Star Formation Newsletter Seminar
11/18
古屋#356 9-15

Chemical evolution in ices on drifting, planet-forming pebbles

Christian Eistrup, Thomas Henning F Planets and their atmospheres are built from gas and solid material in protoplanetary disks. Recent results suggest that solid material like pebbles may contribute significantly to building up planetaryatmospheres. In order to link observed exoplanet atmospheres and their compositions to their formation histories, it is importantto understand how icy pebbles may change their composition when they drift radially inwards in disks. Our goal is to model
the compositional evolution of ices on pebbles as they drift in disks, and track how their chemical evolution en-route changes
the ice composition relative to the ice composition of the pebbles in the region where they grew from micron-sized grains. A
state-of-the-art chemical kinetics code is utilised for modelling chemical evolution. This code accounts for the time-evolving
sizes of the solids that drift. Chemical evolution is modelled locally for 0.1Myr at two starting radii, with the micron-sized
solids growing into pebbles simultaneously. The pebbles and local gas, isolated as a parcel, is then exposed to changing physicalconditions, intended to mimic the pebbles drifting inwards in the disk midplane, moving to 1 AU on three diﬀerent timescales.
A modelling simplification is that the pebbles are not moved through, and exposed to new gas, but stay in the same chemicalgas surroundings in all models. For ice species with initial abundances relative to hydrogen of > 10 5 , such as H2 O, CO2 ,CH3 OH and NH3 , the abundances change by less than 20timescales (10kyr and 100kyr). For less abundant ice species, and thelongest drift timescale (1Myr), the changes are larger. Pebble drift chemistry generally increases the ice abundances of CO2 ,HCN and SO, at the expense of decreasing abundances of other volatile molecules.

Gap Opening and Inner Disk Structure in the Strongly Accreting Transition Disk of
DM TauLogan Francis, Nienke van der Marel, Doug Johnstone, Eiji Akiyama, Simon Bruderer, Ruobing Dong, Jun
Hashimoto, Hauyu Baobab Liu, Takayuki Muto, Yi Yang F Large inner dust gaps in transition disks are frequently
posited as evidence of giant planets sculpting gas and dust in the disk, or the opening of a gap by photoevaporative winds.
Although the former hypothesis is strongly supported by the observations of planets and deep depletions in gas within the gap
some disks, many T Tauri stars hosting transition disks accrete at rates typical for an undepleted disk, raising the questionof how gap opening occurs in these objects. We thus present an analysis of the structure of the transition disk around the
T Tauri star DM Tau, which is strongly accreting (⇠ 10 8.3 M yr 1 ) and turbulent (↵ = 0.078 ± 0.02). Using the DALI
thermochemical code, we fit disk models to simultaneously reproduce the accretion rate, high level of turbulence, the gas tracedby ALMA band 6 observations of 12 CO, 13 CO, and C18 O J=2–1 lines, and the observed dust emission from the mm continuum
and spectral energy distribution. We find a shallow depletion in gas surface density of ⇠ 10 relative to the outer disk and a gas
rich inner disk is consistent with the observations. The planet mass of < 1 MJup implied by the gap depth is in tension withpredictions for dust trapping in a highly viscous disk, which requires a more massive planet of of ⇠ 10MJup . Photoevaporativemodels including a dead zone can qualitatively reproduce some features of the DM Tau disk, but still struggle to explain thehigh accretion rates and the observed mm continuum flux.

Cosmic-ray ionization rate in protoplanetary disks with sheared magnetic fields

Yuri I. Fujii, Shigeo S. Kimura F We investigate the eﬀects of magnetic field configurations on the ionization rate bycosmic rays in protoplanetary disks. First, we consider cosmic-ray propagation from the interstellar medium (ISM) to theprotoplanetary disks and showed that the cosmic-ray density around the disk should be 4 times lower than the ISM value.
Then, we compute the attenuation of cosmic rays in protoplanetary disks. The magnetic fields in the disk are stretched to theazimuthal directions, and cosmic rays need to detour while propagating to the midplane. We show that the detouring eﬀectively
enhances the column density by about two orders of magnitudes. In the case of the disk around IM lup, this increases theionization rate over an order of magnitude for r & 100 au. On the other hand, for r . 100 au, the cosmic rays are shieldedat the disk midplane while the ionization rate is also enhanced at z ⇠ 2H. Our results are consistent with the recent ALMA
observation that indicates the radial gradient in the cosmic-ray ionization rate. The elevated ionization rate in the outer radiiof disks may activate the magnetorotational instability that was thought to be suppressed due to ambipolar diﬀusion. These
results will have a strong influence on the dynamical and chemical evolutions of protoplanetary disks.

Monitoring accretion rate variability in the Orion Nebula Cluster with the Wendelstein
Wide Field Imager

S. Flaischlen, T. Preibisch, M. Kluge, C. F. Manara, B. Ercolano F The understanding of the accretion process
has a central role in the understanding of star and planet formation. We aim to test how accretion variability influences
previous correlation analyses of the relation between X-ray activity and accretion rates, which is important for understanding
the evolution of circumstellar disks and disk photoevaporation. We monitored accreting stars in the Orion Nebula Cluster from
November 24, 2014, until February 17, 2019, for 42 epochs with the Wendelstein Wide Field Imager in the Sloan Digital Sky
Survey u’g’r’ filters on the 2 m Fraunhofer Telescope on Mount Wendelstein. Mass accretion rates were determined from thevariability on timescales from weeks to 2 years. The variability has likely no significant influence on a correlation analysis of the
X-ray luminosity and the mass accretion rate observed at diﬀerent times when the sample size is large enough. The observed
anticorrelation between the X-ray luminosity and the mass accretion rate predicted by models of photoevaporation-starved
accretion is likely not due to a bias introduced by diﬀerent observing times.

Methanol deuteration in high-mass protostars

M. L. van Gelder, J. Jaspers, P. Nazari, A. Ahmadi, E. F. van Dishoeck, M. T. Beltrán, G. A. Fuller, Á.
Sánchez-Monge, P. Schilke F The deuteration of molecules forming in the ices such as methanol (CH3 OH) is sensitive
to the physical conditions during their formation in dense cold clouds and can be probed through observations of deuterated
methanol in hot cores. Observations with ALMA containing transitions of CH3 OH, CH2 DOH, CHD2 OH, 13 CH3 OH, andCH18
3 OH are investigated. The column densities of CH2 DOH, CHD2 OH, and CH3 OH are determined for all sources, where thecolumn density of CH3 OH is derived from optically thin 13 C and 18 O isotopologues. Consequently, the D/H ratio of methanol
is derived taking statistical eﬀects into account. Singly deuterated methanol (CH2 DOH) is detected toward 25 of the 99 sourcesin our sample of the high-mass protostars. Including upper limits, the (D/H)CH3 OH ratio inferred from NCH2 DOH /NCH3 OH wasderived for 38 of the 99 sources and varies between ⇠ 10 3 10 2 . Including other high-mass hot cores from the literature,
the mean methanol D/H ratio is 1.1 ± 0.7 ⇥ 10 3 . This is more than one order of magnitude lower than what is seen for
low-mass protostellar systems (2.2 ± 1.2 ⇥ 10 2 ). Doubly deuterated methanol (CHD2 OH) is detected toward 11 of the 99
sources. Including upper limits for 15 sources, the (D/H)CH2 DOH ratios derived from NCHD2 OH /NCH2 DOH are more than twoorders of magnitude higher than (D/H)CH3 OH with an average of 2.0 ± 0.8 ⇥ 10 1 which is similar to what is found for low-masssources. Comparison with literature GRAINOBLE models suggests that the high-mass prestellar phases are either warm (> 20
K) or live shorter than the free-fall timescale. In contrast, for low-mass protostars, both a low temperature of < 15 K and aprestellar phase timescale longer than the free-fall timescale are necessary.

Methanol deuteration in high-mass protostars

M. L. van Gelder, J. Jaspers, P. Nazari, A. Ahmadi, E. F. van Dishoeck, M. T. Beltrán, G. A. Fuller, Á.
Sánchez-Monge, P. Schilke F The deuteration of molecules forming in the ices such as methanol (CH3 OH) is sensitive
to the physical conditions during their formation in dense cold clouds and can be probed through observations of deuterated
methanol in hot cores. Observations with ALMA containing transitions of CH3 OH, CH2 DOH, CHD2 OH, 13 CH3 OH, andCH18
3 OH are investigated. The column densities of CH2 DOH, CHD2 OH, and CH3 OH are determined for all sources, where thecolumn density of CH3 OH is derived from optically thin 13 C and 18 O isotopologues. Consequently, the D/H ratio of methanol
is derived taking statistical eﬀects into account. Singly deuterated methanol (CH2 DOH) is detected toward 25 of the 99 sourcesin our sample of the high-mass protostars. Including upper limits, the (D/H)CH3 OH ratio inferred from NCH2 DOH /NCH3 OH wasderived for 38 of the 99 sources and varies between ⇠ 10 3 10 2 . Including other high-mass hot cores from the literature,
the mean methanol D/H ratio is 1.1 ± 0.7 ⇥ 10 3 . This is more than one order of magnitude lower than what is seen for
low-mass protostellar systems (2.2 ± 1.2 ⇥ 10 2 ). Doubly deuterated methanol (CHD2 OH) is detected toward 11 of the 99
sources. Including upper limits for 15 sources, the (D/H)CH2 DOH ratios derived from NCHD2 OH /NCH2 DOH are more than twoorders of magnitude higher than (D/H)CH3 OH with an average of 2.0 ± 0.8 ⇥ 10 1 which is similar to what is found for low-masssources. Comparison with literature GRAINOBLE models suggests that the high-mass prestellar phases are either warm (> 20
K) or live shorter than the free-fall timescale. In contrast, for low-mass protostars, both a low temperature of < 15 K and aprestellar phase timescale longer than the free-fall timescale are necessary.

