星形成ゼミ速報資料
May 15, 2020

ray s. furuya
tokushima univ.

00https://arxiv.org/pdf/2003.11033.pdf

more parallel

more perpendicular

Figure 7. The step functions of the relative angle between theorientation of the major axes of the cores identified in GAS data,
PAmajor , and the orientation of the polarization-inferred magnetic
field from Planck, BPOS , for Ophiuchus (blue), Perseus (red), Taurus (cyan), and all regions combined (black). The dashed gray line
shows the expected distribution for no preference in orientation.

shows cumulative distributions of the core backgroundmagnetic field alignment angle. Results for individual regions within each cloud are included in Appendix A.
We note that there are systematic di↵erences among
the three clouds examined in the relative alignment of theircores with respect to the pc-scale magnetic field. Namely,
Taurus shows a preference for its cores to align perpendicular to the background magnetic field, rather than parallel toit. Perseus shows a relatively random distribution between
its core major axes and the background magnetic field direction. Ophiuchus shows a preference for parallel alignment of
its cores’ long-axes and the background magnetic field. Thisdi↵erence is quantitatively reflected by the median values of
the relative angles between background magnetic fields and02https://arxiv.org/pdf/2003.09511.pdf

anuscript no. ms

JW908

JW293
JW180

●は本研究, ▪ は先⾏研究(表4から)Veiling同定はJW647
JW647
JW847

Fig. 1: Distribution of the targets in the ONC. Figure made with
Aladin Lite interactive sky maps (Bonnarel et al. 2000; Boch &Fernique 2014).

03

4.1. Veiling determination
authors suggested a criterion in which a mid-M dwarf should
be considered an accretor if it has a Balmer jump larger than
4.2.Line flux ⇨ Line luminosity ⇨ Acc. rate
0.5. This threshold was proposed after the authors measured the
BJobs⇨indiska sampleof low-mass stars and checked that the non4.3. IR excess
properties
accreting stars had values systematically below 0.5.
The values measured for the BJobs are listed in Table 4 for
all the targets. According to this criterion, the only star that isclearly accreting is JW647, with a BJobs of 1.1. The remaining
targets have values that match the threshold value and we cannot infer anything about accretion activity for these three cases
solely from the observed Balmer jump. Nevertheless, it could
be that JW180, JW293, and JW908 are transiting from CTTS
(classical T Tauri star) to WTTS (weak-line T Tauri star) evolutionary stage. JW847 was classified as a K6, and for that reason
we should be cautious when using this criterion, since this is not
an M-type star. Although this criterion should be valid for mid- Fig. 4: Balmer emission lines in velocity for JW647 with overM dwarfs, Rugel et al. (2018) used this criterion from K6 to M6 lapping inverse P Cygni profiles. Each color corresponds to adi↵erent Balmer emission line. The H7 line is blended with Ca ii
type stars belonging to the ⌘ Chamaeleontis association.
We found several emission lines among the targets’ spectra, H.
except for JW847. The remaining YSOs show several Balmer
多数の輝線でinverse P Cyg.検出 ⇨ ongoing acc. in diff. layers
lines in emission, as well as He I lines. The star JW647 shows
additional emissions in the NIR arm for the Paschen and Brackett lines. The existence of these emissions is already indicativeof ongoing accretion in these YSOs. Though the low resolution
in the current spectra does not allow an accurate estimate of theradial velocity of these objects, the spectral emission lines position are consistent with the stellar radial velocity. In Appendix
B we show the profiles of some of the emission lines available
for JW180, JW293, JW647, and JW908 (red lines) and comparewith the corresponding templates (blue lines).
In the particular case of the JW647 spectrum, the Balmer
emission lines from H4 (486.1 nm) to H10 (379.8 nm) show an
inverse P Cygni (IPC) absorption present in all the profiles (seeFig.4). The red edge of this redshifted absorption falls around
300 km s 1 , which is the typical value found for infalling material that is accreting onto the star (e.g., Edwards et al. 1994).
Such IPC profiles are also observed for the Na i D and He i Fig. 5: H10, Na i D and He I emission lines in velocity for JW647(1082.9 nm) lines, as shown in Fig. 5. The He i lines at 587.6 with inverse P Cygni profiles. Each color corresponds to a difand 667.8 do not show IPC profiles. In this last figure, the red- ferent line. The IPC for the Na i D line is marked in the figure.
shifted absorptions do not overlap, since we would expect emis-04&

