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

01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.

05

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

Buenos Aires, Argentina
10
Fernández López et al.
tituto de Radioastronomı́a y Astrofı́sica, Universidad Nacional Autónoma de México, P.O. Box 3-72, 58090,
Morelia, Michoacán, México
nal Astronomical Observatoryof Japan,National
Institutesof Natural
Sciences,
2-21-1 Osawa,
Mitaka, Tokyo
A ringedpole-onoutflowfrom
DO Taurirevealedby ALMA
181-8588, Japan
1 Luis A.Institut
2 Luisdel
2 Marı́aartamentdAstronomia
i Meteorologia
de Ciències
U. de Barcelona,
Martı́i
ManuelFernández-López,(IEEC-UB),
Zapata,F.Cosmos,Rodrı́guez,
M. Vazzano,1FranquèsE-08028
Barcelona,
Spain
Andr
és1,E.
Guzm
án,3 andRosario López4

https://arxiv.org/pdf/2003.01148.pdf

Instituto Argentino de Radioastronomı́aABSTRACT(CCT-La Plata, CONICET; CICPBA), C.C. No. 5, 1894, Villa Elisa,
Buenosincluding
Aires, Argentina
We present new ALMA Band 6 observations
the CO (2-1) line and 1.3 mm
Instituto
de Radioastronomı́ay Astrofı́sica,
Universidad
NacionaldeTauri.
México,The
P.O. Box 3-72, 58090,
continuum
emission from thesurroundingsof the youngstellarAutónoma
object DO
México
ALMA CO molecular data show threeMorelia,di↵erentMichoacán,series of ringsat di↵erent radial veational
Astronomical
Observatory
Japan,220
Nationalof Natural
Sciences, 2-21-1
locities.
These rings
have radii ofaround
au andInstitutes
800 au. We
make individual
fits to Osawa, Mitaka, Tokyo
181-8588, Japanthe rings and note that their centers are aligned with DO Tauri and its optical highDepartamentMeteorologia
de structures
Ciències delCosmos,with
U. de Barcelona, Martı́ivelocity jet.dAstronomia
In addition,i wenotice that(IEEC-UB),
the velocityInstitutof theseincreases
Franquès 1, E-08028 Barcelona, Spainthe separation from the young star. We discuss the data under the hypothesis that therings represent velocity cuts through three outflowing shells that are possibly driven
ABSTRACTby a wide-angle wind, dragging the environment material along a direction close to thepresent
ALMA
Band
observations
includingthemomentum
CO (2-1) andline and 1.3 mm
line ofWesight(i= 19new). We
estimatethe 6dynamicalages, themass, thethe continuum
energy of eachindividual
outflowshell and those ofof theresults
emissionfromthe surroundings
the wholeyoungoutflow.
stellarTheobjectDO Tauri. The
are ALMA
in agreementwith those foundoutflows
fromClass IIseriessources.
makerough
CO molecular
data inshow
threedi↵erent
of We
rings
at adi↵erent
radial veestimate
for thesize ringsof thehave
jet/wind
needs
be of
. 15individual
au.
locities.
Theseradiilaunchingaround region,
220 au which
and 800
au.toWemakefits toWe report the physical characteristics of DO Tauri’s disk continuum emission (almost
the rings and note that their centers are aligned with DO Tauri and its optical highface-on and with a projected major axis in the north-south direction) and its velocity
velocityjet. In (north-south),
addition, we indicative
notice thattherotation
velocityforofa theseincreases withgradientorientationof disk
1-2 M structures
central star.
the separation
from[SII]
the imageyoungofstar.
We discussdataa measurement
under the hypothesisthat theFinally
we show an HST
the optical
jet andthe
reportof itsrings represent
velocity
cuts through three outflowing shells that are possibly 1driven 1
orientationin the planeof the sky.
Figure 3. Color scale image of the ALMA CO [J=2!1] velocity channels from -10.2 km s to 8.2 km s .

