7. ALMA’s view of the M-dwarf GSC 07396-00759’s edge-on debris disc: AU Mic’s coeval twin
Patrick F. Cronin-Coltsmann, Grant M. Kennedy, Christian Adam, Quentin Kral, Jean-François Lestrade, Sebastian Marino, Luca Matrà,
Simon J. Murphy, Johan Olofsson, Mark C. Wyatt
8. Scattering and sublimation: a multi-scale view of μm-sized dust in the inclined disc of HD 145718
Claire L. Davies, Evan A. Rich, Tim J. Harries, John D. Monnier, Anna S. E. Laws, Sean M. Andrews, Jaehan Bae, David J. Wilner,
Narsireddy Anugu, Jacob Ennis, Tyler Gardner, Stefan Kraus, Aaron Labdon, Jean- Baptiste le Bouquin, Cyprien Lanthermann, Gail H.
Schaefer, Benjamin R. Setterholm, Theo ten Brummelaar
9. Do the majority of stars form as gravitationally unbound?
František Dinnbier, Pavel Kroupa, Richard I. Anderson
10. Successive deuteration in low-mass star-forming regions: the case of D2-methanol (CHD2OH) in IRAS 16293-2422
Maria N. Drozdovskaya, Laurent H. Coudert, Laurent Margulès, Audrey Coutens, Jes K. Jørgensen, Sébastien Manigand
11. The impact of cosmic-ray attenuation on the carbon cycle emission in molecular clouds
Brandt A. L. Gaches, Thomas G. Bisbas, Shmuel Bialy
12. Importance of source structure on complex organics emission. I. Observations of CH3OH from low-mass to high-mass protostars
M. L. van Gelder, P. Nazari, B. Tabone, A. Ahmadi, E. F. van Dishoeck, M. T. Beltrán, G. A. Fuller, N. Sakai,
Á. Sánchez-Monge, P. Schilke, Y. -L. Yang, Y. Zhang ⋆ALMA’s view of the M-dwarf GSC 07396-00759’s edge-on debris disc: AU Mic’s coeval twin
Patrick F. Cronin-Coltsmann,1,2★ Grant M. Kennedy,1,2 Christian Adam,3 Quentin Kral,4 Jean-François Lestrade,52 ALMA OBSERVATIONS
GSC 07396-00759 was observed with ALMA in Band 7 (0.87 mm,

3

+3”

0.5

+2”

0.4

+1”

0.3

0”

0.2

-1”

0.1

-2”

0.0

-3”
+3”

+2”

+1”

0”
-1”
RA Offset

-2”

-3”

Flux Density (mJy/beam)

produced, thus tracing more directly the location of the planetesimalbirth ring. Resolved sub-mm observations such as those presented
in this paper serve a key role in breaking the degeneracy between 6
and A 0 and solving the discrepancy between the total intensity andpolarimetric scattered light model radii.
GSC 07396-00759 is itself a wide separation companion of the・デブリ円盤GSC 07396-00759のアルマ観測の報告論文
well-studied close-binary V4046 Sgr at a distance of 12300 au (Torres
・ALMA Band 7
et al. 2006; Kastner et al. 2011). V4046 Sgr possesses both a gas-rich
circumbinary disc and evidence of ongoing accretion (e.g. Stempels
・β Picにある天体& Gahm 2004; Öberg et al. 2011; Rosenfeld et al. 2013; Rapson
・M-dwarf の円盤
et al. 2015; Kastner et al. 2018; D’Orazi et al. 2019; MartinezBrunner et al. 2022). The au幅のトーラ
survival of the more primordial-like disc・mmダストは、70 auにおいてFWHM48
of V4046 Sgr may be attributed to its binary nature, as Alexander
スでよく記述できた(2012) find close binaries to possess longer lived discs than single
stars. Nevertheless, the association of the two systems draws into
・COは検出できなかった。
question the nature of the disc around GSC 07396-00759 which the
new ALMA observations presented herein can shed further light on.
This paper presents the new Band 7 ALMA observations of
GSC 07396-00759 in §2, followed by a description of the modelling
process and modelling results in §3 and §4. In §5 we present ouranalysis with respect to the previous scattered light observations andwe place the disc in the context of both the growing M-dwarf disc
population and the wider debris disc population across spectral types.

Dec Offset

7
Sebastian Marino,6,7 Luca Matrà,8,9 Simon J. Murphy,10 Johan Olofsson,11,12
Mark
C.
Wyatt
The edge-on debris disc of GSC 07396-00759

0.1

Figure 1. Naturally-weighted
image of the disc around GSC 0739600759. The ellipse in the lower left corner shows the beam size of
0.68⇥0.5500 . The star is not detected. At a distance of 71.4 pc the apparent disc radius is ⇠70 au. Contours are drawn at ±2f, 4f, 6f, 8f, 10f
with 1f = 40`Jy beam 1 . The Gaia location of the star is marked with a + at
273 35’31.2"±0.26 mas 32 46’11.09"±0.20 mas. Zero offset is the ALMA
image phase centre at 273 35’31.3" 32 46’10.9" (J2000).
00

introArticleA planet within the debris disk around thepre-main-sequence star AU Microscopii• デブリ円盤• 10Myrs 超の年齢

Received: 16 February 2019

• ガスが晴れ、ダストは二次ダストと期待されている Accepted: 17 March 2020
Published online: xx xx xxxx
Check for updates• が、近年のアルマ観測から、ガスの検出等あり。コレらはダスト破壊に寄る二次ガスト期待される。

• 中心星に対して近赤外が1%以下の明るさ• Herschel DEBRIS survey ̶ FGK型星では17%で円盤が見つかるのに、M型星では2/89 しかみつからなかった。

• 感度上げたHerschelのサーベイでは3/18見つかった• なんでレアなのか？暗いのか？あるいは惑星形成の効率が低いのか？
• stellar encounter, photoevaporation, stellar wind によるダスト剥ぎ取りなども考えられている。

• M型星のデブリ円盤の代表格はAU Micだった。
• 9.72pc, Ldisc/Lstar=4e-4,Peter Plavchan1ಞᅒ, Thomas Barclay2,13, Jonathan Gagné3, Peter Gao4, Bryson Cale1,
William Matzko1, Diana Dragomir5,6, Sam Quinn7, Dax Feliz8, Keivan Stassun8,
Ian J. M. Crossfield5,9, David A. Berardo5, David W. Latham7, Ben Tieu1, Guillem Anglada-Escudé10,
George Ricker5, Roland Vanderspek5, Sara Seager5, Joshua N. Winn11, Jon M. Jenkins12,
Stephen Rinehart13, Akshata Krishnamurthy5, Scott Dynes5, John Doty13, Fred Adams14,
Dennis A. Afanasev13, Chas Beichman15,16, Mike Bottom17, Brendan P. Bowler18,
Carolyn Brinkworth19, Carolyn J. Brown20, Andrew Cancino21, David R. Ciardi16,
Mark Clampin13, Jake T. Clark20, Karen Collins7, Cassy Davison22, Daniel Foreman-Mackey23,
Elise Furlan15, Eric J. Gaidos24, Claire Geneser25, Frank Giddens21, Emily Gilbert26, Ryan Hall22,
Coel Hellier27, Todd Henry28, Jonathan Horner20, Andrew W. Howard29, Chelsea Huang5,
Fig.
1.—
ALMAR.image
the 1.3Kenworthy
mm continuum
emission
21
31
32 from AU Mic.
, Stephen
Kane30of, Matthew, John Kielkopf, David Kipping33, The ellipse in theJoseph
Huber
21
13
1
15
cornerrepresents
0.!! 80
× 0.!! 69(8 × 7 34AU)
synthesizedbeam.
, EthanKruse, Natashathe
Latouf, PatrickLowrance, Bertrand
Mennesson,
Chrislower
Klenkeleft
20
29
35
36,37,38,39,40, Elisabeth Newton41,
Matthew Mengel , Sean M. Mills , Tim Morton , Norio Narita
America Nishimoto21, Jack Okumura20, Enric Palle40, Joshua Pepper42, Elisa V. Quintana13,
we attributeto systematic
calibration
issuesresultingfrom thepoorerweather conditions of
13
43,44,45
13
25,
Veronica
Roccatagliata,
JoshuaE.
Schlieder,
AngelleTanner,Aki
Roberge
Article the earlier
48
49 aspect ratio >10:1,
observations.
The emission
is 18confinedto Brauna narrow
bandWalp
with
G. Tinney47, Andrew
Vanderburg, Kaspar von, Bernie,
Johanna Teske46, C.
4,29
46
21
22
Sharon Xuesong
Wang , Denise
Weigand, RusselWhite, The emission is not resolved
Jasonwith
Wangan ,orientationconsistent
with thescattered
light
disk.
20
20
13
Robert A. Wittenmyer , Duncan J. Wright , Allison Youngblood , Hui Zhang50 &in the direction perpendicular to the elongation. There are clear peaks near both extrema
Perri Zilberman51