CO(J = 1-0) Observations toward the Filamentary Cloud in the Galactic Region of
153.60 6 l 6 156.50 and 1.85 6 b 6 3.50

Weihua Guo, Xuepeng Chen, Jiancheng Feng, Li Sun, Shiyu Zhang, Chen Wang, Yang Su, Yan Sun, Qingzeng
Yan, Shaobo Zhang, Xin Zhou, MiaoMiao Zhang, Min Fang, Ji Yang F We present observations of J=1-0 transitionlines of 12 CO, 13 CO, and C18 O towards the Galactic region of 153.60 6 l 6 156.50 and 1.85 6 b 6 3.50 , using the Purple
Mountain Observatory (PMO) 13.7 m millimeter telescope. Based on the data, one main filament and five sub-filaments arefound together as a network structure in the velocity interval of [ 42.5, 30.0] km s 1 . The kinematic distance of this molecular
cloud (MC) is estimated to be ⇠ 4.5 kpc. The median length, width, excitation temperature, line mass of these filaments are⇠ 49 pc, ⇠ 2.9 pc, ⇠ 8.9 K, and ⇠ 39 M pc 1 , respectively. The velocity structures along these filaments exhibit oscillatory
patterns, which are likely caused by the fragmentation or accretion process along these filaments. The maximum accretion rateis estimated to be as high as ⇠ 700 M pc 1 . A total of ⇠ 162 clumps and ⇠ 103 young stellar objects (YSOs) are identified inthis region. Most of the clumps are in gravitationally bound states. Three HII regions (G154.359+2.606, SH2-211, SH2-212)
are found to be located in the apexes of the filaments. Intense star forming activities are found along the entire filamentary
cloud. The observed results may help us to better understand the link between filaments and massive star formation.

Methanol deuteration in high-mass protostars
M. L. van Gelder1 , J. Jaspers1 , P. Nazari1 , A. Ahmadi1 , E. F. van Dishoeck1, 2 , M. T. Beltrán3 ,G. A. Fuller4, 5 , Á. Sánchez-Monge5 , and P. Schilke5
1

Leiden Observatory, Leiden University, PO Box 9513, 2300RA Leiden, The Netherlands
e-mail: vgelder@strw.leidenuniv.nl
2
Max Planck Institut für Extraterrestrische Physik (MPE), Giessenbachstrasse 1, 85748 Garching, Germany
3
INAF-Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy
4
Jodrell Bank Centre for Astrophysics, Department of Physics and Astronomy, University of Manchester, Oxford Road, Manchester,M13 9PL, UK
5
I. Physikalisches Institut, Universität zu Köln, Zülpicher Str.77, 50937, Köln, Germany
Received XXX; accepted XXX
ABSTRACT
Context. The deuteration of molecules forming in the ices such as methanol (CH3 OH) is sensitive to the physical conditions during

their formation in dense cold clouds and can be probed through observations of deuterated methanol in hot cores.
Aims. The aim is to determine the D/H ratio of methanol for a large sample of 99 high-mass protostars and to link this to the physicalconditions during the formation of methanol in the prestellar phases.
Methods. Observations with the Atacama Large Millimeter/submillimeter Array (ALMA) containing transitions of CH3 OH,
CH2 DOH, CHD2 OH, 13 CH3 OH, and CH18
3 OH are investigated. The column densities of CH2 DOH, CHD2 OH, and CH3 OH are determined for all sources, where the column density of CH3 OH is derived from optically thin 13 C and 18 O isotopologues. Consequently,
the D/H ratio of methanol is derived taking statistical e↵ects into account.
Results. Singly deuterated methanol (CH2 DOH) is detected at the 3 level toward 25 of the 99 sources in our sample of the highmass protostars. Including upper limits, the (D/H)CH3 OH ratio inferred from NCH2 DOH /NCH3 OH was derived for 38 of the 99 sources andvaries between ⇠ 10 3 10 2 . Including other high-mass hot cores from the literature, the mean methanol D/H ratio is 1.1 ± 0.7 ⇥ 10 3 .
This is more than one order of magnitude lower than what is seen for low-mass protostellar systems (2.2 ± 1.2 ⇥ 10 2 ). Doubly
deuterated methanol (CHD2 OH) is detected at the 3 level toward 11 of the 99 sources. Including upper limits for 15 sources, the(D/H)CH2 DOH ratios derived from NCHD2 OH /NCH2 DOH are more than two orders of magnitude higher than (D/H)CH3 OH with an averageof 2.0 ± 0.8 ⇥ 10 1 which is similar to what is found for low-mass sources. Comparison with literature GRAINOBLE models suggeststhat the high-mass prestellar phases are either warm (> 20 K) or live shorter than the free-fall timescale. In contrast, for low-mass
protostars, both a low temperature of < 15 K and a prestellar phase timescale longer than the free-fall timescale are necessary.
Conclusions. The (D/H)CH3 OH ratio drops by more than an order of magnitude between low-mass and high-mass protostars due toeither a higher temperature during the prestellar phases or shorter prestellar phases. However, successive deuteration toward CHD2 OH
seems equally e↵ective between low-mass and high-mass systems.
Key words. astrochemistry – stars: formation – stars: protostars – techniques: interferometric – ISM: moleculesmation.
The gaseous atomic D/H ratio can be increased in theprestellar phases through the exothermic reaction (Watson 1974;
Aikawa & Herbst 1999; Ceccarelli et al. 2014),++
H3 + HD ⌦ H2 D + H2 +

E,

(1)

where E = 232 K. Since in the cold (. 20 K) prestellar cores+
the backward reaction in Eq. (1) is less efficient, H2 D is enhanced and the atomic D/H ratio in the gas phase can be ef+
fectively increased through dissociative recombination of H2 Dwith free electrons. Moreover, gaseous CO is the main destructor++of H3 and H2 D (Brown & Millar 1989; Roberts et al. 2003) and4
3
thus the heavy CO freeze-out in dense (& 10 cm ) prestellar
cores additionally stimulates the increase of the gaseous atomic
D/H ratio. In turn, the enhanced atomic D/H ratio in the gas cantranslate into a higher D/H ratio of molecules forming in the ices
Article number, page 1 of 17

A&A proofs: manuscript no. ALMAGAL_D_H_methanol_paper
Table C.1. continued.

SourceType(1)(D/H)CH3 OH(D/H)CH2 DOH

Refs

G034-C1(MM9)I20293-WC
I22134-G
I22134-B

HMSC
HMSC
HMSC
HMSC

<8.7(-4)<1.9(-3)<1.7(-3)<6.7(-3)

–
–
–
–

27
27
27
27

Notes. The (D/H)CH3 OH and (D/H)CH2 DOH ratios are either directly taken from the reported literature or computed using Eqs. (2) and (3) using thecolumn densities from the reported literature. A 30% uncertainty was assumed in cases where no uncertainty was reported.
(1)
LMP: low-mass protostar, IMS: intermediate-mass protostar, HMS: high-mass protostar, LMPC: low-mass prestellar core, HMSC: high-mass
starless core.

Fig. 1. Integrated intensity maps of the CH3 OH 80,8 71,6 (Eup = 97 K, left), CH2 DOH 171,16 e0 170,17 e0 (Eup = 336 K, middle), and CHD2 OH
70,1 e1 61,1 e1 (Eup = 74 K, right) lines for 881427. The color scale is shown on top of each image. The image is integrated over [-5,5] km s 1with respect to the Vlsr of source A. The white vertical line in the colorbar indicates the 3 threshold. The source positions based on the continuum
emission are indicated with the white stars. The white ellipse in the lower right of each image depicts the beam size and in the lower left a physicalscale bar is displayed.
A&A proofs: manuscript no. ALMAGAL_D_H_methanol_paper

tra are extracted from the same positions as van Gelder et al.
(2022). In G023.3891+00.1851, the emission of CH2 DOH peakso↵set by about half the beam (⇠ 0.600 ) and therefore the spectrum is extracted from the peak of CH2 DOH 171,16 e0 170,17 e0(Eup = 336 K). For all other sources, the the peak in CH3 OH coincides with the peaks of CH2 DOH and CHD2 OH. For sources
also included by Nazari et al. (2022), our spectral extraction
locations are the same as theirs, which are extracted from thepeak position of the CH3 CN 124 114 integrated intensity maps,
except for 721992 and G023.3891+00.1851 where the CH3 OH
80,8 71,6 and CH2 DOH 171,16 e0 170,17 e0 emission peaks o↵set
from the CH3 CN 124 114 emission by about 100 . It is important
to note that these spectral extraction positions are di↵erent by
up to 100 from van Gelder et al. (2022) who extracted their spectra from the peak continuum pixel for all sources. Therefore, thecolumn densities derived in this work may deviate from theirs.
The reason why our spectra are extracted from the peak pixel of
CH3 OH is to have the highest signal-to-noise in methanol lines
and its isotopologues the extracted spectra.

on the work of Pearson et al. (2012). The line list of CHD2 OH
is taken from Drozdovskaya et al. (2022), which is mostly basedon the the work of Coudert et al. (2021).