Astrophysics
https://www.aanda.org/articles/aa/pdf/2020/03/aa32243-17.pdf
Univ. Bordeaux, LAB, UMR 5804, 33270 Floirac, France

E. Di Folco et al. 2020
1

e-mail: emmanuel.di-folco@u-bordeaux.fr
CNRS, LAB, UMR 5804, 33270 Floirac, France
3
Univ. Grenoble Alpes, CNRS, IPAG, 38000 Grenoble, France
4
IRAM, 300 rue de la piscine, 38406 Saint Martin d’Hères, France
5
LESIA, Observatoire de Paris, PSL Research Univ., CNRS, Univ. Paris Diderot, Sorbonne Paris?Cité, UPMC Paris 6,
Sorbonne Univ., 5 place Jules Janssen, 92195 Meudon CEDEX, France
2

An ALMA/NOEMA study of gas dissipation and dust evolution
in the 5 Myr-old HD 141569A hybrid disc
1,2

1,2

1,2

3

4

1,2

Folco 2017
, J. Péricaud, A.
Dutrey2019, J.-C. Augereau , E. Chapillon , S. Guilloteau
ReceivedE.6 Di
November/ Accepted 30
October
V. Piétu4 , and A. Boccaletti51,

ABSTRACTUniv. Bordeaux, LAB, UMR 5804, 33270 Floirac, France
e-mail: emmanuel.di-folco@u-bordeaux.fr
Context.
The study of gas-rich debris discs is fundamental to characterising the transition between protoplanetary discs and debris
2
CNRS,
LAB,
UMR 5804, 33270 Floirac, France
3discs.
Univ. Grenoble Alpes, CNRS, IPAG, 38000 Grenoble, France
4Aims. We determine the physical parameters of the brightest gas-rich debris disc orbiting HD 141569A.
IRAM, 300 rue de la piscine, 38406 Saint Martin d’Hères, France
1
5Methods. We analyse images from the NOrthern Extended Millimeter Array (NOEMA) and the Atacama Large Millimeter/
LESIA, Observatoire de Paris, PSL Research
Univ.,
CNRS,
Univ.
Paris
Diderot,
Sorbonne
Paris
Cité,
UPMC
Paris 6,12
13
13
submillimeter
Array(ALMA)
in
CO,
CO
J
=
2!1,
and
CO
J
=
1!0
transitions.
We
incorporate
ALMA archival data of the
Sorbonne Univ., 5 place Jules Janssen, 92195 Meudon CEDEX, France
12

