SFN #333 (37-44本目)
百瀬宗武(茨城大・理)詳細解説は以下の2本• #40: Modeling disk fragmentation and multiplicity in massive starformation (G. André Oliva and Rolf Kuiper)• #43: Gas trapping of hot dust around main-sequence stars (TimD. Pearce⋆, Alexander V. Krivov and Mark Booth)

x
x1500
run
nr
n✓
n
ndisk
x30
x1500
@t
achieved
inthemidplane
(z
=
0);
and
the
azimuthisuniformly
achieved
ing
of
the
gas,
shear
of
the
disk
and
other
gravito-radiationpres
number
of
cells
that
resolve
thedisk’sphysics(column
5);
cell
The
cloud
dynamics
aremodeled
as
an
ideal
gas
with
the
thus
providingalinkbetweenthetwo
phenomena.
ThesimulaThis
choiceofcoordinatesisexplained
andjustified
in
more
1.50
77.8
10
3
The
variables
involvedinaaredetailed
below.
The
Poisrad11
discretize
x1equations:
34au
32
7.0 ·and
10 energy
6.36359hydrodynamical
processes.
Instead,atime-independent
grid
Accretioninfragmented
disks
isexpected
to
not
be
a
smooth
of pr
size
at
r
=
30
(column
6),
cell
size
at
r
=
1500
au
(column
tions
in
Meyer
et
al.
(2017,
2018,
2019)
show
accretion
bursts;
where
⇢,
P,
E
are
the
density,pressuredensity,rehydrodynamics
6
discretized.
Inthemidplane
the
cells
are
approximately
cubical,
6.36
359
4
son equation of self x2
gravity
is solved
by meansof a di↵usion
detail in Kuiper et al.
(2011),
ina nutshell,a spherical
gridradiuswith two
0.74
37.5
10
67the
21 and
64
5.3
·the
10
3.07computational
167•was
Physics
whose
spatialbut
resolution
scales logarithmicallywiththey performed
extensive accretion
analysis
onofthesome
accretion
process,butcharacterizedbyanepisodic
frag-process, spectively;
isacceleration
sourcevisthevelocity,
a
7).
x
is
also
minimum
cell
size
of
the
doext
30
5
ansatz.
MoredetailsontheimplementationofthePoissonsolver77.8
7This c
1.50
x4
134
41
128
4.2
·
10
guarantees
strictangularmomentumconservation
aroundthewithtwoexample
cell
sizes
given
as
x
in
Table
1.
intensity
andfrequencyofthebursts.
term.
Theseequationsaresolvedwiththehydrodynamics
mod3.0740:
167
10
0.368
18.4
used,
allowing
for
very
high
resolution
in
the
areas
of
most
interments.
The
releaseofgravitational
potential
energycreates
an
main
in
the
disk’s
midplane,andxrepresentsroughlythe1500
Modeling disk fragmentation and multiplicity in massive star
6 (2010a).
detail2.3.
in K
for
the
self-gravity
modulearegiven
in
Kuiper
et
al.
0.74
37.5
x8
268
81
256
3.3
·
10
@⇢
ule
of
the
numerical
grid
code
Pluto
(Mignoneetal.
2007),
withest. Weset
upthe
a seriesof simulations
withincreasing
resolutions,centralmassive
protostar,
andlogarithmic
grid
in
r
allowsincreaseinluminosity,i.e.,anaccretion
burst.
Accretion
burstscell
size= inthe outer region of the disk.7
+
r
·
(⇢v)
0
(1)
guarantee
choiceofandcoordinatesisexplained
andjustified
in
more
1.50
77.8 formation (G.This
The
gas
is
assumedtobecaloricallyperfect,
governed
x16
536
161
512
2.6 that· 10 is,0.368 and18.4
André
Oliva
Rolf
Kuiper)Massive
stars
do
not
typicallyform
inisolation.
Studiesonadditional
modulesforhandling
radiationtransport
selfandexplorethephysicalprocesses
that
occur
in
fragmentationo↵er ancloser
explanation
the luminosity
burststar,
events in regions of @t
to thetoforming
massive
mulation (column 1), num- for a focus on the phenomena
centralThembythecalorical
equation
of
state
P
=
(
1)E
(where=multiplicity
inmore
evolvedsystemsof
massive
stars
show
that
gravity.
int
detailin
Kuiperetal.
(2011),butinanutshell,aspherical(howfragments
andinteract),
thebeenproperties
of in,
thee.g.,frag-grid@massivestarevolve
formation
which
have
reported
Hunter
0.74
37.5
focu
Table
1:
Designationcode
ofmassive
eachEsimulation(column 1),of
num- for agene
whilesavingcomputational
power.
An
explanation
on
how
well
a large portion of them are spectroscopic binaries (see,5/3,
e.g.,theSana
Thegravityoftheformingstar,
theself-gravity
value
for
H
at
low
temperatures,
and
is
the
internal
olumns 2–4); approximate
2
int
I
)
=
⇢a
(2)
(⇢v)
+
r
·
(⇢v
⌦
v
+
P
extthe frequency-dependent opacity; andis theopticaldepth;
(⌫,coordinate
r),
流体の式：
mentset (orbits,
massCarattiandtemperatures),theirfate and(whethertheyal.
(2017),oGarattietal.
(2017)Sugiyamaetal.
while sav
ber
of
cells
for
each
(columns 2–4);
approximate
@t
et
al.
2012;
Kobulnicky
et
al.
2014;
Dunstalletal.
2015).
The
obthe
fluid
and
the
radiation
forcesareincorporated
into
the
code
guarantees
strictangularmomentumconservation
aroundthe【内容】大質量星形成とその周りの円盤進化（分裂，連星形成）をかつenergydensity).
does
thischoiceofgrids
resolvethephenomena
studied
here
is
0.368
18.4
00 au, i.e., the approximate, thestellarradius.
equation
isaau,
integrated
for
R?the
evolvefurtherRecently,
and eventuallycompanion
andthethe possibility
does thisnumberof cells
in theThis
regionr < that
1500
i.e.,
approximate(2019).
Chen ofetbecomeal. (2020)
reportedonthesuggest
observation
servations
fragmenting
accretionstars),
disks
acceleration
sourceterm,
sucha? the+ asg+ eacharad , ray di@E via
ext =Radiationtransport
isincorporatedbythemethoddescribed
presented
in Sect. 9.2,
asofwellascomparison
to thegridchoicesmassive
protostar,
andthelogarithmic
grid
r burstallowsbin in theeachdisk’s
timephysics
step of(column
the hydrodynami((E +ande↵ectsthathasonfragment
statistics.
+ andrrection· numberP)v)= ⇢v· aresolve(3)cell presented
offrequency
cells
that
5);
’s てない高い解像度でシミュレーション。星の進化・ダスト進化を含む
physics (column 5); cell central
ext
diskresolution
substructuresassociatedwithevent,
thatclosebinariesmayformanbyaccretion
disk infragmentation
and
later
in⇢(r, tin Kuiper(2010b),but
advancedto6),a cell
two-temperature
ap-au (column of previou@t et al.
size
at
r
=
30
au
(column
size
at
r
=
1500
cal
simulation.
ward
migrationof thecompanions(Meyer The
et al. simula2018).
of previous
studies.
thus providing
a linkbetweenthetwo phenomena.
zeat(column
r = 15001),
au (column
for
a
focus
on
the
phenomena
closertotheforming
massive
star,
onGridnumproach, which wewillsummarizein the rest
ofsizethisofsection.
We
GM
?
7).
x
is
also
the
minimumcellthecomputational
do-dust30
Thefrequency-dependent
opacity(⌫)
isthesum ofrethe
base自己重力RHDコードを用い，分裂片に対しsubgridやsinkを使The
outcomeofoursimulation
wasalreadyused
in
Ahmadi
=
e
a
tions
in
Meyer
et
al.
(2017,
2018,
2019)
show
accretion
bursts;
where
⇢,
P,
E
are
the
density,pressure
andenergydensity,?
re of the computational do- while saving computational power.
2 theoftreat the star asanemitterradiation;
thedustdust
andgasrepresents
present
inroughly
mainindisk’s
midplane,andopacities,
x1500
the
ropacities.
An
explanation
on
how
well
In
this
study,
we
present
thehighest-resolution
self-gravityand
gas
For
the
we
use
the
tabulateds 2–4);
approximate
et al.they(2019)
forproducingsynthetic
observations
with
ALMA
performed an extensive analysis on the accretion process,istheacceleration
sourcespectively;visthevelocity,
anda2.3. We
Initiacextthetodisk.
2 addition
the
cloud
absorbit,andre-emitit,inthethermalradicell
size
in
the
outer
regionofrepresentsroughlythe
わず可能な限り流体計算で構造を高解像度に分解。円盤の進化とそこか, wherer sg =(1993),
4⇡G⇢ including 79 frequency bins,
radiation-hydrodynamical
simulations up toquandate on disk frag- avalues
1500
sg = rbysgLaor& Draine
and
NOEMA.
Inthat
paper,
many
observationally-relevant
intensity
andfrequencyofthebursts.
term.
Theseequationsaresolvedwiththe Thishydrodynamics
mod加速度：
does
thischoiceofgrids
resolvethephenomena
studied
here
is
2.3.
Initialandboundary
conditions
i.e.,
the
approximate
ation
due
purelytohydrodynamic
compression.
treatment
mentationaroundaforming
massive(proto)star.
We
continue
The clouinitia
DrE
r
·
F
k.
and
we
calculatethe
local
evaporation
temperature
of
the
dust
tities were computed, including 1.37 mm continuum images,
?
R
ule
of
the
numerical
grid
code
Pluto
(Mignoneetal.
2007),
wither radiation
R
Thefo
らできる分裂片の進化，分裂片周りにできるsecondarydisksとその分裂
allowsus to adivide
the
total
flux
F
into
two
contrirad =the approachtaken by Meyer
et al.
(2018),
in whichno sink
general
tot
in
Sect.
9.2,
as
well
as
comparison
to
the
grid
choicesgrainsbyusing
theformulaofIsella&Natta(2005).
The
gas
sics
(column 5); cell presented⇢c forc r), theintegrated
intensity
anddointensity-weighted
