2 12
#


#

-1

53



2

entative frequency and frequency coverage of each
A band used in the synthetic multiband analysis in GHz.

1

2

3

Bands [3, 4, 5, 6, 7, 8, 9, 10] as one band set. Then, at a given

The Synthetic ALMA Multiband Analysisof theof the TWto Hya
which corresponds
the range ofradius, we
set Dust
Iν,syn,Properties
ProtoplanetaryDisk(100%  x ) IO ,model - IO ,syn - (100% x ) IO ,model for ν=ν1

1
1
2
andTsukagoshi
ν2, where
accuracyof amplitude
calibration
for ALMA
Kim, Hideko
Nomura, Takashi,theRyoheiKawabe2,3,4, and Takayuki
Muto5
he Model Radial Intensity Seongjoong
Proﬁles
at
Each
ALMA
Band
1
Department of Earth and Planetary Sciences, Tokyo InstituteofTechnology,
2-12-1
Ookayama,
Meguro-ku,
Tokyo
152-8551,
Japan
data x=10% for Bands 3, 4, 5 and 6; x=15% for Bands 7
2
National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan3
the ﬁrst part of the synthetic multiband
analysis,weand8; and x=20%
Bands
9 andJapan
10 (Warmels et al. 2018,
The Graduate University for Advanced Studies(SOKENDAI),
2-21-1 Osawa, for
Mitaka,Tokyo 181-0015,
4DepartmentofAstronomy,
Schoolof
Science,
UniversityofTokyo,
Bunkyo,Tokyo
113-0033,
Japan
ate theat each• model89 3Hradial
6 intensity
0 %. 6 proﬁlesc ALMAunec
T weShinjuku-ku,
5 0
UO1,syn, UO2,syn, and βsyn from IO1,syn ,p.155).
Next,
derivelTokyo
Division of Liberal Arts, Kogakuin University,
1-24-2 Nishi-Shinjuku,
163-8677,Japan
For theuse K674K24Kpo
thesolutionofc
the 2019 January
Received 2018
September 10;
revisedaccepted
28; published2019 (2)February25• calculation, wewhere
ß27;
cJanuarylwith
IO2,syn,poand 2019
Equations(1) andthe synthetic dust
Bν(Tformal
temperature
Td andd) is the Planck function at dustve transfer
equation for
dustmcontinuum
temperature
• 8Ky
K
Wl
d dustc opticala)surT
frequency
ν andτνemission,is thedepth
for whichTd,syn
we =5–60
adopt K. Then, we estimate IO3,syn using
Abstract
Td,syn, UO1,syn , UO2,syn , βsyn, and Equations (1) and (2). Finally,
Analyzing
multiband
observationsof
dust
continuum
emission is one of the useful tools to constrain dustC
IO (r )  BO (Td (r ))[1 
exp
(

U
(
r
))]
,
(
1
)
U

U
(
O
O
)
(2) of disks.
Oτν,syna, syntheticβsyn] that satisfy
weextract
sets[Td,synO00properties that help us to understand the physical properties of thethe
protoplanetary
We ,performin the disk fromy proﬁles of dust
esolution ALMA
nty of dust size
tures in the disk,
affect the dust
012), more direct
erstanding of thedust temperature.
e proﬁle and then

ALMA multiband analysis to ﬁnd the best ALMA band set for constraining the dust properties of the TW Hya

by disk.
assuming
that
the [10,dust
obeys the power law
We ﬁnd thatthe Band6, 3]opacity
set is the
2 best set among the possible combinations of ALMA Bands [3, 4, 5,
β
6, 7, 8,.9, In
10]. thisWe alsoﬁnd twofor thegood ALMA
providing narrow constraint ranges onκν∝ν
case,
theconditions
spectralindex
α ofbandthesetsdust
dust properties: (1) Band 9 or 10 is included in the band set, and (2) there are enough frequency intervals between
continuum
can bewrittenas that give good constraints on dust properties: the combination of
the bands. emission
These are related
to theconditions
optically thick and thin bands is required,andlarge β (β is the power-law index of dust opacity, κν∝ν β) and low
h
O
k
T
(
r
)
B d
O
eTo examine(r ) results, we apply the multiband analysis todust temperature are h
preferable.
our syntheticUOanalysis
B
(
r
)