CO J = 3!2 transition and present continuum maps at 0.87, 1.3, and 2.8 mm. We use simple parametric laws with the Diskfit code
Received
6 November
2017 / Accepted
30 Octoberand MCMC
exploration
to characterise
the 2019
gas disc parameters and report a first attempt to characterise its chemical content with
IRAM-30 m.
Results. The continuum emission is equally shared between
a compact (.50 au) and a smooth, extended dust component (⇠350 au).
ABSTRACT
Large millimetre grains seem to dominate the inner regions, while the dust spectral index is marginally larger in the outer region. The
12
13
18
CO isThe
optically
thick,
while
COdiscs
is opticallythin with⌧13 CO ⇠ 0.15the(Ctransition
O is notbetween
detected).
The 13 CO surface
density
Context.
study ofgas-richdebrisis fundamental
to characterising
protoplanetary
discs anddebris is constrained
discs.
to be one order of magnitude smaller than around younger Herbig Ae stars, and we derive a gas mass M12 CO = 10 1 M . We confirm
Aims.
We determine
the physicalparameters
disc orbiting
141569A.
the presenceof a small
CO cavity(RCO of= the
17 brightest± 3 au), gas-richand finddebris
a possibly
larger HD
radiusfor the optically thin 13 CO J = 2!1 transition1
Methods.
We analyse
imagesfromobserved
the NOrthern
Extended Millimeter
Array(NOEMA)withandthethecomplex
Atacama ring
Large
Millimeter/(35 ± 5 au).
We showthat theCObrightness
asymmetryiscoincident
structures
discovered with
12
13
13
12 J = 2!1, and CO J = 1!0 transitions. We incorporate ALMA archival data of thesubmillimeter
Array
CO,TheCO
VLT/SPHEREin (ALMA)
the innerin90 au.
CO temperature T 0 (100 au) ⇠ 30 K is lower than expected for a Herbig A0 star, and could be
12
CO J = 3!2 transition and present continuum maps at 0.87, 1.3, and 2.8 mm. We use simple parametric laws with the Diskfit code
indicative of subthermal excitation.
and MCMC exploration to characterise the gas disc parameters and report a first attempt to characterise its chemical content with
Conclusions.
With the largest amount of dust and gas among hybrid discs, HD 141569A shows coincident characteristics of both proIRAM-30
m.
toplanetary
discs (central
regions),
and debris
at large
distance.
its extended
morphologicalcharacteristics
and young age, it
Results.
The continuum
emission
is equallyshared discs
betweena compact(.50 Togetherau) and a withsmooth,dust component(⇠350 au).
appears
to be agrains
good seemcandidateto witness
the transientphasetheofdust
gas spectral
dissipation,
an apparently
large
Large
millimetre
to dominate
the innerregions, while
indexwithis marginallylarger in
the gas-to-dust
outer region.ratio
The (G/D > 100)
12favouring a faster evolutionof dustgrains. thin with ⌧13 CO ⇠ 0.15 (C18 O is not detected). The 13 CO surface density is constrained
CO is optically thick, while 13 CO
is opticallyto be one order of magnitude smaller than around younger Herbig Ae stars, and we derive a gas mass M12 CO = 10 1 M . We confirm
Keywords.
techniques:interferometric– protoplanetarydisks –
13
thepresenceof aaccretion,
small CO accretion
cavity (RCOdisks= 17–±methods:
3 au), and observationalfind a possibly –larger
radius forthe optically thin
CO J = 2!1 transition
stars:
pre-mainsequencelines:(35± 5 au).
We showthat the– radio
observed
COstars
brightness asymmetry is coincident with the complex ring structures discovered with
12
VLT/SPHERE in the inner 90 au. The CO temperature T 0 (100 au) ⇠ 30 K is lower than expected for a Herbig A0 star, and could beindicative of subthermal excitation.

A&A 635, A94 (2020)

eA&A 635, A94 (2020)

Fig. 4. Observed line profiles and superposed best models obtained with Diskfit (colour dashed lines) for, from left to right: 12 CO J = 2!1
A&A 635, A94 (2020)
13
CO J = 2!1 NOEMA data, and 12 CO J = 3!2 ALMA data.
Table 4. Results of Diskfit modelling for the 12 CO and 13 CO with 1
error bars.

Fig. 1. Left column:
continuum
emission
all contours
are setwith33 spacing,spacing, panel
a: ALMA
data at 0.87mm,at =
0.051
mJy beam=1 ,0.051 mJy beam 1 ,lumn: continuum
emissionmaps,
all maps,
contours
are setwithpanel
a: ALMA
data
0.87
mm,
contours; (c) NOEMA data at 1.3 mm, = 0.078 mJy 1beam 1 ; (e) ALMA data at 2.8 mm, = 0.008 mJy beam 1 . We note that
1 the scale of panel c
OEMAis data
at 1.3 mm, = 0.078 mJy beam ; (e) ALMA data at 2.8 mm, = 0.008 mJy beam . We note that the scale of panel cchanged to include the more extended emission. Right column: real part of the visibility (with spatial binning) as a function of the u, v radius in(mas) innclude thetheFourier
moreplane,
extended
Right tocolumn:
reala,partthe visibility (with spatial binning) as a function of the u, vx0radius
panels b,emission.
d, and f: corresponddata in panelsc, andofe, respectively.
y0 (mas)ne, panels b, d, and f: correspond to data in panels a, c, and e, respectively.