https://doi.org/10.1038/s41586-020-2400-z

MacGreger et al. 2012

A planet within the debris disk around theand in the middle of the structurestar(detected
at allMicroscopii
four epochs). The emission is marginallypre-main-sequenceAUbrighter at the northwest end than the southeast end, and shows small undulations along its

AU Microscopii(AU Mic)
is thesecondclosest pre-main-sequencestar,
at a distancelength, though
noneof thesevariations
are significant. We
interpretthe ofobserved structure
12
9.79 parsecs
and with an age
of 22
million years(1). AUtheMicnearly
possesses
a relatively
rarewith
as a superpositionof twocomponents:
edge-ondust belt
limb-brightened
1
2,13
3
4
ಞᅒ, Thomas Barclay , Jonathan Gagné , Peter Gao , Bryson Cale1,
3
https://doi.org/10.1038/s41586-020-2400-z
Peter
Plavchanand spatiallyresolved
edge-ondebrisdisk
extending
from
about
35 toat210
ansae, and (2) a new, distinct,
andcompact
featurelocatedthecenter of the belt.
1
5,6
7
8
,
Diana
Dragomir
,
Sam
Quinn
,
Dax
Feliz
, Keivan Stassun8,
William
Matzko4
Received: 16
February 2019 units from the star , and with 5,9astronomical
non-Keplerian, David A.exhibiting
Berardo5, David
W. Latham7, Ben Tieu1, Guillem Anglada-Escudé10,
Ian J. M. Crossfieldclumps
5–7
5
5
5
11
Accepted: motion
17 March 2020
, RolandVanderspek, SaraSeager, Joshua N. Winn
, Jon M. Jenkins12,
Ricker. Detection of newlyGeorge
formedplanetsaroundsuch
a staris challenged
by theStephen Rinehart13, Akshata Krishnamurthy5, Scott Dynes5, John Doty13, Fred Adams14,
Published online:
xx xxofxxxx
presence
spots, plage, flaresand other manifestationsof15,16magnetic‘activity’ on the13, Chas BeichmanFormalism, Mike Bottom17, Brendan P. Bowler18,
Dennis A. Afanasev
3.2.
Modeling
8,9
19
21
star
. Here we report observationsof a planet
transiting
AU20Mic.
TheCancinotransiting
Check forupdates, Carolyn
J. Brown, Andrew, David R. Ciardi16,
Carolyn Brinkworth
Mark Clampin13, Jake T. Clark20, Karen Collins7, Cassy Davison22, Daniel Foreman-Mackey23,
planet, AUBuilding
Mic b, has
anorbitalperiod of 8.46 days,
an orbital distanceofet al.21 (2011, 2012)24
22
on the phenomenologicalmethodology
of 25Wilner
to Hallanalyze, Claire Geneser, Frank Giddens, Emily Gilbert26, Ryan,
Elise Furlan15, Eric J. Gaidos
27
28
20
29
5
0.07 resolved
astronomical
units, aemission
radiusof 0.4
Jupiterradii,
andwea massof ,less, ToddHenry, Jonathan
HornerAndrew
W. 0.18
Howard , Chelsea
Huang,
Coel Hellier
millimeterfromdebrisdisks,
constructathan
parametricmodel
to quantify
21
30
31
32
, Stephen R. of
Kane, Matthew
Kenworthy with, JohnaKielkopf, David Kipping33,
JosephHuber
Jupitermassesat
3σconfidence.
Our
observationsaplanetco-existingdebris13
the observed properties
ofKlenkethe 21AUMic
emission.
We1, consider
two34modela, EthanKruse, Natasha Latouf
Patrick Lowrance, Bertrandcomponents:
Mennesson15,
Chris
20
29
36,37,38,39,40
41
disk offer
the opportunity
to testthe“outer”
predictions
ofandcurrent
modelsplanet, Sean
M.
Mills
, Tim
Morton35,of
Norio
Naritato, Elisabeth
Newton,Matthew
Mengelverticallythin, axisymmetricbelt,
anadditionalsourceaccountforthecentral
21
20
40
42
13
America Nishimoto , Jack Okumura , Enric Palle , Joshua Pepper , Elisa V. Quintana ,formation and evolution.
13
43,44,45
13
25, Joshua E. Schlieder , Angelle Tanner ,Aki Roberge , Veronica Roccatagliata
46
47
Johanna Teske , C. G. Tinney , Andrew Vanderburg18, Kaspar von Braun48, Bernie Walp49,
4,29

Plavchan et al. 2020

46

21

22

GSC07396-00759
A&A 613, L6 (2018)• M1V, 71.4pc• total intensity (Sissa et al. 2018)とpolarimetry (Adam et al. 2021)
で円盤うかってる• S18: 96auまで広がった、傾斜角
84.5度の円盤。非対称あり。1.5-2倍.

70auにピークあり• A21: ピーク107auだけど大体S18と同じ結果

Fig. 1. New disk detected around GSC 07396 00759. IRDIS 5 modes PCA of H2H3 images rescaled to stellar flux before (top) and after (bottom)
the subtraction of the most contaminant stars, identified with star-like points in the upper figure. The gray-shaded region in the center corresponds
to the SPHERE coronagraph. The dash-dotted line is parallel to the disk semi-major axis and crosses GSC 07396 00759. The bright backgroundobjects are masked behind star-shaped regions in the upper image.
A&A 653, A88 (2021)

Table 1. Overview of observational SPHERE data sets for
GSC 07396 00759.