3

C
, [9,
(36,) 4] set provides the dust properties
ALMA archival data
of
the
TW
Hya
disk
at
Bands
4,
6,
7,
and
9.
The
Band
h
O
k
T
(
r
)
U
(
r
)
B
d
O
k B Td (rwhile) e the Band [7,6,14] set gives
e the dust
 1properties deviating from the model at all radiiclose to the model proﬁle,with too broad a constraint range to specify the accurate values of dust temperature, optical depth, and β. Since
wheretheexpectedBoltzmann
constant
andanalysis,
h is wetheconﬁrm
PlanckB is arethese kfeaturesby the synthetic
multibandthat the synthetic multiband analysis isconsistentWe
with notethe results
real data.
constant.
thatderived
we from
simplyassume that the source

Key words:
protoplanetarydisks – stars: individualfunctionis methods:Sν=Bobservational
dust temperature
Td and(TW Hydrae)
ν(Td) and – theabsorption coefﬁcient κνρd (ρd is the dust density) are constant
The origin of gap structures in the TW Hya disk is also stillalong the line 1.ofIntroduction
sight in Equation (1) for simplicity.
under
we deriveALMA
the frequency-independent
radialdebate.
proﬁles
SinceFirst,
the high-resolution
observation of HL Tau
Dust properties, such as dust temperature Td, dust opacity κν,(ALMAPartnershipet al. 2015),
has been
one of the (1)–(3) and theτ0,model(r) andβmodelTW(r)Hyausing
Equationsand dust opacity power-law index β, are the key parameters to
representative protoplanetary disks (PPDs) that have axisymobserved
radialintensity
proﬁles,I(r),
andspectraldistinguish index,
the models explaining the origin of those disk
metric ringed structure. The central star of TW Hya isobs
a T Tauristructures.
They
αobsa(r),at ∼0.8
190
together
the assumption ofare expected to behave differently in disk
(Andrews
et al. 2012).with
The gasstar withmass ofMeGHz,

(100%  x ) IO3,model - IO3,syn - (100% x ) IO3,model . Performing these calculations for every radius, we obtain the minimum
and maximum values of Td,syn, τν,syn, and βsyn, which correspondto (100%  x ) IO ,model - IO ,syn - (100% x ) IO ,model at threefrequencies, ν=[ν1, ν2, ν3], as shown in Figure 2.

3. The Results of the Synthetic ALMA Multiband Analysis

in the synthetic intensities between 20 and 45 au, as shown in
Figure 2, we calculate the average normalized deviation ofTd,syn,max from Td,model for quantitative comparison. Figure 1
presents examples of the averaged normalized deviationof Td,syn,max from Td,model within 20 au<r<45 au, thatauis, (1 /n 20  45 au ) r45 20
au (Td,syn,max (r )  Td,model (r )) / Td,model (r ),where n20–45 au is the number of grids among r=20–45 au.
The bottom left triangle shows the results for the Band [10, x1,y1] sets, and the top right triangle shows those for the Band [x2,y2, 3] sets, where x1=[9, 8, 7, 6, 5, 4], y1=[8, 7, 6, 5, 4, 3],x2=[10, 9, 8, 7, 6, 5], and y2=[9, 8, 7, 6, 5, 4]. According to
the calculation, the Band [10, 6, 3] set gives us Td,syn,max, which
deviates ∼21% from Td,model, on average, within 20 au<r<
45 au. It is the best band set among all 56 possible band sets.
Based on the analysis in Figure 1, Figure 2 shows theconstraint ranges of the synthetic dust properties of four good
ALMA band sets ([10, 7, 3], [10, 6, 3], [9, 7, 3], and [9, 6, 3])
and one bad ALMA band set ([7, 6, 3]) as examples selected

