星形成ゼミ	
  2016/12/2	
  SFN	
  #286	
  11-­‐15		
  長谷川哲夫（国立天文台）	

(Kharchenko
et al 2013).
Out of thefunctions
total 341 clusters,
175 parameters.
ofbuilt with various
distributionof the IMF
The synthe
the fraction of ”lonely” O stars in the clusters. A lonely
them
containpopulation,
at least one stellar
O star evolution,(M∗ ! 15 Msample
num! ). Theincompleteness,the binaryand ejected
O star in a cluster is a single O star with the additionalberof single andoflonely
O stars
in the observational
sampledistributions
the IMFparameters
are requiredin order to reproduce th
http://arxiv.org/pdf/1609.04858
constraint that the next massive system in the cluster is less
Variations
the
IMF
in
the
Milky
Way
3the existence of a clu
isGalactic
NO,singleclusters.
= 89ofandN=
29,
respectively,
andtheO,lonely
They also do not lend support to
Variations omassive than 10 M! (i.e., absence of high mass B stars with
total
number ofstars is NO formulation= 688. Thus,ofthe
We proposeaO
probabilistic
thefractions
IMF whereby the paramete
massesbetween10and15M! ). The fraction of lonely Oτ15single
is theanddurationof starthe inHydrogenandcatalog
Heliummeasured
burningin a cluster is called ”single” if it is the only living star, or aoflonelyO
the Way
MWSC
Massive stars reveal
variationsof the stellar initial mass function
the
Milky
distributionfunctionscenteredaround= 0.91,
0.4
theduratiina cluster isincalled”single”
if it isthe only γliving
star,Γor=a 1.37, τandstars
is system
given
by:
ch =
15 isM
phasesEq.
for 1aandstarEq.
witha massof 15
M! (Ekströmal.
binarywith any of its components, that has a mass
using
2 are
fO,single(MWSC)= 12.9%etandstellar clusters ! 15 M! in the cluster. The fraction of single O stars3 in aphases for a starbinarysystemwithanyof0.27its components,thathasvalues.
a mass
σ
=
0.60,
and
σ
=
M
around
these
Γ
M
"
ch
This
brings=down
f2012).
(MWSC)
4.2%.the number of clusters useful for2012). This bring!O,lonely
15 M! in the cluster. The fraction of single O stars3 in a
5
N3,4
our
purposes
the MWSC to NMWSC,cl = 341. The inpopulationofclusters
thus given
by:O,lonelySami Dib1,2 , Stefan
Schmeja
and, is
Sacha
Hony
Accepted
byinMNRAS
fO,lonely=(2)
our purposes in
population of clusters is thus given by:dividual stellar masses are estimated from the relation beN
1
Niels Bohr Institute & Centre forOStar and Planet Formation, University of Copenhagen,ØsterVoldgade
5-7,
DKdividual
stellar m
http://arxiv.org/pdf/1605.08438
tween
logM∗ and the absolute visual magnitude MV given
NO,single
4
MODELS
where
NO,lonelyis thetween logM∗ and
1350, Copenhagen, Denmark.
fO,single=, total number of lonely stars in the(1)NO,singleby
Schilbachetal.
(2006).
The
absolutemagnitude
M
is
–	
  if	
  t=he	  O	
  star	  ,(or	  binary)	
  is	
  the	
  only	  living	
  sVtar	  NoOf	
  ideaParameters	  the	
  sDepartamento
hape	
  
the	
  
for	
  
the	
  
fO,single(1)
clusters.
The basic
ofIMF	  the method
relies on the compari- “single”	
  2 that	  describe	  by Schilbach et a
Unidad de Astronomı́a,deFisica,Universidad
de Atacama, Copayapu
485,
Copiapo,Chile.magnitude
4.1
Generatingof zero-age
clusters
Nthe
O populations
computed
fromapparent
mV , thedistance,
son
of
f
and
f
measuredforarecentcatalogue
Variations
O,singleO,lonely
with	
  
>
=15	
  
M
sun	
  
3 of	
  young	  GalacBc	
  
where
N
is
the
total
numberofsingle
O
stars
and
N
computedfrom toO
O,single
populaBon	
  clusters:	  	
  Astronomisches Rechen-Institut, Zentrum für Astronomie der Universität Heidelberg,Mönchhofstraße
12-14,
69120
andtheNextinction
EB−Vareallsingle
listedOinstars
the and
MWSC
where
is thetotalwhich
numberofNOO,single ofofstellarMilkyWaywith thosederivedfor “lonely”	
  The
possibility
detectingmassive
O
stars
in
the
Galaxyis thetotalclusters
numberinofthe
O stars
in allclusters.
We alsomeasureandtheextinctio	
  the	
  numbersingle	
  
O
star	
  
(or	
  
inary)	
  
ith	
  
talso
he	
  n
ext	
  
(Kharchenko
et al 2013).
Out
of b
the
total w
341
clusters,
175 ofHeidelberg,
is the–total
of 	
  O
stars
in
all
clusters.
measure12τ(Kharchenko• Slopes	
  in	
  the	
  lGermanyow	
  and	  igh	
  stellar	
  mclustersass	
  egimes,	  γclusters.
	  and	
  Γwith,	
  A lonely
populations
ofofstellar
thatinaregeneratedvariisbyistherelatively
short
of We
these
stars
anda
thehfraction”lonely”
O rstarsthe
et ain bounda clustercalled”single”
if it lifetimeisthe!onlylivingstar,numor
15 is the durati
4
them
contain
at
least
one
O
star
(M
15
M
).
The
∗
!
Technische Informationsbibliothek,Welfengarten
1b,
30167
Hannover,
Germany
massive	  system	
  
<
10	
  
M
sun	
the
fractionof”lonely”
O
stars
in
the
clusters.
A
lonelyous
priorfunctionsforthedistributions
of
the
IMF
parameby
the
value
of
the
Galactic
starformation
rate(SFR).
The
O
star
in
a
clusterisasingle
O
star
with
the
additionalthemcontainat lphasesforastarbinarysystem
with
any
of
its
components,
that
has
a
mass
5
respecBvely	  berof single
lonelystars intheobservational
sampleOHeidelberg,
star
in stellar
a andclusterisÜberle-StraßeaOthatsingleO comparedstar2,
with totheadditional
Institut für Theoretische
Astrophysik,
ZentrumfürAstronomie
derapplied
UniversitätAlbert3ters.
A numberof important
corrections
havebemodelsofclustersaretheobservaconstraintthat thenext
massivesysteminthe tocluster
is lessberof
singleand2012).
This
bring
in
a
!
15
M
in
the
cluster.
The
fractionofsingle
O
stars
!
is
No
= 89
NO,lonely
29, respectively,
theO,single
constraintthatthemassiveinmong	  the cluster
is lessf	
  are“single”	
  