Only transitions with Eup
50 K are used to derive thecolumn densities since lines with lower Eup likely include also
emission from non-thermally desorbed methanol and emission
possibly related to outflows. For 13 CH3 OH, the 141,13 132,12(Eup = 254 K) transition gives the only constraint on the column
density for many sources as the other transitions su↵er from severe line blending. Similarly, for CH1870,7
3 OH only the 81,8
(Eup = 86 K) and 141,14 132,12 (Eup = 239 K) transitions provide constraints on the column density as well as some information on the excitation temperature. Furthermore, for CH2 DOH
the 52,4 e1
41,5 e1 (Eup = 59 K) line, as well as several
other lines, have rather low Einstein Aij values (< 10 5 s 1 )and are often blended with other COMs. Moreover, the spectroscopy of the CH2 DOH 181,17 o1 182,17 e0 line is unreliable
and shows large discrepancies in Aij between the JPL catalog entry (Aij = 1.8⇥10 5 s 1 ) and that derived by Coudert et al. (2014,
Aij = 8.9 ⇥ 10 7 s 1 ) and is therefore also excluded from the
2.2. Deriving the column densities
analysis. Consequently, the 171,16 e0 170,17 e0 (Eup = 336 K)
The column densities of all methanol isotopologues are derived transition of CH2 DOH provided the best constraint on the colusing the spectral analysis tool CASSIS2 (Vastel et al. 2015) un- umn density of CH2 DOH. However, although the 51,5 e0 41,4 e0
der the assumption of local thermodynamic equilibrium (LTE). (Eup = 36 K) transition is excluded from the fitting, it can pro13 DOH 17
Fig.line
2. Spectral
fits
of CH
e0 CH
1718
e0 (E
= 336 K,vide
top row)
and CHDone1 61,1 etemperaturerow) asfor
information
the70,1
excitation
ofbottom
CH2 DOH
The
lists ofline
CH
and
OH
are
2CH3 OH,1,16
up taken
2 OH
1 (E up = 74 K,
3 OH,
30,17
3
881427A(left), 881427B
andet881427C(right).
TheEndresdata corrected
for the LTE
Vlsr areshown
in black
the best fit for
K is
ex = 150
the best-fit
model
shouldnotandoverproduce
thisTline.
Lastly,(Mülleral. 2001,
2005;
from
the CDMS
catalog(middle),
in red.
etshown
al. 2016).
These entries include the first three (CH3 OH) and for CHD2 OH, the 70,1 e1 61,1 e1 (Eup = 74 K) transition is the13

18

References. 1: van Gelder et al. (2020); 2: Appendix D; 3: Lee et al. (2019a); 4: Bianchi et al. (2017b); 5: Manigand et al. (2020); 6:
Drozdovskaya et al. (2022); 7: Jørgensen et al. (2018); 8: Taquet et al. (2019); 9: Jacobsen et al. (2019); 10: Yang et al. (2020); 11: MartínDoménech et al. (2019); 12: Martín-Doménech et al. (2021); 13: Chahine et al. (2022); 14: Hsu et al. (2022); 15: Lee et al. (2019b); 16: Ligterink
et al. (2021); 17: Fuente et al. (2014); 18: Ospina-Zamudio et al. (2018); 19: Belloche et al. (2016); 20: Müller et al. (2016); 21: Bøgelund et al.
(2018); 22: Neill et al. (2013); 23: van der Walt et al. (2021); 24: Ambrose et al. (2021); 25: Lattanzi et al. (2020); 26: Bizzocchi et al. (2014); 27:
Fontani et al. (2015).

Appendix D: Doubly deuterated methanol in B1-c, Serpens S68N, and B1-bS
Using the database entry of CHD2 OH provided by Drozdovskaya et al. (2022), transitions from CHD2 OH can also be searched
for in a few COM-rich low-mass protostars. Here, this is done for B1-c, Serpens S68N (hereafter S68N), and B1-bS from the2017.1.01174.S ALMA program. The content of oxygen-bearing COMs for these sources was presented by van Gelder et al. (2020),
but no public database entry was yet available for CHD2 OH at that time.
Only one strong transition of CHD2 OH (71,2 o1 70,1 e0 , Eup = 68 K) is available for these sources which lies on the very edgeof the covered frequency range. For B1-c and S68N, this transition is detected at the 3 level, but given that only half the line isobserved this detection is still tentative. Using the same method for deriving the column densities as used by van Gelder et al. (2020)
and assuming an excitation temperature of 150 K, we derive column densities of 2.0±0.

A&A proofs: manuscript no. ALMAGAL_D_H_methanol_paper

ph.SR] 9 Aug 2022

Monitoring accretion rate variability in the Orion Nebula Cluster?
with the Wendelstein Wide Field Imager
1
1
1
2
1
S. Flaischlen , T. Preibisch , M. Kluge , C.F. Manara , and B. Ercolano
1

Universitäts-Sternwarte, Fakultät für Physik, Ludwig-Maximilians-Universität München, Scheinerstr. 1, 81679 München, Germany
2
European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching bei München, Germany
Received November 9, 2021; accepted July 25, 2022
ABSTRACT
Context. The understanding of the accretion process has a central role in the understanding of star and planet formation.
Aims. We aim to test how accretion variability influences previous correlation analyses of the relation between X-ray activity andaccretion rates, which is important for understanding the evolution of circumstellar disks and disk photoevaporation.
Methods. We monitored accreting stars in the Orion Nebula Cluster from November 24, 2014, until February 17, 2019, for 42 epochswith the Wendelstein Wide Field Imager in the Sloan Digital Sky Survey u0 g0 r0 filters on the 2 m Fraunhofer Telescope on Mount
Wendelstein. Mass accretion rates were determined from the measured ultraviolet excess. The influence of the mass accretion ratevariability on the relation between X-ray luminosities and mass accretion rates was analyzed statistically.
Results. We find a typical interquartile range of ⇠ 0.3 dex for the mass accretion rate variability on timescales from weeks to ⇠ 2years. The variability has likely no significant influence on a correlation analysis of the X-ray luminosity and the mass accretion rate
observed at di↵erent times when the sample size is large enough.
Conclusions. The observed anticorrelation between the X-ray luminosity and the mass accretion rate predicted by models ofphotoevaporation-starved accretion is likely not due to a bias introduced by di↵erent observing times.
Key words. accretion, accretion disks – open clusters and associations: individual (Orion Nebula Cluster) – protoplanetary disks –stars: pre-main sequence – stars: statistics – X-rays: stars

10:00.0-05:20:00.0
30:00.0

DEC [J2000]

36:00.0

30.0

05:35:00.0

34:30.0

RA [J2000]

Fig. 1. WWFI u0 g0 r0 color composition of the ONC (image credit:
Wendelstein Observatory). Overlaid are the stars monitored in all threebands. The yellow symbols indicate stars that have a match with the Xray sources listed in the COUP catalog (J/ApJS/160/319/coup, Getman
et al. (2005)). The star symbols further indicate sources that were monitored for at least five epochs and allowed an estimate for the mass accretion rate.

s.
A
g

a,
s
3
e

↵

e
e

0.5 Myr

1.6 M€

0.1%

3 Myr

2900 K

1.5

1.0 M€

13150 K

0.6 M€

10 Myr3700 Klog(L [L€])4200 K1.0%

1.0

0.4 M€

4500 K
4850 K
10.0%

00.2 M€

0.1 M€

5200 K

0.55830 K
50.0%

0.0

30 Myr-1

AV = 1 maglog(Teff [K])3.7 3.6 3.5
-1

0

1

u' - g'2

3

4

Fig. 3. Color-color diagram of the WWFI sample, dereddened with theextinction values determined by Manara et al. (2012) and plotted as 2D
gaussians according to their photometric uncertainties. The values arecolored according to their T e↵ value. Overlaid are the mean colors foreach star as solid dots. The cross in the upper left corner indicates their
typical range of variability. The thick line shows the photospheric colors
for non-accreting stars. The thin lines represent tracks along which thesources are displaced from the photospheric track for increasing accretion. They converge in a point representing the pure accretion spectrum,described by a hydrogen slab model. The dotted lines indicate constantaccretion to total luminosities ratios, Lacc /Ltot .

-2

3.7

3.6
log(Teff [K])3.5

Fig. 4. Hertzsprung-Russel diagram of the observed sources. Overlaid
are the PARSEC 1.2S isochrones and mass tracks from Bressan et al.
(2012). The dots represent the mean bolometric luminosity for eachstar as a function of T e↵ . The vertical bars indicate the minimum andmaximum range of L⇤ for each star. The cross at the bottom shows
the typical uncertainty. In our analysis, we only regarded sources with
0.2 M  M  2.0 M and 5.5  log(⌧[yr])  7.3 in order to exclude
outliers in the Hertzsprung-Russel diagram.

log(dMacc / dt) - log(ádMacc / dtñ)

m
n
d
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1 Myr

2700 Kg' - r'

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s.
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0.1%
2900 K

1.53150 K

3700 Kg' - r'

a
H
d

2.0

4200 K

1.0%

1.04500 K
4850 K
10.0%

5200 K

0.55830 K
50.0%

0.0

-1

AV = 1 mag

0

1u' - g'2

3

4

30 Myr

00.2 M€

0.1 M€-1log(Teff [K])3.7 3.6 3.5-2

V1493 Ori

V1555 Ori

V1475 Ori

V786 Ori

V1477 Ori

V2400 Ori

V1552 Ori

V2080 Ori

V2420 Ori

V1481 Ori

V417 Ori

LN Ori

V488 Ori

V2057 Ori

JW 117log(L [L€])0.4 M€

0.5

MZ Ori

10 MyrV401 Ori

0.6 M€

V1444 Ori

1

KZ Ori

1.0 M€

1.0

V358 Ori3 Myrlog(dMacc / dt) - log(ádMacc / dtñ)

1.6 M€

V1531 Ori

0.5 Myr

V2023 Ori

1 Myr

1.5
V1550 Ori

2

0.0

-0.5

-1.0

log(Teff [K])3.7 3.6 3.5

-1.5
3.7

3.6
log(Teff [K])3.5

Fig. 4. Hertzsprung-Russel diagram of the observed sources. Overlaid
are the PARSEC 1.2S isochrones and mass tracks from Bressan et al.
(2012). The dots represent the mean bolometric luminosity for eachstar as a function of T e↵ . The vertical bars indicate the minimum andmaximum range of L⇤ for each star. The cross at the bottom shows
the typical uncertainty. In our analysis, we only regarded sources with
0.2 M  M  2.0 M and 5.5  log(⌧[yr])  7.3 in order to exclude
outliers in the Hertzsprung-Russel diagram.