velocity maps
is modules
theopticaldepth;
(⌫,frequency-dependent
opacity; andMassivestars
notformpeakin thatisolation.
Studiesisbutions:on
additional
handling
radiationtransportulati
particles
are typicallyset on purpose,sofragmentation
described
The initial density profile
issphericallysymmetric,
and
has
the
the flux
from
the
star,
F
,
and
the
flux
from
2thermal
1 and self?
g
.
We
also
requireopacityissettoaconstant
value
of
0.01
cm
of CH
11
plots,
andself-gravity
ToomreQ thethat
R? , the stellar radius. This equation is integrated for each ray di3 CN(124 in
4 ), position–velocity
multiplicity
more
evolved assystemsof massive
stars show
gravity.
previous
studies.
self-consistently
theinterplay
of
of
gas,
coolsion=まで高解像度トレース。分裂片を捉える際に高解像度計算の重要性を示
1500 au (column ofgeneral(re-)emission
from
dust
and
gas, F. bin
form
the
flux
of
the
formingstar
atthestellarradius
R
,
for
which
we
rectionandfrequency
in
each
time
step
of
the
hydrodynamimaps,
takingintoaccount
severalinclinations.
We
refer
the
?
of thearegas,
shear of the binaries
disk and (see,other e.g.,gravito-radiationa large portioningof them
spectroscopic
Sana StellarThegravity
ofisthesolved
forming
massivestar,
theself-gravity
ofncy-dependent
opacity;and⇢(r, t = 0)T
irradiation
by
means
of
the
time状態方程式：P=(γ-1)
E
,
where
γ=5/3
The
variables
involvedinaaredetailed
below.
The
Poiscalsimulation.
use
tabulated
evolutionary
tracksforaccretinghigh-mass
stars,radhe すため，異なるグリッドモデルでも比較。
computational doreader
tothatreference
for
an
ample
discussionontheobservhydrodynamical
processes.
Instead,time-independent
grid fluid
et al. 2012; Kobulnicky
et al. 2014;
Dunstallet al.a 2015).
The obthe
andthetransport
radiation
forcesis areincorporated
into
the
code
independent
radiation
equation
(with
the
valid
assumps integrated for each ray dison
equationofself
gravitysolved
by
means
of
a
di↵usionThefrequency-dependent
opacity
(⌫)
is
the
sum
of
the
dust
calculated by Hosokawa & Omukai (2009).
!
abilityoftheresultspresented
here.
whose
spatialresolution
scaleslogarithmicallywithradiuswasservations of fragmenting accretion disks suggest the possibility⇢
via thetheansatz.
acceleration
source
term,
such
that
aext
=we
aPoisson+time
athe+tabulated
arad ,
the?use
sgsolverMoredetailsontheimplementation
of
the
tion
that
photontravel
time
is
small
compared
to
the
and
gas
opacities.
For
the
dust
opacities,represents
step of theroughlyhydrodynamiFor
theremainingthermal(re-)emission
contribution,
F isused,mayallowing
forby
very
high
resolution in theareasof mostinter(Hatlowtemperature想定)
We choos2
2.3.
Initialandboundary
conditions
that
close
binariesform
disk
fragmentation
and
later
inand
for
the
self-gravity
modulearegiven
in
Kuiperetal.
(2010a).
⇢(r, t = 0) = ⇢0
step
of
the
simulation,andonlyconsidering
absorption),which
valuesby
Laor&
Draine(1993),
including79
frequencybins,
est. We set up a series of simulations with increasing resolutions,assumed to be frequency-independent. First, we take the zeroth ⌦(R
5 30【用いたモデル】
This
is organized
as follows.
Sections
2 and 4cloud, ⇢0
r0
The
gas
is
assumedtobecaloricallyperfect,
thatis,governed
wardpaper
migrationofthecompanions(Meyeretal.
2018).
andwecalculatethe
local
evaporation
temperature
of
the
dust
yieldsand explore
the thephysicalprocessesandthat theoccur
in fragmentation
momentof theequation
radiationtransport
equationGM
The valuepresent the methodology
of bothsimulations,
post?
by
the
calorical
of
state
P
=
(
1)E
(where=y (⌫) •is the
sum
of
the
dust
grainsbyusing
theformulaofIsella&Natta(2005).
Thegas
int
輻射場：中心星からの放射はHosokawa&
Ohmukai(2009)流用era? =(how fragments
evolveand interact),
the propertiesof the fragInitial condition & Boundary
conditions
ulations aThe
initialdensity
profileissphericallysymmetric,
and
has
the
2
2
1 the internal
processingofthegenerated
data.
Sections
3
and
5–7
present
5/3,
the
value
for
H
at
low
temperatures,
and
E
is
r
g
.
We
also
requireopacityissettoaconstant
value
of
0.01
cm
2
int
In
this
study,
we
present
thehighest-resolution
self-gravitywhe
ments (orbits, mass and temperatures), their fate (whether they
ities, we use the tabulated We choose = 3/2,
sion
in Se
Z
2
our
results
andadiscussionofdisk
fragmentation,
thefragments
energydensity).
and
from
the
total
mass
and
radius
of
the
◆
✓
the
flux
of
the
formingstar
atthestellarradius
R
,
for
which
we
r
2
⇢
?
generalform
r radsg , wherer sg = 4⇡G⇢
evolve further simulations
and eventuallyup
becomecompanion
radiation-hydrodynamical
to dateon diskstars),frag-and atheTheinsg = @E
R?
The⌧(⌫,r)
cluding79
frequency
bins,
Radiationtransport
isincorporatedbythemethoddescribed
themselves
andcompanion
formation.
Section8
containsacon(4⇡B
cE
)
(5)
r
·
F
=
⇢
初期設定：200M⦿,
r=0.1pcのガス球
123
use
tabulated
evolutionary
tracksforaccretinghigh-mass
stars,
F? (⌫, r) = F? (⌫, R? )e(⌫, r)⇢dr
P , whererad ⌧(r, ⌫)rad=pendent opacity; ande↵ectsresolution
hasronfragment
statistics.
cloud,⇢
isdetermined
to
be
⇡
4.79
·
10
g
cm
at
=
1
au.
mentationarounda thatforming
massive(proto)star.
We continue
is se
0
0
@t
DrE
r
·
F
? etral.by
Rbut &
in Kuiper(2010b),advanced
to(2009).
a two-temperatureapcalculated
Hosokawa
OmukaiR?
on temperature of the dust
vergence study of our results, and Sect. 9, a literature review ander weRwill summarize in the rest of this section. We
the approachtaken
by Meyer
et al. (2018),
in which no sink arad = proach,
⇡ 9.
rated
for
each
ray
diThe
value
of
was
chosenbasedontheresultsofprevious
simwhich⇢Fortheremainingthermal(re-)emission
contribution,
F
is
⇢c
c
(4)
comparison
our results
withprevious
studies.
4! ⇢particlesofare
Thepurpose,outcomeof oursimulation
was alreadyused in Ahmadi
a & Natta (2005). The gas
=
aT
is
the
black-bodyenergydensity,
where
B
rad
set
on
so
that
fragmentationisdescribed⌦(R,desc
t=0
treat
the
star
as
an
emitterofradiation;
the
dust
and
gas
present
in c is theassumedtobefrequency-independent.
First,
wetakethezerothβp=-3/2
ulationsandobservationsofmassive
dense
cores
(see
the
discusetal.
(2019)
forproducingsynthetic
observations
with
ALMA
2
1
r
ofcm
theghydrodynamispeed
ofabsorb
light
inradiation
vacuumandisequation
the Planckmean opacity.
. We also require ⇢(r, t = 0) = ⇢01
self-consistentlyasthe interplayof self-gravityof 流体自身の再放射を解く
the gas, cool- quan- the
cloud
it,
and
re-emitit, inP addition
to the thermal
radi- This rame
momentofthetransport3
Articlenumber,
page
2
of
22
and
NOEMA.
Inthat
paper,
many
observationally-relevant
ρ0 = 4.79E-12 g/cm
sion
in
Sect.
9.3).
密度分布
0
equation
is solved
by means ofcompression.
the flux-limiteddi↵usion (FLD) keep
ation
due purely
to hydrodynamic
This treatment
ing
of
the
gas,
shear
of
the
disk
and
other
gravito-radiationlar radius R? , for which wetitieswere
computed,
including
1.37
mm
continuum
images,r0 velocity
Thevariables
involved
in consists
arad
are ondetailed
The
PoiswhereR@ 1auallowsus to divide
the totalradiation
flux
Ftotbelow.
intotwo
contriapproximation,
which
setting
F
=
DrE
,
that
is,
rad
dent
The
initialangular
is
given
by
the
profilehydrodynamical
processes.
Instead,atime-independent
grid
integrated intensity and intensity-weighted peak velocity maps
stars,@EradofThe ratioson
equationgravityisstar,solvedby)canmeansofa di↵usionsaccretingthe sumhigh-massof the dust
butions:
the self
flux
from
the
F?cE
, and
thebe
fluxtreatedfrom
thermalassuming
that
radiationtransportasadi↵usion
chos
(4⇡B
(5)
r
·
F
=
⇢
whose spatial ofresolution
scaleslogarithmicallywithradiuswas
CH3 CN(1211),
position–velocity
plots,
andToomreQPradrad
0次の輻射輸送式
4
4
is
set
to
@t details(re-)emission
from
dust
and constantgas, F. is Dof=thec/⇢
ansatz.
Moreontheimplementation
Poissonsolver2009).
problem.
Thedi↵usion
,
where
is
the
R
man
maps,
takingaccount inseveralinclinations.
refer theallowing
for= veryhighinto
resolution
the areasof most We
interwe use the tabulated We choose = 3/2,
βp
-3/4
! ⌦used,⇡9.84·1Stellarirradiationissolved
by
means
of
the
timefortheself-gravity
modulearegiven
in
Kuiperetal.
(2010a).
and
from
the
total
mass
and
radius
of
the
4
flux
limiter,
and