Parameter
Date
Filters
Total integration time [s]Total rotation of the field of view [ ]⌧0 [ms]SR

Value
2017 Jun. 15
YJ H2H3
6016
112.8220
0.73(between 0.95 and 1.35 µm, 1.700 ⇥ 1.700 field of view; FoV) and
IRDIS (Dohlen et al. 2008) in dual-band imaging H2H3 mode
(at 1.59 and 1.67 µm Vigan et al. 2010, 1100 ⇥1100 FoV) simultaneously (see Tab. 1). The data were reduced with version 0.15.0
of the SPHERE Data Reduction and Handling (DRH) pipeline(Pavlov et al. 2008), and the images were further processed using
the SpeCal software (Galicher et al., in prep.). Both packages are
hosted at the SPHERE Data Center (DC) in Grenoble2 (Delorme
et al. 2017). Additional details on the adopted procedures are provided in Zurlo et al. (2014), Mesa et al. (2015), and Maire et al.
(2016).
2.1. Point source detection and planetary upper limits(Bonfils et al. 2013; Dressing & Charbonneau 2015). The presence of planetary systems around both GJ 581 and Proxima The IFS YJ wavelength-collapsed image gives00 a 5 contrast limit), which drops to(Mayor et al. 2009; Anglada-Escudé et al. 2016) is very promis- <11 mag in the innermost regions (<0.25
00⇠12 mag for separations wider than ⇠0.3 . The IRDIS images
ing in this perspective.
For these reasons, the detection of spatially resolved disks lead 00to a contrast limit of less than 12 mag at a separation of⇠0.6 and ⇠13.5
around low-massstars polarimetric
is of highimaging
interest.
We present
Fig. 1. M-type
SPHERE/IRDIS
observationsof GSC 07396-00759. Shown from left to right are the total intensity Itot (log stretch)and theGSC
Q and
U images(bothlikely
in lineardebris
stretch).disk
The with
Q andtheU images were convolved with a Gaussian point spread function ( = 2 pixel) to
the newly imaged
07396
00759
increase the(Spectro-Polarimetricvisibility in this plot. The coronagraphic
mask isindicated by the green circular region in each panel. North is to the top and east to
instrument SPHERE
High-contrast
Exothe left in each panel. It should be noted that the disk is not visible in the total intensity image (left panel). The structure appearing to extend fromplanet REsearch;
GSC artifact.
07396 00759 is
the NWBeuzit
to the SE et
is a al.
point2008).
spread function
a very active but not accreting M1-type star associated with
V4046 Sgr (Torres et al. 2006; Kastner et al. 2011), which islocationthe color-magnitude
diagram (CMD).
For theitself a close theirbinarywith inaccretion
signature (Stempels& Gahmseven remaining objects the results could not be determined2004) and a gas-rich
circumbinary disk (Rosenfeld et al. 2013).
unambiguously; however, all but one have separations above 500
The two systems
probably
the objects
Pictoris(aproj. are> 400AU), andmembers
the colors ofof thoseare Movsimilar to4

P. F. Cronin-Coltsmann et al.
Separation (au)250 200 150 100 50 0

50 100 150 200 250

Flux (mJy/beam)

SE Side
0.4

0.2

0.0

4

• 0.87 mm観測、• NWとSEで若干の非対称。

NW Side

3

2

1

0

1

Separation (arcsec)

2

3

4

Figure 2. Profile of the disc along its major-axis; the flux of the centre pixel
along the disc major-axis is plotted in green, blue swathes show the RMS anda Gaussian with the same FWHM as the beam is plotted in orange at the peakradial flux. Zero separation is the best fitting model centre from §3.

of the parameter chains is 270 steps. We use 100 walkers and verify
that all the chains have converged upon completion.
We first implement a simple Gaussian torus model, with parameters defined by the following equation for a model dust volume
density distribution =(A, I):=(A, I) / 4

1
2

!

"
A A0 2fA

2⇥ 4 I /2⌘2

(1)

where A 0 is the radius of peak flux, fA is the Gaussian scale width(where the FWHM is 2.355*fA ) and ⌘ = A ⇥ C0=(k) and where k isdisc opening angle. In their scattered light modelling S18 use a fixed
k of 0.04, found by Thébault (2009) to be the ’minimum naturalobserved aspect ratio’ for dust grains observed at visible to mid-IR
wavelengths. Dust grains observed at mm wavelengths whose orbits
are not affected by radial forces are not expected to conform to thisminimum aspect ratio, however trialling a similar model 54.060664(eteC.991.

We first
a simple
Gaussian
torus
model,
withparaminset
showing
the distribution
model discGivencentres thein comparison
thatof radius.
spatial resolution, the us
observed
aspectimplement
ratio’ for dust grainsobserved
at visible tomid-IR
the stellar
location and ALMA astrometric precision.
eters definedby thefollowing
equationwhose
for orbitsa modelto dust
volumewavelengths.
Dust grainsobserved
at mm wavelengths
notspecific,equallya
top-hatdistributionorsing
The residuals show no remaining structure, demonstrating that anarenotaffectedbyradialforcesarenotexpectedtoconformtothisdensity distribution =(A, I):
have been
used
(e.g.
Kennedyetal. 2018), the imp
azimuthally
andradially
symmetric
model
fits
the
data
well.
Only
a
minimum aspect ratio, however trialling a similar model with k as
single 2f residual overlapsradialwith thebounds of thedisc,a negative of disc width. The
symmetryanda measurea free parameter finds k unresolved in the ALMA data with a 3f
residual in the north-west. At 1-2f this feature is likely noise and!We thus" 2choose to fix k to 0.04 in our modelling
upper limit of 0.18.
eters
are
presented
in
Table
1
along
with
those
o
1 A A0accounts for the shape of the disc profile, Figure 2.
I 2S18.
/2⌘ 2
2 the
fAmodelling offorconsistency
with
2A21’s(1)=(A, I) / 4
⇥4
law
model
and
S18
and
scattered
light
mod
We
use
the
median-parametermodel
tocalculate
a
j
value
of
Our second model follows the equation used in S18 for direct
721281.0 as well as
calculating
the BayesianInformation
Criterion
derivedfromthemodellingispresented
in
Figu
The
edge-ondebrisdiscofGSC
07396-00759
5comparison,i.e.
aDouble
Power
Law
with
different
densityslopeswhere A 0 is the radius of peak flux, fA is the Gaussian
scale
width
(BIC;
Schwarz1978) of 721384.5. The BIC penalises models forinterior and exterior to A 0 :
dirty
image
of
the
residuals
after
subtractionofaincludingextra
to identify whether an improvement in(where the FWHM is 2.355*f ) and ⌘ = A ⇥ C0=(k) andwhere
k parametersisble 1. Median disc parameters, j2 and BIC values for Gaussian and double powerA law models. Best fitting parameters for S18’s total intensity scattered
2 is justification to conclude
themediansoftheposterior-parameter
distributi
j
a
model
is
a
significantly
betterfit
toht modelling and A21’s polarimetric scattered
light modelling are also includedforcomparison.
Uncertainties
are
the
16th
and
84th
percentiles.
Offsets
are
#
&
1/2
disc
opening
scatteredlightmodelling
S18
use
a
fixed
$ % 20angle.
$ %In20theirout
inasured from the disc model centre to the Gaia
Upper limits are at 3f abovethe
the data.
mean, i.e.
thedefined
99.87th as ⌫ ⇠ = j 2 + #
2
2
It
is
⇥ ln #dofin, andas we 3 left. Figure 3 l
A DR2 location ofA the star at the time of observation.
ParametersI/2⌘
contours
overplotted,
Figurecentile. The disc flux uncertainty
the 10%
ALMA
calibration
uncertainty.
The 4 cos( l) to
upperbelimit theincludesthe ALMA astrometricprecision.
=(A,I)includes/0.04,+ fluxby⇥ 4(2009)(2)’minimum
k
of
found
Thébault
naturalto atolarge
number
0 vector along the major-axis of the disc. j2 and BIC valuesfit
e 4 cos( l) upper limit is calculated from theA 0projection of theAoffset
relative
Gaussianmodel of visibilities (#dof = 2⇥ #vis = 2⇥209496) the
inset
showingthedistribution
of
model
disc
cen
inclusionofevenasingleextra
parameter
imposesalarge
penalty.
Ah values 721281.0 and 721384.6
respectively,
calculated
from
a
model
producedusing
themedianparameters.
observed aspect ratio’ for dust grains observed at visible to mid-IR
where 0 in and 0 out are the inner and outer slopes respectively.
tothestellarlocationandastrometricpre
BIC of greater than 6 is considered’strong’
evidence anda ALMA
BIC
wavelengths.
Dustobserved
at fluxmm
whoseorbitsBoth models
possessa grains
parameter
for Intensity
the total
ofwavelengths
thePolarimetricdisc Scattered
Parameter
Gaussian
DoublePower
Law Total
Scattered
Light
Light
of greater than 10 is considered’decisive’
evidence
thatnotheremaining
lower
The
residuals
show
structure,deasarewellnot
as aninclination,aposition
angle
and
RA
and
Declination
affectedbyradialforcesarenotexpectedtoconformtothisvaluedmodel
issignificantly preferred to fit the data (Kass & Raftery
+0.03
+0.03
00
RA Offset ( ) (Dec) offsets
0.06
0.06 0.03centre from the ALMA phase-centre.
azimuthally
andradially
symmetric
model
fits
th
of 0.03the disc model
1995).
minimumphase-centre
aspect 0.00
ratio,+0.04+0.04 however trialling a similar model with k as
Dec Offset (00 )The ALMA0.00
is 0.03
found to be slightly offset itself from
0.04
The median parameters singleof this discmodel
largely alignwell with
2f
residual
overlapswiththeboundsofa freeparameterfinds
k unresolvedin the
ALMA
data
with
a
3f
4 cos( l) 3f theUpper
Limit DR2
0.17
0.16
Gaia
(Gaia Collaboration
et al. 2016, 2018)locationofthe parameters found from S18’s
and A21’s
scatteredlight modelling.
residualinthenorth-west.
At
1-2f
this
feature+3+3+0.1 reported offsets 84.30.3
star
at
the
time
of
observation.
Allsubsequent
Inclination ( )the
85
85
82.7
upper limit3of 0.18. We
thus choose 0.1
to fix k to 0.04 in 0.3The
ourmodelmodelling3
inclination and position angle are within 1f of both. Our
+0.1
+0.7
+1
+1
have had that32Gaiatophase-centre
offsetsubtracted
such
that
the
accounts
for
the
shape
of
the
disc
profile,FigurePA ( )
32
31.1
31.3
radiusmeasurement
isinsignificant
agreement
with
the
S18
model
1
1
0.1
0.7
for consistencywiththemodellingof
S18.
offsetmeasurements
arerelative
to
the
Gaia
locationat the time of+0.21
Disc Flux (mJy)
1.84+0.22
1.83
We
use
the
median-parameter
model
to
calcu
0.21
0.21
Our
secondmodel
follows
theequation
used
in
S18
for
directobservation.
We
also
includeaparameterfor
scalingtheweightings
+0.9
+8.0
+4.1
+2
Radius (au)70.2 4.7
77.7 7.1
69.9 0.8
107 2721281.0
as
well
as
calculatingtheBayesianInf
2 https://almascience.nrao.edu/documents-and-tools/cycle6/alma-technicalofcomparison,
the u-v data +4.3
pointsastheirabsolute
uncertainty
canbeoffsetas
Scale Width (au)20.3 4.1 i.e. a Double Power Law with different
27+11density slopes
described in Matrà et al. (2019b)
and Kennedy (2020).
handbook(BIC; Schwarz 1978) of 721384.5. The BIC pe
+4.5
+0.2