(top)
opac
sets
the d
[9, 6
show
the m

from
tem
τB3,
βsyn
plot
Ban
set,
blac
proﬁ
τB3,

3.1. The Synthetic Multiband Analysis Results
We perform a synthetic ALMA multiband analysis (seeSection 2) for all possible combinations of three bands among
ALMA Bands 3–10. Among a total of 56 possible combinations, some ALMA band sets provide us narrow constraint
ranges on the radial proﬁles of Td,syn, τν,syn, and βsyn, while theothers have very broad constraint ranges on the synthetic dust
properties. Since the upper limit of the synthetic dust
temperature (Td,syn,max) is sensitive to the observational errors
in the synthetic intensities between 20 and 45 au, as shown in
Figure 2, we calculate the average normalized deviation ofTd,syn,max from Td,model for quantitative comparison. Figure 1
presents examples of the averaged normalized deviationof Td,syn,max from Td,model within 20 au<r<45 au, that3

LETTER TO THE EDITOR

Resolving the MYSO binaries PDS 27 and PDS 37
with VLTI/PIONIER
E. Koumpia1 , K. M. Ababakr10 , W. J. de Wit2 , R. D. Oudmaijer1 , A. Caratti o Garatti3 , P. Boley4,5 , H. Linz6 ,S. Kraus7 , J. S. Vink8 , and J.-B. Le Bouquin9,?

•
•
•

1c
3 ,
9 7

d

R B
0
/
HKE
3 (,
7 ;74> 6 DC F

SP ue
~
ca
.( HKE ,8
9LM
OI (CM 9 c
R5 77 2C 77Se

School of Physics and Astronomy, E.C.LM
Stoner Building, University of Leeds, Leeds LS2 9JT, UKe-mail: ev.koumpia@gmail.com)
19001, Santiago de Chile, Chile
LM 23 ESO Vitacur, Alonso de Córdova 3107 Vitacura, CasillaLM
Dublin Institute for Advanced Studies, Astronomy & Astrophysics Section, 31 Fitzwilliam Place, Dublin 2, Ireland
4
Moscow Institute of Physics and Technology, 9 Institutski per., Dolgoprudny 141701, Russia
5A&A
623,Federal
L5 (2019)
Ural
University, 51 Lenin Ave., Ekaterinburg 620075, Russia
6
Max Planck Institute for Astronomy, Königstuhl 17, 69117 Heidelberg, Germany
7
University of Exeter, School of Physics, Astrophysics Group, Stocker Road, Exeter EX4 4QL, UK
8
Armagh Observatory and Planetarium, College Hill, Armagh BT61 9DG, Ireland
9
Université Grenoble Alpes, CNRS, IPAG, 38000 Grenoble, France
10Erbil Polytechnic University, Kirkuk Road, Erbil, Iraq
1

Received 12 November 2018 / Accepted 20 February 2019
ABSTRACT
Context. Binarity and multiplicity appear to be a common outcome in star formation. In particular, the binary fraction of massive(OB-type) stars can be very high. In many cases, the further stellar evolution of these stars is a↵ected by binary interactions at somestage during their lifetime. The origin of this high binarity and the binary parameters are poorly understood because observational
constraints are scarce, which is predominantly due to a dearth of known young massive binary systems.
Aims. We aim to identify and describe massive young binary systems in order to fill in the gaps of our knowledge of primordial
binarity of massive stars, which is crucial for our understanding of massive star formation.
Methods. We observed the two massive young stellar objects (MYSOs) PDS 27 and PDS 37 at the highest spatial resolution provided
by VLTI/PIONIER in the H-band (1.3 mas). We applied geometrical models to fit the observed squared visibilities and closure phases.
In addition, we performed a radial velocity analysis using published VLT/FORS2 spectropolarimetric and VLT/X-shooter spectroscopic observations.
Results. Our findings suggest binary companions for both objects at 12 mas (30 au) for PDS 27 and at 22–28 mas (42–54 au) for
PDS 37. This means that they are among the closest MYSO binaries resolved to date.
Conclusions. Our data spatially resolve PDS 27 and PDS 37 for the first time, revealing two of the closest and most massive (>8 M )YSO binary candidates to date. PDS 27 and PDS 37 are rare but great laboratories to quantitatively inform and test the theories onformation of such systems.
Key words. stars: formation – binaries: close – techniques: interferometric – stars: individual: PDS 27 – stars: individual: PDS 37 –stars: pre-main sequence