oand
r	
  next“lonely”	
  O=system	
  stars	
  
O	
  and
sthat
tars	
  
69120 Heidelberg,
Germany.
toclusters ofandto mass
their Bstellar
con-FracBon	  • CharacterisBc	
  mass,	  Mthe	
  than 10 synthetic
tions
generatedinthefollowing
way:aassuming
allin	  massive
M! (i.e., absencehighstars withis NO,single
89
our
purposes= in
populationof ofclusters
is
thus
given
by:
ch.	
  zero-age
total
number
O!stars
isabsence
NO
= of
688.
Thus,
the
fractionsmassivethan
10M(i.e.,
high
mass
B
stars
with
tent
beforetheycanbecomparedtotheobservations.
The
stars
form
in
clusters,
the
total
mass
contained
in
the
young
a	
  
p
opulaBon	
  
o
f	
  
c
lusters	
massesbetween
10
and
15
M
).
The
fractionoflonelyO
totalnumberof!
dividualstellarm
E-mailat gmail.com
ofsinglebetween
and lonely
star
MWSC
catalogThe	
  method	  	
   contact: sami.dib
masses10 O
and
15inMthefractionof measured
lonelyO! ). Thethat
descriptionof by:
the observational sample of clusters is given
populationof
Galactic
stellarclusters
arelikely,basedstars is givenofsingle
and
lone
tween
logM
and
∗
using
1 NandEq.
2 are fO,single(MWSC) = 12.9% andO,single
isEq.
given
by:containWeexclusively	
  investigate whether
stellarinitialmassfunction(IMF)
is described
universal, or whetheritsignificantly
amongfstars= varies, O stars (M(1)§. the3,hwhile
theass	  syntheticmodelsare• relies	
  on	
  inthe	
  
igh	
  
m
content	  of	
  oftclustershe	
  clusters,	
  
on
their
age,
to
O,singleusing
Eq. 1 and∗ ! 15 M! ) is given by:
by
Schilbachet afO,lonely(MWSC)NO = 4.2%.
young stellar clusters
the MilkyWay.
We
proposeamethodtouncover
the
range
of
variationoftheparameters
in in
§. 4.
f
(MWSC)
O,lonelyNcomputedfrom tO,lonelybut	
  ithats	
  able	
  
t
o	
  
y
ield	
  
i
nformaBon	
  
o
n	
  
t
he	
  
d
istribuBons	
  
o
f	
  
!NO,single
fO,lonely= IMF for, the population of young Galactic(2)clusters.
whereis the total number of single O stars and NO
NO,lonelyτ15 parametersdescribe the shapeof theThese
and the extinctioNO
fO,lonely= SFR(t) × ,dt, are the slopes
(2)
Σ
=
(3)
is
the
total
numberof O .stars
in allclusters. We also measureclN
O M
parameters	  escribe	
  
t
he	
  
I
MF	
  
o
ver	
  
t
he	
  
e
nBre	
  
s
tellar	  in the lowthat	
  
and d
high
stellarmass
regimes,γ
andΓ,
respectively,
andthecharacteristic
mass,
The
method(Kharchenko et ach
0
4
MODELS
where NO,lonely is the total number of lonely stars in thethefraction
ofon”lonely”
O stars
in theclusters.
A inlonely4 MODELS
where
N
is
the
total
numberlonelystars
thereliesexclusively
on
the
high
mass
contentoftheclusters,
but
is
able
to
yield
information
the
distributionsof3
OBSERVATIONAL
CATALOGOF
themcontain at lO,lonelyclusters. The basic idea of the method relies on the comparimass	
  range.	
  	
  
where
SFR(t)
is the3200	
  
time
star
formationO
starGeneratinginTheadata:	  cluster
is aofdependent
single
O of
star
with
the
additionalcthe
lusters,	
  azero-age
ge	
  
1	
  M
yr	
  
	
  –rate	
  7	
  Goveryr	
  4.1
populations
clusters
clusters.
basic~idea
methodreliesonthecompariber of single andparameters that describe
IMFandover
the entire
stellarrange.
ThisObservaBonal	  is achievedbycomparingthefractionsofson CLUSTERSof thefO,single
fO,lonelymeasured
formassa recent
catalogue
4.1 Generatinthelast τ15thattimescaleofmassivethe lifetime
ofin theGalaxy.isTheconstraint
the next
systemfor
clusterlessson
ofpossibility
faO,single
and
fge	
  
athe
recentcatalogue• Compare	  the	
  lonely
fracBons	
  oobservationsf	
  Osingle	
  onely	  massive	  O	
  sderivedtars	
  is NO,single = 89• 	
  341	  clusters	
  
wover
ith	
  
asuch
<a 	
  relatively
t15measured	  (12.3	
  MO,lonely
single andmassivestars
inausedand	
  recentcatalogofthethoseMilkyclusters
withlibrary
ofdetecting
simulatedclustersof stellar
clusters
inthelin
Milky
Way
with
for
The
ofM
massive
Oyr)	
  
stars
inBtheGalaxyGalactic
SFR
short
periodofstars
time
can
The
this
paper
come
from
theWayMilkymassivethan
10(i.e.,
absence
of
high
mass
with
!
of boundstellarclustersin the
Milky
Way
with
those
derivedfor
The possibility
total
number ofo
5 Neffects
populationsofthat
are generated
withsynthetic
various
distributionfunctionsoftheparameters.
The
clusters
corrected
the
of
is
the
short
lifetime
ofbe
these
stars
and
	
  =	
  are
8by
9,	
  
N
	
  for
=	
  215
9,	
  
	
  6cl88	  • builta	
  rwithecent	  catalog	  oStellarf	
  the	
  Mstellarilky	
  clusters
W
ay	
  IMF
c(MWSC)
lusters	  beassumedtobe10
constantΣ
canapproximatedWay
Clusters
survey(Kharchenko
etvarial.• NO,	  singleO,	
  lrelatively
onely
O).	
  =
massesbetween
and
Mand
The
fraction
ofwithlonelyO!
populationsofstellarclusters
thataregeneratedvariisboundby theofsingle
and
lone
4
ous
prior
functionsforthedistributions
of
the
IMF
parameby
the
value
ofby:
the
Galactic
formation(SFR).
The
binary population,
stellarevolution,
sampleincompleteness,and ,ejectedstars.
findings
that
broad
by
Σ
SFR×τ
.indicate
We consider
threevaluesrateof theGalactic
2012;
Kharchenko
et al.
2013;
Schmeja
et al. 2014)
which• OfO,	
  
stars
	
  clOur=is	
  ≈1given2.9%,	
  
f15
	
  =	
  distributions
4star
.2%	
  −1
ous
functions
theof theIMF
paramesmodels
ingleprior
O,	
  
lfor
onely
• the
a	
  
l
ibrary	
  
o
f	
  
s
imulated	  clusters	
  
b
uilt	
  
w
ith	
  
v
arious	  by theEq.
value
of th
using
1 and
ters.
A
numberofimportantcorrections
have
to
be
appliedofstellarclusters
thatarecomparedtotheobservadistributions of the lists
IMF∼parameters
arewithrequiredin order∼to1 reproduce
singleandlonelyin areSFR
ofofnumber
0.68,
1, of
and
1.45
M!O
yrstarsthat
thelower,
cen3200 clusters
ages between
Myr and ∼the7	
   fractions
ters. A
importantcorrections
haveto be thatappliedstellarfmodels(MWSC)
O,lonelyof
to thezero-ageclusters
theirstellartions
are upper
generatedin thefollowing
way:theassuming
all
tral,
and
estimates
obtained
from
count
of
young
distribuBon	  uncBons	
  onotf	
  tsynthetiche	
  parameters.	
  	