5.1.Comparison with opt/NIR emission
A94, page 4 of 16

16

5.2. Gas-to-dust ratiod require a surface density of the ordervalues of the surface density are at least
smaller than those found for the younger,e Herbig Ae star MWC 480: Piétu et al.
ance of 100 au, ⌃0 = 8 ⇥ 1016 cm 2 for2
for 12 CO. This system is taken here asof the very few where the surface denrecisely constrained through similar discmass of CO gas based on ⌃0 and usededge value R = 232 au inferred from

12

i( )
PA ( )
Vsys (km s 1 )Rout (au)Rin (au)

CO J = 3!2

43 ± 14±156.05 ± 0.07
86.60 ± 0.06
6.05 ± 0.01
273 ± 117 ± 312

CO J = 2!1

74 ± 217 ± 457.7 ± 0.3
85.8 ± 0.2
6.07 ± 0.01
277 ± 317

13

CO J = 2!1

15 ± 33
19 ± 2857.2 ± 1.4
88 ± 1
5.92 ± 0.02
232 ± 1135 ± 5

av
0.5
0.5
0.5
V0 (km s 1 )4.44 ± 0.01
4.4 ± 0.3
4.57 ± 0.05
dv (km s 1 )0.435 ± 0.003
0.41 ± 0.01
0.29 ± 0.05
T 0 (K)28.1± 0.2
33 ± 1215+32
q0.28 ± 0.01
0.10 ± 0.09
0.36 ± 0.30
15
⌃0 (CO) (cm 2 ) 3.5 ±2.0 ⇥ 1017 5.5±0.2. ⇥ 1016 4.9+2.3
1.1 ⇥ 10p
2.7 ±0.5
2.8 ± 0.1
1.8 ± 0.5
H0 (au)17 ± 117.8 ± 0.5
9
16
21.25
h
1.45 ± 0.05
1.3 ± 0.7

twice the value of the hydrostatic scale height (Hhydro = 8 au
for a disc with T 0 = 30 K, as measured from the optically thictransitions of 12 CO. This is consistent with direct measurementof the 12 CO layer location in HD 163296 (de Gregorio-Monsalv
et al. 2013) and the Flying Saucer (Guilloteau et al. 2016), wher
CO is located at 2 3 scale heights (Dutrey et al. 2017).
In our preliminary fits, the velocity exponent proved to b
very close to the Keplerian value av = 0.5, and we adopted thi
fixed value for the MCMC exploration reported in Table 4. A
100 au, the rotation velocity is better constrained for 12 CO lines
with a value V0 = 4.44 ± 0.01 km s 1 that can be converted int
a central stellar mass of 2.22 ± 0.01 M . This value is slightl
smaller than the mass of 2.39 ± 0.05 M reported by White et a(2016), but is very consistent with the spectral analysis of Merí13
et al. (2004) that yielded M? = 2.00+0.18
0.15 M . The CO analysi
leads to a slightly larger mass M? = 2.35 ± 0.05 M .
4.2. Temperature and density laws

Fig. 6. Global scheme of dust andThegas
distribumodellingof the two optically thick transition
profiles
with
p
⇠
3
and
requireasurfacedensityofthe
CO J = 2!1
and order
CO J = 3!2
providesbetween
very consisten
range
1tion in HD 141569 summarizing themost recent
estimates for the excitation temperature, T ⇠ 30 K withof 6 ⇥ 10 cm . These values of the surfacerelatively
densityflatareatleastradial profile q < ing
0.4 (qisotope= 0.28 ± selec
0.01 foresolved
observations.
CO
J
=
3!2
and
q
=
0.10
±
0.09
for
CO
J
=
2!1).
Th
one
order
of
magnitude
smaller
than
those
found
for
the
younger,
Notes. Parameters in italics are fixed. The physical parameters
12