1. Introduction
In recent years, substantial progress has been made in the fieldof high-mass star formation. The various theoretical scenarios proposed for high-mass star formation suggest that massis accreted through a circumstellar disk (Jijina & Adams 1996;

hydrodynamical simulations establish that disks are viableagents for accretion (e.g., Rosen et al. 2016; Klassen et al. 2016;
Kuiper & Hosokawa 2018). For a review on the topic, see
Beltrán & de Wit (2016), Hartmann et al. (2016).
Although the formation of massive individual stars is becom-d0) CM
V

LETTER TO THE EDITOR

Resolving the MYSO binaries PDS 27 and PDS 37
with VLTI/PIONIER

dE. Koumpia1 , K. M. Ababakr10 , W. J. de Wit2 , R. D. Oudmaijer1 , A. Caratti o Garatti3 , P. Boley4,5 , H. Linz6 ,78, J. S. Vink , and J.-B. Le Bouquin
E. Koumpia et al.: Resolving the MYSO binaries PDS 27 and PDS 37 S.
withKraus
PIONIER

9,?

1

School of Physics and Astronomy, E.C. Stoner Building, University of Leeds, Leeds LS2 9JT, UKe-mail: ev.koumpia@gmail.com
2
ESO Vitacur, Alonso de Córdova 3107 Vitacura, Casilla 19001, Santiago de Chile, Chile
3
Dublin Institute for Advanced Studies, Astronomy & Astrophysics Section, 31 Fitzwilliam Place, Dublin 2, Ireland
4
Moscow Institute of Physics and Technology, 9 Institutski per., Dolgoprudny 141701, Russia )5
Ural Federal University, 51 Lenin Ave., Ekaterinburg 620075, Russia
6
Max Planck Institute for Astronomy, Königstuhl 17, 69117 Heidelberg, Germany
7
University of Exeter, School of Physics, Astrophysics Group, Stocker Road, Exeter EX4 4QL, UK
8
Armagh Observatory and Planetarium, College Hill, Armagh BT61 9DG, Ireland
9
Université Grenoble Alpes, CNRS, IPAG, 38000 Grenoble, France
10Erbil Polytechnic University, Kirkuk Road, Erbil, Iraq

• 315 )-e s
woae
* 7
2
Fig. 2. Best-fit geometrical models (panel a) flattened ring (Red.
binary (R0() T ⇠r10) )and0( (panel
TmT b)cR
visibilities (V 2 ) and closure phases of PDS 27. The black •points
observ+ D with
9= verticalT
0 error0 bars are
% the
n~

a representative best-fit model. The two models show a similar fit, and therefore we show model b as•
, ,%()
%(, 7
•
e s
wob
p u
ABSTRACT•97et D 7 d. Binarity and multiplicity appear to be a common outcome in star formation. In particular, the binary fraction of massive
Assuming that theContext
extendedH-bandemission
is
due
to
hot
directly
test
the*theories o(OB-type) stars can be very high. In many cases, the further stellar evolution of these stars is))a↵ected aby binary interactions
at someRkghstage during their lifetime. The origin of this high binarity and the binary parameters are poorly understood because observational
constraints
are scarce,is predominantly due to a dearthTheof known young
massive binary systems. wavedust, the angular sizes
canbewhichestimated.
PIONIER7h R ( tion disk fragmentation
Aims. We aim to identify and describe massive young binary systems in order to fill in the gaps of our knowledge of primordial
binarity of massive stars, which is crucial for our understanding of massive star formation.
à37 at=the highest= spatial
7radid7 theoreticalTlength range (1.533 µm–1.772
is stellar
sensitive
thermalsupportthepr
Methods. We observed the µm)
two massive young
objects (MYSOs) PDSto
27 and PDS
resolution provided
Received 12 November 2018 / Accepted 20 February 2019