   velocity
Galacticclusters. fThey
also
do
lend
supportthetoexistenceof aconcluster mass-maximum
stellarmass
relation.
Gyr.
Theclusters
areIMF	  detected
astoanddensity
and
enN
to
the
zero-age
syntheticclusters
and
to
their
stellarcontionsaregeneratO,lonelytent before theycanTwobe compared
to Skythe observations.
TheTotal	
  stellar
form
clusters,
mass
in o
the
m
ass	
  
contained	
  the	
  totalyoung	
  pcontained
opulaBon	  f	
   young
fthe
=in
, the
(2)
O,lonelyobjects
indescribedthein	  
GLIMPSEsurveyof theGalacticplane
hancementsin theMicronSurvey(2MASS)
propose calusters	  probabilistic
offor	  thethe	  IMFAllparametersof stars
IMF
areby
Gaussian
tent
beforethey
comparedto theobservations.
The
stars form in clus
NOcan bestellar• The	
  sWe
yntheBc	
  are	
  formulation
corrected	
  ewhereby
ﬀects	  othef	
  PPMXLthe	
  descriptionof the observational
sampleof clusters
is given
populationof
Galacticclustersthatarelikely,based(Robitaille&
Whitney
2010).
The
individual
clustermasses(Skrutskie
et
al.
2006)
and
the
propermotions
surGalacBc	
  stellar	  clusters	
  
t
hat	
  
a
re	
  
l
ikely,	
  
b
ased	
  
o
n	
  
t
heir	
  
distribution functions
γ = 0.91,
Γ=
andareMdescribed
, and
with
ofstarsσγ =0.25,
description
ofdispersions
theobservational
sampleofMclusters
is givench = 0.41 M"onpopulationof Ga
in centered§. 3, whilearoundthe synthetic
modelsof 1.37,
clusters
their
age,
to
contain
O
(M
!
15
)
is
given
by:
4
MODELS
where
N
is
the
total
numberoflonely
stars
in
the
∗
!
O,lonely
stochasticallysampled
from
the
mass
reservoir
Σcl us(Röser
et aroundal. 2010).
The
survey includes clusters up toage,	
  tarebinary	  populaBon,	  svey
tellar	  evoluBon,	  sample	  σΓ =0.60, and σMch
=
0.27
M
these
values.
in
§.
3,
while
the
syntheticmodelsofclusters
aredescribedo	
  contain	
  
O
	
  
s
tars	
  
(
M
>=	
  
1
5	
  
M
)	
  
	
  
on
their
age,
to c
"
in §. 4.
⊙ relies on the compariclusters.
The cluster
basic ideaof∗	
  function
the method
ing
mass(i.e.,
the mass function ofa distance of ∼ 10 kpc from the position of the Sun with
4.1 Generatinin §.an4.!initial
τ15
incompleteness,	
  
a
nd	
  
e
jected	  O	  stars.	  	  son of fO,single andfO,lonelymeasured
for a recent
catalogue
Accepted by MNRAS! τ15
clusters
birth,ICLMF).
The ICLMF
is taken
to (3)
bea substantial fraction of the clusters being located within aΣcl = at their
SFR(t)
× dt,
ofpower-law,stellarclustersin theMilky
Way with
those derived
forThe
possibilityoabetweentheminimumandmaximumclusterΣ=SFR(0distance
"
1.8
kpc
(see
Figure1inSchmejaetal.
2014).
TheOur	
  ﬁndings:	
  
	
  
cl
http://arxiv.org/pdf/1605.08438
populationsof stellar
clusters
thataregeneratedwith vari3 OBSERVATIONAL
CATALOG
is bound0 by themasses
of
M
and
M
,
and
is
given
by:
files
in the catalog list the B,
V, and J, H,OFK magnitudes ofcl,mincl,max
where
SFR(t) is the time dependent
star formationover
3 Dprior
OBSERVATIONAL
CATALOG• Broad	
  distribuBons	
  eachof	
  tCLUSTERS
he	
  
IMF	
  parameters	
  are	
  required	
  	
  istriburion	  f	
  cluster	  masses	
  
aoft	
  OF
their	
  
brate
irth	
  
ous
functionsofor
the distributions
the
IMF
parameby
the SFR(t)value ofisth
wheretstar in each cluster present in the catalog, along with ICLMF:	
  the CLUSTERS
last τ15 timescale of the lifetime of the Galaxy. The
ters.
A
numberofimportantcorrections
have
to
be
appliedmodelsofτ15
stellar
the
last
time
properties
asinposition,
age,come
clustermembership
dNcl
• No	
  support	
  for	  the	
  eother
xistence	  of	
  suchaused	
  cluster	
  ass-­‐maximum	
  Galactic
SFR overTheobservations
thism
paper
from
the Milky−βsuch a relatively short period of time can=zero-age
Acl × Msynthetic
,
(4)
to
the
to be
their
stellarcon5
tions
are SFR
generatcl usedGalacticove
Theobservationsin clusters
this
paper
from
the Milky
probability,
motions,
when available,
the etspecbeto beconstant
and
Σand
can
approximateddMassumedWay
Stellarproper
Clusters
surveyand,(MWSC)(Kharchenko
al.
cl comeclstellar	
  mass	  relaBon.	
  