The thecolor intensity
range goes from
3 mJy beam along
to 30 mJy abeam(2.1 K to 21closeK). The position
by a wide-angle wind, dragging
environment
material
direction
to theof the
1.3 mm continuum peak is marked with a white star. The white dotted ellipse represents the fit to the
Keywords:
Star-formationline of sight (i= 19 ). We estimate
thevelocity
mass,
the momentum
andlarge ellipsethe
seen indynamical
the channel at -1.3ages,
km s . The
is indicatedin the upper left cornerand thesynthesized beam (0. 21 ⇥ 0. 16; PA= 7 ) is represented as a cyan ellipse in the bottom right corner of eachthe energy of each individual channel
outflowshell and
+1.0those of the whole outflow. The results
respectively.
1

1

00

00

1

07

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-

08

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-09

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.
Figure 5. Generic surface density profile of gas and dust.
4.4. Inner disk size
The profile is described by a power law ⌃(r) = ⌃c rc /r, andFigure5. Genericsurface
profile ofbygasdust
and
dust.
the dropin the innerdust density
disk is described. The
inThener
profileis describeda powerlaw ⌃(r)= ⌃describedc rc /r, andand outerradius ofby
innerand outerdisk areby
the Rdrop
ininnerthe, R
inner
dustRdisk
described byThe. The
industgas
surfacecav andouter ,isrespectively.
sub , Rner density
and outerradiusof inner anddisk are describedbyprofileis describedby outer
the gas-to-dust
ratios ⇠inner
Rsub, Rinnerand⇠outer, R. cav and Router , respectively. The gas surface
density profile is described by the gas-to-dust ratios ⇠innerand ⇠Forouter .the outer disk, we take Rin = Rcav from the az-

imuthally averaged intensity profile to be representativeFor
thecavity
outer radius.
disk, weRin
Rcav radiusfrom theaz-isof theIn takerealitythe=cavity
edge
imuthally
intensity
be representative
usually averaged
more complex
than profilea sharpto
edge(see e.g. Pinilla
et al.
2018)radius.
but as we
only aim
an approximateof thecavityIn reality
theforcavity
radius edgeprois
file ofmore⌃d (r)
compared
to athe
inner
disk,
this
usually
complex
than
sharp
edge
(see
e.g.approach
Pinillais sufficient.
valuesRcav are generally
et al.
2018) but Our
as wederived
only aim
for foran approximate
pro20%comparedof the literature
Rcavthisderivedusing
file withinof ⌃d (r)to the values
inner ofdisk,
approachmore detailed
methods.
is sufficient.
Ourfitting
derivedvalues for R
are generally

104.1. Misalignment between the inner and outer disks
4.2. NIR vs. mm emission

Depleted inner disks in transition disks

4.3. Dust depletion in inner diskAllof Innerthe disks
our sample have a dust < 1, with
4.4.
diskinsize
median of dust ⇡ 10 2 , indicating significant dust de4.5. Gas content of inner disk
letion relative to the outer disk. As our sample covers
4.6. range
Consequenceof the presenceof innerdiskthewide
of disk properties,
this implies
thatmechanism 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

11

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 toFuro-cho,
the Editor
Institute for Advanced Research, Nagoya University,
Chikusa-ku, Nagoya, Aichi, 464-8601, Japane-mail: yuri.f@nagoya-u.jp
2
Department of Physics, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, 464-8602, Japan
3
Division of Science, National Astronomical Observatory of Japan, 2-21-1, Osawa, Mitaka, 181-8588 Tokyo, Japan1