by VLTI/PIONIER in the H-band (1.3 mas). We applied geometrical models to fit the observed squared visibilities and closure phases.
In addition,
performed
radial (Red.
velocity2 analysis
using published
VLT/FORS2
2
Fig. 2. Best-fit geometrical models (panel a) flattened ring (Red.
⇠ 10)weand(panel b)abinary⇠ 12)) comparedwith theobserved spectropolarimetric and VLT/X-shooter spectroobservations.
visibilities (V 2 ) and closure phases of PDS 27. The black pointsscopic
with verticalerror bars are the observed data, and the blue triangles correspond to
Results. Our findings
suggestbinaryforfit.
both objects at 12 mas (30 au) for PDS 27 and at 22–28 mas (42–54 au) fora representative best-fit model. The two models show a similar fit,
and therefore
we showmodelb as acompanions
representative
PDS 37. This means that they are among the closest MYSO binaries resolved to date.
Conclusions. Our data spatially resolve PDS 27 and PDS 37 for the first time, revealing two of the closest and most massive (>8 M )binarydirectly
candidates
PDS of27youngand PDS
37 arerare but greatlaboratories
2
Assuming that the extended H-band emissionis dueYSO
to hottest tothedate.
theories
binaryformation
throughaccre- to quantitatively inform and test the theories onformationofsuchsystems.
dust, the angular sizes can be estimated. The PIONIER wave- tion disk fragmentation (Meyer et al. 2018). Our finding mightation of the dust in the temperature range 1500–2000 K. The nel as a possible mecha
angular distance of thefromstar canbinaries (<10 au), having• 4 dust
K()%(*4 the
0(-,
2 then0(, be2 estimated
8 7
R? T ?
• 0( - 7 * ) 7 315 *- ( , 7 * . 7 315 )- component. Such system
using
d
=
,
where
d
is
the
distance
of
the
dust
from
the
2
2 is sensitive
length range (1.533 µm–1.772 µm)
radisupportthetheoreticalpredictions
of
the
disk
fragmentation
chanT d to thermal• 315 )-drnkb 0( * 7 acRation of the dust in the temperature range 1500–2000 K. The nel as a possible mechanism for the formation of close MYSO
theTh
short-period (<10 d)angular distance of the dust from the star can then be•estimatedbinaries(<10au), having
a high-mass
and an accreting low-mass
315
*b
0*
.
7
Rutyi
8
d
star,
R?
and
T
?
are
the
radiusandtemperature
of
the
star,
and
T
d
using d =, where d is the distance of the dust from the component. Such systems are expected to be the progenitors of
Future interferometr
the short-period
massive spectroscopic
binaries.
Introductionhydrodynamical
simulations P
establish thatdisks are l
viableàe(<10 d)dn(e.g., VLTI)
b37
Sk
ac
star, R? and T ? are the radius and temperature of the1.star,and T disthedusttemperature.
The
stellar
PDS
and
PDS
27
Futureinterferometric radii
observations of
of
PDS
27
is the dust temperature. The stellar radii of PDS 37InandPDS years,
27 substantial progress has been made in the field agents for accretion (e.g., Rosen et al. 2016; Klassen et al. 2016;
recentand PDS 37 will provide a more complete uv-plane,
which
is
and
PDS 37 will provid
Kuiper& Hosokawa2018). For a review on the topic,see
are ⇠13 R and ⇠11.7 R , respectively (Vioque ofet al.
2018),
high-mass starformation.
Thebettervarioustheoretical scenarnecessaryforthecharacterizationofthesystems.
The
Beltrán
&deWitet(2016),
Hartmann
et al. (2016).
are
⇠13
R
R
,
respectively(Vioqueal.
2018),
while
their temperatureis ⇠17 500and
K (Ababakr⇠11.7
et al.
2015).
For
ios proposed forhigh-mass
mass
additional
datastar
willformation
make it suggest
possible thatto constrain
theAlthough
circum- the formation of massive individual stars is becoma dust temperature of 1500 K (graphite grains), an isangulardustthrough a circumstellar disk (Jijina & Adams 1996;
necessary for the betteaccretedstellar and circumbinary environment of the two components of
Key words. stars: formation – binaries: close – techniques: interferometric – stars: individual: PDS 27 – stars: individual: PDS 37 –stars: pre-main sequence