12

0

12
grainsMiotelloe
13
T , ⌃ , V , H are scaled at a radial distance of 100 au. The offset values temperature is ill constrained for the optically thin CO tran
gas-richdisc around the Herbig Ae star MWC 480: Piétu et al. thewith
mostmassivethe analysisof th
are given with respect to the phase centres, whose coordinates are RA = sition. A value of 30 K is consistent12
16 detection
2 with SMA by Flaherty et al. (2016
15
:
49
:
57.73,
Dec
=
03
:
55
:
16.62
for
the
CO
J
=
3!2
line,
and
CO
J
=
3!2
5.3.
Originofthegas(2007)
report,atadistance
of
100
au,
⌃
=
8
⇥
10
cm
for
5
3
0
debrisdiscs
repor
RA= 15and: 49 : 57.75,
Dec 18= 03
for= 2!1 and
who used aassumfixed temperature exponent q = 0.5 and founrange between 1013 CO
M: 55 2:,16.34
basedmodels12the CO Jon
CO Jand= 2!1 6
data.
⇥10
10 cm
for
CO. This systemtaken here as optically
T 0 = is33+11
than the gasthintemperatur
CO
4 K). It is somewhat smallerof about
K derivedfrom 12 CO line for a similar, albe
ing isotope selective
photo-dissociation
andCO
freeze-out
ona reference
as it is one of the very
few
where
the 50surfacedenCO mass due tobetween13
the CO isotopologues. The inner rim value (17 au) for younger and more optically thick disc around the Herbig A
12
ofis2017).
CO hasbeen
precisely
constrained
similardiscCOcoherent
with HDthespectroscopic
detectionof warm harbours
CO throughstar MWC 480(Piétu etal. 2007). [CO/H
Given the 2
starluminosity o] abundan
grains Miotello etsitythroughal.
141569
also
one
of
IR
ro-vibrational
lines
by
van
der
Plas
et
al.
(2015),
with
30
L,
blackbodygrainsinanopticallythin
disc
are predicteemissionmodelling.
gas
a modelled distributionof components
the gas between 14 and 45amongau (after to thehave a gas-richtemperature of 60 K atongoinga distance of
100dissi
au, anthe most massive moleculargas
We derived
a stellar
totaldistance).
mass of CO gas based⌃0 andcorrecting
for the revised
wouldonbe muchhotter usedthan the detected gas. The derived ga
The
inclination
andet
positionare found based
temperatureis also significantly smaller than the range of kineti
debris discs reported
in
Moór
al.angle(2017)
supposedly
therangeminimum
outer
disc
edge
valueto Rbeoutin ithe
== on
232
au inferredfrom
i = 56 58 and PA = 86 ± 1 for 12 CO lines, andtemperatures computed by Thi et al. (2014) with their Prodim
13
13
5. Discussion
modellingbased on unresolvedof [OI], C[II] an
53 ± 2COand PA= 90 (hence± 2 for CO,
is in good massline
a whichminimum
value).
Becausemost detections
optically thin COthe
isotopologues.
Even
if weagreement
underestimate
the12with the optical values of i = 52.5 ± 4.5 and PA = 85.4 ± 1
CO J = 3!2 lines around HD 141569. In their modelling, thof13
the mass
liesetin
the Theinner
withgasa ispowerlaw disrespectively(Augereaual. 1999).
disc isregions
flared, although
heated by Polycyclic
Aromatic
Hydrocarbons(PAH) an
5.1.
Comparison
CO mass due to tribution,
opticaldeptheffectsortheuncertain
theCOflaring exponent
h
is
not
well
constrained,avalue
consistentcooledby[OI]
andCOdisclines, and the computed temperatur
the computedvalue
issensitive
to
the
inner
with h = 1.25 is found for both 12 CO transitions, while it is nat- reaches about 100 K at 100 au in the inner disc and drops dow
13[CO/H2 ] abundance,
low
mass
of
edge,
andconstrained
wea takeintoaccount
the ofinnercavitywithTheurallysuch
notfor theoptically
thinsupports
transition
CO.theto 40 process
K atdetected
500 au (i.e. wellbeyond theouterdistribution
edge of the emissioo
12
12
For
CO,
a
scale
height
H
=
17
au
is
found
at
100
au.
This
is
we
detectwith
ALMA/NOEMA).
The
excitation
0 in the ALMA high-resolution maps (Rthe COinemission
and mmtemperature
wavelenw
in =ongoing gas dissipation
this5
Myr-old
disc.
pageAssuming
8 of 16
17A94,
au).
a standard isotopic ratio 12 CO/13 CO = 77, paring the respec
23
these parameters yield M12 CO = 0.10+0.05
detected at optic
0.02 M (=4 ⇥ 10 kg),
0