https://arxiv.org/pdf/2003.05052.pdf

Formation of single-moon systems around gas giants
Received ; accepted

Yuri I. Fujii12 and Masahiro Ogihara3

ABSTRACTtute for Advanced Research, Nagoya University, Furo-cho, Chikusa-ku,
Nagoya, Aichi, 464-8601, Japan
ail: yuri.f@nagoya-u.jp
Context.
Several Nagoya
mechanisms
have been
proposed
to explainNagoya,the formationof satellite
artmentof Physics,
University,
Furo-cho,Chikusa-ku,
Aichi, process
464-8602,
Japan systems, and relatively large moons
areofthought
be born incircumplanetarydisks. Making
a single-moon
systemis known
to be moresion
Science,toNational
Astronomical
Observatoryof Japan,
2-21-1, Osawa,
Mitaka,181-8588
Tokyo,difficult
Japan than multiple-moon or
moonless systems.
Aims. 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
moons, which change their direction and speed depending on the properties of circumplanetary disks.
ed of; accepted
Methods. We modeled dissipating circumplanetary disks with taking the e↵ect of temperature structures into account and calculated
the orbital evolution of Titan-mass satellites in the final evolution stage of various circumplanetary disks. We also performed N-body
ABSTRACT
simulations of systems that initially had multiple satellites
to see whether single-moon systems remained at the end.
Results. The radial slope of the disk-temperature structure characterized by the dust opacity produces a patch of orbits in which thext. Several
mechanisms
havebeen migration
proposed to
the formationof satellite
relatively
Titan-mass
moons cease
inwardandexplaineven migrate
outwardprocess
in a certain
range ofsystems,
the diskand
viscosity.
The large
patchmoons
assists moonsught
to be bornin incircumplanetary
Makinga single-moon
systemis known
to befallmore
difficultthan multiple-moon or
initially
locatedthe outer orbitsdisks.
to remainin thedisk, while thosein theinner orbits
onto
the planet.
ess Conclusions.
systems.
We demonstrate for the first time that systems can form that have only one large moon around giant planet. Our N-body
Wesimulations
aim to find suggest
a way tosatellite
form a systemwitha single
large moon,
Titan
Saturn. We
examine the orbital migration
formationwas
not efficientin the suchouterasradiiof aroundcircumplanetarydisks.
ons, which change their direction and speed depending on the properties of circumplanetary disks.
words. Planetsand circumplanetarysatellites: formation– Planets
and satellites:
Titanstructures– Planetsinto
and accountsatellites:anddynamical
evolution
ds.KeyWe modeleddissipating
disks
with taking
the e↵ect individual:of temperature
calculated
stabilityof–Titan-mass
Planet-disksatellites
interactions–Planetsand satellites:
planets
bitalandevolutionin thefinal evolution
stagegaseousof 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
Introduction
y located in the outer orbits to remain in the disk, while those in the inner orbits fall onto the planet.
usions.
We demonstratethegiant
first time
thathassystemsform disthat have only one large moon around giant planet. Our
ellite formation
aroundforgas
planets
beencanwidelyMassN-bodyinfalltionsinsuggestsatelliteof
formation
was not
efficientin theouter
radii of circumplanetary disks.
ssed
the context
the Galilean
moons.
The
small
moons
Viscous evolution

und gas/ice
in our solar
systemcan also
explained
ords.
Planetsgiants
and satellites:
formation– Planets
andbesatellites:
individual: Titan – Planets and satellites: dynamical evolutionatidally
spreading
solid
disk
scenario(Charnoz
et
al.
2010;
ability – Planet-disk interactions –Planets and satellites: gaseous planets
da & Charnoz 2012; Hyodo et al. 2015) when it is possito provide the enough material for the initial solid disk.