R? T ?2
2 T d2d

Gaia-2MASS 3D maps of Galactic interstellar dust within 3 kpc
R. Lallement1 , C. Babusiaux2, 1 , J.L. Vergely3 , D. Katz1 , F. Arenou1 , B. Valette4 , C. Hottier1 , and L. Capitanio1
1

l

•
A
• (71
•
•
• (,
T4
•
•
•
•
•

y

O

O

l2

i

g
S

rps o
O n
l
s ABSTRACTi S gfT4

O

gO
C % =sGaia stellar measurements are currently revolutionizing our knowledge of the evolutionary history of the Milky Way. 3D maps of theinterstellar dust provide complementary information and are a tool for a wide range of uses. We aimed at building 3D maps of thedust in the Local arm and surrounding regions. To do so, Gaia DR2 photometric data were combined with 2MASS measurements toderive extinction towards stars that possess accurate photometry and relative uncertainties on DR2 parallaxes smaller than 20%. We
applied to the individual extinctions a new hierarchical inversion algorithm adapted to large datasets and to a inhomogeneous target
distribution. Each step associates regularized Bayesian inversions along all radial directions and a subsequent inversion in 3D
of all their results. Each inverted distribution serves as a prior for the subsequent step and the spatial resolution is progressively
increased. We present the resulting 3D distribution of the dust in a 6 x 6 x 0.8 kpc3 volume around the Sun. Its main features are foundto be elongated along di↵erent directions that vary from below to above the mid-plane: the outer part of Carina-Sagittarius, mainly>??
located above the mid-plane, the Local arm/Cygnus Rift around and above the mid-plane and the fragmented Perseus arm are oriented
close to the direction of circular motion. The more than 2 kpc long spur (nicknamed the split) that extends between the Local Arm
and Carina-Sagittarius, the compact near side of Carina-Sagittarius and the Cygnus Rift below the Plane are oriented along l⇠40 to
55 . Dust density images in vertical planes reveal in some regions a wavy pattern and show that the solar neighborhood within ⇠500
pc remains atypical by its extent above and below the Plane. We show several comparisons with the locations of molecular clouds,
HII regions, O stars and masers. The link between the dust concentration and these tracers is markedly di↵erent from one region tothe other.

(

+C
am
n
54 BE
.M )
caO
P

s

iv:1902.04116v1 [astro-ph.GA] 11 Feb 2019

s

s
uP 3
s

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O
7 /+ OG AEDn()s ceu
1 8 55 gn
O

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m

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1 8 55•••

GEPI, Observatoire de Paris, PSL University, CNRS, 5 Place Jules Janssen, 92190 Meudon, France e-mail:rosine.lallement@obspm.fr
2
Univ. Grenoble Alpes, CNRS, IPAG, 38000 Grenoble, France
3
ACRI-ST, Sophia-Antipolis, France
Fig. 3. Dereddened Hess diagram for a subset of stars with a paralla
4
ISTerre, Université Grenoble Alpes, France
relative uncertainty smaller than 10%. The grey scale corresponds to thsquare root of the stellar density. The Red Clump is the most promine
Received ; acceptedfeature which shape can be compared to Fig. 2 of Ruiz-Dern et a(2018).