	
  
tent
beforetheycanbecomparedtotheobservations.
The
stars
form
in
clus
4
be
assumedtob
12WayStellar
Clusters
survey(MWSC)(Kharchenko
et
al.
tral
type.
The
resolved
stellarcontentofeachcluster
are
by
Σ
≈
SFR×τ
.
We
considerthreevaluesoftheGalactic
2012; Kharchenko et al. 2013; Schmeja et al. 2014) , which
15
cl A
where
constant
given
by: 4is given
cl is the normalization
description
observational
sampleofclusters−1
populationof Gaby Σcl ≈ SFR×τ
2012;ofKharchenko
et1.45al. 2013;
Schmejaal.
2014), whichnot corrected
forItheof thepopulaSFR
0.68,of1,the
and
M! yr
that etarethelower,
cenProposal:	
  a	
  probabilisBc	
  fhowever
ormulaBon	
  of	
  the	  MF	
  lists ∼ 3200
clusters
withageseffects
between∼ 1binary
Myr and∼ 7in§. and3, 3200
while
theestimates
syntheticmodelsof clusters
are describedon
theirage, toSFR
of 0.68,
1, ca
lists
∼
clusters
withobtained
ages
between∼ 1count
Myr
and
∼ 7
tion.
this
work, are
we areinterested
in clusters
that could,
tral,
upper
from
the
of
young
Gyr. In
The
clusters
detectedas densityand velocity
en!
Mcl,max•
parameters	
  with	  Gaussian	  distribuBon	  f
uncBons	
  
	
  
4.
in
§.
tral,
and
upper
e
−β+1
Gyr.
The
clusters
aredetectedasdensityandvelocityenbased
on
their
age,
harborhigh-mass
stars
(M
!
15
M
),
stellarobjects
inthe
GLIMPSEsurveyoftheGalacticplane∗!
hancements in the Two Micron All Sky Survey(2MASS)
Acl × Mcl
dMcl = Σcl .
(5)
! τ15
stellarobjects
inhancements
in
the
Two
MicronAll
Sky
Survey(2MASS)(Robitaille&
Whitney
2010).
The
individual
clustermasseswhich
impliesclusters
younger
than
τ
≈
12.3
Myrs,
where
M
(Skrutskie
et
al.
2006)
and
the
propermotions
PPMXL
sur15
cl,min•Center:	
  	
  γ	
  =	
  0.91,	  Γ	
  =	
  1.37,	
  and	
  Mch	  =	
  0.41	
  M⊙	
  
Σ
SFR(
cl =
(Robitaille&Wh(Skrutskie
et al. 2006)
and themotions
PPMXL
arestochasticallysampledfromproper
the mass
reservoir
Σcl surusvey (Röser et al. 2010). The survey includes clusters up to0•
Dispersions:	
  3aσγdistance	
  =	
  0.25,	
  
σ
	
  
=
	
  
0
.60,	
  
a
nd	
  
σ
	
  
=
	
  
0
.27	
  
M
	
  
	
are
stochasticallyvey(Röseretal.
2010).
The
surveyincludesclusters
up
to
4
ing
initial
mass
the
mass
functionof 1.8	
  3 	
  an
CATALOGOFof ∼ Γ10 kpc from the position
Mch of the Sun⊙ withM
5OBSERVATIONAL
x10
	  Mcluster,	
  Mcl,min	
  =function	
  5SFR0,	
  2cannot0,	
  (i.e.,
10	
  be
M
beta	
  
=constant
	
  2,	
  2.2,	
  
5 	
  =
⊙,	
  reality
where
is t
instantaneousinaSun
For simplicity, we will use the term ”star” to define both indi- cl,max
ing an SFR(t)initial clus
a The
distanceof ⊙∼ birth,
10Galactic
kpcICLMF).
fromtheThepositionof isthewithclusters
at their
ICLMF
taken
to
be
CLUSTERSa substantial fraction of the clusters being located within a
the
last
τ
time
(i.e.,
thebirthofsinglemassivestar
inthe
Galaxy
will
boost
the
vidual stars or binary systems
15
clustersattheirbfraction ofclusters being
located withina substantial
power-law, between
thetheminimum
and maximum
clustera" 1.8 kpc (see Figure 1 in Schmeja et al. 2014). The
4distance
The
full
list
of
clusterparametersisavailSFR),
but the assumption
is thismadepaper
here thatthefromtime thedependent
Galactic
SFR betoveTheobservations
used
in
come
Milky
a
power-law,
distance
"
1.8
kpc
(see
Figure1inSchmejaetal.
2014).
The
masses of Mcl,min and Mcl,max , and is given by:
files in thelist the B, V, and J, H, K magnitudes ofable
atcatalog
http://vizier.cfa.harvard.edu/viz-bin/VizieR?Galactic
SFR will
fluctuate
aroundthe values
chosen in thiset
work
beassumedto b
Way
Clusters(MWSC)(Kharchenko
massesof Mcl,min
files inStellar
the catalog
list survey
the B, V,
and J, H,
K magnitudes al.
ofeach star in each cluster present in the catalog, along with
4 issue).
source=J/A+A/558/A53
(see
also
da Silva et al.
2012
for further
discussion
on this
by
Σ
≈
SFR×τ
2012;
Kharchenko
et
al.
2013;
Schmeja
et
al.
2014)
,
which
cl
each
cluster present in the catalog, along withother properties such as position, age, cluster membership
dNcl star in each−β
SFR of 0.68, 1, a
Acl ×clusters
M , with ages between ∼ 1 Myr and ∼(4)7
lists ∼=3200

Accepted by ApJ

1/2	

1.

2.

3.

4.

(fiducial), 20, and 10 M! . Our fiducial value of β is 2 as thisbuilt with various distribution functions of the IMF parameters. The synthe
is in agreement withthe slopethe cluster mass function at
Accepted
byofApJ
the binary population, stellar evolution, sample incompleteness, and ejectedintermediate- to high cluster masses in nearby galaxies (e.g.,
distributions of the IMF parameters are required in order to reproduce th
http://arxiv.org/pdf/1609.04858
Elmegreen & Efremov 1997; Zhang & Fall 1999; Hunter et
Galactic clusters. They also do not lend support to the existence of a clu
al. 2005; de Grijs & Anders 2006; Selman & Melnick 2008;
We propose a probabilistic formulation of the IMF whereby the paramete
Larsen 2009; Chandar et al. 2010; Fall & Chandar 2012) and
Massivestars
revealvariations
ofthestellarinitialmassfunction
the Milky
distributioninfunctions
centeredWayaround γ = 0.91, Γ = 1.37, and Mch = 0.4
with theoretical expectations (Elmegreen 2006; Dib et al.
stellarclustersσΓ = 0.60, and σMch = 0.27 M" around these values.
2011; Dib 2011a,b; Dib et al. 2013). We also consider cases
3,4with β = 2.2 and Sami
β = 1.8.
For1,2eachclusterSchmejawith an assigned
Dib, Stefanand Sacha Hony5
Accepted by MNRAS
Variations of the IMF in the Milky Way 7
mass Mcl , the massesof star-systems (i.e., individual stars
1
Niels
Bohr
Institute&
CentreforStar
andPlanetFormation,
UniversityofCopenhagen,ØsterVoldgade 5-7, DKhttp://arxiv.org/pdf/1605.08438
or binary systems) in the clusters are randomly sampled1350,
Copenhagen,Denmark.
using a tapered power law (TPL) distribution function (deFor	  Marchi
each	
  cet
luster	  w2ith	  an	
  assigned	
  ass	
  MDepartamento,	
  the	  manyasses	
  Unidadde Astronomı́a,de Fisica, Universidad de Atacama, Copayapu 485, Copiapo, Chile.
al. 2010;
Parravanoet al.m2011).
Withoutcl3
Astronomisches
Rechen-Institut,für Astronomie der Universität Heidelberg, Mönchhofstraße 12-14, 69120
binary(i.e.,	
  fraction,a stellar s”system”
mass sMcanof	
  sassignedtar-­‐systems	  individual	
  
tars	
  
or	
  bofinary	  ystems)	
  ∗Zentrum
Germany
correspond
toaan
individual
star
or to a binary
system.
The
12in	
  the	  clusters	  re	
  Heidelberg,randomly	  sampled	
  
u
sing	
  
a
	
  
t
apered	  4
TPL function is givenbyTechnische
Informationsbibliothek, Welfengarten 1b, 30167 Hannover, Germany

