disc can be modelled. For example, Bik & Thi (2004)-> assume
MYSOsのうち約25%だけで観測されている
a simple isothermal disc, Berthoud et al. (2007) assume
the surface density and temperature of the disc decrease as powerlaws. Carr (1989) and Chandler et al. (1995) determine the temperatureand density structure by balancing the heating and coolなぜか？
ing mechanisms at work on the surface of a thin alpha disc (seeShakura & Sunyaev 1973) which is isothermal in the vertical direction.
To fit the emission using a disc model, we first divide the disc
into 75 radial rings each with 75 azimuthal cells. Each cell is assigned a temperature and surface density calculated from the relevant disc description (see Section 3.1). We assume Keplerian rotation for the disc, and the velocity of each cell to the line-of-sight isdetermined assuming the disc is at an inclination i to the vertical.
Our model of the CO emission is based on Wheelwright et al.
(2010), which was in turn based on that of Kraus et al. (2000), andbriefly described here. The population of the CO rotational levels,
to a maximum of J = 100, for the v = 2–0 vibrational transition

(model)Chambers (2009)の analytical modela Keplerian disc with a decreasing mass accretion rate as a function of time

⌃CO = 10 4 ⌃Qvisc > Qirr

<latexit sha1_base64="NF3YucBeV6pHG8HsM8dYSyYKFsI=">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</latexit>

Qirr > Qvisc<latexit sha1_base64="Ge5e3zHhIlPXjJ1A0GS84U1VkH0=">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</latexit>

MYSOs that are thought to be; Kraus et al. 2010; Grellmann
et al. 2013).
M⇤ = 20 M
ence for the presence of discs= as1.1
104 L
ch discs,L
such
the ⇥
accretion
known. This is in part because
ntioned above generally trace
ellar environments of MYSOs,
n inner gaseous disc. There are
Os often exhibit Br emission,n shown that this can originate
thus does not provide a uniquenother emission feature that iso-vibrational CO v = 2–0 first
This emission requires warm
1011 cm 3 ) gas. These are theons of circumstellar discs andsed as a tracer of discs (Carral. 1995; Najita et al. 1996).

<latexit sha1_base64="hEImRWrR1szFQ95R4kzNMm8/8CY=">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</latexit>↵visc = 0.1

Td = 1500 K<latexit sha1_base64="hdc6a/ukaiWXihEvvSZVu1xzkKk=">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</latexit>0

Mdisc = 10 M<latexit sha1_base64="ZFi1jM+A5bqJGD3PaCLO5Y7/y9Y=">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</latexit><latexit sha1_base64="4pTj2JyzSRqxRdqzJ0xkpQJvFvA=">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</latexit>

earance of the CO bandheadced using a model of emission

rinit = 200 au

CO
v=2–0

<latexit sha1_base64="l47u3BVDbrZ3kUj47m8JgujA55c=">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</latexit><latexit sha1_base64="AVqz+xct27/cY6Ml1XlNgYPlz3o=">AAACh3ichVHLSiNBFD227/iKzmZgNiHBwYXE20E0CIKOm1n6mKhgJHS3FS3sF92VgDbZy/yAC1cKIsPAbMe9G3/AhZ8gs4wwm1nMTadFVNRbVNWpU/fcOlVl+rYMFdFth9bZ1d3T29efGhgcGh5Jj46th14tsETJ8mwv2DSNUNjSFSUllS02/UAYjmmLDXN/qbW/URdBKD33mzrwxbZj7LqyKi1DMVVJZ4NK2THUXuBE0pWqkZnPFIjKkw+kUWtU0jnKUxyZl0BPQA5JLHvpC5SxAw8WanAg4EIxtmEg5LYFHQSfuW1EzAWMZLwv0ECKtTXOEpxhMLvP4y6vthLW5XWrZhirLT7F5h6wMoNxuqEf1KRr+kl39O/VWlFco+XlgGezrRV+ZeT7x7W/76ocnhX2HlVvelaoohh7lezdj5nWLay2vn543FybWx2PPtMZ/WH/p3RLV3wDt35vna+I1ROk+AP058/9EqwX8jrl9ZXp3MKX5Cv68AlZTPB7z2IBX7GMEp97hF/4jUutX5vSZrRiO1XrSDQf8CS0xf9pqpao</latexit>ri