is
the
Rosselandmean
opacity.
Thechangemission contribution, F isreadertothat
reference
for
an
ample
discussionontheobservpola⇢
Rest. We set
up
a series of simulations
with increasing resolutions,aTis theequation
black-bodyenergydensity,c is the described
whereradiation
Brad = Rlimited-1
この式をFlux
diﬀusion
近似で解く
independenttransport
(with
the
valid
assumpΩ=9.84E-11s0
g 79
frequency
Theofgas
is assumed
tovacuum
bethe
caloricallythatis, opacity.
governedabilityof the processes
results12presented
here.
internal
energyofsystemisperfect,⌦(R, t = 0) = ⌦0
3 in fragmentation
speed
of
light
in
and

is
the
Planckmean
This rameter sI
角速度分布
nt.
First,
we take thebins,
zeroth cloud,andexplorethephysical
that
occur
P
tion
that
the
photontravel
time
is
small
compared
to
the
time
⇢
is
determined
to
be
⇡
4.79
·
10
g
cm
at
r
=
1
au.
@ 10auR0 (how fragments00
by the caloricalequationof meansstate Pof =(flux-limited
1)Eint di↵usion(where (FLD)=
equationissolvedbythekeepsclouthemperature
of
the
dust
evolveandinteract),theproperties
ofthefragstep of the simulation, and only considering absorption), whichuationThis paper is organized as follows. Sections 2 and
4
5/3, the valuefor H2 at which
low temperatures,and E
the internal
approximation,
consists on setting
Fint= is DrE, that is,

The
value
of
was
chosenbasedontheresultsofprevious
simraddent situaof thyields⇢ments(orbits,mass
andtemperatures),
their
fate
(whether
they
@E
int
present the methodology of both the simulations, and the postatta (2005). The gas
assuming
that
radiationcEtransport
canbe treated as a di↵usion (6)energydensity).
chosen
in
=
⇢
(4⇡B
)
r
·
F
as
w
内部エネルギー変化
P
rad
rad
?
evolvefurtherandeventually
becomecompanion
stars),
and
the
where
R
is
the
cylindricalradius,andwechoose=3/4.
ulationsandobservationsofmassive
dense
cores
(see
the
discusprocessingofthegenerated
data.
Sections
3
and
5–7
present⌦
2
1 ※重力エネルギーと回転エネルギーが半径によらず5%，現実のコアを真似
problem.
The di↵usion
constant isbyDthe= methodc/⇢R , whereis the man et al@t
Radiationtransport
is incorporated
described
g . We also requireThee↵ectsthat
resolution
hasonfragment
statistics.
Z
our results and apotential
discussion ofenergy
disk fragmentation, the fragments✓RR is◆2the Rosseland mean opacity.
r The change
flux
limiter,
and
The
ratio
of
kinetic
energytogravitational
polar
velo
in
Kuiperetal.
(2010b),buttoa
two-temperature
ap? advanced
sion
in
Sect.
9.3).
⌧(⌫,r)
disk
=
c
⇢T
.
We
solve
equations(5)
where,
for
the
ideal
gas,
E
themselves and companion formation. Section 8 contains a con- Fこの式を(5)と合わせて解く（twov⌧(r, ⌫) == F? (⌫,
R? ) of theesystem
, int
where
(⌫, r)⇢dr
初期温度を10K,g/d=100(ダストのκ(ν)計算に使う）
ofr)internalenergyis rest? (⌫,ius R? , for whichwe(5) is set
In sumproach,
which
we
will
summarize
in
the
of
this
section.
We
toto 5%,
which fixes The
the outcome
normalization
parameter
⌦
r
0
R
tion
vergence
study
of
our
results,
and
Sect.
9,
a
literature
reviewandand (6) for the unknowns Erad and T by using the so called twoof
oursimulation
wasalreadyused
in
Ahmadicloud,
soThe
initialangularvelocity
is
given
by
the
profiletreat thetemperaturestar as an emitterofradiation;
the
dust
and
gas
present
in(4)comparisonof our resultsprocesswith previous⇡ 9.84 · 10 11 s 1 at R0 = 10 au. The
normalizationis studies.
ting high-mass stars,
condlinearization approach, described in Commerçon

ody energy density, c is the?

et al. (2019) for producing synthetic observations with ALMA

temperature linearization approach)@Eint it, and re-emit it, in addition to the thermal radithe cloudabsorbet al.
(2011).

situation,

tial cOverview of the temporal evolution
G. André Oliva and Rolf Kuiper: Modeling disk fragmentation and multiplicity in massive star formation• Geometry

initial setup

r＝30au - 20625au (=0.1pc), log的なメッシュ，

disk formation epochfragmentation epoch

quiescent epoch

rotation profile
density profile

30au以内はsink, 中心に大質量星ができる設定

fragment

sink cellmassive protostar

surviving fragment(s)gravity
disk

midplane density

Θ：cosで等間隔，赤道面で高解像度

spiral arm

Φ：等間隔

円盤Spiral
+ 分裂片

n✓
11
21
41
81
161

n
32
64
128
256
512

ndisk
7.0 · 103
5.3 · 104
4.2 · 105
3.3 · 106
2.6 · 107

x30
6.36
3.07
1.50
0.74
0.368

x1500
359
167
77.8
37.5
18.4

Table 1: Designation code of each simulation (column 1), number of cells for each coordinate (columns 2–4); approximate
number of cells in the region r < 1500 au, i.e., the approximate
number of cells that resolve the disk’s physics (column 5); cellsize at r = 30 au (column 6), cell size at r = 1500 au (column
7). x30 is also the minimum cell size of the computational domain in the disk’s midplane, and x1500 represents roughly thecell size in the outer region of the disk.
is the optical depth; (⌫, r), the frequency-dependent opacity; andfor each ray diR※観測可能性の論文は別に出版済み（ALMA,? , the stellar radius. This equation is integrated
NOEMA）
rection and frequency bin in each time step of the hydrodynamiAhmadi et al. 2019cal simulation.
The frequency-dependent opacity (⌫) is the sum of the dust

achieved in the midplane (z = 0); and the azimuth is uniformly
discretized. In the midplane the cells are approximately cubical,
with two example cell sizes given as x in Table 1.
This choice of coordinates is explained and justified in moredetail in Kuiper et al. (2011), but in a nutshell, a spherical grid
guarantees strict angular momentum conservation around thecentral massive protostar, and the logarithmic grid in r allows
for a focus on the phenomena closer to the forming massive star,
while saving computational power. An explanation on how well
does this choice of grids resolve the phenomena studied here ispresented in Sect. 9.2, as well as comparison to the grid choicesof previous studies.

※secondcollapseはtemperature

nr
34
67
134
268
536

扱えないが
高温領域ありToomre parameter

run
x1
x2
x4
x8
x16

vertical density※5つの異なる高解像度計算，x8,
x16をメインに議論
G. André Oliva and Rolf Kuiper: Modeling disk fragmentation and multiplicity in massive star formation（他は主に解像度依存性を議論するための比較計算）

Fig. 1: Time evolution of the system (run x8). In the elaboration of the plots, snapshots of the simulation were taken specifically at
3.0, 8.0 and 17.5 kyr, for each respective column. The rightmost column shows double the size of the other two (the dotted squarecorresponds to the area shown in the snapshotslocatedthe left).no.
Forfrag-main-arxiv
the rightmost column, notice the existence of a surviving
A&A
proofs:tomanuscript
fragment at r ⇠ (900, 1200) au for the midplane views.

2.3. Initial and boundary conditions

The initial density profile is spherically symmetric, and has thegeneral form⇢(r, t = 0) = ⇢0

r
r0

!⇢

Article number, page 5 of 22

中心星の進化
間欠的な降着有

(a)

(b)

(c)

Fig. 2: (a) Mass, (b) luminosity and (c) accretion rate of the central massive protostar, as formed in run x16. The dotted line in panel(b) that corresponds to the stellar luminosity, is calculated using the evolutionary tracks of Hosokawa & Omukai (2009).