0

0

12

0

12

12

13

06

Figure 6. Left: Reconstruction of the outflow from DO Tauri from the ring fits (ring center and majoraxis), assuming that the rings are circunferences with radius equal to the measured semi-major axis and theoutflow is 19 inclined with respect to the line of sight. The crosses mark the position of the ring centersafter a 253.6 rotation in the plane of the sky, so that the blue lobe of the outflow matches the positive z-axis.
Distances and velocities are corrected by the outflow inclination. A star marks the position of DO Tauri.
Right: Same but forcing the center of each ring to be in a straight line along a putative linear outflow axis
coincident with the z axis.

namical ages from 600 yr to 5000 yr, with deprojected gas-velocities as low as 1.3 km s 1 respect
to the cloud velocity. These rings subtend thelargest angles from DO Tauri in projection.
Within the individual shells, not all the rings
have the same dynamical time, unlike one would
expect in the wind-driven model (Lee et al.
2000). These di↵erences can be accounted forif there are any inhomogeneities in the ambient cloud that may decelerate the outflow material at di↵erent rates in di↵erent directions ✓.

Moreover, deviations from the model are also
expected if the outflow is not steady (Lee et al.
2001) as is the case for DO Tauri, where multiple shells are observed.
An interesting alternative scenario for the
DO Tauri outflowing shells is that they are generated by successive jet-driven bowshocks (Ostriker et al. 2001). In this model, a narrow jet
produces an expanding bowshock when bumping into the ambient medium. The velocity ofthe outflow thus created increases as a power-

5071 West Saanich Road
Typeset using LATEX twocolumn style in AASTeX63

Victoria, BC, V9E 2E7, Canada
https://arxiv.org/pdf/2003.00079.pdf
loganfrancis3@uvic.ca
34 Banting fellow
5 astro@nienkevandermarel.com

Dust depleted inner disks in a large sample of transition disks through long-baseline ALMA
(Accepted February observations
27th, 2020)
1, 2, 3
Submitted
toand
ApJ Nienke van der Marel
Logan Francis

1, 2, 4, 5

1 Department of Physics and Astronomy, University of Victoria

ABSTRACT

3800 areFinnertyRoad,
ElliotBuilding
Transition disks with large inner dust cavities
thought
to hostmassivecompanions. However,Victoria,
BC, V8P
5C2,
Canadathe disk structure inside the companion orbit andhow material
flows
towardan actively accreting star
2 NRC Herzberg Astronomy and Astrophysics
remain unclear. We present a high resolution
continuum study of inner disks in the cavities of 38 transition disks. Measurements of the dust mass from5071
archival
WestAtacama
Saanich Large
Road Millimeter/Submillimeter
Array observations are combined with stellar properties
energydistributions to assemble
Victoria, andBC, spectral
V9E 2E7,
Canada3 loganfrancis3@uvic.ca
a detailed picture of the inner disk. An inner dust disk
is detected in 18 of 38 disks in our sample. Of
4 Bantingthe 14 resolved disks, 8 are significantly misaligned withthe outerdisk. The near-infrared excess is
fellow
uncorrelated with the mm dust mass of the innerdisk. The size-luminosity correlation known for pro5 astro@nienkevandermarel.com
toplanetary disks is recovered for the inner disks as well, consistent with radial drift. The inner disks
are depleted in dust relative to the outer disk and their dust mass is uncorrelated with the accretion(Accepted February 27th, 2020)
rates. This is interpreted as the result of radial drift and trapping by planets in a low ↵ (⇠ 10 3 ) disk,
or a failure of the ↵-disk model to describe angular momentum
transport
Submitted
to ApJand accretion. The only disk
in our sample with confirmed planets in the gap, PDS 70, has an inner disk with a significantly larger
radius and lower inferred gas-to-dust ratio than other disks in the sample. We hypothesize that these
ABSTRACT
inner disk properties and the detection of planets are due to the gap having only been opened recently
Transition
disks withlarge inner dust cavities are thought to host massive companions. However,by young,
actively accreting
planets.