rs

inner radiussublimation radiusrttransition radiusroouter radiusFigure 1. A representative schematic diagram of the disc model considered
T isnsplit into three radial zones. The firstfor this work. The disc2 radial
1 zone=()
0 = 3.0cm
0 radius ri and the dust sublimation(between the inner
radiusrs ) isgconsideredTeto be purely gaseous with opacity  (see Equation 1). The second radial zone
(between rs and the transition radius rt ) is dominated by viscous heating
Te = 1380 K
with opacity 0 . The final radial zone (between rt and the outer radius ro ) is
dominated by radiative heating, also with opacity 0 . Hot dust close to thesublimation radius is represented by a blackbody emitting at 1500 K.
<latexit sha1_base64="6oy17F8uTcLQQ3hY7UCjiOu9HDc=">AAACinicSyrIySwuMTC4ycjEzMLKxs7BycXNw8vHLyAoFFacX1qUnBqanJ+TXxSRlFicmpOZlxpaklmSkxpRUJSamJuUkxqelO0Mkg8vSy0qzszPCympLEiNzU1Mz8tMy0xOLAEKxQuoxmQnFhQkxhso2CoY6xnE6MTkJpZkFOVWJ+fGGcXopMdV6xrW1sYLKBvoGYCBAibDEMpQZoCCgHyB5QwxDCkM+QzJDKUMuQypDHkMJUB2DkMiQzEQRjMYMhgwFADFYhmqgWJFQFYmWD6VoZaBC6i3FKgqFagiESiaDSTTgbxoqGgekA8ysxisOxloSw4QFwF1KjCoGlw1WGnw2eCEwWqDlwZ/cJpVDTYD5JZKIJ0E0ZtaEM/fJRH8naCuXCBdwpCB0IXXzSUMaQwWYLdmAt1eABYB+SIZor+savrnYKsg1Wo1g0UGr4HuX2hw0+Aw0Ad5ZV+SlwamBs1m4AJGgCF6cGMywoz0DA30DANNlB2coFHBwSDNoMSgAQxvcwYHBg+GAIZQoL3dDBsZdjHsZuJhMmKyZLKGKGVihOoRZkABTC4AZi2WiA==</latexit><latexit sha1_base64="p4edV6eHYqpTpFD5+SVrC3ATLqY=">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</latexit><latexit sha1_base64="Qj7oEREzKcrzuFXm+mJs3gjmesE=">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</latexit>n=<latexit sha1_base64="KipNIRKli6eEyDrn7hCwzgNb9Yg=">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</latexit>

14

Table 1. Star and disc parameters adopted for the model.

CO first overtone and mass accretion rate in MYSOs

30̇ [0⊙ yr−1]
8

4.0

A

7

4
3
2
0
0

4.0

1
lRg 5 [au]

3.0

2

4
3
2
1
0

−1

0

1
lRg 5 [au]01lRg λ [μm]

−1

2

−1

0

1
lRg 5 [au]

2

−9

D

−10

lRg )λ [W m−2 μm−1]

3.5

lRg 7eff [.]

5

2.0
−1

7.8(−6)6.5(−8)62.5

1

1.1(−3)8.4(−5)

C

7

lRg τ

5

−1

B

3.5

lRg 7mid [.]lRg Σ [g Fm−2]

6

8

3.0
2.5
2.0

−11
−12
−13
−14
−15
−16

1.5

−1

0

1
lRg 5 [au]

2

−17

−1

2

3

Figure 2. Disc properties and observable signatures for the MYSO model for the range of accretion rates considered. A) Disc surface density as a functionof radius. B) Disc mid-plane temperature as a function of radius, vertical dashed lines indicate the location of the corresponding dust sublimation radius. C)
Disc optical depth as a function of radius. D) Disc effective temperature, the dashed line indicates the effective temperature profile of a flared, irradiated disc.
E) Spectral energy distributions (SEDs), the dashed line indicates the contribution from the central star. F) Predicted CO v = 2–0 first overtone bandhead
emission, normalised to the adjacent continuum. The thicker lines in panel A denote the spatial extent of the region which emits 80 per cent of the CO v = 2–0
flux for each model.