The fragmenting accretion disk
A&A proofs: manuscript no. frag-main-arxiv(a) Keplerianity (midplane)(b) Density (midplane)(d) Temperature (midplane)(e) Radial mass flow (sph. shell)(c) Surface density

Fragmentsの進化色々(1) fragmentの形成：渦状腕の形成→分裂 (Takahashi+ 2016)
A&A proofs: manuscript no. frag-main-arxiv
G. André Oliva and Rolf Kuiper: Modeling disk fragmentation and multiplicity in massive star formation

run x8spiral arm collision

within spiral arm

fragment creation mechanisms

gravityrotationA

new fragment
inhomogeneity

creasenew fragment
spiral arm AB(a)spiral arm B

1

2

3

4

Fig. 6: Fragment creation mechanisms. The color scale for the midplane density maps is the same as the one shown in Fig. 1.
crease; in the case of fragment 59, the crease was formed in aspiral arm of the secondary disk around fragment 40.
The second process, spiral arm collision, is illustrated in panels B1 and B2. When two spiral arms or regions of high density
collide, they create perturbations that make the region Toomreunstable and therefore, a collapse is triggered. The example inpanel B3 is from run x8, and shows the formation of fragment
32, which is generated by this mechanism. Panel B4 provides anadditional example from run x16, where two spiral arms, connecting fragments 32 and 68 to the inner disk, have collided andgave rise to fragment 71.
Early during the fragmentation epoch, both processes occur
predominantly in the primary disk. However, towards the endof the fragmentation epoch, and as fragments gain more mass,
the fragmentation inside substructures becomes dominant: spiralarm breakdown and spiral arm collisions become more frequentin the secondary disks and yield fragmentation. This behavior
was observed especially in runs x4 and x16. This hierarchicalfragmentation is in principle analogous with the observations

9 kyr, although we do not consider it as of great interest, since it
is not observed in the other runs (see Fig. 20).
Lifetimes of the fragments (color code) and the radial location when they are formed (vertical axis) are shown in Fig. 7b,
as a function of time (horizontal axis). We see that the longest
lived fragments are formed in the outer disk, and that the innerdisk forms fewer fragments over time. This trend is tied to thefact that fragmentation is occurring in the spiral arms of the primary disk. The figure was generated with the data from run x8.
In run x16, as the spiral arms of the secondary disks fragment,
new long-lived fragments start to form again in the inner disk.

※ 2つの機構：spiral内での収縮＆

spiral arm同士の衝突

6.3. Mass

The masses of the fragments are presented in Figs. 8 and 9 (corresponding to runs x8 and x16, respectively), obtained using themethod described in Sect. 4. The masses of the fragments are ofa few solar masses, and increase over time. Peaks and sudden increases are observed, and correspond to fragment mergers, thatare described in Sect. 6.6. Some decreases and oscillatory behav-(b)Fragments間の相互作用など(4)

マージャー，相互作用…
A&A proofs: manuscript no. frag-main-arxiv

計算の分解能依存性

A&A proofs: manuscript no. frag-main-arxiv

ローカルなジーンズ長を分解しないとFragmentation の詳細には迫れないtheexact source unit
(e.g. a collisional
disc or cometary
low mid-infrared(MIR)
excessesinwards
and steep
grain
size
star-grain
separation
vector, debris
respectively.
Material
migratingthrough
Poynting-Robertson
In this paper we investigateapotential
mechanism
2017). Transient
dynamical
upheavals,
suchas the disintegration). We then followFthe= Fevolving
size
, and
(1)
distributions(Sezestre,
Augereau& atThébault2019),
grav + Frad(PR)
drag andpiling up
the sublimationzone
cannot2.1.1
Forces
Theto location
combinede↵ects of radiation pressure andto generate NIR excesses acrossdiversetypes
andHeavystellar
Bombardment,
could
supply (Bonsor
materialofthegrain.
and Latemay
requirespecific
systemarchitectures
produce enough hot dust to reproduce observations, since
where FF is thetotal
force and Fgrav and Frad are
43: Gas trapping of hot dust around etmain-sequence
stars
the
veryRaymond
inner regionsof thesystem;however,such induce
PR-drag
a
force
on
the
grain:
al.
2014;&
Bonsor2014;
Faramazetal.
In the absence of radgas, the dust grain is subject to gravity
ages, without requiring specific systemarchitecturesor remain near the sublimation
the timethat small grains
those
due
to gravity and radiation, respectively. The
eventsare tooshort-lived
to explain
theas frequency2017).
Transientdynamical
upheavals,
suchthe(Tim D. Pearce⋆, Alexander V. Krivov
andMark
Booth)
andradiation
forces.
Its equation of motion isregion
is
too
short
(van
Lieshout
et
al.
2014;
Sezestre,
exceeding constraints on MIR
dust
migratingofHeavy
observations(Bonsor,Raymond& Augereau2013). 2.1.1 Forcesgravitational force isLate emission:
Bombardment,
could
supplymaterialto✓◆Augereau & Thébault 2019). Trapping grains via theMaterial
migratinginwards
Poynting-Robertson
the veryinner
regionsof thethe throughsystem;however,suchinwards
underradiation
forcessublimates
near
star,
ṙ
v
In the absence of gas, theF dust
grain
is subject
to gravity
Di↵erential
Doppler
E↵ectisine↵ective
against PR-dragdd【内容】幅広いSpタイプ，ageの主系列星（おおよそ1/5）で見られる，
=
F
+
F
,
(1) (3)grav
radGM? m ,
(PR)andpiling up toat thesublimation
zone cannot F
=
|F
|
1
r̂
eventsaredragtooshort-lived
explainthefrequency
grav
radradiation forces. Its equationof motion
is
Fgrav
=
r̂,
(2)
(Sezestre,
Augereau& Thébault 2019), and andwhilstreleasing gas which then traps
subsequent
grains.
These
2
c
c
r
produce enoughhot dust
to reproduce
observations,sinceof observations(Bonsor,RaymondAugereau2013).
where F is the total force and Fgrav and Frad are
謎めいた近赤外線の輻射超過の謎に迫る。落下してきたダストが蒸発す
magnetic
trapping
has&been
proposed(Rieke, Gáspártimethat small
grainsremainnear the sublimation
hot grains, the source of Material
thethenear-infraredemission,
migratinginwards
through
Poynting-Robertson
where
G, M⇤ , m,
and r̂ are thegravitationaldue
to gravity
andr radiation,
respectively.
Theconstant,& Ballering
2016)
the e↵ectivenessof the mechanismthoseis
where
the ratio
ofisFdust
radiation
to the andF=+grainFrad ,mass,pressure(1)
ることによって発生するガスによりダストが円軌道化＆安定化させられgrav
regionis tooshort(vanLieshout
et al.zone
2014;
Sezestre, is gravitational
(PR)
drag
and
pilingup
atthesublimation
cannotstar
mass,
star-grain
separationforce
unclear(Kral
et al.
2017a; Kimura et al. 2020).
are held on stable orbits by gas.
The
idea
was
briefly
Augereau&
Thébault2019).
Trapping
grainsvia the whereforce,
produceenoughhot
dust
toreproduce
observations,sincestar-grain
unit
gravitational
theseparation
dust
velocity,is thed isandṙdrespectively.
Frad
are radial
F is v
the
total
force
and
Fgravvector,
In
this
paper
we
investigateapotential
mechanism(1)
ダストにる機構を新たに提唱。比較的少ない質量供給で観測可能な輻射超過
explored before (Lebreton ettheal.time2013),buttherequiredDi↵erential
DopplerE↵ect
is ine↵ective
against PR-drag those due to gravity
thattosmall
grainsremainnearacrossthe sublimation
The andcombinede↵ectsof radiationpressure andradiation,
respectively.
The
generate NIR excesses
diversestellar typesof
and
GM
m
?
component
v
,
r̂
is
the
radialunit
vector
and
c
is
the
d
F
=
r̂,
(2)
(Sezestre,
Augereau&
Thébault2019),
andwhilstgrav（量，寿命）が作れる上，サイズが自動的に一定に揃う予言が観測的特
region
is
too
short
(van
Lieshout
et
al.
2014;
Sezestre,
PR-draggas quantity appeared too high to becompatible
withgravitational
force is induce a forcer2Frad on the grain:
ages,
without requiring
specific system architecturesor
働く力：magnetic
trapping 2019).
has been
proposed(Rieke,Gáspár
speed
ofmigrating
light (Burns, Lamy & Soter 1979). Radiation
Augereau& exceedingThébault
Trapping
grainsvia theconstraintsonMIR
emission:dust
observations (Su et al. 2016).
WeDoppler
perform
detailed
徴（中間赤外での超過量が近赤外に比べて少ない）を説明できる（太陽where G, M⇤ , m, r and r̂ are the gravitational✓◆ constant,& Ballering
2016)
the ise↵ectivenessof the mechanism
isDi↵erentialE↵ectine↵ective
againstPR-draginwards under radiation forces sublimatesnear
the star,ṙdcircular
vd andpressure
counteracts
gravity,
so=
a |F
grain
on
aseparation
orbit
βは輻射圧と
GM
?m
star
mass,
dust
grain
mass,
star-grain
|
1
F
r̂
(3)
unclear
(Kral
et
al.
2017a;
Kimuraetal.
2020).
grav
radanalyses and show that the(Sezestre,gas quantities
neededare
Fgrav =r̂,(2) ,Augereau
Thébault2019),
and whilstgrains. These型の場合）ようになった（ただし，A型星に関してはまだ）。
releasing &gaswhich thentraps subsequent2ccr
star-grain
separation
unit
vector,respectively.
hasareducedvelocity
In
this
paper
we
investigateapotential
mechanism
magnetic
trapping
has beenGáspár 重力の比
hot grains,
the proposedsource of (Rieke,
the near-infraredemission, The combined e↵ects of radiation pressure andmuch smaller than the previous
estimate.
where G, M⇤ ,wherem, r and isr̂ aregravitational
constant,
thetheratioof radiationpressure to theto generate
NIR
acrossofdiverse
stellar types& Ballering
2016)
theexcessese↵ectivenesstheis andare heldonstable orbits
by mechanism
gas. The idea
was briefly
inducea force
Fstar-grain
the grain:
radvonstar PR-dragmass, dust
grain
mass,
andṙd is the radial
The
work
is
laid
out
as
follows.
In
Section2
wegravitational
force,
dust
velocity,
ages,
without
requiring
specific
systemarchitecturesord is the separationunclear
(Kral
et
al.
2017a;
Kimuraetal.
2020).
【背景】
explored before (Lebreton et al. 2013), but the requiredpstar-grain
separation
unit
vector,component of vd , r̂ isrespectively.
the radial unit vector and c is theexceedingconstraintsonMIR
emission: mechanism
dust migrating
this paper
weinvestigateapotential
describe the evolution of dust In
grains
close
to
the
star
✓
gas quantity appeared too high to be compatible withv=v
1,ṙ ◆ pressure(4)
Hot
dust trap
KepdThe
combinede↵ectsofradiation
and
speed
of
light
(Burns,
Lamy
&
Soter
1979).
Radiation
inwards
underradiation
forcessublimates
near
the
star,
v
• AFGKの主系列星の20%が近赤外線超過を示す
to generate NIR
excessesacrossdiversestellar
types
and
d
d
observations(Suet gasal. 2016). We perform detailed= counteracts|F| the1gravity,Fradr̂ a grain, on a circular(3)
gravonin the absence of gas. In Section
3
weoutlineourPR-drag
induceaforce
Fgrain:
pressure
so
orbit
rad
releasing
gas
which
then
traps
subsequent
grains.
Theseccages, withoutanalyses
requiringand
specificarchitecturesor needed areshow systemthat thegas quantities
and temperature
T velocity.
by P = ⇢kB T /(µmu ). Substituting
2.
is
the
Keplerianorbitalwherev
Kep• 星のごく近傍の1000Kくらいのダストの存在を示唆
hasareducedvelocityhotgrains,thesourceofthenear-infraredemission,exceedingconstraintsonMIR
emission:
dust
migrating2
model, and show that grains can becometrappedinpreviousamuch smaller
than theestimate.
4⇡s⇢dof
ds, where
dust Hotgrain
density,yields in ga
where
is dm
the= ratio
radiationpressure
to dustthe trapped✓◆ ⇢d is the
W
are
held
on
stableorbits
by
gas.
The
idea
was
briefly
inwards
underradiation
forcessublimates
near
the
star,
ṙ
v
輻射圧の効果でダストはゆっくり回転ddthesublimation
rate
as
The
work
is
laid
out
as
follows.
In
Section2
we• 説明の難しい様々な特徴
gravitationalgas disc. We examine the implicationsof
oursimulations,|Fgravv| d is1the dustr̂velocity,
Frad = force,, ṙd is the(3)radialptwexplored
before(Lebreton
etal.
2013),buttherequired
releasing gas describe
which thentraps
subsequent
grains.
Theseccthe evolution of dust grains close to the starv=d ⇢k= BunitvTKep1u ). Substituting, c is the(4) Nume
componentof vd , r̂ istheradialvectorandw
andtemperature
T
by
P
/(µm
2.2
includingobservational
comparisons,inSection4.
We
gas
quantity
appeared
too
high
to
be
compatiblewith• より長波長側の超過の有無とはあまり関係なし
hot grains, thesourceofthenear-infraredemission,s
Sublimation
2 (Burns, Lamy & Soter 1979). Radiationin the absence of gas. In Section 2.1.2
3 we outline
our
gas
speed
of
light
where
is
the
of
radiationpressureto⇢eqthe
sin
dm
=
4⇡s
⇢ratio⇢d Keplerianis ds
the dust
grainyieldsd ds, whereobservations
(Su
et
al.
2016).
We
perform
detailed
kBdensity,
Td velocity.
istheorbital
where
v
are
held
on
stableorbits
by
gas.
The
idea
was
brieflyKepWe
impleme(2)昇華：熱力学的な考察から温度の関数でdiscuss the results in Section 5, and conclude
in Section
model, and showthat grains can become trapped
inpressurea the sublimation. orbit(7)
counteracts
gravity,so a=grainṙdonathecircularcorate
asgravitational
force,
v
is
the
dust
velocity,isradiald• MIRの超過量が著しく少ないSEDやPolarizationの観測は，ダスト
dt2⇡µmu ⇢danalysesandshow that
the2013),gas quantities
needed are
two-dimensio
explored
before(Lebreton
et
al.
but
the
requiredgas disc. We examine the implicationsof oursimulations,ahasthea reduced
We
implement
component
ofsublimation
vd , r̂velocity
is the radialprescription
unit vector and of
c is Lebreton
the
6.
much
smallerthantheprevious
estimate.
withvariablegas quantity including
appeared observational
too high to becomparisons,compatible withsSoterT
in Sectionspeed
4.
Weof light2.1.2
サイズがsteepで昇華領域すぐ外側にあることを示唆→星のタイ
Sublimation(Burns,Lamy&1979).
RadiationThisisequivalent
toEquation
17
ofLebretonetal.
(2013)
サイズの進化
single
dust
g
et
al.
based
on
that
of
Lamy
(1974).
Particles
The (Su
worketis al.
laid2016).
out asWe
follows.
In Section
2 (2013),
weobservations
perform
detailed
k
T
⇢
ds
in
B
eq
d
p
discuss the results in Section 5, and conclude in pressure
Section counteracts
if nogas=discpresent.
The
densitygravity,so a isgrain
on a circularorbitof(7)evaporating.
completely su
describetheevolutionof
dust
grains
close
to
the
star
v
=
v
1
,
(4)
analyses
and
show
that
the
gas
quantities
needed
are
Kep
d
th
dt
2⇡µm
⇢
We
implementthesublimationprescriptionofLebretonu
プとダスト存在領域の半径には相関あり
devaporate hasfroma grainat attemperature
Td at6.
γは昇華の効率gas
saturation pressure,⇢eq , ais rate
found froma thea reduced
velocity
distance of