the disk structure inside the companion orbit and how material flows toward an actively accreting star
Keywords:
formation
protoplanetary- planetarysystems protoplanetary- accretion,
remainstars:
unclear.
We -present
a high disks
resolution
continuum
study of innerdisks
disks
in the cavities of 38 trandisks - stars: variables:
T Tauri,
Herbigsition accretion
disks. Measurementsof the dust
mass
fromAe/Be
archival Atacama Large Millimeter/Submillimeter
Array observations are combined with stellar properties and spectral energy distributions to assemble
1. INTRODUCTION(e.g. Regály et al. 2012), which can create local ena detailedof the gallery
innerofdisk.
innerdustin disk
isthedetected
18whereofto38disks
Figure1. ALMA picture
image continuum
the 38An
transition
disks
our insample.
The pressure
size inis scaled
thesize grains
ofin
theourouter
hancements
gas
dust
aresample. Of
toplanetary
disks
are
circumstellar
reservoirsofdisk. theThe beamsize is shownin the8bottom
left; the scalebarmisaligned
at the bottomwith
is 30 auin length.
Notethe outerdisk of AB excess is
14 resolved
disks,
are significantly
the
outer
disk.thatThe
near-infraredtrapped
and
grow
to
mm
sizes
(Pinillaetal.
2012).
ndAur
dust
found out
surrounding
young
stars,and data.
areis resolved
due to a lackof short
baselinetrapping
is necessary
to explain theobserved emisuncorrelated with the mm dust mass of the This
inner
disk. Thesize-luminosity
correlation
known for pro-

Figure 5. Generic surface density profile of gas and dust.
The profile is described by a power law ⌃(r) = ⌃c rc /r, andthe drop in the inner dust disk is described by dust . The inner and outer radius of inner and outer disk are described by
Rsub , Rinner , Rcav and Router , respectively. The gas surface
density profile is described by the gas-to-dust ratios ⇠innerand ⇠outer .

For the outer disk, we take Rin = Rcav from the azimuthally averaged intensity profile to be representativeof the cavity radius. In reality the cavity radius edge isusually more complex than a sharp edge (see e.g. Pinilla
et al. 2018) but as we only aim for an approximate profile of ⌃d (r) compared to the inner disk, this approachis sufficient. Our derived values for R
are generallyDepleted inner disks in transition disks

All of the disks in our sample have a dust < 1, withmedian of dust ⇡ 10 2 , indicating significant dust deletion relative to the outer disk. As our sample covers
wide range of disk properties, this implies that themechanism responsible for the dust depletion operates
apidly, on timescales shorter than the lifetimes of theoungest disks.
Furthermore, the value of dust remains constantcross a range of accretion rates: we see no antiorrelation (rcorr = 0.052 ± 0.54) of dust with accretionate, consistent with the millimeter-grains being decouled from the accreting gas.

17

↵ <= 10 3 . This results in a pile-up of mm grains at
the pressure bump, and a rapid inward radial drift ofmillimeter grains in the inner disk which can not be replenished due to a cuto↵ of the flow of dust grains fromthe outer disk. Smaller dust grains may continue to flow
through the gap after the outer pressure bump has been
established, and grow to larger sizes again in the innerdisk through coagulation, but for a sufficiently massive
planet even the smallest dust grains cannot flow inwards
any more. Inward drift results in depletion of mm-dustof the inner disk as dust grains may either sublimate
at the sublimation radius or grow to large pebbles androcks.
4.4. Inner disk size

4.1. Misalignment between the inner and outer disks
4.2. NIR vs. mm emission
4.3. Dust depletion in inner disk
4.4. Inner disk size
4.5. Gas content of inner disk
4.6. Consequence of the presence of inner disk