• ガウシアンモデル• double power law• S18とよくあった。

• 後で見せる図の通り、非対称性は赤外と電波で違った。赤外に見えた強い非対称は電波では見えなかった（特にこれと行った議論はなし。）

U8=

U>DC
#Parametersj2
BIC

3.5 1.9
interior and exterior
to A 0 :MNRAS 000, 1–12 (2021)

#8 $
0

A
=(A, I) / 0
A0

8.9+1.9
2.0% 20+1.9
in
9$

A+14.9+A0

2.8 0.2

2.6+0.1
0.1% 20out & 1/2⇥4

I 2 /2⌘ 2

where 0 in and 0 out are the inner and outer slopes respectively.

(2)

including extra parameters to identify whether
2
j is justification to conclude a model is a signi
the data. It is defined as ⌫ ⇠ = j2 + #Parameters ⇥fit to a large number of visibilities (#dof = 2⇥ #v
inclusion of even a single extra parameter impose

The edge-on d
8

P. F. Cronin-Coltsmann et al.

ALMA Band 7
IRDIFS H2/H3
IRDIS DPI

Normalised Flux (arb. units)

1.0

0.8

SE SideNW Side

0.6

0.4

0.2

0

Figure 6. . Comparison of GSC 07396-00759’s disc as imaged in ALMA Band 7 with +2f, 4f, 6f, 8f, 10f contours (top, aligned with model centre atzero offset), ALMA best-fitting Gaussian torus model (second from top), SPHERE/IRDIFS H2/H3 (second from bottom) and SPHERE/IRDIS DPI (bottom).
The horizontal dash-dotted lines cross through the location of the model centre for the ALMA data/model and the star for the SPHERE data, parallel to themajor-axis of the disc. The central regions of the SPHERE data have been removed to account for the coronagraphic masks and high noise levels surrounding
the masks. The vertical dashed lines pass through the ALMA best-fitting model radius of the disc and zero offset.

Figure 7 shows a comparison of the profiles of the three data sets,
for the ALMA data derived from the flux of the centre pixel along
the major-axis and for the SPHERE data derived from the brightest
pixel in a slice of the disc perpendicular to the major-axis at eachseparation step, the differing approaches warranted due to the significantly higher resolution of the SPHERE data. The scattering phasefunctions will heavily dampen the visual radial extent of the disc in
the scattered light data, thus Figure 7 is intended for a comparisonof the potential brightness asymmetries in each dataset rather thanapparent radii. However, even with the effects of the scattering phaseon a possible sub-mm brightness asymmetry of less than a factor⇠1.5. It is not unfeasible that a brightness asymmetry is present in
the sub-mm, but we infer that it is very unlikely to be at the samelevel as seen by IRDIFS and unlikely to be at the same level as seen
by IRDIS DPI. The time baseline between observations is too shortfor dust causing an asymmetry to be removed totally from the system, which would happen on orbital timescales of ⇠750 years, andso the asymmetry must be enhanced in small grain sizes. Thus whatever mechanism is causing the brightness asymmetry more strongly
affects the more mobile small micron sized dust grains, and is not-3 -2.5 -2 -1.5 -1 -0.5 0 +0.5 +1 +1.5 +2 +2.5 +3
Separation (arcsec)

Figure 7. Comparative brightness profiles of the ALMA Band 7 and
SPHERE/IRDIS total intensity and polarimetric data. For the ALMA data,
the flux of the centre pixel along the disc major-axis is taken at each separation
step. For the SPHERE data the peak brightness is taken from a slice of pixels
at each separation step along a swathe parallel to the disc major-axis. Eachprofile is normalised to its brightest component. The gray swathe shows the
ALMA RMS. The IRDIS DPI image has been smoothed by a uniform filterof width ten pixels. Zero separation is the best fitting model centre from §3.

unknown for GSC 07396-00759. As V is size dependent, this would
result in differently apparent asymmetries depending on the grain
size probed by the observation (Jackson et al. 2014; Kral et al. 2015).
A warp in the north-west of the disc is observed in both scattered
light data sets. In Figure 6 slight evidence for a warp in the ALMA

Figure 8. mm-wave
luminosity. Error bar
type stellar hosts arewidth as a fixed width
et al. 2020). Transpar
the parameter distribu

large for its type wthat GSC 07396-00
To visualise thethe radius-luminos
addition of the sa
malhaut C (Cronin
et al. 2020). CPDfixed FWHM of 0.
for a radius in the
mm-wave resolved

s profiles of the ALMA Band 7 andpolarimetric data. For the ALMA data,
disc major-axis is taken at each separationbrightness is taken from a slice of pixels
he parallel to the disc major-axis. Each

The edge-on debris disc of GSC 07396-00759

9

R (au)

102

101
10 2

10 1

L (L )

100

101

Figure 8. mm-wave resolved debris disc radii plotted against host stellar
luminosity. Error bars represent disc FWHM or upper limits. The five latest
type stellar hosts are highlighted in colour, CPD-72 2713 is plotted without awidth as a fixed width of 0.2R was assumed to facilitate fitting a radius (Moóret al. 2020). Transparent grey lines show a sample of 1000 power laws fromthe parameter distributions of Matrà et al. (2018).