The disc is assumed to be flared and its viscous nature is describedby the standard alpha disc model (Shakura & Sunyaev 1973). We use

where Te = 1380 K and n = 14, based on the analytic opacity fitsof Stepinski (1998). Throughout all zones in the disc, we assume an

0
−1

−1

line-to-continuum-ratios

0

1.6

1
lRg 5 [au]2(high accretion rate)

large size of CO emitting region(large continuum emission)
high-densities and optically-thickF

1.5-> low ratios) / )FRnW

1.4
1.3(intermediate accretion rates)

1.2

ss accretion
rate in MYSOs
1.1

3

high ratios (~1.5)

1.0
2.292

2.294

2.296
lRg λ [μm]

2.298

2.300

0̇ [0⊙ yr−1]
1.1(−3)(low accretion rate)

rates considered. A) C
Disc surface density
as a function
8.4(−5)small size of CO emitting region
cation of the corresponding dust sublimation
radius. C)
7.8(−6)drop in surface density (~2 orders)effective temperature profile of a flared, 6.5(−8)
irradiated disc.
star. F) Predicted CO v = 2–0 first overtone bandhead-> low ratiosof the region which emits 80 per cent of the CO v = 2–0

J. D. Ilee et al.

6

1.0
0.9
1.4

R = 500
/Rw 5

R=
7000
0HdLum 5

R = 50000

1.1 × 10−3 0⊙ yr−1

F / FFRnt

1.3
1.2
1.1
1.0
0.9

Figure 4. Simulated observations of the CO spectra presented in Figure 2, with a spectral resolution R = 500, 7000 and 50,000 (left, middle, right respectively).
All spectra possess the same signal-to-noise ratio of approximately 100. Vertical ticks mark the wavelengths of the v = 2–0 and 3–1 transitions in each panel.
Only moderate accretion rates result in detectable emission for all spectral resolutions considered, and very high spectral resolution is required in order toensure detection for all accretion rates considered.
Cooper et al. (2013) の観測ではR~500

that if this scenario is correct, the objects that do not exhibit CO
states in terms of the J K colour is not very large (approximately->
bandheademissionのdetection
rate
~ 25%
bandhead emission due to rapid accretion should possess a signifi1 magnitude).
Therefore,that the NIR colours of MYSOs with andcant continuum excess due to hot dust. For our models, the K bandwithout CO bandhead emission appear similar does not yet exclude

Accepted by MNRAS
http://arxiv.org/pdf/1804.09128

BANYAN. XII. New Members of Nearby Young Associations from Gaia-Tycho Data

14 Jonathan Gagné , Olivier Roy-Loubier , Jacqueline K. Faherty , René Doyon and Lison Malo
1,2

3

4

3

5

1

Carnegie Inst. of Washington DTM, 5241 Broad Branch Road NW, Washington, DC 20015, USA; 2 NASA Sagan
Fellow; 3 Inst. for Research on Exoplanets, Université de Montréal, Dépt. de Physique, C.P. 6128 Succ. Centre-ville,
Montréal, QC H3C 3J7, Canada; 4 Dept. of Astrophysics, American Museum of Natural History, Central Park Westat 79th St., New York, NY, USA; 5 Observatoire du Mont-Mégantic and Inst. for Research on Exoplanets, Universitéde Montréal, Département de Physique, C.P. 6128 Succ. Centre-ville, Montréal, QC H3C 3J7, Canada
E-mail contact: jgagne at carnegiescience.edu
We present a search for stellar members of young associations within 150 pc of the Sun based on Gaia-Tycho andan updated version of the BANYAN Σ software to determine Bayesian membership probabilities that includes Gaia2MASS color-magnitude diagrams. We identify 32 new F0–M3-type bona fide members of the 10–200 Myr-old ScoCen, Carina, Tucana-Horologium, Columba and Octans associations and the AB Doradus, β Pictoris and Carina-Near
moving groups. These new bona fide members have measurements of their full kinematics and literature data consistent
with a young age. We also confirm the membership of 66 previously known candidate members using their Gaia-Tycho
trigonometric distances or new literature radial velocities, and identify 219 additional new candidate members, mostof which do not yet have a radial velocity measurement. This work is the first step towards a completeness-correctedsurvey of young association members based on Gaia-DR2 in the near future.
Accepted by ApJ
http://arxiv.org/pdf/1804.03093
13