2/2	

power	
  law	  (TPL)	
  d5istribuBon	  funcBon	  Institut für Theoretische Astrophysik, Zentrum für Astronomie der Universität Heidelberg, Albert-Überle-Straße 2,!
"$γ+Γ %&
69120
Heidelberg,# Germany.
M∗
dN∗
−Γ
= A∗ × M∗
1 − exp −,(6)
dlogM∗
Mch at gmail.com
E-mail contact: sami.dib••

Figure 1. The figure displays the probability distribution functions of the three parameters that describe the IMF used in thiswork. The acronym δF-GF refers to delta functions of the parametersat thepositionsof the Galactic
field values,
whereasinvestigate
whetherstellarinitial massfunction(IMF)
is universal,
or whether
it varies
significantly among
where dN∗ is theWe
numberof stellar
systemsthewiththe logaδF-OBS
referstodeltafunctionslocatedatthemeanvaluesrithm of their masses
betweenlogM+ dlogM
young
stellarlogM
clustersthe∗ MilkyWay.
We propose a method to uncover the range of variationofof the parameters∗ andin∗,the parameters derived by Dib (2014a) for a sample of 8 youngand A∗ is the normalization
coefficient
which
given
by:for the population of young Galactic clusters. These parameters are the slopesthat describe
the shapeof istheIMF
Galactic stellar clusters. The cases GPD-σobs , GPD-σobs /2, andin the low and high stellar mass regimes, γGPD-σand obs
Γ,/4respectively,
and withthe characteristic
mass,disMch . The method
correspond to cases
a Gaussian probability%& mass content tribution! exclusively" # on $the high' M∗,maxof the IMF
whose
is related
to distributions ofreliesof the clusters,
butparameters
is able toyieldhalf-width
informationon theγ+ΓM∗
1, 0.5, and
0.25massthe valuesof thedispersionof eachbyparameterin the fractions of
Mcl . the entire
A∗ ×M∗−Γ1 − exp that− describe thedM∗ =overparameters
IMF
stellarrange.
Thisis achieved
comparingM
chM∗,minthesampleof Dib(2014a).
FDP-σcorresponds
to massa casewhere in two realizations of the ICLMF. The left panel displays a
Figure5. Theinitial,present-day,andobssingleO-star cluster
functions
single and lonely massive O stars in a recent casecatalogof theMilky Way clusters
withthea IMF
library ofcluster
simulatedclusters
in which thedistribution
set of three parametersdescribe
are each randomly drawn from a GPD-σobs probability
the probability
functionthatof eachparameterofiseachgiven(7) of thebuilt with various distribution functions
IMF
parameters.
The
syntheticclusters
arecorrected
fortheeffectsof describe the IMF is similar to the
distributionfunctionwhereas
the
right
panel
displays
a
case
in
which
the
set
of
three
parametersthatby a boxcar function whose width is given by 2 × σobs . The lower
valuesof the parameters fortheejected
Galactic field
mass function.
All other parameters
set toMcl,min = 50 M! , M∗,min = 0.02 M! ,the binary
population,
evolution,
incompleteness,andOparametersstars.
Ourcorrespondfindings
indicateare
that
broad
and
upper
truncations
for
each
of
the
to
The TPL function
describes
the IMFstellar
with only
three sampleM∗,max = 150 M! , and β = 2. The figure displays the initial cluster mass function (ICLMF) and the present-day cluster mass function
M*,min	  =	
  0.02	
  distributions
Msun	
  
the
lower
andCLMF
upper
limitsof these
derivedby andDib lonely
the regime
IMF parameters
are requiredin Theorder
to isreproduce
thefractionsofsingleObeen
stars
in an age, and has been correctedparameters, the slope
in the lowofmass(γ), the slope(CLMF).
the conversionof parameters
the
ICLMF after
each
individual
cluster has
assigned
M*,max	  =	
  min[Mcl,	
  
150	
  
Msun]	  oTheyr	
  v(Γ),
alues	
  xpected	  (2014a).
for theto
effects
the stellar binary
and mass-maximum
stellar evolution. The numberof clusters that contain single O stars (within the intermediate-to-highmassregimeande
thenotcharGalactic
clusters.
also
dolend support
theof existenceof afraction
clusterstellardistribution
mass relation.

! 15 M! (CLMF-O), peaks at a few tens of stellar masses and most of the clusters in the CLMF-O have masses " 400 M! .
acteristic
massThe
minimumstellar mass,
M∗,min , of theM∗IMF
from	
  
(Mcl	
  
–	
  M(M
*,max)	
  relaBon	  ch ).proposeWea probabilistic
formulation
whereby the parameters of the IMF are described by Gaussianis always taken to be 0.02 M . The maximum stellar mass,