Scattering and sublimation: a multi-scale view of `m-sized dust in the
inclined disc of HD 145718
1¢
2
1
2
1
Claire L. Davies, Evan A. Rich, Tim J. Harries, John D. Monnier, Anna S. E. Laws,

3
4,5
3
6,7
2
Sean M. Andrews, Jaehan Bae, David J. Wilner, Narsireddy Anugu, Jacob Ennis,

2
1
1,8
2,9
6
Tyler Gardner, Stefan Kraus, Aaron Labdon, Jean-Baptiste le Bouquin, Cyprien Lanthermann,stro-ph.SR] 17 Jan 2022

Gail H. Schaefer,6 Benjamin R. Setterholm,2 Theo ten Brummelaar,6 and the G-LIGHTS collaboration
1 Astrophysics Group, Department of Physics and Astronomy, University of Exeter, Stocker Road, Exeter, EX4 4QL, UK
2 Astronomy Department, University of Michigan, Ann Arbor, MI 48109, USA

HD 145718• 4GPIでHD145718を観測した。

3 Center for Astrophysics | Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138, USA•

Earth and Planets Laboratory, Carnegie Institution for Science, 5241 Broad Branch Road NW, Washington, DC 20015, USA
5 Department of Astronomy, University of Florida, Gainesville, FL 32611, USA
6 Steward Observatory, Department of Astronomy, University of Arizona, Tucson, USA
i=67-71度、PA=-1.0-0.6度、75auまで広がる
7 The CHARA Array of Georgia State University, Mount Wilson Observatory, Mount Wilson, CA 91023, USA
8 European Southern Observatory, Casilla 19001, Santiago 19, Chile
9 Institut de Planetologie et d’Astrophysique de Grenoble, Grenoble 38058, France• アスペクト比は0.24 in J band, 0.22 in H
band
Accepted XXX. Received YYY; in original form ZZZ• ダストが巻き上げられている証拠である
ABSTRACT

We present multi-instrument observations of the disc around the Herbig Ae star, HD 145718, employing geometric and Montedimmining
eventもあった。
•Carloradiative transfer models to explore the disc orientation, the vertical and radial extent of the near infrared (NIR) scattering
surface, and the properties of the dust in the disc surface and sublimation rim. The disc appears inclined at 67 71 , with position
angle, PA = 1.0 0.6 , consistent with previous estimates. The NIR scattering surface extends out to ⇠ 75 au and we infer an5

HD 145718

HD 145718
6EJ

5C. L. Davies et al.

Table 1. Results of our geometric modelling of the (a isophotes of the and -band & q images. Column 1: isophote surface brightness; columns
2, 3 and 4: elliptical ring radius, inclination, and position angle; column 5:height of the scattering surface above the disc midplane at radius A .
(a(mJy /arcsec2 )
(1)

A
(au)
(2)

8
( )
(3)

PA
( )
(4)

⌘scat (A )
(au)
(5)

-band
0.70
71.4+0.6
68.1+0.6
0.7+0.3
9.5+0.4
0.7
0.4
0.4
0.6
+0.7
+0.3
+0.5
0.75
71.0+0.6
68.3
0.5
9.6
0.7
0.4
0.4
0.6
0.80
70.7+0.6
68.2+0.7
0.6+0.3
9.8+0.5
0.7
0.4
0.6
0.5
+0.7
+0.3
+0.5
0.85
69.5+0.6
67.1
0.1
10.3
0.7
0.4
0.6
0.5
+0.8
+0.4
+0.6
0.90
69.1+0.7
66.9
0.6
10.8
0.9
0.6
0.5
Figure 3.
(D, E)-plane
coverageof 0.5the 9.2
interferometry.
Left:
-band
+0.6
0.95
66.9+0.6
67.7+0.8
0.1+0.3
0.9
0.4
0.6
0.5
+0.8 points)+0.6
VLTI/PIONIER
(dark
green
data
and9.0CHARA/MIRC-X(lime green
1.00
66.6+0.6
68.4
0.3+0.3
0.9
0.3
0.6
0.6
Figure 4. Example isophotes extracted from the - (left) and -band (right)
+0.6
+0.8
+0.3
+0.5
1.05 Right:
66.0 0.6
69.0
0.6 0.3
8.5 (brown
data points).
-band
VLTI/GRAVITY
data&points).
0.8
0.5
a surfaceis
brightness of 0.7 and 1.3 mJy arcsec 2 , respectively,
q images atNorth
+0.6
+0.8
+0.3
1.10
65.4 0.6
68.6 0.9
0.2 0.4
8.8+0.5
0.5
and their corresponding best fitting elliptical ring model.
up; east is1.15
left.
+0.8
+0.3
+0.5
64.7+0.6
68.6
0.2
9.1
0.9
0.3
0.6
0.5
1.20
63.6+0.5
67.8+0.8
0.1+0.3
9.4+0.5
0.8
0.3
0.5
0.5
+0.9
+0.3
+0.7
1.25
62.9+0.5
67.8
0.2
9.4
1.0
0.4
0.6
0.6