SMA observations of the polarized dust emission in solar-type Class 0 protostars: themagnetic field properties at envelope scales
Maud Galametz1 , Anaelle Maury1 , Josep M. Girart2,3 , Ramprasad Rao4 , Qizhou Zhang5 , Mathilde
Gaudel1 , Valeska Valdivia1 , Eric Keto5 and Shih-Ping Lai61Astrophysics Dept., CEA/DRF/IRFU/DAp, Univ. Paris Saclay, UMR AIM, F-91191 Gif-sur-Yvette, France; 2 Inst.
de Ciencies de l’Espai (ICE, CSIC), Can Magrans, S/N, E-08193 Cerdanyola del Valles, Catalonia, Spain; 3 Inst.
d’Estudis Espacials de Catalunya (IEEC), E-08034 Barcelona, Catalonia, Spain; 4 Inst. of Astron. and Astrophys.,
Academia Sinica, 645 N. Aohoku Pl., Hilo, HI 96720, USA; 5 Harvard-Smithsonian Center for Astrophysics, 60 Garden
street, Cambridge, MA 02138, USA; 6 Inst. of Astronomy and Dept. of Physics, National Tsing Hua Univ., Hsinchu
30013, Taiwan
Although, from a theoretical point of view, magnetic fields are believed to have a significant role during the earlystages of star formation, especially during the main accretion phase, the magnetic field strength and topology ispoorly constrained in the youngest accreting Class 0 protostars that lead to the formation of solar-type stars. We
carried out observations of the polarized dust continuum emission with the SMA interferometer at 0.87mm, in order toprobe the structure of the magnetic field in a sample of 12 low-mass Class 0 envelopes, including both single protostars
and multiple systems, in nearby clouds. Our SMA observations probe the envelope emission at scales 600 ? 5000 auwith a spatial resolution ranging from 600 to 1500 au depending on the source distance. We report the detectionof linearly polarized dust continuum emission in all of our targets, with average polarization fractions ranging from2protostellar envelopes. The polarization fraction decreases with the continuum flux density, which translates into
a decrease with the H2 column density within an individual envelope. Our analysis show that the envelope-scale
magnetic field is preferentially observed either aligned or perpendicular to the outflow direction. The alignment of theoutflowing gas and the magnetic field does not seem to depend on the polarization fraction nor polarized intensity in
our sample of Class 0 envelopes. However, our results suggest a relation between the orientation of the magnetic field
and the rotational energy, with a larger occurrence of misalignment in sources where strong rotational motions aredetected at hundreds to thousands of au scales. We also show that the best agreement between the magnetic field andoutflow orientation is found in sources showing no small-scale multiplicity and no large disks at 100 au scales.
Accepted by A&A
http://adsabs.harvard.edu/cgi-bin/bib_query?arXiv:1804.05801