13

Kanagawa, K. D., Tanaka, H., & Szuszkiewicz, E. 2018, ApJ, 861, 140
Keith, S. L. & Wardle, M. 2014, MNRAS, 440, 89
5. Discussions and conclusions
Kretke, K. A. & Lin, D. N. C. 2012, ApJ, 755, 74
We demonstrated the qualitative pathway to establish a single- Miguel, Y. & Ida, S. 2016, Icarus, 266, 1
Mosqueira, I. & Estrada, P. R. 2003a, Icarus, 163, 198
moon system:
Mosqueira, I. & Estrada, P. R. 2003b, Icarus, 163, 232
Ogihara, M. & Hori, Y. submitted, ApJ
1. Moons in the outer orbits are captured in the patch with out- Ogihara, M. & Ida, S. 2012, ApJ, 753, 60
ward migration.
Ogihara, M., Kobayashi, H., Inutsuka, S.-i., & Suzuki, T. K. 2015, A&
A65
2. Inner orbits are cleared by type I migration.
3. The disk disappears before the final moon falls onto the Paardekooper, S.-J., Baruteau, C., & Kley, W. 2011, MNRAS, 410, 293
Ronnet, T., Mousis, O., Vernazza, P., Lunine, J. I., & Crida, A. 2018,
planet.
224
Sasaki, T., Stewart, G. R., & Ida, S. 2010, ApJ, 714, 1052
script no.
Wemanuscript
find that there is a favorable value of the viscous param- Shakura, N. I. & Sunyaev, R. A. 1973, A&A, 24, 337
eter to form a system that has a single Titan-mass satellite; this Shibaike, Y., Okuzumi, S., Sasaki, T., & Ida, S. 2017, ApJ, 846, 81
value is ↵ = 10 4 in our settings. With ↵ = 10 3 , more than Shibaike, Y., Ormel, C. W., Ida, S., Okuzumi, S., & Sasaki, T. 2019, A
79
one of the moons tend to survive if they have formed. In the
Suetsugu, R. & Ohtsuki, K. 2017, ApJ, 839, 66
case of ↵ = 10 5 , all the moons would be lost unless the disk Tanigawa, T., Maruta, A., & Machida, M. N. 2014, ApJ, 784, 109
A&A proofs: manuscript no. manuscript
dissipation has accelerated. As shown in Fig. 3, the direction of Tanigawa, T., Ohtsuki, K., & Machida, M. N. 2012, ApJ, 747, 47
migration changes with the mass of moons, thus the conditions Turner, N. J., Lee, M. H., & Sano, T. 2014, ApJ, 783, 14

to be a single-moon system di↵ers in the cases for other masses.
Other than the migration parameter, the timescale for the disk
dissipation is also an important factor.
We employed the ↵-disk model for simplicity, and assumed
the value of ↵ as a constant both in time and space. Even in adissipating CPD, the MRI may not contribute (see Fig. 6 of Fujii
Article number, page 4 of 4
initial5x103yr
3x1045yr
1x10 yr

1 Fig. 3. Migration map
10 for a disk with ↵100
= 10 4 at 5000 years after the[Rp]dissipation has startedr(corresponding
to the green lines in Fig. 2). The

color bar shows the value of /(1 + 0.04K). The direction of a migration
is inward/outward in the blue/red region.
initial3

14

T. Giannini1 , A. Giunta2 , D. Lorenzetti1 , G. Altavilla1, 2 , S. Antoniucci1 , F. Strafella3 , V. Testa1

https://arxiv.org/pdf/2003.13383.pdf
1INAF-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

Do subsequent outbursts of the same EXor source present similarfeatures?
Received date / Accepted date
T. Giannini1 , A. Giunta2 , D. Lorenzetti1 , G. Altavilla1, 2 , S. Antoniucci1 , F. Strafella3 , V. Testa1
ABSTRACT

1
Astronomico
Roma,whose
via Frascati
I-00078Montemonitored
Porzio Catone,
Context.INAF-Osservatorio
V1118 Ori is a classical
EXordisource
light 33,
curve
has beenover Italy
the past thirty years (although not contine-mail: teresa.giannini@inaf.it
uously).
2 It underwent a powerful outburst in 2005, followed by ten years of quiescence and a less intense outburst in 2015. In 2019, a
ASI - Agenzia Spaziale Italiana - Via del Politecnico, 00133 Roma, Italy
new intensebrightness increase was observed ( g ⇠ 3 mag).
3
Dipartimento di Matematica e Fisica, Universitá del Salento, 73100 Lecce, Italy
Aims. This new accretion episode o↵ers the opportunity to compare the photometric and spectroscopic properties of di↵erent outburstsof the Received
same source.
allowsdate / This
Accepted
dateone to highlight di↵erences and similarities among di↵erent events by removing any possible bias