Fig. 5. Boxplot showing the accretion rate variability of the targets.
The vertical solid lines indicate the range of the accretion rates and theheight of the boxes the interquartile range. The circles show the accretion rates for each target and epoch. The values are normalized to themedian values and color-coded according to their e↵ective temperature.

to photospheric emission. In addition, we limited the sample according to 0.2 M  M  2.0 M and 5.5  log(⌧[yr])  7.3 in1.5log(ádMacc/dtñ) - log(dMacc,fit/dt(M, t))

Slope: -0.37 ± 0.24
r: -0.36 ± 0.23

1.0

0.5

0.0

-0.5

-1.0

-1.5

log(Teff [K])3.7 3.6 3.5
-1.0

-0.5
0.0
0.5
log(LX, char) - log(LX,char, fit(M, t))

1.0

Fig. 8. Residual accretion rates vs. residual X-ray luminosities for the
ONC taking both the mean mass and the mean isochronal age dependence into account. The dotted line shows the best fit obtained with
LINMIX_ERR. The solid bars indicate the maximum and the minimum
residual accretion rates for each source.

ute of Astronomy and Astrophysics, Academia Sinica, 11F of Astronomy-Mathematics Building, AS/NTU No.1, Sec. 4, Roosevelt
Rd, Taipei 10617, Taiwan, ROC
11Gap
and
Inner
Disk Structurein theShinjuku-ku,
Strongly
AccretingTransition Disk of DM Tau
DivisionOpeningof Liberal Arts,
Kogakuin
University,
1-24-2 Nishi-Shinjuku,Tokyo
163-8677, Japan
onal Astronomical Observatory of Japan (NAOJ), National Institutes of Natural Sciences (NINS), 2-21-1 Osawa, Mitaka, Tokyo
Logan Francis ,1, 2 Nienke van 181-8588,Japander Marel ,3, 1 Doug Johnstone ,4, 1 Eiji Akiyama,5 Simon Bruderer,6
13 Department of Astronomy,
7, 8, 9 7-3-1 Hongo, Bunkyo-ku, Tokyo10113-0033, JapanThe Universityof Tokyo,
Ruobing Dong ,1 Jun
Hashimoto,Hauyu Baobab Liu , Takayuki Muto,11 and Yi Yang 12, 13
1 Department of Physics and Astronomy, University of Victoria

ABSTRACT

3800 Finnerty
Elliotof
Building
Large inner dust gaps in transition disks are frequently
posited Road,
as evidence
giant planets sculpting
Victoria,
BC, V8P 5C2,
Canadagas and dust in the disk, or the opening of a gap by
photoevaporative
winds.
Although the former
2 loganfrancis3@uvic.ca
hypothesis is strongly supported by the observations of planets and deep depletions in gas within the
LeidenUniversity,
P.O. atBox
9513,
2300-RAThe Netherlands
gap some disks, many3T
TauriObservatory,stars hostingLeidentransition
disks accrete
rates
typicalfor anLeiden,
undepleted
Herzberg
Astronomy
and occurs
Astrophysics,
West We
SaanichVictoria,
BC, V9E 2E7, Canada
disk, raising the4 NRC
questionof how
gap opening
in these5071
objects.
thus Rd,
present
an analysisof 5thestructureof the transition
disk aroundthe TArts,
Tauri
star DM Tau,
which is strongly
Divisionof Fundamental
Educationand Liberal
Departmentof Engineering,
Niigataaccreting
Institute of Technology 1719 Fujihashi,
945-1195,
Japan code, we fit0.02). Using Niigata
the DALI
thermochemical(⇠ 10 8.3 M yr 1 ) and turbulent (↵ = 0.078 ±Kashiwazaki,
6 Max-Planck-Institutfür theExtraterrestrische
Giessenbachstrasse
1, gas85748
Garching, Germany
disk models to simultaneously
reproduce
accretion rate, Physik,high levelof turbulence, thetraced7 Astrobiology
by ALMA band
6 observationsof 12National
CO, 13 CO,
and C18of
O Natural
J=2–1 lines,
and theobserved
dust
emission
Center,Institutes
Sciences,
2-21-1
Osawa,
Mitaka,Tokyo 181-8588, Japan
8 Subaru
from the mm continuum
andspectral energy
distribution.
WeObservatory
find a shallow
depletion
in gasTokyo
surfaceTelescope,
National
Astronomicalof Japan,
Mitaka,181-8588, Japan
9densityof ⇠ of
10 Astronomy,
relative to theouterand aGraduate
gas rich innerdisk isfor
consistent
the observations.
Department
SchoolofdiskScience,
University
Advancedwith
Studies(SOKENDAI), Mitaka, Tokyo 181-8588, Japan
implied by theAcademia
gap depth
is in tension
predictions for dust trappingThe
planetofmassof < 1 M
10
JupAstrophysics,
Institute
Astronomy
andSinica,11F of with
Astronomy-Mathematics
Building, AS/NTU No.1, Sec. 4, Roosevelin a highly viscous disk, which requires a more massive
planetof of Taiwan,⇠ 10MJup. Photoevaporative
Rd, Taipei
10617,
ROC
11 Divisionmodels including
a dead ofzone
can qualitatively
reproduce
some1-24-2
featuresof the DM Tau
disk, but still
LiberalArts, Kogakuin
University,
Nishi-Shinjuku,
Shinjuku-ku,
Tokyo 163-8677, Japan
struggle
to Astronomical
explain the highaccretion ofrates
and(NAOJ),
the observed
mm continuum
12 National
ObservatoryJapan
National
Institutes offlux.
Natural Sciences (NINS), 2-21-1 Osawa, Mitaka, Tokyo
181-8588,Japan
13 Department of Astronomy, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan

Keywords: stars: formation - protoplanetary disks - planetary systems – protoplanetary disks - accretion, accretion disks - stars: variables: T Tauri, Herbig Ae/Be

ABSTRACTTable 2. Image properties

AASTeX v6.3.1 Sample article

Line

Beam FWHMa (00 )Approx. Beam FWHM (au)RMSrobustmultiscale (pix)a

uvtaper (00 )

cont.
12
CO
13
CO
C18 O

0.045 ⇥ 0.032
0.312 ⇥ 0.296
0.301 ⇥ 0.286
0.892 ⇥ 0.840

7
62
60
178

0.018 mJy/beam
2.9 mJy/beam · km/s
2.7 mJy/beam · km/s
6.2 mJy/beam · km/s

0.5
2.0
2.0
2.0

0, 6, 20, 40
-

0.3
0.3
0.3

Note—
a6 The size given is the full width at half maximum(FWHM)of the major and minor axes of the clean beam ellipse.
Francis etal.

7• 観測結果と使⽤した
データのまとめ
AASTeX v6.3.1 Sample article

7b The pixel size is 5 milliarcsec for all images.

In the following Sections, we describe the detailed
structure of the DALI models used to interpret the DM
Tau observations and determine the gas and dust structure within the 21 au cavity.
4.1. Chemical Network and Gas Composition
The underlying chemical network is the same as inprevious DALI studies, and is based upon the reactions in the UMIST2006 database (Woodall et al. 2007)
with some extensions for non gas-phase reactions described by Bruderer et al. (2009) and Bruderer et al.
(2012). Molecular data for collisions and radiative rates
are taken from the LAMDA database (Schöier et al.
2005); the calculation of the reaction rate coefficientsfor CO in particular are described by Yang et al. (2010)
and Jankowski & Szalewicz (2005). The elemental composition of the disk gas used in the DALI chemical net-

work is assumed to be that of the di↵use ISM (Bruderer
et al. 2012), and the gas phase abundances of each element relative to hydrogen used are listed in Table 3.
Although we assume ISM abundances for carbon andoxygen, gas mass measurements of DM Tau from HD
imply that the CO abundance may be lower than the
ISM value, a point which we return to in our discussionof the modelling caveats in Section 6.2.
4.2. Surface density structure
The radial surface density structure for DM Tau isshown in Figure 4, and closely follows the transition disk
structure previously implemented in DALI by Bruderer(2013), with some modifications to account for the inner dust ring. The surface density profile for gas in theouter disk is a radial power law which transitions to an
exponential cut-o↵ at a critical radius rc , as motivatedFigure 3. Spectral energy distribution for DM Tau, redcircles are photometric measurements, black dots are Spitzer
IRS spectra. Top panel: overall SED; Bottom panels: zoom
in on the near to mid infrared portion.

Figure 1. Top panels: 1.3 mm dust continuum images of DM Tau and zoom in on the 21 au dust cavity; lower left panels:
moment 0 maps of each observed CO line; lower right panels: Flux of each CO line integrated over the disk vs the velocity. The
beam for the continuum and moment 0 images is shown in the bottom-left of each panel as a white ellipse.

Figure 2. Deprojected and azimuthally averaged intensity
profiles of the 1.3 mm dust continuum and moment 0 maps
for each observed CO line. The full width at half maximum(FWHM) of the beam is shown by the scalebar.