DJ1

DJ2

EH

AH

-band
and time-consuming radiativetransfer modelling (Section 5). Our
et al. 2020)
+0.6
+0.5
elliptical0.80
ring model
was67.8
prescribed
as a8.0
circularringNewvilleof radius,A, in-to explore the posterior probability distribution
71.6+0.5
0.1+0.3
0.7
0.3
0.4
0.5
of the parameters in our model. The values and uncertainties
71.3+0.4
68.6+0.5
0.8+0.2
8.3+0.3
4of, each
0.4
0.3
0.3
0.5
clined by0.85
angle,
8,
rotatedthroughpositionangle,
PA
andtranslated
+0.4
+0.5
+0.2
+0.3
quotedinTable 1 correspond to the median and 1f quantiles of these
0.90
70.4 0.4
69.0 0.5
0.7 0.3
7.7 0.3+0.5+0.4
probability distributions.
0.95
70.0RA,
68.6
1.0+0.3
8.0
in right ascension,
and+0.6
declination,
Dec,
by coordinates(X RA, We do not incorporate the uncertainty on
0.3
0.4
0.5
0.6
+0.5
+0.6
+0.3
+0.4
the distance (Table 2) in our A and ⌘scat (A) uncertainties.
1.00
69.5 0.5
68.5 0.7
1.0 0.4
8.3 0.4
X Dec) from
the
image
centre.
Assuming
ourobservations
trace light
+0.4
+0.5
+0.2
+0.4
Our fits to the - and -band ( a isophotes provide broadly
1.05
69.4 0.4
69.6 0.5
0.6 0.3
7.8 0.4+0.4+0.5
69.4the0.3+0.2
7.7+0.4
consistent
results for
scattered1.10
by dust68.3
closetothe centresof the disc geometry: 67 . 8 . 69 and
0.4
0.3
0.4we expect
0.5 disc surface,
+0.4
+0.5
+0.2
1.15
68.2 0.4
69.4 0.5
0.2 0.3
7.7+0.4
0.7.
PA.
0.6 in -band; 68 . 8 . 71 and 1.0 .
major
0.3
⇢ J and ⇢1.20
offset
from
the
image
centrealongavectorwhich,
+0.4
+0.5
+0.2
+0.4
H to be67.5
69.4 0.5
0.3 0.2
7.7 0.3
PAmajor . 0.1 in -band. As such, the disc appears more inclined
0.4
+0.4
+0.5
+0.2
+0.4
1.25
67.5
68.8
0.5
8.3
when projected onto0.4the sky,0.6lies perpendicular
to theanddisc
PA.closer
Thus,oriented
to 0 PA in our GPI images than has previously
0.3
0.4
+0.6
+0.2
+0.4
1.30
66.7+0.4
68.3
0.6
8.5
been inferred from geometric modelling and image reconstruction of
0.7
0.3
0.4
we can 1.35
relate PA,
X0.4RA,
and
X 0.2
Dec
the
+0.6
+0.2 to 6.9+0.4 height, ⌘ scat (A), of the
65.6+0.4
69.9
PIONIER interferometry (Lazareff et al. 2017; Kluska et al. 2020).
0.4
0.2
0.4
0.6
+0.4
+0.5
+0.2
+0.4
1.40
65.4
70.2
0.1
7.0
scattering surface above
the+0.5
disc midplaneat radius Our
A: results are more consistent with findings from Fourier-plane
0.4
0.2
0.4
0.6
+0.2
+0.4
1.45
65.1+0.4
70.7
0.2
6.8
0.2
0.4
0.5
analysismm continuumand -band interferometry: 8 = 70.4±1.2✓ 5.64.6◆0.4 comparison
FigureTop:betweenthe-band ofscattering
surfaces
+0.4
+0.6
+0.2
+0.4 - and
1.50
70.5
0.4
7.0
0.4
0.3
0.4
0.6
c +0.6models+0.2with different
and PA = 1 ± 1 inferred from 1.3 `m ALMA observations (Ansdell
1 X RA
from
TORUS
valuesof 5 . All other model
1.55
64.5+0.4
70.4
0.5 0.3
7.1+0.4,
PA = tanresulting
0.4+
0.4
0.6
et al. 2020); 68 < (4)8 < 72 and PA = 2 ± 2 inferred from GRAVITY
+0.4
+0.7
+0.3
+0.5
1.60 X Dec
63.8
69.6
0.6
7.7
2
parameters
wereidentical
in
the
two
models.
Bottom:zoom-inon
inner et al. 2019). We discuss these
0.4
0.7
0.3
0.5
observations (Gravitythe
Collaboration

and

1.65

62.8+0.4

69.0+0.7

0.6+0.3

7.8+0.5

0.4 -band scattering
0.7
0.3
0.5
results
further, particularly
in relation to HD 145718’s photometric⇠1.70
2 au of the
ray-tracing
algorithm.
+0.7+0.3surface+0.6traced by our
62.3+0.4
70.0
0.7
7.0
0.4
0.8
0.3
0.5
variability,
in Section
6.1. thick+0.7
The
spreadin datapointsthepartially
optically
1.75 horizontal
62.1+0.4
70.0+0.7
0.6+0.3
7.0highlights
0.4
0.9
0.3
0.6
⇣
⌘
The values in Table 1 suggest a scattering surface aspect ratio+0.8
1/2 7.0+0.7
1.80
61.9+0.4
70.0
0.6+0.3
0.4
0.9 of2the0.3dust sublimation
0.6
natureof theupper
layers
rim.
+0.52
+0.8
+0.3
+0.7
(⌘scat (A)/A) in the range ⇠ 0.13 0.16 ( -band) and ⇠ 0.10 0.13

(X Dec)⌘scat (A) 1.85
= 3 (X 61.6
RA)0.4 +69.8
0.7 0.3 , 7.1 0.7
0.9

Figure 2. Annotated - (top) and -band (bottom) Stokes & q images highlighting the main features ⇢J , ⇡J1 , ⇡J2 , ⇢H , and H (see Section 3.1.1 fordetails). The IWA of the coronographic mask is indicated by the black ringin the centre of the image.

3.3 Archival multi-wavelength photometry and infrared
spectroscopy(5)( -band). This is at the lower end of the range found by e.g. Avenhaus
et al. (2018) and Ginski et al. (2016) who used NIR scattered light imwhere 3 is the stellar distance.
Wefollow
Vioqueetal.of(2018)
and discs with concentric ring features to estiages
six protoplanetary( -band) or ( a < 0.80+3.2
mJy arcsec 2 ( -band) were not used as theyedge
at A in andacorresponding
more loosely curved
surfacemate
this ratios,
at finding ⌘scat (A)/A = 0.09 0.25.
scattering
surfaceadopt= 152.5to theinverseofemerges
theGaiaabove
dataaspect
did not3sufficiently
trace3.0
the pc,apexesof the ellipse. Limiting
the rangefrom settled
this simplerim
isophote fitting procedure also suggest
A > Aused. inThe
therangesmall
grainsTheoutresultsof theof ( a isophotes
this emergenceway
results in a oflimitedof discin5
release(DR)
2 parallax(Gaia Collaboration et al. 2016,
Our surface of HD 145718 may be more vertithat the2018).
-band scatteringradii (andextends
therefore ⌘thebeing explored.
scat (A))
mas-scale
NIR brightness distribution
tolargercally extended
than the scales.
-band scattering surface. This is not wholly
elliptical ring model is then fully prescribed using fourparameters:
unexpectedaslongerwavelengths
This improves the fit to the shorter baseline visibilities which are of light should penetrate deeper
A, 8, PA, and ⌘scat (A).
into the disc due to the grain size dependent vertical stratification
4.1 Inferreddisc geometry inandthepotential
flaringof the larger
discover-resolved
modelsusing
5 values.
of the disc as a result of vertical settling (e.g. Pinte et al. 2007;
Beforeextracting
scattering
surface the ( a isophotes, we first masked the & q imagesDuchêne et al. 2010). We examine this in more detail using MontetoTheexcludethecentralpixelswithin
the
IWA
of
the
coronograph.
The models in Section 6.2.
Carlo radiative transfer
minimize function of lmfit (version 1.0.1; Newville et al.
2020) coordinates
was used to fit ourof
ellipticalmodel to the data.
Specifically,
Lookingclosely at our best-fit ⌘scat (A) and A values, the height ofpixel
the (ring
tracingthe ⇢ J and⇢ H featuresa isophotes
Maximum
size ofsurface-layer
dust grainsthe scattering surface also appears to increase with radius suggesting
we minimised
the radial distance
betweenthe cylindrical coordinates
were
then
isolated
from
the
full
list
returnedthe contourof the isophote and the elliptical ring at the same azimuthalby
angle.
we may be function
probing the degree of flaring of the disc scattering surface
resultsare valuesummarised
Table
1 and thewe2007).
show
examplefits
in thesmall
outer ofdisc.
We explore
this further, and assess the robustness
ofOurmatplotlib.pyplot(HunterThe
western
side
each
The
of 0inaffects
radiusat whichthegrainsemergemax
in Fig. 4. To estimate the uncertainties on our fits, we used theof the relatively simplistic fitting procedure we have employed inellipse-tracing( settled
isophotefrom
elliptical
likelyshowed
above thediscdeviatedrim. Isella
& an
Natta
(2005)shape,
previously

910

C. L. Davies et al.

parameters were identical in the two models. Bottom: zoom-in on the inner⇠ 2 au of the -band scattering surface traced by our ray-tracing algorithm.
The horizontal spread in data points highlights the partially optically thicknature of the upper layers of the dust sublimation rim.

size of non-settled grains is increased from 0.3 `m to 0.6 `m. Each image is2 ⇥ 2”.