[astro-ph.SR] 30 Mar 2020

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
ABSTRACT
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
brightnessstageswith theEXor
Large
Binocular
Context.
V1118 Ori
is a classicalsourcewhose Telescope.
light curve has been monitored over the past thirty years (although not continResults.
The last
event shows
the following1) tenamplitude
similar thanand lower
than
in 2005;
2) duration
uously).
It underwent
a powerful
outburst incharacteristics:
2005, followed by
years of quiescenceandina 2015less intense
outburst
in 2015.
In 2019,aless than
yearbrightness
as in previous
events;3) rise (decline)
speed of 0.018 (0.031) mag/day, which is di↵erent from previous cases; 4) a
newoneintenseincrease
was observed( g ⇠ 3 mag).
gradualblueing
theaccretion[g r] episodecolor iso↵ers
observed
over time,towhile
the the[r photometrici] color remains
roughly unchanged;with few
exceptions,
Aims.
This ofnewthe opportunity
compareand spectroscopic
properties of5)di↵erent
outburstsof the same lines
source.(mainlyThis allows
one to highlight aredi↵erences
andobserved
similarities
eventsby removing
any possible
the near-infrared
H i recombination)
the samein among
2015; di↵erent6) the massaccretion
rate peaks
at Ṁaccbias⇠ 10 71
the intrinsic
propertiesof thedown
star-disk
M yr related
and todecreases
in abouta monthto asystem.
few 10 8 M yr 1 .
Methods.Our
We analysis
discoveredshows
the 2019
Ori outburst of
by dataexaminingg-bandoutbursts
light curveofacquiredby theZwickyFacility
Conclusions.
thatV1118
the comparison
from thedi↵erent
the samesourceis aTransient
non-trivial
exercise,andfollowed
thedecreasing
phase
with
the
Rapid
Eye
Mount
telescope
in
the
griz
bands.
Twonear-infrared
spectrawere
also
acquiredwhich allows obtaining important clues useful to drive theoretical e↵orts towards a better understanding of the EXor phenomenon.

at di↵erent brightness stages with the Large Binocular Telescope.
Results.Stars:
The last
event shows
the following
characteristics:
1) amplitude
similar than in 2015
andHerbig
lower thanin 2005; 2) duration
Key words.
pre-mainsequence– Stars:individual(V1118Ori) – Stars:variables:
T Tauri,Ae/Beless 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 1arise.
ntroductionin predicting the relatively short cycle time of the episod
Conclusions. Our analysis shows that the comparison of data fromaccretion
di↵erent outburstsof the same
source areis a only
non-trivial
exercise, about tphenomenaand theresuggestions
which allows
obtaining
useful toSequence
drive theoretical
ptive variables
belongto a importantclass of clues
Pre-Mainob- e↵orts towards a better understanding of the EXor phenomenon.

mechanism responsible for the outburst onset: thermal instab
s usually
dividedintotwo
sub-classes:
EXor(Herbig
1989)
Key words. Stars: pre-main sequence – Stars:individual (V1118 Ori)
Stars:variables:
T Tauri,
HerbigAe/Be of a massive planet (Lodaties– (e.g.
Bell & Lin
1994),
presence
more energetic FUor (Hartmann & Kenyon 1985) systems & Clarke 2004), and close interactions in a binary system (Bo15

A&A proofs: manuscript no. V1118ori_v2

Fig. 2. Last 30-years optical light curve of V1118 Ori. V-band data are taken from Giannini et al.(2017) and references therein (mainly Audard
et al. 2010), while in orange are depicted R-band photometric points retrived from the Palomar Transient Factory survey. In red are depicted the
ZTF+REM g-band data of the 2019 outburst.
Table 4. Brightness variation speed observed during the last four outbursts of V1118 Ori.