We assume= 1, which corresponds to a vertically
isothermal disk with an alpha viscosity prescription⌫ = ↵cs H (Pringle 1981) and radial temperature profile
T / r 1/2 (Hartmann et al. 1998). The surface density
for the dust in the outer disk follows the same relation,
Figure 3. Spectral energy distribution for DM Tau, red
but with a constant scaling set by the gas to dust ratio
circles are photometric measurements, black dots are Spitzer
gas/dust . To reproduce the observed dust outer and inner dust rings of DM Tau (Section
we introduce
twopanel: overall SED; Bottom panels: zoom
IRS 2),
spectra.
Top
depletion factors in surface density relative to the outerin on the near to mid infrared portion.
disk, dust1 and dust2 , which begin at radii of rcav = 21
and rinner = 3.5 au respectively. We find that the powerto bethe di↵use ISM (Bruderer
emed
withinthethat
21 auofcavity.
4. MODELLING

Although we assume ISM abundances for ca
work theis assumed
to be thatabundancesof the di↵use ISM
oxygen, gas mass measurements of DM Tau, andgas phaseof (Bruderereach eletal.
2012),
and
the
gas
phase
abundancesofeach
elFigure
3.
Spectralenergy distribution for DM Tau, redurementsofCO
emission
in
disks
can
imply
that
the
CO
abundance
may
be
lower
4.1.
ChemicalNetworkandGas
Composition
iveement
to hydrogenused
arelistedinTable
3.
are photometric measurements, black dots are Spitzer
relative to hydrogen used are listed circles
in
Table
3.
IRS spectra. Top panel: overall SED; Bottom
panels:zoom a point which we return to in ourISMvalue,
tracerofassumethegasabundances
surfaceeaAlthoughassumeISM
abundances
forisfordensity,
carbonandinon thenear
to midThe
underlying
chemical
networkthesame
as infraredin portion.
we
ISM
carbonandofthemodelling
caveatsin
Section6.2.
oxygen,gas
massmeasurements
of
DM
Tau
from
HD
ting
COstudies,emissiongas surface
viousthe
DALI
andtois abased
upon the reac-

mass measurements of DM TauWefrom
assume HD= 1, which corresponds to a vertically
imply that the CO abundance may be lower
than disk
the with an alpha viscosity prescription
isothermalnsinsimple;the UMIST2006
database(Woodallet al.the
2007)
not
the
CO
abundancevariestheCOabundance
may
be
lower
than
⌫ =discussion↵c H (Pringle 1981) and radial temperature profile
ISM value, a point which we return to in our
4.2.
Surfacedensity
structurehsomeextensionsfornongas-phasede(Hartmann
et al. 1998). The surface density
T /reactions
rofthemodelling
caveatsin
Section
6.2.
isk
due
to
photodissociation
inthe
upa point which we return to in our for
discussion
the dust in the outer disk follows the same relation,
ibed by Bruderer et al. (2009) and Bruderer
et scaling
al. set by the gas
Theradialsurface density structure for D
but
with
a
constant
to
dust
ratio
ezeouttowards
the cold6.2.
midplane. The
lling caveats
in Section.Spectral
To reproduce
thedistribution
observedshown
dust
outer
and
in-red
4.2.
Surfacedensity
structure
12).
Molecular
data
forcollisions
andradiative
rates
inFigure4,
andclosely
follows
thetran
Figure3.
energyfor
DM
Tau,
Figure 2. Deprojected and azimuthally averaged intensity
nerdust
rings of DMmeasurements,
Tau (Section 2),
we introduce
two
mical
modellingcode(Brudereretal.
circlesarephotometric
black
dots
are
Spitzer
profiles of the 1.3 mm dust continuum and moment 0 maps
depletion
factors
in surface
densityrelative
topanels:
the outerTheradialsurfacedensity
structure
for
DM
Tau
is
taken
from
the
LAMDA
database(Schöieretal.
structurepreviously
implemented
in
DALI
by
IRS
spectra.
Toppanel:
overall
SED;
Bottomzoom
for each observed CO line. The full width at half maximum
disk,
andmid infrared, whichportion.
begin at radii of r = 21
4.2.
Surfacedensity
structurehese
issuessolvingforthegas
tem(FWHM)
oftheFigurebeam byis shown
by thescalebar.
in
on
the
near
to
shown
in
4,
and
closely
follows
thetransition
disk05); the calculation of the reaction rate
(2013),
with some modifications to account= 3.5 au respectively. We findthat the power
and r coefficients
structurepreviously
implemented
in
DALI
by
Brudererlaw
rise in dust surface density of our model between
abundance
in
a
model
disk,
providedin particular
arestructure
described
by
Yang
et
al.
(2010)
ner
dust
ring.
The
surfacedensity
profileforbysurface
analyticalmodelsof a self-similar
viscously evolving
lCO
density
for
DM
Tau
is
We
assume=1,whichcorresponds
toavertically
21forand the
3.5 auincan provide a good match to the surface(2013),
withsome
modifications
toaccount
accretion disk with a time-independent radial distribuFigure 4. Surface density structure of the gas and dust
brightness
of
the
inner
dust
ring
withouttheneedtoinisothermal
disk
with
an
alpha
viscosityprescriptiond
Jankowski&
Szalewicz(2005).
The
elemental
comouterdisk
isaradial
power
law
which
transit
dust
structure
and
model
for
the
stellar
ner
dust
ring.
The
surfacedensity
profile
for
gas
in
the
model
in
DALI
used
to
simulatetheDM
Tautransition
disk.
& Pringle
1974;
tion of4,viscosityr : (Lynden-Bellgureand⌫ /closely
follows
thetransition
disk
troduce
additional1981)
modelandparameters
for its outer edge⌫=↵c
H
(Pringleradialtemperature
profile The dashed lines show the truncated power law profile for thesHartmannetal.
1998):
ition
theispreviously
disk
gaspowerusedin whichthe
DALI
chemical
netexponential
cut-o↵
ata
criticalradiusr,
as
1/2
outerofdisk
a radiallawtransitions
to
an
and
dust
surfacedensity,
allowingforasimplermodel.
c
gas
and
dust
with
no
depletion.
DALI
has
been
used
for
de(Hartmann et al. 1998). The surface density
Tby/ r Bruderereviously
implemented
in
DALI
For
the gas surface density, corresponding depletion#"
exponential cut-o↵atacriticalradiusr,
asmotivated✓ ◆✓ ◆cfor the dust in the outer disk follows the same relation,
factorsofandinterior to the same radii asrrssurfacedensity
withintransition
disk
h some⌃(r)modifications
toaccountin.
(1) butfor=⌃
expwith atheconstant
scaling set by the gas to dust ratio
4.3. Vertical structure and dust populationsrr
gas/dust . To reproduce the observed dust outer and inThe vertical density structure of the gas disk is aAg.
COobservations(BruderervanThe
surfacedensity
profile 2013;
for
gas
in
the
Deprojected
and azimuthally
averaged
intensity
ner dust rings of DM Tau (Section 2), we introduce two Gaussian with scale height angle h(r) = h (r/r ) ,the 1.3 mm dust continuum and moment 0 maps
depletion
factors
in surface density relative to the outer where is a radial power law index which allows for flar2015,2016),
andmoreover,also
persserveda radial
power
law
which
transitions
toan
CO line. The full width at half maximum
ing of the disk and the physical scale height is H ⇠ rh.
disk,
and
,
which
begin
at
radii
of
r
=
21
dust1
dust2
cav
of the beam is shown by the scalebar.
To approximate vertical dust settling, two populations
adiativetransfer
necessarycompar=3.5
aurespectively.
We
find
that
the
power
and
r
cut-o↵ ata criticalradius rfor,asmotivatedinnercof small (0.005 - 1 µm) and large (0.005 - 1000) µm
law rise in dust surface density of our model between dust grains are included; the small dust grains follow
models continuumof a self-similar viscously
mcaldust
andevolving
SED.
s
1/2