distribution! functions centered around γ = 0.91,= 1.37,atand
0.41
dispersionsof σγ = 0.25,
ch = of" , and witheitherΓlocatedthe MvaluestheMparameters
derivedby
M! which is the mass of the M∗,max , is either given by min[Mcl , 150 M! ] (correspondaverage, at larger distances from the Sun. The normalized
The completeness correction is calculated for each reσ
=
0.60,
and
σ
=
0.27
M
aroundthesevalues.
Γ
M
"
ch
Dib
(2014a),orthe
Galactic
fieldvalues
that
are
given
by
lky Way (e.g., Figer et al.
function fcomp = R2−10 /max(R2−10 ) constitutes the comalization of the cluster mass function with respect to theing to the case of stochastic sampling) or is dictated by at al. 2007; Harayama et al.
Γfsample
0.57,
and Msurvey.
M! (Parpleteness function. A cluster is admitted for the comparison
youngγclusters
the MWSC
In =this0.42
work,
ield =of1.35,
f ield =in
ch,f ield
Acceptedby
MNRAS
clustermass-maximum
stellarmass
relation
(M
−
M
)
∗,max
cl
lore values of Mcl,min = 50
with
the approach
we use Thesein orderfamilies
to accountfor the effectofravanoet al. 2011).
of models
are labeled
δF- the observational data if its completeness probability
by Vanbeveren (1982) and later by Weiducial value of β is 2 as this relation proposedhttp://arxiv.org/pdf/1605.08438
fcomp is larger than a uniform random number drawn becluster
incompletenessis basedon thepopulations ofandlow Galactic
OBS
and
δF-GF
(DeltaFunction
Observations
the cluster mass function at dner & Kroupa (2004). We test models in which the distween 0 and 1. For the families of ICLMFs generated in thismass B stars in the clusters (i.e., stars with masses between
Field,
respectively). We also test flat probability distribuses in nearby galaxies (e.g., tributions of the parameters (Γ, M , γ) are either given
work, typically only about half of the clusters in the ICLMF
2M! # M∗ # 10M! ) whose total number in a cluster ischang & Fall 1999; Hunter ettions(FPD).
These
are describedby boxcar
be- the filter of the completeness function and are used inpassN∗,2−10. For eachrealizationof the ICLMF,
after thefunctions
corby delta function (all clusters have the same value of the6; Selman & Melnick 2008;
tween
(0.4,
1.5)
for
γ,
(0.7,
2.4)
for
Γ,
and
(0.05,
1)
M
forcomparison with the observational data. Additional exrectionsfortheeffectsofthebinarypopulation
andstellar!the; Fall & Chandar 2012) and parameters), Gaussian functions, or boxcar functions. A reof the completeness function for various values of βevolution
been takenfunctions
into account,we computethe of amples
M
distributionoftheparametersthech . The have
Elmegreen 2006; Dib et al. cent study found that the mean values of the parameters
and its effect on the derived values of fO,single and fO,lonely
distributionof 12
low mass
B starsφ(N
6 (top∗,2−10 ). Fig.
IMF
for
all
of
these
modelsaredisplayed
in
Fig.
1.
13). We also consider cases among a relatively small sample of young Galactic stellar
are discussed in App. B.
panel, left) displays an example of the distribution of φFig. 2 displays a few examples of the generated ICLMFs
ch cluster with an assigned clusters are Γ
for one of the ICLMF realizations from the GPD-σobs famobs = 1.37, γobs = 0.91 and Mch,obs = 0.41
tems (i.e., individual stars
withthe expoily ofvarious
models permutations(full black line) of
andthefor Galactic
the young SFR,
clusters
M! with standard deviations of σΓobs = 0.60, σγobs =ers are randomly sampled
nent
of
the
ICLMF
and
the
lower
cutoffin the
MWSC
catalog(β),(purpledashedline) massplottedversusin cluster) distribution function (de 0.25, and σMch,obs = 0.27 M! , respectively (Dib 2014a).
5 aCOMPARISON OF MODELS TO
log(N∗,2−10+ 1). ),
The
unnormalized
ratio ofthethese
two dismasses(Mcl,minandFig. 3 displays
systemIMFs foret al. 2011). Without any When drawing the parameters from Gaussian distributions,tributions(R2−10= φobs/φmodelfrom) is plottedin theFig. realization
6 (middle
few
selectedclusters
drawn
one
of
of
theOBSERVATIONS
r ”system” of mass M∗ can the distributions are always centered on these observed
panel, left). A similar example is shown in the right panel
5.1 Models based on stochastic star formation
ICLMF
in the GPD-σ ICLMF
familyof models (i.e., with varying
or to a binary system. The
for one realization of theobs
from the δf-GF family ofmean values. We test dispersions of the Gaussian distriIMFs).
Additional
technical
detailsonthesamplingofthethis family of models, stellar masses in eachmodels.
Allcompleteness
functions
that
we
have
computedIn
butions of (σΓobs , σγobs , σMch ), (σΓobs , σγobs , σMch ) /2, andICLMF
and of the
IMF cluster
are presented
in App.
§. A.
for the different
synthetic
mass functions
displayacluster are randomly sampled in the mass range" #(σΓobs
,
σ
,
σ
)
/4,
and
apply
lower
and
upper
cutoffs$γ+Γ %&
γobs
MchFigure1. Thefigure displays the probability distribution funcsimilar behavior, namely a peak at LogN∗,2−10 ≈ 1.8 − 2,
[0.02, min(Mcl , 150)]M! for the set of parameters (Γ, Mch ,M∗−,(6) of (0.4,(0.70, 2.4)
for Γ, theandtions 1.5)of the forthreeγ,parametersthat describe
IMF(0.05,
used in1)thisM! forwith a decrease for both increasing and decreasing valuesγ) that are assigned to the cluster. When comparing theMch
The acronym
δF-GFtorefersdelta functionsof the limits
paMchwork.
, whichcorrespond
thetolower
and upper
deof N∗,2−10
around thepeak.
Weassume a completenessoffractions of single and lonely O stars (fO,single and fO,lonely )4.2
Assigningages
tosimulatedclusters
rameters at the positions of the Galactic field values, whereas
lar systems with the loga-

1 andmodel
2 are the thescale height
dust-to-gas
ratio for the innercavityWe find that: (1) HCO+ lin
s = 0.01. Columns
anddataandwith
the ProDiMo
code.
region. Columns 3 and 4 are the 2 and 2red values for full line-wings at velocities ⇠1.8 togas
in thecavitywithin<50
AUof the star. (2) Reproducing
1
4.0 km s 1 and 8.8 presence
to 11.0 km s of
. We
assume11 degrees
of freedom
for 2red(wherethere
are 14 data points and3 fitted parameters).
Lastly, column
5 is the corresponding
insignificant
suppressionof cavity
dust (byfigurea factor>104 compared to thethe text.
scale-height
withinthecavity
(H
/R
∼
0.6).
An
ISM
dust-to-gas ratio (2200H0,cav d : gcav
Fig.
red

regardless(AU) of the scale-height or cavity gas geometry, while a smaller sca(1) 15 (2)(3) (3)(4) The(5) cavity gas mass is consistent with the surfac
HCO Detection of Dust-Depleted Gas in the Inner Hole of thewith
LkCa
Pre-Transitionala reduced
d:g.
60
10 6
9.0 0.810Diskinwards to the sublimation radius (corresponding to mass Md ∼ 0.03 M"
to4 ,beruledout. 3 , W.-F. Thi5 , P.
E. Drabek-Maunder1 , S. Mohanty1 , J. Greaves2 , I. Kamp3 , R. Meijerink
M.
Spaans+Woitke611.

2.