Hot Dust Evolution
without gas

•
•
•
•
•

the absenceof previous
gas. In Section
3 we outline our gas
fomuchinsmaller
than theestimate.
et al.Clausius-Clapeyron(2013), based onequationthat of Lamy (1974). Particles
ThevariableistheKeplerianorbitalvelocity.
wherev
かなり短い時間で昇華，吹き飛ばされないのはなぜか？
This Kepisequivalentfrom
to Equation
Lebreton et al.T(2013)
model,
and
show
that
grainscanbecometrapped
in
a
re
The
work
is
laid
out
as
follows.
In
Section2
weevaporateapgrain17atoftemperatured at a rate instantaneou
2 HOT DUST EVOLUTION IN THE
if no gas disc is present. The density of evaporatingdegas disc.
We examineof toourthesimulations,describe
the evolutionof thedustimplications
grains closestarρeq: 飽和蒸気圧に
v
=
v
1
,
(4)
✓
◆
✓
✓
◆
◆
Kep
d
the
scale
fac
P
1
Collisional ABSENCE
cascade は時間がかかりすぎて無理
eq
2 observational
HOT DUSTEVOLUTION
IN THEgas at saturation pressure,⇢eq , is foundfrom the Td
OF A GAS
DISC
⇢
Td
eq
includingcomparisons,inSection4.
We
in the absence of gas. In Section 3 we outline our gas
p
f
=
,
(5)
2.1.2
Sublimation
forconvergen
log10 equation
log10= B A Peq
, (8)
evap
おけるガス密度，3
ABSENCE
OF
A
GAS
DISC
Clausius-ClapeyronistheKeplerianorbitalvelocity.
where
v
g
cm
K
K
Kep
fevap
= Tpd
,
(5) for g
discuss
the resultsin Section
and conclude2⇡µm
model,and showthat grains
can 5,
becometrappedininSectionau kB
results
Commet ー ダストサイズ分布が説明できない
2⇡µmu kBof
Td LebretonWe
implementthesublimationprescription
We first describe the evolution
of
hot
dust
close
to
the
6.
gas disc. We examine
implicationsof our simulations,described in
We first thedescribe
the evolutionof hot dustTclose
to thedにすごく敏感where◆ A and ✓B ◆are1 material-specificquantities
✓
✓
◆
2.
et
al.
(2013),
based
on
that
of
Lamy
(1974).
Particles
where
f
is
the
flux
of
particles
evaporating
from
the
where
f
is
the
flux
of
particles
evaporating
from
the
evap
⇢
T
T
includingobservational
comparisons,inSection4.
We
evap
一時的なダスト放出（Gianteqd (Lebreton et al.
d 2013); for carbon,
star intheinfluenceabsence of a ofgas disc, under the influenceofSublimation
determined
empiricallystar in the absence impactなど）：寿命短すぎ
of a gas disc, underthe
2.1.2evaporate
log10grain
log
=
B
A
, (8)
10
at
a
rate
from
a
grain
at
temperatureT3dsurface,
P
and
µ
are
the
saturationpressure
and
eq
W
g cm
K = 7.2294 pressure
Kdiscuss the resultsin Section
5, andconclude inThis
Section
A
=
37215
and
B
(Zavitsanos&
Carlsonradiation
forces andsublimation.
evolutioncannotgrain
surface,
P
and
µ
are
the
saturation
andeq
radiation forces and sublimation.
evolutioncannotmolecular
weight ofevaporating
material
respectively,
PR効果によるダスト落下：ダストの量が稼げない
the1973;
sublimationprescriptionof Lebreton
PR
Sezestre,
Augereau& Thébault2019).
Hence ⇢eq
6. 2 Thiskeep
hot dust
close
to theINstar
for long enoughWeto implement
be
HOT
DUST
EVOLUTION
THE
where
Aevaporating
B arematerial-specificquantities
molecular etweightofmaterialbe
2.3 Result
mbasedisisandtheunit
krespectively,
is the Boltzmannal. (2013),
on atomic
thatof mass
Lamy(1974).
extremely
sensitivetoT .and Particles
P※SED modelから，Carbonのダスト考える

Hot dust trapped in gas around main-sequence4
ガスがない時のダスト進化(G2stars
type)