• amax=0.5 micronがよい

edge at A in and a more loosely curved surface emerges above this at
A > A in . The emergence of the small grains out of the settled rim
extends the mas-scale NIR brightness distribution to larger scales.
This improves the fit to the shorter baseline visibilities which areover-resolved in the models using larger 5 values.
Maximum size of surface-layer dust grains•

models with larger 0 max . The * q images also decrease in brightness
with increasing 0 max .
5.4 Best-fitting TORUS model

The TORUS model providing the best overall fit was found to have
⌘0,gas = 10 au, V = 1.15, 'out = 75 au, 0 max = 0.50 `m, 8 = 72
and PA = 0 . The corresponding model & q and * q images arecompared to our GPI observations in Figures 7 and 8, respectively.
The model SED and mas-scale images are compared to the respective
HD 145718 13
observational data in Figure 9.
The model & q image is able to broadly replicate the ( a level,
location and extent of the main ⇢ H and H features in the observed-band image (Figure 7). Reducing 8 or increasing the height of thescattering surface by increasing ⌘0,gas and/or V causes the separation
between the elliptical and the arc feature in the model image toincrease. Increasing 0 max decreases the overall ( a in the & q and* q images and reduces the back-scattering efficiency, resulting ina larger dark portion on the west side of the elliptical feature in
the - and -band model & q images, like those seen in Figure 6.
The weaker back-scattering we observe in the disc of HD 145718
has also been observed in scattered light imaging of other inclined
discs (e.g. DoAr 25 Garufi et al. 2020; IM Lup Avenhaus et al. 2018),
suggesting that the surface layers of discs may be routinely populated
by grains of size, 0 & _/2c. These larger grains possibly have an
aggregate structure which provides them with aerodynamic support

The value of 0 max affects the radius at which the small grains emerge
above the settled disc rim. Isella & Natta (2005) previously showedon thethat
degreeof grains
flaringcan
in thesurfacelayerstemperaturesof dusty andasgaseouslargersurvive
at higher
they are morecomponents of protoplanetary discs have begun to be made (Ginski
efficient at cooling. This same process is responsible for the effectet al. 2016; Avenhaus et al. 2018; Pinte et al. 2018; Villenave et al.
we see here. Increasing 0 max therefore affects the NIR flux level
2020; Rich et al. 2021). Elliptical models, similar to those we employ
and the shape of the visibilities in much the same way as seen for
in Section 4, have been used to determine the height of the scattering
single grain size models (Isella & Natta 2005; Davies et al. 2018,
surface in concentric ring features of discs exhibiting substructure,2020). Changing 0 max also affects the scattering phase function: atwith power law profiles (Equation (7)) then used to constrain thethe relatively high inclinations we explore, we see an asymmetric & q
flaring exponent of the scattering surface, Vscat . At the resolution ofbrightness distribution and increasing 0 max results in a decrease incurrent observations, HD 145718 does not show indications of discback-scattering efficiency, relative to forward scattering (Figure 6).
substructure and so these same methods are not applicable.
The extent of this difference is consistently more marked in the Assuming, first of all, that our surface brightness isophotes doband image than the -band. This is associated with the dependence
trace concentric disc annuli, we use the results of our isophote fittingof the scattering phase function on the grain size (Stolker et al.
in Table 1 to derive an initial estimate for the flaring of the - and2016b; Tazaki et al. 2019). One can also see from Figure 6 that the-band scattering surfaces close to the apparent outer edge of thearc features on the eastern side of the & q images are dimmer fordisc. Specifically, we employ the power law parameterisation
for thevertical height of the scattering surface (e.g. Equation (7)). BasedMNRAS 000, 1–18 (2021)
on the range of A values in Table 1, we adopt a canonical radius,
Figure 11. Application of our isophote fitting procedure (Section 6.1) to theA 0 = 65 au such that ⌘0 is the height at 65 au (which we denote ⌘65 ).
synthetic - and -band & q images computed from our best-fitting TORUS
To estimate Vscat and ⌘65 , we performed least-squares fitting to themodel. Radii and heights extracted from the - and -band images are plottedlinear relationin magenta and green, respectively. The power law fits to these data are shown
Figure 7. Left: - (top) and -band (bottom) & q images for our best TORUS model (⌘0,gas = 10 au, V = 1.15, 'out = 75 au, 0max = 0.50 `m, 8 = 72 andlog (⌘scat (A))= log10 (⌘65extracted) + Vscatfrom
logtheseau).
(12)
10 (A/65
PA = 0 ). Middle: observed & q images overlaid with 0.8 and 4.0 mJy arcsec102 surface
brightness contours
model images (white solid anddashed lines, respectively). Right: zoomed-in view comparing the 0.8 and 4.0 mJy arcsec 2 contours extracted from the model (black solid and dashed lines,drew(cyan
10,000of respectively).
⌘scat (A) and A from splitrespectively) and the 0.8 and 1.8 mJy arcsec 2 contours extracted from Specifically,
the observed & qwe
imagessolid realisations
and dashed lines,

normal distributions, based on their lower and upper bounded errors,
and repeated the fit each time. The best-fit values and uncertainties on
against settling. Alternatively, this may indicate a relative dearthof andSED
themedianshape ofand
the1f
fullupper
SED well.
alsoquartiles
show theVscat⌘65 reproduces
are then theand Welower

by the dot-dash lines, with the shaded areas representing the 1f uncertainties
on ⌘65 and Vscat (see plot legend). The gscat = 1 scattering surfaces at 1.25 `m( -band) and 1.65 `m ( -band), as measured by TORUS, are shown by thedashed lines. The cross-hair in the lower right corner represents the pixel
scale in our GPI and TORUS images.

Do the majority of stars form as gravitationally unbound?

František Dinnbier, Pavel Kroupa, Richard I. Anderson F Some of the youngest stars (age . 10 Myr) are clustered,
while many others are observed scattered throughout star forming regions or in complete isolation. It has been intensively
debated whether the scattered or isolated stars originate in star clusters, or if they form truly isolated, which could help
constrain the possibilities how massive stars are formed. We adopt the assumption that all stars form in gravitationally boundstar clusters embedded in molecular cloud cores ( -1 model), which expel their natal gas, and compare the fraction of stars
found in clusters with observational data. The star clusters are modelled by the code nbody6, which includes stellar andcircumbinary evolution, gas expulsion, and the external gravitational field of their host galaxy. We find that small changes in
the assumptions in the current theoretical model estimating the fraction, , of stars forming in embedded clusters have a large
influence on the results, and we present a counterexample as an illustration. This calls into question theoretical arguments
about in embedded clusters, and it suggests that there is no firm theoretical ground for low in galaxies with lower starformation rates (SFRs). Instead, the assumption that all stars form in embedded clusters is in agreement with observational
data for the youngest stars (age . 10 Myr). In the -1 scenario, the observed fraction of the youngest stars in clusters increases
with the SFR only weakly; the increase is caused by the presence of more massive clusters in galaxies with higher SFRs, which
release fewer stars to the field in proportion to their mass. The -1 model yields a higher fraction of stars in clusters for older
stars (age between 10 and 300 Myr) than what is observed. This discrepancy can be caused by interactions with molecular
clouds.