gas/dust

dust1

dust2

cav

inner

2

c

c

gas1

gas2

c

c

c

4.3. Vertical structure and dust populations
The vertical density structure of the gas disk is a
Gaussian with scale height angle h(r) = hc (r/rc ) ,where is a radial power law index which allows for flaring of the disk and the physical scale height is H ⇠ rh.
To approximate vertical dust settling, two populationsof small (0.005 - 1 µm) and large (0.005 - 1000) µm
dust grains are included; the small dust grains follow
the gas with scale height angle h, while the large dust
grains are more concentrated towards the midplane andhave a reduced scale height angle of h, with fixed to
0.2. The dust surface density is partitioned between thetwo populations by a large grain fraction fls and (1 fls ) for the small grains. The large grain fraction is byrelevantelling,aformalmodel
fitting
based ontemperature 3580 K and luminosity 0.24 Ldisk.
and
CO
lines
to
the
The parameters of the fiducial DALI modelfit
are produst den
Stellar ofmodel
the stellar4.4.
properties
DMand
Tauradiation(Section field2). UV heat- 4.5. Model grid
AASTeXv6.3.1
Samplearticlevided in Table 3. To descent)show the accuracy
with whichisimpractical.
Ou
are show
projected
imagesaThecentralstar
isapproximatedasablackbodywiththefiducialmodel
reproducestheobservations,theouting from accretion is included by adding the contribuTable 3. DM 9
Tau Parameter Space
midplan
AASTeXv6.3.1
Samplearticle
The
grid
used
for
the
calculationconsists
of
200
cells
in
stead
to imuthally
obtainm4
put of the DALI raytracer
is comparedwith the ade-fiducial
on 4.6. Raytracing and Model Images
temperature
3580 K blackbody
and luminosity
averagedtionof an additionalwith 0.24
Tacc L= 10based
K andthe ⌧ =
Parameterazimuthally averaged Value
projected
continuum, CO isotopothe stellarluminosity
properties of DM Tau(Section
2).
UV
heataccretion
Theof
sam
the radial direction and 80 cells in the vertical direction.
reproducesthefeaturesmanneras
theobs
logues,SED and CO line
over the disk
DMfluxes
Tau integrated
Using
the
converged
outputofthethermochemical
5 au ofing from accretionis included by adding the contribu- 4.7. Model fitting approach⌃212present
throughout
0.65
g
cm
ingas,cFigure 5. A direct comparisonof the output images
To
resolve
the
parts
of
the
disk
with
sharp
transitions
dust
continuum,
the
CO,
4
full
disk
pare
the
model
SED
GM
Ṁ
tion of an additional blackbody ⇤with Tacc =modelling,
10 K and10
gas/dust
the DALI code performs andraytracing
simumoment maps fromthe raytracer is provided in Fig,
(2)
Lacc = ⇡The grsubl , and 0.0343 au 0 maps, and SED, with a,rinand dust
surfacedensity(i.e.,
rR⇤ gas Due
paaccretion luminosity
subl
inner
ure 19DALIof the appendix.
to
the
large
computational
cost
of
the
modobserved
SED
ovewith he2.5, 3.5, 4.5 To
aulations to produce model images andrinnerline
cubes.
The radial
profileof the dust emission is reasonably
2
r
21
au
ation
of
)
the
cell
size
grows
exponentiallystarting
from
these
r
cav
tures
within
the
21
au
dus
cav
and
R
the
where G is the gravitationalGM
constant,
M
⇤
⇤
by
the
photometry
gradient
elling,aformalmodel
fitting
approach(e.g.
well
described 124.1
by is
the
model, however, the model under⇤ Ṁrc
au permatchtheALMA
observations,theraytracing
the disk
=
⇡
,
(2)
L
i
acc
mass and radius of the star, andtheestimates
the 0.03,
emissionin radthe outerdisk beyond ⇠ 60 if the gas
=
10
,
where
=
0.01
au
radii,
i.e,stellar
hc is the0.06, 0.09
wishto
investigate
R⇤ Ṁdescent)cellaccreminminmoleculnear
tomid
infrareisimpractical.
Ourmodellingstrategyisinformedim-with the model disk at an inclination
ofobservations
35.2 of Hashimoto et al. (2021)
0.2
au. The ALMA
tion rate. Modelling the UV heating is particularly
CO is pminimum
radialcellwidth,iistheradialcell
index,
and
cial
model
withinthecavity0.015,
0.15,
1.0
gas1 shown several low contrast dust rings are present at
haveR⇤somethewhere Gofis 200
the gravitationalM⇤ and
In
order
to
obtai
portantfordiskchemistry,
but issubjecttoonsists
cells
in constant,stead
toobtainafiducial
model
which
approximately
it can su
and distance of 144 pc (see Sections these2gas2 and3)witha0.15, 1.0, 10.0
points in the outer disk, which we do not attempt
mass and radius
thepaucity
star, andṀ thestellarUV
accresphereouncertainty
due toofthe
ofdetermines
highqualityob-cell growth rate. The 200 radial
the
cells
with
the
stellaraccretionrat
1.0(-50), 2.7(-2)
dust1
simulations
using
to reproduce
as ourfocus is on the dust cavity and innerheservations,verticaldirection.
reproducesthefeaturesoftheobservations:
the
mm
pixel
size
of
5
milliarcsec.
The
model
SED
was
createdtion
rate. ModellingtheUV
heatingisparticularly
iminward
1.0(-50), 6.0(-10), 6.0(-9), 6.0(-8), 6.0(-7), 6.0(-6)
dust2
and di↵erent approaches using detailed steldisk.
The model
SED also
agreeswell with the modelobseraredistributed
in
this
way
to
provide
50
cells
from
0.01
in
the
fiducial
param
0.2
12
13
18
decrease
raytracingofthecportant
for
the
disk
chemistry,butissubjecttosomethlarsharptransitions
models havebeen used in other astrochemical
codes
dust bycontinuum,
CO,
and
C
O
momentraytracing
the diskfrom CO,0.09 to3000µm
andcalcuvations,although
0.85 the exact shape of the near-infraredfls (outer disk)
The lowc
to
3
au,
50
from
3.1
to
21
au,
and
100
from
21
au
to
uncertainty
due
to
the
paucityofhighqualityUV
obfect
of
the
inner
disk
and
(Woitke et al. 2016). For the observed accretion rate ofsilicatefeature0.24
is not reproduced, specifically,
the andflux SED. I
L
imagesdeeper i
latingF
overtheentireraytraced
image.
Sampling
of
e.,DM
r
,
r
,
and
0
maps,
and
SED,
with
a
particular
focus
on
the
strucsubl
inner
8.3
1
T
3580
K
servations,anddi↵erent
approaches
usingdetailedstel⇤at ⇠ 7 microns is overestimated, suggesting some deM yr ,thethe accretion
Tau of ⇠ 10edge ofluminosity
the calculation grid at 500 au. Vertically,80
layersininemission.
1
usedto
estimate
log(
Ṁ
)
-9.3,
-8.3,
-7.3
[log(Myr)]
tails approximatelyof the inner30diskwestructure
are missing. Hashimotolaramodels
haveused in
codes
the
SED
was
performed
atwavelengths
y startingfromwithin
the
21
au
dust
cavity.
Additionally,
=
0.24.
as
fractionof beenthatthesefromtheotherstar astrochemical
istures
Lacc /L1
dust tem⇤LX
10 erg settheal. (2021)
have
performedTo
radiative
transfermodeling
cells
arearrangedtofollowthescaleheightofgascompare
the
DALI
mo
7
(Woitkeetal.
2016).
For
theobserved
accretion
rate
of
,
after
which
and
r
layerso
T
10KThis relationship assumes that all of the gravitationalXccorresponding
tothephotometricdata,
exceptfor
theofthe ofsametheSED
andshow that the dip at ⇠ 7 microns=
0.01
au8.3isMthe
wishtoinvestigate
ifgas
surfacedensityfidu171
min⇣cr
5 ⇥ 10s 1
density,
DM
Tau
of
⇠
10
yr
,
the
accretion
luminosity
energy liberated by accretion disk.
is radiated away, which
and
CO
lines
to
the
observatissensitive to 1.0(-50),
the dust1.0(-5),
size 1.0(-3)
distributiondensity
between 1 and
via
⌃
,
f
gas,c
PAH
the
lowe
5-20
µm
range,
where
steps
of
0.33
µm
were
used
for
/L⇤ = 0.24.
as aa reasonablefractionof approximationthat andfrom the stariscial
Laccmodel
adialcell index,
within the cavity of the disk is 3Gas
commensurateisfor magnetosphericacau,
and can be reproduced by a model with a depleAbundanceis frozen
projected
images
and
mome
,
un
tors
This
relationshipassumes
that
all
of
the
gravitational
dust1
dust2
H
1
tion
in theModelsurfacedensityof micron sized dust grainscretiononto
pre-main-sequencestars(Hartmannetal.
comparison
withtheSpitzer/IRS
spectrum.
conthe CO
The
200
radial
cells
with
the
stellaraccretion
rate,
and
to
explorevariations
4He
7.59(-2)energy liberated by accretion is radiated away,
4.6.which
Raytracing and Model Images of 10 (their Figure 5).imuthally
We have also
experimented radial
averagedin2016).
approximately
repr
decreaseC
1.35(-4)
tinuumimageswerecreatedbyraytracingatawavewithvaryingtheamountof small dust grains from theisareasonableapproximationformagnetosphericacde 50
cells heatingfrom of0.01
the X-rays
fiducial
model parameters to understandtheefeach ofSimilarly,
the disk frominstellarisN
2.14(-5)mannerastheobservations
of
DM
Tau
displaysublimation radius to 3.5 au and similarly
find
there
is
Using
the
converged
outputofthethermochemical
cretiononto
pre-main-sequencestars(Hartmannetal.
key radilengthof
1.3mm,
followedbyconvolution
with
the
obO
2.88(-4)
taken
intoaccountbyaddingan
X-rayluminosity
of
100
from
21 1 au toaMgsmallone↵ecttheon theCOnear to mid infrared shape, howfect of the inner disk and cavity structure
4.17(-6)
pare
the
model
SED
produc
CO free302016).
ingalowabundan
LX = 10 erg s with a thermal
spectrumatT=modelling,
the
DALI
code
performs
raytracing
simuX continuum beam and deprojection
ever,
weby
weretheunableto reproduce the exact observed
servedsame
Si
7.94(-6)
region.
7
Similarly,
heating
of
the
disk
from
stellar
X-raysis0010au.
Vertically,80
emission.
SED
shape, which
require more careful
K, which is reasonably consistent with the observedS
1.91(-6)may observed
SEDmodellingover theincrease
tot
PAH
fractionf
PAHlationstoproducemodel
imagesandline
cubes.
To
procedure
Sectiontaken luminosity
into accountby =addingan10X-rayluminosityof as described for the observations
30
1
Fe the innerin
4.27(-6)ofringgeometry that is beyond the scope of
1
3
⇥
erg
s
(Dionatos
X-ray
of
L
X
temperaleLXheightgas
Tocomparethe
DALI
modelsforthemmcontinumm
30 of the1bythephotometry
and
the
S
b
ultimately
reNote—Numbers
written as a(b) indicate a ⇥ 10 . sion,
Where a rangeof
thispaper.
=
10
erg
s
with
a
thermalspectrum
at
T
=
match
the
ALMA
observations,theraytracingisperX
et al. 2019) given the intrinsic variability of 3.
X-raySimilarly,
emismodel
line
cubes
were
createdassuming
sharp drvaluesisindicated,parameters
denoted
bold
are
the
fiducial
model
7
which isareasonably
consistentwiththeobserved
10
and
CO
lines
to
the
observations,
we
took
the
outputtomidparameters.
Parameters inderednear
are the non-fiducial
valuesinfrared.
forthe case that opticallysion.K, Finally,
backgroundcosmicray
ionization
rate
We
note
PAH
formed
with
the
model
disk
at
an
inclination
of
35.2
30
1 keplerian velocity structure of the diskaandraytracof no inner disk.
X-ray luminosity of LX = 1 3 ⇥ 10 erg s (Dionatos
Within•観測結果とfiducialモデルの⽐較