Gas Diskの導入
ダスト流入→ダストの昇華→ある半径でデルタ関数的にガス発生，それが粘性拡散してできる平衡回転円盤を考える
鉛直方向は静水圧平衡とし，ガス温度はHot dust黒体の輻射平衡温度で与える
trapped in gas around main-sequence stars 4vgas = vKep(1) ガスの
回転速度

⌘⌘

✓

cs
vKep

1

⌘,

◆2

(9)

(10)

and cs is the isothermal sound speed, given by

cs =





where

p



s

kB Tgas
.
µmu

(11)

Since gas is assumed to be produced by dust sublimation,
its molecular weight µ is assumed to be that of the dust.
For the parameters in our model the factor ⌘ ⌧ 1, so thebulk gas velocity is approximately Keplerian.
For a thin disc the midplane gas density ⇢gas isrelated to surface density ⌃ bygas disc ontion in the(25)

As well as sublimating, grains embedded in gas can growgrain embedded in gas oftheusame2⇡µm
kB Tgas molecular weightasWematerial
accretes onto
them. ofContinuingwithaccrete particles
at a ratein gas can grownow consider
the e↵ectthe above
gasthedisc on
As well as sublimating,grains embedded
where facc is the flux of gas particles accreting onto theprescription of Lebreton
et al.
(2013)
andLamy(1974),
a
F
=
F
+
F
+
F
,
(25)
grav
gas
rad
migrating dust. The grain equation
ofvdmotionin theas (26)
material accretes onto them. Continuing with the
v
⌘
v
.
gas
grain embedded in gas of the same molecular weight will
grain and Pgas is the gas pressure. Combining this withpresenceof gasatisa rateprescription of Lebreton et al. (2013) and Lamy (1974), a
accreteparticles
Equation 6 for sublimation, the grain mass changes at ais the gas drag force. This force is related towhere F
gas

ガスがある時のダスト進化
(G2
type)
We do not consider turbulent motion in the gas,grain
hence
embedded in gas of the same molecular P
weight will
gas

p
f
=
,
(
rate
acc
the
gas
velocity
v
is
the
bulk
velocityfromEquationv, the grain velocity relative
gas to the gas:accrete particles at a rate Hot dust trapped in gas
aroundumain-sequencestars 7
2⇡µm
k
T
B
gas
s related(1)toダストに働く力： 9. F
= FgravP+
Frad Equation+ Fgas , 4, for a grain(25) on a circulargas
Combiningwithpfacc =,(31)  2⇡µmu kB Tgas
orbit



dm
2
where
f
is
the
flux
of
onto
where Fgas is the gas drag force. This force is related to (fgas particles
accP
fevap ) µmuaccreting
,
(32)
=
4⇡s
gas

acc
f
,
(31)
v
⌘
v
v
.
(26)
acc = p dt
gas
d
where
f
is
the
flux
of
gas
particles
accreting
onto
the
v,
the
grain
velocity
relative
to
the
gas:
ガスダストの相対速度差：acc
grain and Pgas
is uthegas pressure. Combining this w
⌘
⇣p
2⇡µm
kB Tgasp(26)
grain and Pgas is the gas pressure.
 disc therefore evolves as
v = Combining
vKep
1this⌘with 1,(27)
and grain6radius
in a gas
Equationforsublimation,
the
grain
mass
changesaWe
donot
considerturbulentmotion
in
the
gas,
hence
Equation 6 for sublimation, the grain mass changes at a
where f
is the flux of gas particles accreting onto thegas, hence
acc
rate
考えている円盤モデルでは，現実的なダストサイズで
β
>
η
v
⌘
v
v
.
(26)

rate
gas
d
the
gas
velocity
v
is
the
bulk
velocityfromEquationm Equation
so dust gas
on a circular orbit is slower than gas if >grain⌘ (e.g.
and Pgas is the gas pressure.
Combining
thispwiths
n a circular （ダストの方がガスよりゆっくり回転），抵抗則はEpstein⇢eq changes⇢gas atTgas
Takeuchi&
Artymowicz
2001).
In
ourparameterspace
9.
CombiningwithEquation
4,
for
a
grain
on
a
circularEquation
6 for sublimation,
the grain
a /Td
kB Tdmassds
We do not consider turbulent
motion
in
the
gas,
hence

.
(33)
=
5
4
dm
⌘
⇠
10
to
10
,
with
the
smallervaluescloser
to
the
rate
2
dt dm
2⇡µmu
⇢d
orbit
the gas velocity
the bulk
Equation
gas is(facc
f4evap )velocityµmu , from (32)= v4⇡s
2 








dt
star.
A
of
10
corresponds
to
a
grain
radiusofseveral
(f
f
)
µm
,
(
=
4⇡s
acc
evap
u
   
9. Combining with Equation 4, for a grain on a circular
dt
This
is
equivalent
Equation
17andofgrey Lebreton
millimetres
aroundaG2
star
orseveralcentimetresfor
Figure 3. Evolution of an initially 10 µm radius solid carbon to
grain orbitinga G2 star. Redlines show evolutionet
in al.
,
(27)
and
grain
radius
in
a
gas
disc
therefore
evolves
as
⌘
⇣
orbit
(2) ダストの成長（凝縮）：熱力学から定式化pdmp2
the presence and absenceof a gas disc, respectively.
The gas density at r = 0.022 au is ⇢ (r ) = 10g cm , and the disc(2013),
noting
that
we
do
not
require
gas
and
to
an
A0
star;
for
gas
quantities
consideredin
thispaper,
(f
f
)
µm
,
(32)
=
4⇡s
u is initially too large to couple
Ṁ ). The grain
to gas,dust
so itsfollows the density profile on Figure 2 (Equation 22,acc
with Ṁ =evap
v = vKep
1 ⌘
1
,
(27)
and
grain
radius
in
a
gas
disc
therefore
evolvesasdt
early evolution is identicalto the gas-free case; the grain migrates inwards under PR-drag and begins to sublimate near the star.
> ⌘ (e.g.
have
the same
temperature.
such
are
not
coupledtogasanyway.
Hences large ⇣grains⌘
However, once the grain becomes sufficiently
small it starts
to couple to the gas, which draws the grain away from the star andpppprotects it from further sublimation and eccentricity excitation. The grain is eventually trapped on a circular orbit just exterior⇢⇢T/Tmeter space
kB
T
ds
eq
gas
gas
d
vin=thevparameter
1
⌘
1
,
(27)
d
space
where
gas
drag
may
be
importantandgrain radiusa gas
therefore
asthe right-hand plots, emphasising
Kep
to the sublimation
region, where ingas dragbalancesdisc
PR-drag.
Note the break inevolves
the time axes on.
(33)=
so dustdton a circularorbit
isslower
than
gas
if
>
⌘
(e.g.
the speed of sublimation in comparison to drift.
soser to the
2⇡µm
⇢
p
u
d
> ⌘, and so dust moves more slowly than gas acrossthes of several⇢⇢
T
Takeuchi
Artymowicz
2001).
Ingas
our
k
T
ds
so dust on a&circularorbit
is slower
than
if parameter> ⌘ (e.g. spaceeqgas
gas /TdBdsregionofinterest.
p3.2.2 Criteria for dust trapping and growth
.
(
=
5
4
This
is
equivalent
toEquation
17
ofLebreton
etal.
3.2
Results
inthepresenceofgas
imetres for⇢⇢
T/T
Takeuchi&
Artymowicz
2001).
In
ourparameter
space
eq
gas
gas
d
⌘ ⇠ 10
to 10 The, withthe smaller
valuescloserB Tddrag formalism
depends
on grainsize toandtheGas v.
has Iftwo dsmain e↵ects on dust:kdragand growth.
dt
2⇡µm
⇢d
u
.
(33)
=
(2013),
notingthat
donotrequire
gas
and
dust
to
5
4we
this paper,
Growth is simple; if gas is dense enough, sufficient
4 withhas
⌘
⇠
10
to
10
,
the
smallervaluesclosertothedtonto the2⇡µm⇢dgas model, we now describe the
the
grain
radius
s
⌧
,
where
is
the
gas
mean-freeu through
star.
A
of
10
corresponds
to
a
grain
radiusofseveralmaterial accretes
grain to o↵setthat lost
Havingimplemented
thehave the same temperature.
way. Hence4
star. A of 10path,corresponds
to ina grainradius ofseveral
then
drag
is
the
Epstein
regime.
The meanevolutionof dust grains
the presenceis equivalent
to inEquation
17ofofgas.Lebreton etmillimetres around a G2 star or several centimetres
forfree Thise important
This is equivalent to Equation 17 of Lebreton et al.
millimetres arounda G2 star or several centimetres forpathiss across the(2013),
noting
that
we
do
not
require
gas
and
dust
an
A0
star;
for
gas
quantities
consideredin
thispaper,(2013),
noting
that
we
do
not
require
gas
and
dust
to
an A0 star; for gas quantities considered in this paper,
have
the
same
temperature.
such
large
grainsarenotcoupledgas
anyway.
Hence
3.2
Resultsin thearepresenceofgasto gasto
have
the
same
temperature.
such
large
grainsnotcoupledanyway.
Henceand v. Ifµmu
p bemay= may, be important(28)3.2.1Generalgrain
evolution
inthepresence
of
gas
in
the
parameter
space
where
gas
drag
importantintheparameter
space
where
gas
drag
s mean-free
Having implemented the gas model, we now describe
2 ⇢gasthe
> ⌘,
soso
dust
moves
slowlythanacrosse mean free>⌘, and
and
dust
moves
more
slowlythan
gastheacross theevolutionof dustgrainsinthemorepresenceofgas. gas
Gas can trap grains larger than the blowout size exterior
where is the collisional cross-section of the gas. Evenregionofinterest.
region of interest.
toin
thethesublimation
region,protecting them from further
3.2
Resultspresence
of
gas
16
2
cm
s = 1 cm,
substitutingµ size= 12.01
The dragfor
formalism
depends
on grainand andv. If ⇠ 10
3.2
Results
insothepresenceofgas from thesublimation
andpreventing
theirejection
The drag formalism depends on grain size and v. If      



