OS

Key words. Dust: extinction;s‒g ISM: lines and bands; ISM: structure
O+ ; ISM: solar neighborhood) ; ISM:( Galaxy+ (+ =O
P f
Fig. 4. Comparison between the extinction A derived here and A d
1. Introduction
One form of 3D mapping of dust is the construction ofra- by Santiago et al. (2016) using APOGEE data.
terminedv sgag dial profiles of color excess
v or SOextinction, sightline by sightline. The first map produced in such a way was based on Hipmodels of the f
Milky Way require measurements+ parcoslPEvolutionaryg) ((Arenou
Oet al. 1992). Later on, maps of radial profiles
residuals) outliers, as illustrated in Fig. 1. The bright stars caof the spatial distribution of massive numbers of stars as well and their derivatives, i.e. reddening or extinction per unitibration
dis- is done using stars with G < 10.5 and is applied to a
dynamical, physical and chemical
properties, T4
all quan- tance, were built by GAEGO> A D AD astities>Gtheircurrently
AEDf‒stars with G < 11 mag. The colour range of our calibration
Marshall et al. (2006), Chen et al. (2013)provided by the ESA satellite Gaia (Gaia Col- and Schultheis et al. (2014) based on the Besançon model1.0of< (G K) < 5.6.
laboration P
et al. 2016, 2018b) and ground-basedt surveys. In this stellar tssynthesis (Robin et al. 2012)gand 2MASS,e The extinction coefficients
0SOare derived using the Fitzpatricpopulation
context, three-dimensional (3D) maps of the Galactic interstel0V0lar (IS) dust are an additional and mandatory tool since they allow de-reddening of stellar spectra and suppression of degeneracies between stellar temperature and dust reddening on the
one hand, and, on the other hand, since they may shed important
additional light on the star formation through the inter-play be-(2007) extinction law and the Kurucz Spectral En
GLIMPSE and VVV photometry, respectively. Majewski &et Massa
al.
ergy Distributions (Castelli & Kurucz 2003), as described(2011) derived individual stellar reddening and radial profiles
et al. (2018). The 2MASS transmissions are takeby combining SPITZER/GLIMPSE and 2MASS. Berry Danielski
et al.
(2012) used SDSS and 2MASS to constrain stellar SEDsfrom
andCohen et al. (2003) and the Gaia transmissions are thos
Weiler (2018). We are selecting here only the top of the HRD
reddening profiles using reddening-free empirical spectra.ofFolWe therefore adapted the surface gravity of the Kurucz spe
lowing a hierarchical Bayesian method devised by Sale (2012),

Gaia-2MASS 3D maps of Galactic interstellar dust within 3 kpc
R. Lallement1 , C. Babusiaux2, 1 , J.L. Vergely3 , D. Katz1 , F. Arenou1 , B. Valette4 , C. Hottier1 , and L. Capitanio1
1

GEPI, Observatoire de Paris, PSL University, CNRS, 5 Place Jules Janssen, 92190 Meudon, France e-mail:rosine.lallement@obspm.fr
2
Univ. Grenoble Alpes, CNRS, IPAG, 38000 Grenoble, France
3
ACRI-ST, Sophia-Antipolis, France
4
ISTerre, Université Grenoble Alpes, France
Received ; accepted
ABSTRACT

Gaia stellar measurements are currently revolutionizing our knowledge of the evolutionary history of the Milky Way. 3D maps of theinterstellar dust provide complementary information and are a tool for a wide range of uses. We aimed at building 3D maps of thedust in the Local arm and surrounding regions. To do so, Gaia DR2 photometric data were combined with 2MASS measurements toderive extinction towards stars that possess accurate photometry and relative uncertainties on DR2 parallaxes smaller than 20%. We
applied to the individual extinctions a new hierarchical inversion algorithm adapted to large datasets and to a inhomogeneous target
distribution. Each step associates regularized Bayesian inversions along all radial directions and a subsequent inversion in 3D
of all their results. Each inverted distribution serves as a prior for the subsequent step and the spatial resolution is progressively
increased. We present the resulting 3D distribution of the dust in a 6 x 6 x 0.8 kpc3 volume around the Sun. Its main features are foundto be elongated along di↵erent directions that vary from below to above the mid-plane: the outer part of Carina-Sagittarius, mainly
located above the mid-plane, the Local arm/Cygnus Rift around and above the mid-plane and the fragmented Perseus arm are oriented
close to the direction of circular motion. The more than 2 kpc long spur (nicknamed the split) that extends between the tendsarm