Intracluster Age Gradients In Numerous Young Stellar Clusters
K. V. Getman1

Accepted by A&A
http://adsabs.harvard.edu/cgi-bin/bib_query?arXiv:1804.05801

Intracluster Age Gradients In Numerous Young Stellar Clusters

16 K. V. Getman , E. D. Feigelson , M. A. Kuhn , M. R. Bate , P. S. Broos and G. P. Garmire
1

1

2,3

4

1

5

1

Pennsylvania State University, University Park PA 16802, USA; 2 Universidad de Valparaiso, Gran Bretana 1111,
Playa Ancha, Valparaiso, Chile; 3 Millenium Institute of Astrophysics, Av. Vicuna Mackenna 4860, 782-0436 Macul,
Santiago, Chile; 4 University of Exeter, Stocker Road, Exeter, Devon EX4 4QL, UK; 5 Huntingdon Institute for X-ray
Astronomy, LLC, 10677 Franks Road, Huntingdon, PA 16652, USA
E-mail contact: gkosta at astro.psu.edu
The pace and pattern of star formation leading to rich young stellar clusters is quite uncertain. In this context, weanalyze the spatial distribution of ages within 19 young (median t < 3 Myr on the Siess et al. (2000) timescale),morphologically simple, isolated, and relatively rich stellar clusters. Our analysis is based on young stellar object
samples from the MYStIX and SFiNCs surveys, and a new estimator of pre-main sequence (PMS) stellar ages, AgeJX,
derived from X-ray and near-infrared photometric data. Median cluster ages are computed within four annularsubregions of the clusters. We confirm and extend the earlier result of Getman et al. (2014): 80% percent of theclusters show age trends where stars in cluster cores are younger than in outer regions. Our cluster stacking analyses
establish the existence of an age gradient to high statistical significance in several ways. Time scales vary with the choiceof PMS evolutionary model; the inferred median age gradient across the studied clusters ranges from 0.75 Myr/pc to
1.5 Myr/pc. The empirical finding reported in the present study – late or continuing formation of stars in the cores ofstar clusters with older stars dispersed in the outer regions – has a strong foundation with other observational studies
and with the astrophysical models like the global hierarchical collapse model of Vazquez-Semadeni et al. (2017).
Accepted by MNRAS
https://arxiv.org/pdf/1804.05077

14

17

Young Star Clusters In Nearby Molecular Clouds
K. V. Getman1 , M. A. Kuhn2,3 , E. D. Feigelson1, P. S. Broos1 , M. R. Bate4 and G. P. Garmire5
1

Pennsylvania State University, University Park PA 16802, USA; 2 Universidad de Valparaiso, Gran Bretana 1111,
Playa Ancha, Valparaiso, Chile; 3 Millenium Institute of Astrophysics, Av. Vicuna Mackenna 4860, 782-0436 Macul,
Santiago, Chile; 4 University of Exeter, Stocker Road, Exeter, Devon EX4 4QL, UK; 5 Huntingdon Institute for X-ray
Astronomy, LLC, 10677 Franks Road, Huntingdon, PA 16652, USA
E-mail contact: gkosta at astro.psu.edu
The SFiNCs (Star Formation in Nearby Clouds) project is an X-ray/infrared study of the young stellar populations in
22 star forming regions with distances ≤ 1 kpc designed to extend our earlier MYStIX survey of more distant clusters.
Our central goal is to give empirical constraints on cluster formation mechanisms. Using parametric mixture models
applied homogeneously to the catalog of SFiNCs young stars, we identify 52 SFiNCs clusters and 19 unclustered stellar
structures. The procedure gives cluster properties including location, population, morphology, association to molecular
clouds, absorption, age (AgeJX), and infrared spectral energy distribution (SED) slope. Absorption, SED slope, andAgeJX are age indicators. SFiNCs clusters are examined individually, and collectively with MYStIX clusters, to givethe following results. (1) SFiNCs is dominated by smaller, younger, and more heavily obscured clusters than MYStIX.
(2) SFiNCs cloud-associated clusters have the high ellipticities aligned with their host molecular filaments indicating
morphology inherited from their parental clouds. (3) The eﬀect of cluster expansion is evident from the radius-age,radius-absorption, and radius-SED correlations. Core radii increase dramatically from ∼ 0.08 to ∼ 0.9 pc over theage range 1–3.5 Myr. Inferred gas removal timescales are longer than 1 Myr. (4) Rich, spatially distributed stellar
populations are present in SFiNCs clouds representing early generations of star formation. An Appendix compares
the performance of the mixture models and nonparametric Minimum Spanning Tree to identify clusters. This work isa foundation for future SFiNCs/MYStIX studies including disk longevity, age gradients, and dynamical modeling.
Accepted by MNRAS
https://arxiv.org/pdf/1804.05075