s

in

acc

gas

s

18

3

滞留ダストのサイズはガス密度だけで決まり，最初のダストサイズによらない! 1r
For gasp
R⇤23⌫) (e.g. より現実的な場合，ダストの寿命など色々面白い話はあったが飛ばすṀacc = 3 2⇡ ↵⇢gas (rs )cs (rs )H (rs ) 1
.
rs
(47)
This equates to 9 ⇥ 10 12 M yr 1 ↵[⇢gas (rs )/10 16 g cm 3 ](45)
for dust trapped around a G2 star, and6 ⇥ 10 10 M yr 1 ↵[⇢gas (rs )/10 16 g cm 3 ] for thataround an A0 star.
mescaleCombining all three mass loss processes, sustainingar anda gas trap requires a mass input rate of
erefored dust⇢
er than⇢gas (rs )111Ṁ = 2 ⇥ 10
M yr ↵ 1 + 0.5
ars. As
10 16 g cm 3
mation(48)
r, thenfor 10 11 M of 1 µm grains trapped around a G2 star,in thisandviscous⇢⇢gas (rs )101Ṁ = 1 ⇥ 10
M yr ↵ 1 + 6
10 16 g cm 3
(49)
for 10 9 M of 10 µm grains trapped around an A0
ntain astar. These mass inflows are small, equivalent to aout the⇠ 1 km radius comet fully sublimating per year if ↵ ⇠ 1.
comets,However, unless ↵ is small they still exceed the dust
xteriormass inflow into the inner Solar System, estimated ass. The5 ⇥ 10 14 M yr 1 (Grün et al. 1985). These low massby twoinflows imply that the mechanism may be common acrossre lost,a diverse range of stellar systems, but is not necessarilyubiquitous unless ↵ is small.
s likely
It should also be noted that gas trapping is

ガストラップが有効となるのに必要なMass flow

そんなにべらぼうに大きくない

Hot dust trapped in gas around main-sequence stars

14

813
028
092

−42.21249223335−42.20670598232−42.20732210284

#37

791
804
709

667
624
605

970
1124
855

T.Yu. Magakian1 , T.A. Movsessian1 , H.R. Andreasyan1 , J.Bally2 and A.S. Rastorguev3,4
Byurakan Observatory of the Nat.Acad.Sci. of Armenia, Byurakan, Aragatsotn prov., 0213, Armenia; 2 Departmentof Astrophysical and Planetary Sciences, University of Colorado, Boulder, CO,USA; 3 Faculty of Physics, Lomonosov
Moscow State University, Leninskie Gory 1, bldg.2, Moscow, Russia; 4 Sternberg Astronomical Institute, Lomonosov
Moscow State University, Universitetskii prospect, 13, Moscow, Russia
1aparDR2.
blue,
d are

http://arxiv.org/pdf/2008.13411

Herbig-Haro flows around BBWo 192E (GM 1-23) nebula

SL 4 dark cloudo 192Co 192D, GN 08.51.1.01
o 192B, GN 08.50.5

Accepted by MNRAS

Most probable

Distance, pc
Min

Max

865
968
1028
958
962

839
768
1004
876
880

893
1301
1053
1055
1060

HH天体のケーススタディ

E-mail contact: tigmag at sci.am
We studied a small comet-shape reflection nebula, located in the dark cloud SL 4 in the Vela Molecular Ridge cloud C,
known as BBWo 192E (GM 1-23), and a young infrared cluster embedded into the nebula, for the evidences of recent
star formation. We obtained the images of BBWo 192E in Hα and [SII] lines and in SDSS i’ with Blanco telescopeat the Cerro Tololo Interamerican Observatory to discover new Herbig-Haro (HH) flows. 2MASS and WISE surveys
were used for the search of the additional member stars of the cluster. We also studied proper motions and parallaxesof the cluster members with the aid of GAIA DR2. Five new groups containing at least 9 HH objects tracing several
distinct outflows were revealed. A previously unreported reflection nebula and a number of probable outflow sourceswere found in the infrared range. The proper motions allowed selecting eight probable member stars in the visualrange. Their parallaxes correspond to a mean distance 800 ± 100 pc for this cluster. The bolometric luminosities ofthe brightest cluster members are 1010 L! (IRAS 08513−4201, the strong source in the center of the cluster) and 2 to
6 L! for the five other stars. The existence of the optical HH flows around the infrared cluster of YSOs suggests thatstar formation in this cloud is on-going around the more massive HAeBe star. By its morphology and other features
this star-forming region is similar to the zone of star formation near CPM 19.
Accepted by MNRAS
http://arxiv.org/pdf/2009.00642

Accretion discs with non-zero central torque
Chris Nixon1 and Jim Pringle1,2
School of Physics and Astronomy, University of Leicester, Leicester, LE1 7RH, UK; 2 Institute of Astronomy,
Madingley Road, Cambridge, CB3 0HA, UK

1E-mail contact: cjn at leicester.ac.uk
We present analytical and numerical solutions for accretion discs subject to a non-zero central torque. We express
this in terms of a single parameter, f , which is the ratio of outward viscous flux of angular momentum from the innerboundary to the inward advected flux of angular momentum there. The standard “accretion” disc, where the central
boundary condition is zero-torque, is represented by f = 0. A “decretion” disc, where the radial velocity at the inner
37

#38

the brightest cluster members are 1010 L! (IRAS 08513−4201, the strong source in the center of the cluster) and 2 to
6 L! for the five other stars. The existence of the optical HH flows around the infrared cluster of YSOs suggests thatstar formation in this cloud is on-going around the more massive HAeBe star. By its morphology and other features
this star-forming region is similar to the zone of star formation near CPM 19.
Accepted by MNRAS
http://arxiv.org/pdf/2009.00642

Accretion discs with non-zero central torque
Chris Nixon1 and Jim Pringle1,2
1

School of Physics and Astronomy, University of Leicester, Leicester, LE1 7RH, UK; 2

標準降着円盤モデルを
中心境界のトルクが０でない時の解析解の導出と現実へのアプリケーションに関する議論

is around a rotating magnetic star which can allow the disc or#39
大橋さん，一言解説をお願いします。

#41

若い星団のメンバーをGaia DR2で同定して力学状態や将来の進化を議論

#42

Magnetic torques on T Tauri stars: accreting vs. non-accreting systems
G. Pantolmos1 , C. Zanni2 and J. Bouvier1
Univ. Grenoble Alpes, CNRS, IPAG, 38000 Grenoble, France; 2 INAF - Osservatorio Astrofisico di Torino, Strada
Osservatorio 20, 10025 Pino Torinese, Italy
1E-mail contact: george.pantolmos at univ-grenoble-alpes.fr
Classical T Tauri stars (CTTs) magnetically interact with their surrounding
disks,
processno.thatis thought toA&A
proofs: amanuscript
Pantolmos_Zanni_Bouvier_v2_arxiv
regulate their rotational evolution. In this work, we compute torques acting onto the stellar surface of CTTs arising
Table 1.(stellar
Varied input
parameters
global properties ofejections)the simulations.
from different accreting (accretion funnels) and ejecting
winds
and andmagnetosphericflow components.
Furthermore, we compare the magnetic braking due to stellar winds in two different systems: isolated and accreting
Case B⇤ /B0⌥⌥open hrA i/R⇤ Ṁacc / Ṁ0 ⌥acc Rt /R⇤ ⌧ sw /⌧acc ⌧me /⌧acc
open / ⇤stars. 2.5D magnetohydrodynamic, time-dependent, axisymmetricsimulationsareemployed.
both systemsa1
0.81255030
0.296
441 For 7.98... the ...
...
...
...
a
stellar wind is thermally driven. In the star-disk-interaction 2(SDI)
simulations
disk
viscous,1.625
25800the accretion
0.230
1360 is Keplerian,
12.0
...
...
...
...
...
a
3.25
1300000.1723860 T Tauri
17.6 systems... the ...
...
...
...
and resistive. Two series of simulations are presented, one for3each
system.
We find thatin classicala4 expansion,
6.5
63500010900
25.6 geometry
...
...
...
...
presence of magnetospheric ejections confines the stellar-wind
resultingin0.131
an hourglass-shaped
of...
a
5
13
2960000
0.0951
26700
33.9
...
...
...
...
...
the outflow. In addition, the formation of the accretion columns
modifies
the amountof openmagnetic
1b
1.625
45000
0.381
6550
23.4 flux exploited
0.489
3.82 1.82-0.3550.486
bby the stellar wind. These effects have a strong impact on the2 stellar
wind 139000
properties0.267
and we show
the stellar-wind
3.25
9890 that
28.1
0.628
11.9 2.64-0.4160.219
6.5the isolated
667000 ones.
0.164We also
18000
37.0
-0.3590.111
braking is more efficient in the star-disk-interacting systems3bthan inderivetorque0.861
scalings,34.7 4.04b9.75 in2220000
0.114 that28900
44.9
1.20
55.9 4.68-0.221-0.0237
over a wide range of magnetic field strengths, for each flow 4componentaSDIsystemdirectly
appliesatorque5b
135420000
52.5
1.61
74.4 4.92-0.173-0.0853
on the stellar surface. In all the performed SDI simulations the stellar
windextracts0.0873
less than41300
2% of themass accretion
rate and the disk is truncated up to 66% of the corotation
radius. All thesimulations
show
a net spin-up
torque.
In In our simulations, a negative (positive) torqueNotes. (a) Isolated-stellar-wind(ISW)
simulations. (b)Star-disk-interaction(SDI)
simulations.
towards(awayorfrom)the star(see also§3.1.1). Consequently,
order to achieve a stellar-spin equilibrium we needindicateseitherangularmoremomentum
massiveflowing
stellar
winds
disks
being
truncatedcloser ⌧sw > 0, ⌧acc < 0, and ⌧me 7 0 (for the sign of⌧me in each SDI case see also Fig. 10).
to the corotation radius, which increases the torque efficiency by the magnetospheric ejections.
Accepted by A&A
http://arxiv.org/pdf/2009.00940