12

Letter to the Editor

Formation of single-moon systems around gas giants
Yuri I. Fujii12 and Masahiro Ogihara3tute for Advanced Research, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, 464-8601, Japan
ail: yuri.f@nagoya-u.jp
artment of Physics, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, 464-8602, Japansion of Science, National Astronomical Observatory of Japan, 2-21-1, Osawa, Mitaka, 181-8588 Tokyo, Japaned ; accepted
ABSTRACT

xt. Several mechanisms have been proposed to explain the formation process of satellite systems, and relatively large moons

ught to be born in circumplanetary disks. Making a single-moon system is known to be more difficult than multiple-moon or
ess systems.
We aim to find a way to form a system with a single large moon, such as Titan around Saturn. We examine the orbital migration
ons, which change their direction and speed depending on the properties of circumplanetary disks.
ds. We modeled dissipating circumplanetary disks with taking the e↵ect of temperature structures into account and calculated
bital evolution of Titan-mass satellites in the final evolution stage of various circumplanetary disks. We also performed N-bodytions of systems that initially had multiple satellites to see whether single-moon systems remained at the end.
s. The radial slope of the disk-temperature structure characterized by the dust opacity produces a patch of orbits in which themass moons cease inward migration and even migrate outward in a certain range of the disk viscosity. The patch assists moons
y located in the outer orbits to remain in the disk, while those in the inner orbits fall onto the planet.
usions. We demonstrate for the first time that systems can form that have only one large moon around giant planet. Our N-bodytions suggest satellite formation was not efficient in the outer radii of circumplanetary disks.

ords. Planets and satellites: formation – Planets and satellites: individual: Titan – Planets and satellites: dynamical evolution

ability – Planet-disk interactions –Planets and satellites: gaseous planets[astro-ph.SR] 30 Mar 2020

https://arxiv.org/pdf/2003.13383.pdf

Do subsequent outbursts of the same EXor source present similarfeatures?
T. Giannini1 , A. Giunta2 , D. Lorenzetti1 , G. Altavilla1, 2 , S. Antoniucci1 , F. Strafella3 , V. Testa11INAF-Osservatorio Astronomico di Roma, via Frascati 33, I-00078 Monte Porzio Catone, Italye-mail: teresa.giannini@inaf.it
2
ASI - Agenzia Spaziale Italiana - Via del Politecnico, 00133 Roma, Italy
3
Dipartimento di Matematica e Fisica, Universitá del Salento, 73100 Lecce, Italy
Received date / Accepted date
ABSTRACT
Context. V1118 Ori is a classical EXor source whose light curve has been monitored over the past thirty years (although not contin-

uously). It underwent a powerful outburst in 2005, followed by ten years of quiescence and a less intense outburst in 2015. In 2019, a
new intense brightness increase was observed ( g ⇠ 3 mag).
Aims. This new accretion episode o↵ers the opportunity to compare the photometric and spectroscopic properties of di↵erent outburstsof the same source. This allows one to highlight di↵erences and similarities among di↵erent events by removing any possible bias
related to the intrinsic properties of the star-disk system.
Methods. We discovered the 2019 V1118 Ori outburst by examining the g-band light curve acquired by the Zwicky Transient Facility
and followed the decreasing phase with the Rapid Eye Mount telescope in the griz bands. Two near-infrared spectra were also acquired
at di↵erent brightness stages with the Large Binocular Telescope.
Results. The last event shows the following characteristics: 1) amplitude similar than in 2015 and lower than in 2005; 2) duration
less than one year as in previous events; 3) rise (decline) speed of 0.018 (0.031) mag/day, which is di↵erent from previous cases; 4) a
gradual blueing of the [g r] color is observed over time, while the [r i] color remains roughly unchanged; 5) with few exceptions,the near-infrared lines (mainly H i recombination) are the same observed in 2015; 6) the mass accretion rate peaks at Ṁacc ⇠ 10 7
M yr 1 and decreases in about a month down to a few 10 8 M yr 1 .
Conclusions. Our analysis shows that the comparison of data from di↵erent outbursts of the same source is a non-trivial exercise,
which allows obtaining important clues useful to drive theoretical e↵orts towards a better understanding of the EXor phenomenon.
Key words. Stars: pre-main sequence – Stars:individual (V1118 Ori) – Stars:variables: T Tauri, Herbig Ae/Be

A&A proofs: manuscript no. V1118ori_v2