18

Resolving the polarized dust emission of the disk around the massive star powering the
HH 80-81 radio jet
J. M. Girart1,2 , M. Fernández-López3 , Z.-Y. Li4 , H. Yang4 , R. Estalella5,2 , G. Anglada6 , N. ÁñezLópez1 , G. Busquet1,2 , C. Carrasco-González7 , S. Curiel8 , R. Galvan-Madrid7 , J. F. Gómez6 , I. de
Gregorio-Monsalvo9,10, I. Jiménez-Serra11 , R. Krasnopolsky12 , J. Martı́13 , M. Osorio6 , M. Padovani14 ,
15

7

1,2

http://arxiv.org/abs/1803.06165

Chemistry of the High-Mass Protostellar Molecular Clump IRAS 16562-3959

19 Andrés E. Guzmán , Viviana V. Guzmán , Guido Garay , Leonardo Bronfman and Federico Hechenleitner
1,2

3

1

1

1

1

Departamento de Astronomia, Universidad de Chile, Camino el Observatorio 1515, Las Condes, Santiago, Chile; 2
National Astronomical Observatory of Japan, National Institutes of Natural Sciences, 2-21-1 Osawa, Mitaka, Tokyo
181-8588, Japan; 3 Joint ALMA Observatory (JAO), Alonso de Cordova 3107, Vitacura, Santiago, Chile
E-mail contact: andres.guzman at nao.ac.jp
We present molecular line observations of the high-mass molecular clump IRAS 16562−3959 taken at 3 mm using
the Atacama Large Millimeter/submillimeter Array (ALMA) at 1.′′ 7 angular resolution (0.014 pc spatial resolution).
This clump hosts the actively accreting high-mass young stellar object (HMYSO) G345.4938+01.4677, associatedwith a hypercompact HII region. We identify and analyze emission lines from 22 molecular species (encompassing
34 isomers) and classify them into two groups, depending on their spatial distribution within the clump. One ofthese groups gathers shock tracers (e.g., SiO, SO, HNCO) and species formed in dust grains like methanol (CH3 OH),ethenone or ketene (H2 CCO), and acetaldehyde (CH3 CHO). The second group collects species resembling the dust
continuum emission morphology and which are formed mainly in the gas-phase, like hydrocarbons (CCH, c-C3 H2 ,CH3 CCH), cyanopolyynes (HC3 N and HC5 N) and cyanides (HCN and CH3 C3 N). Emission from complex organic
molecules (COMs) like CH3 OH, propanenitrile (CH3 CH2 CN), and methoxymethane (CH3 OCH3 ) arise from gas in thevicinity of a hot molecular core (T ≥ 100 K) associated with the HMYSO. Other COMs such as propyne (CH3 CCH),
acrylonitrile (CH2 CHCN), and acetaldehyde seem to better trace warm (T ≤ 80 K) dense gas. In addition, deuterated
ammonia (NH2 D) is detected mostly in the outskirts of IRAS 16562−3959, associated with near-infrared dark globules,
probably gaseous remnants of the clump’s prestellar phase. The spatial distribution of molecules in IRAS 16562−3959
supports the view that in protostellar clumps, chemical tracers associated with diﬀerent evolutionary stages — starless
to hot cores/HII regions — exist coevally.
Accepted by The Astrophysical Journal Supplement Series
https://arxiv.org/pdf/1804.06544

Chemical survey toward young stellar objects in the Perseus molecular cloud complex