Gas trapping of hot dust around main-sequence stars

円盤・Tタウリ星系のTim D. Pearce1 , Alexander V. Krivov1 and Mark Booth1

Astrophysikalisches Institut und Universitätssternwarte, Friedrich-Schiller-Universität Jena, Schillergäßchen 2-3, D07745 Jena, Germany1

磁場構造モデルから，E-mail contact: timothy.pearce at uni-jena.de
磁気制動の効果や自転進In 2006 Vega was discovered to display excess near-infrared emission. Surveys now detect this phenomenon for one fifth
化を議論
of main-sequence stars, across various spectral types and ages. The excesses are interpreted as populations of small,

hot dust grains very close to their stars, which must originate from comets or asteroids. However, the presence of suchgrains in copious amounts is mysterious, since theyrapidlysublimateor be blown
outtheoftemporalthe system.
Fig. should
1. Logarithmic
normalized
density (colormaps)
showing
evolution ofHere
a star-disk-intercation simulation. The snapshots wereafter 5, dust
10, 20, migratingand 30 stellar inwards
rotation periods,P⇤ . The
far-left panel
illustrates
the inner domain of this simulation, with the vertical white
we investigate a potential mechanism to generate taken
excesses:
underradiation
forcessublimateslines indicating the location of the truncation radius Rt (dashed black core) and corotation radius Rco (solid black core). Each plot includes magnetic
near the star, releasing modest quantities of gas whichthen traps subsequent grains. This mechanism requires neither
field lines (white lines) and velocity-field vectors. The cyan lines delimit the stellar-wind flux tube and the red lines mark the Alfvén surface.

#44
赤外線と電波の観測を組み合わせ，
メタノールのガスと氷，水氷の分布をCO分布と合わせて議論
A&A proofs: manuscript no. aanda

G. Perotti et al.: Linking ice and gas in the Serpens low-mass star-forming region

Fig. 3. L-band optical depth towards the SVS 4 sources (black). The
lines
representlaboratory
ice data
employedin thethe lines represent the CO:CH3 OH 1:1 laboratory spectrum (orange),
Fig.coloured
2. M-band
opticaldepththetowards
the SVS
4 sources(black).
Thefitting:coloured
pure H2 O (dark blue), the H2 O:CH3 OH 38% (light blue), the CO:CH
and thereproducing
total fit (magenta).
black
the CDE-corrected
Lorentzian
the pureThe
CO dashed(cyan) andthelines
totalarefit (magenta). The dashed black lines are used as a reference for ⌧=0.
3 OH 1:1 (orange),
2 starting from SVS 4 2 to SVS 4 12
used as a reference for ⌧ = 0. The cyan boxes illustrate the selectedThefitting
ranges.ofTheof thefrom
fit SVS
goodnessthegoodness
fit 2⌫ starting
4 2 to SVS 4 12 is 0.95, 0.22, 0.79, 0.32, 0.83, 0.74, 0.30, 0.25, 0.87, and 0.64.
⌫
is 0.59, 7.47, 0.55, 9.15, 0.79, 4.14, 0.72, 0.43, 0.25, and 22.5.

The spectral fitting procedure developed by Suutarinen though the O-H stretching contribution of CH3 OH necessarily
because the blue component does not constrain the methanol(2015a)
ice towards
the cluster(DevlinZamirri toet theal. 2018).
and adopted
in thissources
study stands
as 1992;an alternative
replaces some of the absorption of H2 O. The aim of this fitting
abundance, but rather that of CO2 ice (Boogert et al. 2015). commonly
The Althoughtheredcomponent
canbeassociated
with
CO:H
2O
used method to detect molecules in interstellar ices
procedure
is to determine the maximum amount of CH3 OH ice
central peak (i.e. middle component) is associated with the C-O
iceal.
(Thiet al.
2006),ettheOH
mixturetoisthethelatter,most likely(Grim et1991;
Brookeal.CO:CH
1999). 3In
contrastthat is hidden below the red wing of interstellar ices, and thus tovibrational mode of pure CO ice. It was fitted using a continuous
carrier ofofthis
feature(Cuppen ettoal.
and ofit isto explain the high CH3 OH abundances that are observed inwhich consists
fittinga polynomial
the2011),
red wing
theassumed
O- help
distribution of ellipsoids (CDE) corrected Lorentzian function
trace warmer
regions
than pureThe opticalgoodnessof thefit thewasgas-phase.
H stretchingmode andanalysingthe 2CO.
residualdepth
at, that is givenby 2⌫ at= 2 /⌫,in order to take into account irregularities in the grain shape 3.53
and µmaddressed
the thereducedfitting ⌫procedure
we adopted
to detectusing
CH3 OH,
Figure 2 shows the optical depth of the sources listed in Ta⌫ is the di↵erence
betweenthe number toof thedata3 points
match the central peak of the observations (Pontoppidan ettempts
al. where
to simultaneously
fit multiple
ice componentsµm andble 1 decomposed by analytical and experimental components
thenumberoffreeparameters
in
the
fit.
2003b).
region to find the maximum amount of CH3 OH that is hidden
using the OMNIFIT fitting utility (Suutarinen 2015b). As outbelow the The
red wing.
This approach
it possible
to condecompositionof makes
the L-bandfeatures,between
The red component, on the other hand, was fitted with

Linking ice and gas in the Serpens low-mass star-forming region
G. Perotti1 , W. R. M. Rocha1 , J. K. Jørgensen1 , L.E. Kristensen1 , H. J. Fraser2 and K. M. Pontoppidan3
Niels Bohr Institute & Centre for Star and Planet Formation, University of Copenhagen, Øster Voldgade 5−7, 1350
Copenhagen K., Denmark; 2 School of Physical Sciences, The Open University, Walton Hall, Milton Keynes, MK7
6AA, United Kingdom; 3 Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
1E-mail contact: giulia.perotti at nbi.ku.dk
The interaction between dust, ice, and gas during the formation of stars produces complex organic molecules. Whileobservations indicate that several species are formed on ice-covered dust grains and are released into the gas phase,the exact chemical interplay between solid and gas phases and their relative importance remain unclear. Our goal is to
study the interplay between dust, ice, and gas in regions of low-mass star formation through ice- and gas-mapping andby directly measuring gas-to-ice ratios. This provides constraints on the routes that lead to the chemical complexitythat is observed in solid and gas phases. We present observations of gas-phase methanol (CH3 OH) and carbon
monoxide (13 CO and C18 O) at 1.3 mm towards ten low-mass young protostars in the Serpens SVS 4 cluster from the
SubMillimeter Array (SMA) and the Atacama Pathfinder EXperiment (APEX) telescope. We used archival data fromthe Very Large Telescope (VLT) to derive abundances of ice H2 O, CO, and CH3 OH towards the same region. Finally,
we constructed gas-ice maps of SVS 4 and directly measured CO and CH3 OH gas-to-ice ratios. The SVS 4 cluster ischaracterised by a global temperature of 15 ± 5 K. At this temperature, the chemical behaviours of CH3 OH and CO
are anti-correlated: larger variations are observed for CH3 OH gas than for CH3 OH ice, whereas the opposite is seen
for CO. The gas-to-ice ratios (Ngas /Nice ) range from 1 − 6 for CO and 1.4 × 10−4 − 3.7 × 10−3 for CH3 OH. The CO
gas-maps trace an extended gaseous component that is not sensitive to the effect of freeze-out. Because of temperature
variations and dust heating around 20 K, the frozen CO is efficiently desorbed. The CH3 OH gas-maps, in contrast,
probe regions where methanol is predominantly formed and present in ices and is released into the gas phase throughnon-thermal desorption mechanisms. Combining gas- and ice-mapping techniques, we measure gas-to-ice ratios of
CO and CH3 OH in the SVS 4 cluster. The CH3 OH gas-to-ice ratio agrees with values that were previously reported
for embedded Class 0/I low-mass protostars. We find that there is no straightforward correlation between CO andCH3 OH gas with their ice counterparts in the cluster. This is likely related to the complex morphology of SVS 4: theClass 0 protostar SMM 4 and its envelope lie in the vicinity, and the outflow associated with SMM 4 intersects thecluster. This study serves as a pathfinder for future observations with ALMA and the James Webb Space Telescope(JWST) that will provide high-sensitivity gas-ice maps of molecules more complex than methanol. Such comparative
maps will be essential to constrain the chemical routes that regulate the chemical complexity in star-forming regions.
Accepted by Astronomy and Astrophysics
https://arxiv.org/pdf/2008.02827

ALMA chemical survey of disk-outflow sources in Taurus (ALMA-DOT) II: Verticalstratification of CO, CS, CN, H2 CO, and CH3 OH in a Class I disk
L. Podio1 , A. Garufi1 , C. Codella1,2, D. Fedele1 , E. Bianchi2 , F. Bacciotti1 , C. Ceccarelli2 , C. Favre2 ,S. Mercimek1,4 , K. Rygl3 and L. Testi5,6,1