Accepted by ApJ

Imperial College London, Blackett Lab., Prince Consort Rd, London SW7 2AZ, http://arxiv.org/pdf/1609.05894
UKof Physics andAstronomy,
Cardiff CF24 3AA
LkCa	
  15	
  –23	
  pSchoolre-­‐transiBonal	
  
disk	
  
with	
  a	
  Cardifflarge	
  iUniversity,nner	
  cavity	  Kapteyn Institute, PO Box 800, 9700 AV Groningen, The Netherlandsin	
  dust	  conBnuum	  +	
  normal	
  gas	
  accreBon	
  rate.	
  	
  Proper motion
survey and kinematic analysis of the Rh
4
Leiden Observatory, Leiden University, PO Box, 2300 RA Leiden, The Netherlands– 26 –
1,2
5• The	
  mMax-Planck-Institutost	
  popular	  hypothesis	  –	
  one	  or	
  Physisk,more	
   Giessenbachstrasse 1, 85748 C.
Ducourant, R. Teixeira2,1 , S. Bontemps1 , D. Despois1 , P. A. B
für extraterrestrische
Garching,
Germany
16
M. UK
Rapaport and J.C. Cuillandre5
St. tAndrews
Physicsw
andAstronomy,
St. Andrews KY16 9SS,
planets	  o	
  carve	
  University,out	
  the	
  School
inner	
  ofcavity,	
  
hile	
  
gas	
  
1
Laboratoire d’astrophysique de Bordeaux, Univ. Bordeaux, CNRS, B18N
E-mail contact: e.drabekmaunder at imperial.ac.uk
conBnues	
  to	
  ﬂow	
  across	
  the	
  gap	  	
  France15 is an extensively studied star in the Taurus region known for its pre-transitional
disk with a large inner cavity
2
SpaBally	
  uLkCanresolved	
  HCO+	
  J=4–3	
  observaBons	
  at	
  JCMT	
  Instituto de Astronomia, Geofı́sica e Ciências Atmosféricas, Universidadein dust continuum and normal gas accretion rate. The most popular hypothesis to explain the LkCa 15 data invokes
05508-900
São
Paulo
SP,
1.— TheHCOUniversitária,
J = 4 gap
! 3 spectrum
initialouterreductionbinnedto 0.3 -km
s Brazil
velocity+	  Model	
  w
ith	
  
he	
  Pplanets
roDiMo	  code	
  out the inner cavity, while gas continues Fig.
one
ortmoreto carve
to flow
acrossfrom thedisk
onto
3thethechannels(red)andspectrumfoldedsymmetrically
about
the
line
centreat
6.4 kms
CENTRA/SIM,
FaculdadedeCiências,
Universidade
de Lisboa, Ed. C+
the central
star. We present spatially unresolved HCO J=4–3 observationsof thespectrum
LkCahas15
JCMT(black). The unfoldeda 1 disk
RMS offrom
0.005 Ktheand thefolded spectrum has a 1
We	
  ﬁnd	
  that:	  	  Lisboa,Portugalof 0.003 K. 4are clearly detected, certifying theand model
the data with the ProDiMo code. We find that: (1) HCO+RMS
line-wings
Centro de Astrobiologı́a, Dpto de Astrofı́sica, INTA-CSIC, PO BOX 78•(1)	
  presence
HCO+	
  line-­‐wings	
  re	
  clearly	
  detected	
  –	
  gstar.
as	
  in	
  
of gas in the acavitywithin <50
AU of the(2) Reproducing the observed line-wing flux requires both aCañada,Madrid, Spain
cavitya 	
  factor >104 compared to the ISM) and5 a substantial increase in the gasthe	
  significant
cavity	  wsuppression
ithin	
  <50	
  ofAU	  of	
  tdusthe	
  s(bytar.	
  CEA/IRFU/SAp,
Laboratoire AIM Paris-Saclay, CNRS/INSU, Universit
within the cavity (H0 /R0 ∼ 0.6). An ISM dust-to-gas ratio (d : g = 10−2 ) yields too little line-wing flux
Research University, F-91191 Gif-sur-Yvette Cedex, France•(2)	
  scale-heightR
eproducing	
  
t
he	
  
o
bserved	  line-­‐wing	
  
ﬂ
ux	
  
regardless of the scale-height or cavity gas geometry, while a smaller scale-height also under predicts the flux evenchristine.ducourant
requires;	  	
  with a reduced
d:g. (3) The cavity gas mass is consistent with the surface densityE-mailprofilecontact:of the outerdisk extended at u-bordeaux.fr–
29–
to the sublimation
radius (corresponding
mass
by a molecularfactor >10complex
appear and in particular the Lynds L1688 dark
The ρlower
Ophiuchi• inwardsa	
  signiﬁcant	  suppression	
  of	
  cavity	
  dto
ust	
  
(by	
  Md ∼ 0.03 M" ), and masses
to be ruled out.
initsrichness
in
young
stars
and protostars, and in its youth (0.5 Myr). It
4	
  compared	
  to	
  the	  ISM)	
  	
  
a	
  
f
actor	
  >10accessible
fromthegroundtostudy the early phases of star-formation. Prop
Accepted by ApJ
Fig. 2.— The blackseparating
points show themembers
LkCa 15 SEDof
taken
from ProDiMowith but very few proper motion
clusters
from benchmark
field stars,• http://arxiv.org/pdf/1609.05894
a	
  substanBal	
  increase	
  in	
  the	
  gas	
  scale-­‐a two-component radial model, described in §4.1 (from Espaillat et al. 2010; Piétu et al.
most of the young sources are deeply embedded in dust and gas. We aim
2007; Ingleby et al. 2009; Neuhaeuser et al. 1995 in A11). The innermost disk is set fromheight	  within	
  the	  cavity	  (H0/R0	
  ∼	
  0.6).	
  An	
  (YSOs)
Ophiuchi
F graincore and partially in the E core
0.1 to 10 AU with stellar
H = 30.5objects
AU at a reference
radiusin
R the= 100ρAU
and maximum−2
size a= 0.25µm.
The innerprogram
disk mass hasat
been
depleted
10 . The
outermost disk Telescope (NTT) with the S
motionthe
ESOby New
Technology
ISM	
  
d
ust-­‐to-­‐gas	
  
r
aBo	
  
(
d	
  
:
	
  
g
	
  
=
	
  
1
0
)	
  
y
ields	
  Proper motion survey and kinematic analysis of theextends
RhofromOphiuchi
cluster
50 to 1000 AU withembedded
R = 85 AU.
years in thenear-infrared. We complemented these observations with var
too	
  
l
irle	
  
l
ine-­‐wing	
  
ﬂ
ux	
  
f	
  
t
he	
  
1,2
2,1 regardless	
  o1
1
2
4
1
C. Ducourant , R. Teixeira , S. Bontemps , D. Despois , P. A. B. Gallitime, H.base
Bouy, J.F. Le Campion, of investigation to 0.5◦ ×0.5◦ . We deof observations
and the field
1
5
M. Rapaport
andoJ.C.
Cuillandre
scale-­‐height	
  r	
  cavity	  gas	
  geometry,	
  while	
  objects. From these, 607 proper motions were derived from SOFI observat
1
Laboratoired’astrophysiquede Bordeaux,Univ. Bordeaux, CNRS, B18N, allée Geoffroy Saint-Hilaire, 33615 Pessac,a	
  smaller	
  scale-­‐height	
  also	
  under-­‐predicts	
  Francethe	
  ﬂux	
  even	
  with	  a	
  reduced	
  d:g.	
  	