Figure 5. Comparison of the DM Tau observations (black lines and red circles for SED photometry) and fiducial model (bluelines). Top Row: deprojected and azimuthally averaged mm continuum intensity, Overall SED, and SED zoomed in on the nearto mid infrared region. Middle Row: deprojected and azimuthally averaged intensity for the moment 0 maps of the 12 CO, 13 CO
and C18 O lines. Bottom row: Flux integrated over the disk vs velocity for the 12 CO, 13 CO and C18 O line cubes. The spectral
resolution of the observed line cubes is 1 km s 1 , while the models are sampled in 0.5 km s 1 steps

of the dust continuum emission at 21 au
disk to shieldthe
thedisk
midplanefromradiation,tgenerale↵ectsofvariations
intheismodel
parametershig
near-infraredexcessoftheSEDslightly•観測結果とfiducialモデルの⽐較
on
the RESULTS
physical conditions of the disk.
5.
ghter while the emission in the outer disk structure,
freezeoutzone
isentirelyabsentinthecavity,
a
gas
and
dust
temperature,andCOabundanc
the the 2.5 au case but underproduced in the
5.1. Fiducialmodel
au is unchanged; the SED is entirely miss- underscores
onset
beginsafew
aufurther
out
in
the
disk
fro
the
valuableroleofthermochemical
mod
case,
suggesting
that
r
is
well
constrained
ov
inner
In
this
Section,we
describethefiducial
DALI
mThe
parametersofthefiducial
DALI
model
fit
are
proSurface
densityatstructureandselected
2D physicalquantities
fromedgethe fiducialDM
Tau
modelmodel.
plottedInfrom
fromsilicates
10
µm
and
now
peaks
in
21
au
cavitythan
inthefiducialcoellingforinterpretingline
emissionfromdisks.
vided
in Table
3. To anshowincreased
the accuracy with
which
12
13
18
largervalue
ofrcauses
gas
temp
inner
=
1
surfaces
for
CO,
CO
and
C
O
lines
are
overlaid
on
each
2D
DALI
panel
as
the
solid,
dashed,
an
for
DM
Tau,
explore
how
well
the
inner
disk
and
the
fiducialmodel
reproducestheobservations,theoutar-infrared rather than at ⇠ 20 µm. The
to the results of DALI modelling by Bruderer (201
(Figureresultinginatheslight< rinnerput isofthe
DALI 23),
raytracer
is comparedde- onectively while the approximate freezeout temperatureatofradii
CO (25.5K)
overlaid
as theorange with
contournner
disk
causesthesee↵ectsbyallowing
find
CO
is
not
photodissociatedwithinthedust
structureareconstrainedbyobservations,andconprojected
azimuthally
averaged
continuum,COisotopo5.2.
Parameterspace
e panels.
in the model CO
withinthe 21cavit
logues,emission
SED and CO line
fluxes integrated
overauthe diskradiation to reach the cavity edge atthe
21 au
without
an
inner
disk,
which
we
discuss
furtherigenerale↵ectsofvariations
the
model
param
in
Figure5. Ae↵ects
directincomparisonofthe output
images ke
Wefurther
exploretheofvaryingvarious
ever,
this
is
poorlyconstrained
by
the
CO
obser
andtheCOcavity,
abundance
E↵ect
Ring
and5.2.1.
moment maps
from ofthe Inner
raytracer Dustis provided
in Figg, gas
theandhotdustdusttemperature,component inas parameterstion 6. for thefiducialmodel
to demonstrate hoonthephysicalconditions
the
disk.
ure of19
ofresolution.
theof
appendix.
due
to
the
lack
res
of thermochemical
modure the21. valuable
The CO roleemissionis brighter in the
The radial profile of the dust emission is reasonably
Dustsurfacedensity
5.2.2.
wellconstrainedbytheobservations
thefiducial
mod
12
well
described
by themodel, however,thedescribedmodel under- ininterpretingline
emissionfromdisks.
9,
but
for
the
e↵ectsofchanging
thewithin3.5
auin the
DALI
model
Many
transition
disks
are
observedtohaveacularly
the more optically thick dust
CO depletion
estimates
the emission
inthe outerdisk beyond⇠ 60 ga
is and The
investigate
the
e↵ect
on
the
radiation
field,
structure
withinthecavitya tranGas
surfacedensity
5.2.3.
au.within
The
ALMA
observationsof cavity
Hashimotoet ofal. (2021)
disk dustor5.1.
ringthecentral(Francis&
Fiducial
model
otopologues, which reach 2-3 times higher and dust
temperature,andCOabundance
within
th
have
shown
severallow
contrast
dust
rings
are
present
at
5.2.
disk
can 2020),
play animportantrole toin e↵ectregulating
t
Marel
which
is
expected
the
su
at
their
⌧
=
1
surfaces;
in
the
outer
disk
these
pointsin theouterscale
disk,
which
we density
do not attempt
culate the vertically averaged gas The parametersDiskheight5.2.4.
cavity.
The
structure
of
the
gas
surfacewitofthefiducial
DALI
model
fit
ar
diationfield
throughout
the
disk
and
is
typicallto
reproduce
as
our
focus
is
on
the
dust
cavity
and
inner
ther
explorethee↵ects of Without
varying various
key
CO in the cavity by shielding the gas in the cav
ion
islargely
unchanged.
an
inner
disk.
The model
SEDcanalso agrees
well withimportan
the obserd by the gas density for the fiducial21
aucavityofDM
Tauprovidestrainedbythemmcontinuum
emission
and
SE
vided
in
Table
3.
To
show
the
accuracy
withrsFigure
for9. Comparison
the fiducialmodel
todemonstratehowstellarradiation(Bruderer2013).
Here,
we
exp
vations,although
the
exact
shape
of
the
near-infraredof the fiducial DM Tau DALI model and a model with no inner dust disk (
=
= 10
for
modelsofplanetdisk
andaccret
↵
is
by
with
the
DMpoorly
Tau observations,constrained
as described in Section 5.2.1. Top
Row:obserdeprojected and azimuthally averaged
mm continuum
The
scale
height
of
the
gas
disk
depends
silicatefeatureis notinteraction
reproduced,
specifically,thefluxontrainedbyzoomed
thein onobservations
thefiducial
model
of
the
inner
dust
ring
at
3.5
au
in
DM
intensity, and SED
the near to mid infrared region.
MiddleRow: deprojected
and azimuthally averagede↵ect
intensity
thefiducialmodel
reproduces
observations,at ⇠ 7 microns is theoverestimated,suggesting some de-th
for the moment 0 maps of the CO, CO and C O lines.
inthecavity.
Here,
we
vary
and
wit
ks,
but
is
typically
assumed
to
be
gas1
gas2
drostatic
equilibriumbalancebetweenthegasof the inner fromdisk structure
missing. Hashimoto
vestigate the e↵ect on the radiation field, gasremoving ittailsentirely
our arefiducial
model,
put
of
the
DALI
raytraceriscomparedwithth
et modelal. (2021) have
performed
radiative
transfermodeling
fiducial
DALI
toassess
how
well
the
rad
au
is one of few
where turbua↵ect
thestellvtemperature,
anddisks
CO abundance
within the and gravity,ting bothandandto amounte↵ectively
zero
dust2
ofdust1
thewill
same
SED
and
show
that
the dip at ⇠ 7 ofmicrons
50 profiles
projected
azimuthally
averagedCOis e↵ectsensitive
to constrain
thedustcontinuum,
size distribution
between1 andisoemission
can
the
gas
surfacebeen detected through high velocity
.
The
on
the
observations
is
shown
i
10
ation absorbed3 bythedisk
surfaceasafunctio
au, and can be reproduced by a model with a depledust1

12

13

dust2

50

18

and
comparetheresults
with
the
gas
surfacetion
inthesurfacedensityofmicronsized
dust
grainslogues, SED
and
CO
line
fluxesintegrated
overth
ns of the CO line (Flaherty et al.
dius. In our DALI
model
setup,
the
scale
heigh
of 10
(their Figure 5). We have also experimented
impliedby
theaccretion
rate
for
an
↵-diskmodbulent broadening of 0.25-0.33 c , orwith varying the amount of small dust grains from the
124

7. CONCLUSIONS

the disk continuum emission, 12 CO, 13 CO, and C18 O
In this paper, we have used thermochemical modelling
es,withSED,
and stellar
accretion rate
to constrain
the DALI
code in combination
with ALMA
images theoperties of the gas cavity and inner disk of DM Tau.
ur major conclusions are the following:

Hashimoto et al. (2021) and Calvet et al. (2005)• The
planetmassspeciesof . 1M
shallow
J implied
Most
volatiles
arelikely inby
thethe
gas
phase
gas
gap and↵=0.078±0.02
meawithin
3.5 aucavity,and mayfrom
thusturbulence
be incorporated
surements(Flaherty
al. 2020), is inconsistent
into planets
forming etwithin.
with the larger planet masses required for dust
trapping in a highly viscous disk. A deeper but
narrower gap unresolved by our ALMA observations could allow for a higher planet mass consistent with dust trapping by a giant planet.