20 Aya E. Higuchi , Nami Sakai , Yoshimasa Watanabe , Ana Lopez-Sepulcre , Kento Yoshida , Yoko
1

1

2

3,4

1,5

Oya5 , Muneaki Imai5 , Yichen Zhang1 , Cecilia Ceccarelli3 , Bertrand Lefloch3 , Claudio Codella6 , Rafael
Bachiller7 , Tomoya Hirota8 , Takeshi Sakai9 and Satoshi Yamamoto5
1

RIKEN Cluster for Pioneering Research, 2-1, Hirosawa, Wako-shi, Saitama 351-0198, Japan; 2 Division of Physics,
Faculty of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8571, Japan; 3 Univ. Grenoblehttps://arxiv.org/pdf/1804.06544

Chemical survey toward young stellar objects in the Perseus molecular cloud complex

20 Aya E. Higuchi , Nami Sakai , Yoshimasa Watanabe , Ana Lopez-Sepulcre , Kento Yoshida , Yoko
1

1

2

3,4

1,5

Oya5 , Muneaki Imai5 , Yichen Zhang1 , Cecilia Ceccarelli3 , Bertrand Lefloch3 , Claudio Codella6 , Rafael
Bachiller7 , Tomoya Hirota8 , Takeshi Sakai9 and Satoshi Yamamoto5
1

RIKEN Cluster for Pioneering Research, 2-1, Hirosawa, Wako-shi, Saitama 351-0198, Japan; 2 Division of Physics,
Faculty of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8571, Japan; 3 Univ. Grenoble
Alpes, CNRS, Institut de Planétologie et d’Astrophysique de Grenoble (IPAG), 38000 Grenoble, France; 4 Institut
de Radioastronomie Millimétrique, 300 rue de la Piscine, Domaine Universitaire de Grenoble, 38406 Saint-Martind’H ‘eres, France; 5 Department of Physics, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan; 6
INAF, Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125, Firenze, Italy; 7 IGN Observatorio Astron’omico
Nacional, Apartado 1143, E-28800 Alcal’a de Henares, Spain; 8 National Astronomical Observatory of Japan, Osawa,
Mitaka, Tokyo 181-8588, Japan; 9 Department of Communication Engineering and Informatics, Graduate School ofInformatics and Engineering, The University of Electro-Communications, Chofugaoka, Chofu, Tokyo 182-8585, Japan
E-mail contact: aya.higuchi at riken.jp
Chemical diversity of the gas in low-mass protostellar cores is now widely recognized. In order to explore its origin,a survey of chemical composition toward 36 Class 0 and Class I protostars in the Perseus molecular cloud complex,
which are selected in an unbiased way under certain physical conditions, has been conducted with the IRAM 30 m
telescope (1.3 mm band) and the NRO 45 m telescope (3 mm band). Multiple lines of C2 H, c-C3 H2 and CH3 OH havebeen observed to characterize the chemical composition averaged over a 1000 au scale around the protostar: C2 H and
16 while CH OH is employed as a proxy of complex organic
c-C3 H2 are observed as a proxy of carbon-chain molecules,
3
molecules. The beam-averaged column densities derived for these molecules show significant chemical diversity among
the sources, where the column density ratios of C2 H/CH3 OH are spread out by 2 orders of magnitude. According toprevious studies, the hot corino sources have abundant CH3 OH but deficient C2 H, their C2 H/CH3 OH column density
ratios being relatively low. In contrast, the warm-carbon-chain chemistry (WCCC) sources are found to reveal the highC2 H/CH3 OH column density ratios. We find that the majority of the sources observed in this study have intermediatecharacters between these two distinct chemistry types. A possible trend is seen between the C2 H/CH3 OH ratio andthe distance of the source from the edge of a molecular cloud. The sources located near cloud edges or in isolated
clouds tend to have a high C2 H/CH3 OH ratio. On the other hand, the sources having a low C2 H/CH3 OH ratio tend
to be located in inner regions of the molecular cloud complex. This result gives an important clue to an understandingof the origin of the chemical diversity of protostellar cores in terms of environmental eﬀects.
Accepted by ApJS
https://arxiv.org/pdf/1804.08245