Successive deuteration in low-mass star-forming regions: the case of D2 -methanol
孤立した星の起源は、星団なのか？ほんとうに孤立して誕生したのか？
(CHD2 OH) in IRAS 16293-2422
すべての星が星団で生まれるモデル（Γ-1）で検証。
Maria N.
Drozdovskaya, Laurent H. Coudert, Laurent Margulès, Audrey Coutens, Jes K. Jørgensen, SébastienManigand F Accurate quantification of the column density of di-deuterated methanol is a key missing puzzle piece in the
星の生まれる割合？Γをちょっと帰れば結果が大きく変わる。
otherwise thoroughly constrained family of D-bearing methanol in the deeply embedded low-mass protostellar system andastrochemical template source IRAS16293-2422. A spectroscopic dataset for astrophysical purposes is built for CHD2 OH andmade publicly available to facilitate accurate characterization of this species in astrochemical surveys. The newly computed line
list and partition function are used to search for CHD2 OH towards IRAS16293-2422 A and B in data from ALMA-PILS. Only
non-blended, optically thin lines of CHD2 OH are used for the synthetic spectral fitting. The constructed spectroscopic database
contains line frequencies and strengths for 7417 transitions in the 0 to 500 GHz frequency range. ALMA-PILS observations in
the 329-363 GHz range are used to identify 105 unique, non-blended, optically thin line frequencies of CHD2 OH for synthetic
spectral fitting. The derived excitation temperatures and column densities yield high D/H ratios of CHD2 OH in IRAS 162932422 A and B of 7.5±1.1not higher than in other low-mass star-forming regions. Di-deuterated molecules consistently have higher
D/H ratios than their monodeuterated counterparts in all low-mass protostars, which may be a natural consequence of H-D
substitution reactions as seen in laboratory experiments. The Solar System’s natal cloud, as traced by comet 67P/ChuryumovGerasimenko, may have had a lower initial abundance of D, been warmer than the cloud of IRAS16293-2422, or been partiallySuccessive deuteration in low-mass star-forming regions: the case of D2 -methanol(CHD2 OH) in IRAS 16293-2422

Maria N. Drozdovskaya, Laurent H. Coudert, Laurent Margulès, Audrey Coutens, Jes K. Jørgensen, SébastienManigand F Accurate quantification of the column density of di-deuterated methanol is a key missing puzzle piece in theotherwise thoroughly constrained family of D-bearing methanol in the deeply embedded low-mass protostellar system andastrochemical template source IRAS16293-2422. A spectroscopic dataset for astrophysical purposes is built for CHD2 OH andmade publicly available to facilitate accurate characterization of this species in astrochemical surveys. The newly computed line
list and partition function are used to search for CHD2 OH towards IRAS16293-2422 A and B in data from ALMA-PILS. Only
non-blended, optically thin lines of CHD2 OH are used for the synthetic spectral fitting. The constructed spectroscopic database
contains line frequencies and strengths for 7417 transitions in the 0 to 500 GHz frequency range. ALMA-PILS observations in
the 329-363 GHz range are used to identify 105 unique, non-blended, optically thin line frequencies of CHD2 OH for synthetic
spectral fitting. The derived excitation temperatures and column densities yield high D/H ratios of CHD2 OH in IRAS 162932422 A and B of 7.5±1.1not higher than in other low-mass star-forming regions. Di-deuterated molecules consistently have higher
D/H ratios than their monodeuterated counterparts in all low-mass protostars, which may be a natural consequence of H-D
substitution reactions as seen in laboratory experiments. The Solar System’s natal cloud, as traced by comet 67P/ChuryumovGerasimenko, may have had a lower initial abundance of D, been warmer than the cloud of IRAS16293-2422, or been partially
reprocessed. In combination with accurate spectroscopy, a careful spectral analysis, and a consideration of the underlying
assumptions, successive deuteration is a robust window on the physicochemical provenance of star-forming systems.

The impact of cosmic-ray attenuation on the carbon cycle emission in molecular clouds

Brandt A. L. Gaches, Thomas G. Bisbas, Shmuel Bialy F Observations of the emission of the carbon cycle species (C,C+ CO) are commonly used to diagnose gas properties in the interstellar medium but are significantly sensitive to the cosmic-ray
ionization rate. The carbon-cycle chemistry is known to be quite sensitive to the cosmic-ray ionization rate, ⇣, controlled by
the flux of low-energy cosmic rays which get attenuated through molecular clouds. However, astrochemical models commonly
assume a constant cosmic-ray ionization rate in the clouds. We investigate the eﬀect of cosmic-ray attenuation on the emission ofcarbon cycle species from molecular clouds, in particular the [CII] 158 µm, [CI] 609 µm and CO (J = 1 - 0) 115.27 GHz lines. We
use a post-processed chemical model of diﬀuse and dense simulated molecular clouds and quantify the variation in both column
densities and velocity integrated line emission of the carbon cycle with diﬀerent cosmic-ray ionization rate models. We findthat the abundances and column densities of carbon cycle species is significantly impacted by the chosen cosmic-ray ionization
rate model: no single constant ionization rate can reproduce the abundances modelled with an attenuated cosmic-ray model.
Further, we show that constant ionization rate models fail to simultaneously reproduce the integrated emission of the lines weconsider, and their deviations from a physically derived cosmic-ray attenuation model is too complex to be simply corrected.
We demonstrate that the two clouds we model exhibit a similar average AV,e↵ – nH relationship, resulting in an averagerelation between the cosmic-ray ionization rate and density ⇣(nH ). We conclude by providing a number of implementation
recommendations for CRs in astrochemical models, but emphasize the necessity for column-dependent cosmic-ray ionization
rate prescriptions.

• di-deuterated methanol (CHD2OH)• ALMA-PILSから、IRAS16293-2422 A and Bについて差gした。
• 105のunique lineを同定した。
• D/H比は高い。 7.5

1.1

assumptions, successive deuteration is a robust window on the physicochemical provenance of star-forming systems.

The impact of cosmic-ray attenuation on the carbon cycle emission in molecular clouds

Brandt A. L. Gaches, Thomas G. Bisbas, Shmuel Bialy F Observations of the emission of the carbon cycle species (C,C+ CO) are commonly used to diagnose gas properties in the interstellar medium but are significantly sensitive to the cosmic-ray
ionization rate. The carbon-cycle chemistry is known to be quite sensitive to the cosmic-ray ionization rate, ⇣, controlled by
the flux of low-energy cosmic rays which get attenuated through molecular clouds. However, astrochemical models commonly
assume a constant cosmic-ray ionization rate in the clouds. We investigate the eﬀect of cosmic-ray attenuation on the emission ofcarbon cycle species from molecular clouds, in particular the [CII] 158 µm, [CI] 609 µm and CO (J = 1 - 0) 115.27 GHz lines. We
use a post-processed chemical model of diﬀuse and dense simulated molecular clouds and quantify the variation in both column
densities and velocity integrated line emission of the carbon cycle with diﬀerent cosmic-ray ionization rate models. We findthat the abundances and column densities of carbon cycle species is significantly impacted by the chosen cosmic-ray ionization
rate model: no single constant ionization rate can reproduce the abundances modelled with an attenuated cosmic-ray model.
Further, we show that constant ionization rate models fail to simultaneously reproduce the integrated emission of the lines weconsider, and their deviations from a physically derived cosmic-ray attenuation model is too complex to be simply corrected.
We demonstrate that the two clouds we model exhibit a similar average AV,e↵ – nH relationship, resulting in an averagerelation between the cosmic-ray ionization rate and density ⇣(nH ). We conclude by providing a number of implementation
recommendations for CRs in astrochemical models, but emphasize the necessity for column-dependent cosmic-ray ionization
rate prescriptions.

• C, C+, COはよく使われるが、これらは宇宙線による電離の影響を受ける。これを理論的に調べた。

5• 一定電離率モデルはよくない• 化学モデルにちゃんとCRモデルを使いましょう