• The gas surface density within the 21 au dust cavity18.
is appears
to=show
only a shallow
depletionbyigure
Midplane (z0) temperature(top panel)andbundanceof various
species
into ices(bottoma factorof ⇠ volatile
10, whichis locked
consistentwithestimates • The inner disk of DM Tau absorbs much of theanel)ofin thethe fiducial
DM Taudensity
model within
10 au.
X/H+H
2
stellar radiation, lowering the gas temperature ingas surface
in the
inner
disk
from
enotes the ratio of the number densities of ice X and thethe cavity. In contrast to the DALI transition disk
thestellaraccretion
rateandviscous↵-diskmodotal gas density. N.B.: the gas and dust temperature at themodelling of Bruderer (2013), CO is able to survive
midplaneare essentiallyin thisregionofof thethe disk.
elling,however,identical
the gasdensity
inner disk
in the shallow gas cavity of DM Tau even without
itself is poorly constrained and could be enhanced
an inner dust disk providing shielding from pho.5 au,
midplaneis cold100(⇠ relative
30 K) andices gapby thea factorof 10
to mosta shallow
todissociation, which is likely the result of H2 forhouldbe frozen
out.
As the innercavityat 3.5 auandstill beconsistentwithouredgeinterpretationofmation at higher gas densities by the H 1 + H !
approached, the midplane temperature rises to ⇠ 200
H2 + e reaction, which provides an alternative
the CO observations and the accretion rate.

K, sufficient to remove essentially all of the ices on therains. Any planets formed within 3.5 au would thus be• The dead zone + photoevaporation models of
xpected to incorporate solids and gas which are respecetdepletedal. (2021)
can produce
transition disks
velyGárate
relatively
or enrichedin volatiles.

with an inner dust disk, outer ring, and high ac7. but
CONCLUSIONS
cretion rate,
are still unlikely as an explanaIn thiswe gaphave inused
thermochemical
modellingdisk, as
tionpaper,for thethe
DM Tau transition
with they
the DALI
code reproduce
in combination
ALMA
imagesdo notthewithhighstellaraccretion
rate or bright mm emission in the dust disk. However, non-viscous angular momentum transport in
the inner disk and uncertainties in the model dust
opacities may contribute to the disagreement between their models and the observations.
• The planet mass of . 1MJ implied by the shallow• Our SED modelling indicates DM Tau is extremely
depleted in PAHs relative to the ISM value, andhas a PAH fraction of at most 10 5 that of theISM, assuming that all PAHs are in the form ofneutral C100 H25 and that the PAH distribution
is uniform throughout the disk. Unlike previous
studies of PAH survival in transition disks (Geerset al. 2006, 2007), our modelling includes UV flux
from accretion in assessing the PAH abundance,
resulting in a lower inferred value.

pathway to CO formation.

• Our modelling of the inner disk indicates a ⇠3.5 au cavity, consistent with previous studies by
Hashimoto et al. (2021) and Calvet et al. (2005)
Most volatiles species are likely in the gas phasewithin 3.5 au cavity, and may thus be incorporated
into planets forming within.

APP

3 Frontier Research Institute for Interdisciplinary Sciences,

University, Sendai 980-8578,
Cosmic-ray ionization rateTohoku
in protoplanetarydisksJapan
with sheared magnetic fields
4 Astronomical Institute, Graduate School of Science,

1, 2
TohokuUniversity,
980-8578,
Japan
Yuri I. Fujii
andSendai
ShigeoS. Kimura

3, 4

1 Graduate School of Human and Environmental Studies,

ABSTRACT

Kyoto University, Yoshida-Nihonmatsu, Sakyo, Kyoto 606-8501, Japan
We investigate the e↵ects of magnetic field configurations on the ionization rate by cosmic rays in
2 Department of Physics, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8602
protoplanetary disks. First, we consider cosmic-ray propagation from the interstellar medium (ISM)
3 Frontier Research Institute for Interdisciplinary Sciences,to the protoplanetary disks and showed that the cosmic-ray density around the disk should be 4
TohokuUniversity,
SendaiJapan
times lower than the ISM value.
Then,
we computethe 980-8578,
attenuationof cosmic rays in protoplanetary
4 Astronomical Institute, Graduate School of Science,disks. The magnetic fields in the disk are stretched to the azimuthal directions, and cosmic rays need
University,WeSendaito detour while propagating Tohoku
to the midplane.
show980-8578,
that the Japandetouring e↵ectively enhances thecolumn density by about two orders of magnitudes. In the case of the disk around IM lup, this increases
the ionization rate over an order of magnitude
for r & 100 au. On the other hand, for r . 100 au, theABSTRACT
cosmic rays are shielded at the disk midplane while the ionization rate is also enhanced at z ⇠ 2H.
We investigatethee↵ectsofmagnetic
field
configurations
ontheionization
ratebycosmicrays
Our results are consistent with the recent ALMA observation that indicates the radial gradient in therotoplanetaryFirst,
weTheconsidercosmic-ray
propagationfrominterstellar
mediumcosmic-raydisks.
ionization
rate.
elevated
ionization ratein the outerradiitheof disks
may activatethe (ISMo the magnetorotational
protoplanetary disks
and thatshowedthat thecosmic-ray
around thedisk should
instability
was thought
to besuppresseddensity
due to ambipolardi↵usion.
These beresultsthan
will havea strong
influenceon wethe computedynamical theand attenuation
chemical evolutionsof protoplanetarydisks.
mes lower
the ISMvalue.
Then,of cosmic
rays in protoplaneta

sks. The magnetic fields in the disk are stretched to the azimuthal directions, and cosmic rays neeo detour while propagating to the midplane. We show that the detouring e↵ectively enhances th
Keywords: Cosmic rays (329), Protoplanetary disks (1300), Magnetic fields (994), Ionization (2068)
olumn density by about two orders of magnitudes. In the case of the disk around IM lup, this increas

Chemical evolution in ices on drifting, planet-forming pebbles
1
1
Christian Eistrup and Thomas Henning

Max Planck Institute for Astronomy (MPIA), Königstuhl 17, Heidelberg, Germany
e-mail: eistrup@proton.me
August 17, 2022
ABSTRACT
Context. Planets and their atmospheres are built from gas and solid material in protoplanetary disks. Recent results suggest thatsolid material like pebbles may contribute significantly to building up planetary atmospheres. In order to link observed exoplanet
atmospheres and their compositions to their formation histories, it is important to understand how icy pebbles may change theircomposition when they drift radially inwards in disks.
Aims. Our goal is to model the compositional evolution of ices on pebbles as they drift in disks, and track how their chemical evolution
en-route changes the ice composition relative to the ice composition of the pebbles in the region where they grew from micron-sizedgrains.
Methods. A state-of-the-art chemical kinetics code is utilised for modelling chemical evolution. This code accounts for the timeevolving sizes of the solids that drift. Chemical evolution is modelled locally for 0.1 Myr at two starting radii, with the micron-sized
solids growing into pebbles simultaneously. The pebbles and local gas, isolated as a parcel, is then exposed to changing physicalconditions, intended to mimic the pebbles drifting inwards in the disk midplane, moving to 1 AU on three di↵erent timescales. A
modelling simplification is that the pebbles are not moved through, and exposed to new gas, but stay in the same chemical gas
surroundings in all models.
Results. For ice species with initial abundances relative to hydrogen of > 10 5 , such as H2 O, CO2 , CH3 OH and NH3 , the abundanceschange by less than 20% for both radii of origin, and for the two smaller drift timescales (10kyr and 100kyr). For less abundant ice
species, and the longest drift timescale (1Myr), the changes are larger. Pebble drift chemistry generally increases the ice abundancesof CO2 , HCN and SO, at the expense of decreasing abundances of other volatile molecules.
Key words. planet formation – astrochemistry – pebble accretion

CO(J = 1-0) Observations toward the Filamentary Cloud in the Galactic Region of 153. 60 6 l 6156. 50 and 1. 85 6 b 6 3. 50

6v1 [astro-ph.GA] 16 Aug 2022

Weihua Guo,1, 2 Xuepeng Chen,1, 2 Jiancheng Feng,1, 2 Li Sun,1, 2 Shiyu Zhang,1, 2 Chen Wang,1 Yang Su,1, 2
Yan Sun,1, 2 Qingzeng Yan,1 Shaobo Zhang,1 Xin Zhou,1 MiaoMiao Zhang,1 Min Fang,1 and Ji Yang1, 2
1 Purple Mountain Observatory and Key Laboratory of Radio Astronomy, Chinese Academy of Sciences, 10 Yuanhua Road, Nanjing

210034, China
2 School of Astronomy and Space Science, University of Science and Technology of China, Hefei, Anhui 230026, China

ABSTRACT
We present observations of J=1-0 transition lines of 12 CO, 13 CO, and C18 O towards the Galactic
region of 153. 606 l 6 156. 50 and 1. 856 b 6 3. 50, using the Purple Mountain Observatory (PMO)
13.7 m millimeter telescope. Based on the 13 CO data, one main filament and five sub-filaments arefound together as a network structure in the velocity interval of [ 42.5, 30.0] km s 1 . The kinematic
distance of this molecular cloud (MC) is estimated to be ⇠ 4.5 kpc. The median length, width,
excitation temperature, line mass of these filaments are ⇠ 49 pc, ⇠ 2.9 pc, ⇠ 8.9 K, and ⇠ 39 M pc 1 ,respectively. The velocity structures along these filaments exhibit oscillatory patterns, which are likely
caused by the fragmentation or accretion process along these filaments. The maximum accretion rateis estimated to be as high as ⇠ 700 M pc 1 . A total of ⇠ 162 13 CO clumps and ⇠ 103 young stellar
objects (YSOs) are identified in this region. Most of the clumps are in gravitationally bound states.
Three H ii regions (G154.359+2.606, SH2-211, SH2-212) are found to be located in the apexes of thefilaments. Intense star forming activities are found along the entire filamentary cloud. The observed
results may help us to better understand the link between filaments and massive star formation.

Keywords: Molecular clouds(1072) — Interstellar filaments(842) — Star forming regions(1565) —Young stellar objects(1834)