majority of both increasing and decreasing speed values range
between 0.011 and 0.015 mag/day. Two significant exceptions
are represented by the increasing speed of the 2005 outburst
outburst (year) R (rise) D (decline) R/D(0.035 mag/day) and the decreasing speed of the last event(0.031 mag/day). More importantly, the data in Table 4 show that(mag/day)while in 2005 the increase was faster (by more than a factor two)
1997a
0.011
0.013
0.85
compared to the decrease, the reverse phenomenon occurred in
2005a
0.035
0.015
2.33
the last outburst.
2015a
0.015
0.015
1.00
These di↵erences provide
indications that heating and coolGiannini et al.: V1118 Ori : 2019 outburst
2019b
0.018
0.031
0.58
ing occur with di↵erent modalities in subsequent outburst events.
We speculate that a role might be played by the temperaturereached at the outburst peak, by the quantity of gas inside theNotes. a V-band data; b g-band data.
accretion columns and by the fraction of the stellar surface involved in the accretion shocks. Indeed, very di↵erent scenarios
unique possibility of comparing the speed of brightness variation for the outburst dynamics are predicted by theoretical models,( mag/ t) calculated with the same method in subsequent events from two ordered funnel streams forming two hot spots on thesurface
Last
optical light
curve of
V1118 Ori.This
V-bandspeed
data are taken
et al.(2017)
and references
therein (mainly
Audard (e.g. Romanova et al. 2004) to multiple unstableof30-years
the sameEXorsource.
canfrom
beGiannini
easilyobtained
as stellar010), while in orange are depicted R-band photometric points retrived from the Palomar Transient Factory survey.’tongues’of thematter that form chaotic spots with irregular shape
the
slope
theoutburst.
linear fit through the photometric points of the In red are depicted
REM
g-banddata ofof
the 2019
and position (e.g. Romanova et al. 2008).
increasing and decreasing phase (Figure 1).
4. Brightness variation speed observed during the last four out- majority of both increasing and decreasing speed values range
For the last outburst, we get g/ t = 0.018 mag/day (rising)of V1118 Ori.
0.011 and 0.015 mag/day. Two significant exceptions
and 0.031 mag/day (declining). Thesebetween
beenbyestimatedarehave
represented
the increasingby
speed 3.1.2.
of the 2005
outburst
Does
an outburst periodicity exists ?
outburst(year) Ras(rise)
D (decline)(0.035 ofmag/day)
andthosethe decreasing
considering
starting
and R/Dending points
the fitfrom speed of the last event(0.031 mag/day). More importantly, the data in Table 4 show that(mag/day)starts (stops) to increase (decrease) monowhicha the brightness
In thangeneral,the intermittence of the EXor’s outbursts does notwhile in 2005 the increase was faster (by morea factor two)
1997
0.011
0.013
0.85
compared to the decrease, the reverse phenomenon
occurredin periodicity and, looking at Figure 2, V1118 Ori
tonically.
Notethis choiceshow any
clear
2005a
0.035that 0.015
2.33 implies that the slope of 0.018
thelast
outburst.
2015a0.015maximum
0.015 speed
1.00 value that can be fitted throughmag/dayis theseems
obey
These di↵erences provide indications thatheatingtoandcool- the same trend. However, to have a more quantib
2019
0.018
0.031
0.58
the rising phase data.
ing occur with di↵erent modalities in subsequent
outburst
events.
tativeconfirmation,
we have performed the Lomb-Scargle analWe speculate that a role might be played by the temperature
The same method applied to the data
ofatprevious
outbursts
ysisof for
all available
photometries (V and g bands) collected inreachedthe outburst peak,by the quantity
gas insidetheaV-band data; b g-band data.
columnsspeaking,and by the fraction
inprovides the V/ t reported in Table accretion
4. Broadly
the of thethestellar
lastsurface
30 years.
The resulting periodogram is characterized bye possibility of comparing the speed of brightness variation
Articlenumber,page
4 ofin8subsequent events
g/ t)
calculatedwith the same
methodsame EXor source. This speed can be easily obtained as
ope of the linear fit through the photometric points of thevolved in the accretion shocks. Indeed, very di↵erent scenarios
for the outburst dynamics are predicted by theoretical models,from two ordered funnel streams forming two hot spots on the
3. Near-IR spectra taken on October 1 (black) and October 20 (red). Main emission lines are labelled.
stellar surface (e.g. Romanova et Fig.
al. 2004)
to multiple unstable’tongues’ of matter that form chaotic spots with irregular shape

Fig. 3. Near-IR spectra taken on October 1 (black) and October 20 (red). Main emission lines are labelled.

16