  2
13Instituto de Astronomia, Geofı́sica e Ciências Atmosféricas, Universidade de São Paulo, Rua do Matão, 1226 - Cidade•(3)	
  Universitária,The	
  cavity	
  05508-900gas	
  mass	
  
i
s	
  
c
onsistent	
  
w
ith	
  
t
he	
  
São Paulo - SP, Brazil
3
CENTRA/SIM,
Faculdadede Lisboa, Ed. C8, Lab. 8.5.02, Campo Grande, 1749-016,
surface	
  density	
  proﬁle	
  of	
  tde
he	
  Ciências,
outer	
  dUniversidadeisk	
  extended	
  Lisboa, Portugal
4inwards	  to	
  dethe	
  sublimaBon	
  (corresponding	
  CentroAstrobiologı́a,
Dptoradius	  de Astrofı́sica,
INTA-CSIC, PO BOX 78, E-28691, ESAC Campus, Villanueva de laCañada,Madrid,Spain
Fig. 6.— Surface density profile of the gas (red) and dust (blue) of the final disk models.
to	
  m
ass	
  Md	
  ∼	
  0.03	
  M⊙),	
  and	
  masses	
  lower	
  by	
  a	
  
5
R Parisdenotes the
sublimation radius(the inner radiusde
for thedust cavity
at 0.1 AU), R
CEA/IRFU/SAp, Laboratoire AIM Paris-Saclay, CNRS/INSU, Université
Diderot,
Observatoire
Paris,
PSL
denote the extent of the cavity (50 AU) and R denotes the characteristic tapering andfactor	  >10	
  University,
appear	
  tF-91191o	
  be	
  ruled	  out.	
 Cedex, France
Research
Gif-sur-Yvettescaling radius (300 AU).
+

3.

1

1

0

0

6

max

c

Rsub

Rcav

Rc

Outer Disk

Dust Cavity

Gas

d:g=10-2

d:g=10-6

Dust

sub

cav

c

E-mail contact: christine.ducourant at u-bordeaux.fr
The ρ Ophiuchi molecular complex and in particular the Lynds L1688 dark cloud is unique in its proximity (∼130 pc),

and model the data with the ProDiMo code. We find that: (1) HCO+ lin
presence of gas in the cavity within <50 AU of the star. (2) Reproducing
significant suppression of cavity dust (by a factor >104 compared to thescale-height within the cavity (H0 /R0 ∼ 0.6). An ISM dust-to-gas ratio (regardless of the scale-height or cavity gas geometry, while a smaller sca
HCO+ Detection of Dust-Depleted Gas in the Inner Hole of thewith
LkCa
15 Pre-Transitionala reduced
d:g. (3) The cavity gas mass is consistent with the surfac– 30 –
Disk
inwards to the sublimation
radius (corresponding to mass Md ∼ 0.03 M"
1
1
2
3
4 be ruled out. 3
to
E. Drabek-Maunder , S. Mohanty , J. Greaves , I. Kamp , R. Meijerink , M. Spaans , W.-F. Thi5 , P.

Woitke6

Accepted by ApJ

1Imperial College London, Blackett Lab., Prince Consort Rd, London SW7 2AZ, http://arxiv.org/pdf/1609.05894
UK
School of Physics and Astronomy, Cardiff University,
Cardiff CF24 3AA– 28 –
3
Kapteyn Institute, PO Box 800, 9700 AV Groningen, The Netherlands
Proper motion survey and kinematic analysis of the Rh
4
Leiden Observatory, Leiden University, PO Box, 2300 RA Leiden, The Netherlands
1,2
5
Ducourant, R. Teixeira2,1 , S. Bontemps1 , D. Despois1 , P. A. B
Max-Planck-Institut für extraterrestrische Physisk, Giessenbachstrasse 1, 85748 C.
Garching,
Germany
16
M. UK
Rapaport and J.C. Cuillandre5
St. Andrews University, School of Physics and Astronomy, St. Andrews KY16 9SS,
2

– 27 –

1

Laboratoire d’astrophysique de Bordeaux, Univ. Bordeaux, CNRS, B18N
France
LkCa 15 is an extensively studied star in the Taurus region known for its pre-transitional
disk with a large inner cavity
2Instituto de Astronomia, Geofı́sica e Ciências Atmosféricas, Universidadein dust continuum and normal gas accretion rate. The most popular hypothesis to explain the LkCa 15 data invokes
Universitária, 05508-900 São Paulo - SP, Brazil
one or more planets to carve out the inner cavity, while gas continues to flow across
3 the gap from the outer disk onto
CENTRA/SIM, Faculdade de Ciências, Universidade de Lisboa, Ed. C
the central star. We present spatially unresolved HCO+ J=4–3 observations of the LkCa 15 disk from the JCMT
Lisboa,Portugal– 31 –Fig. 4.— Best-fit model to the emission from the disk cavity at radii from 0.1 to 50 AU,
and model the data with the
ProDiMo code. We find that:(1) HCO+ seeline-wings 4are clearly detected,
certifying theSection 4.2.2. Settling parameters are a = 0.01µm and= 0.01, the gas reference scale
Centrode Astrobiologı́a, Dpto de Astrofı́sica, INTA-CSIC, PO BOX 78
heightwithin
is H = 60 AU
and d:g=
10 .of the star. (2) Reproducing the observed line-wing flux requires both apresence of gas in the cavity<50
AU
Fig. 7.— Left:Cañada,
Best-fit modelMadrid,
to both the innercavity and the outer disk (see Section B.3)
Spainsignificant suppression of cavity dust (by a factor >104 compared to the withISM)
a substantial
total anddisk
is 0.10 M . Right:increase
HCO+ J = in
4 !the3 andgas
dust continuum (105 massCEA/IRFU/SAp,
AIM
Paris-Saclay, CNRS/INSU, Universit−2 depths per radius for the Laboratoire
840 µm) opticalbest-fit models. HCO+ remains opticallyscale-height within the cavity (H0 /R0 ∼ 0.6). An ISM dust-to-gas ratio (dand
:
g
=
10
)
yieldstoolittleline-wing
flux
thin ⌧ < 1 atResearchradii r  10 AU.
The 840 µm dust
continuum Gif-sur-Yvetteis optically thin at radii Cedex, France
University,
F-91191
regardless of the scale-height or cavity gas geometry, while a smaller scale-height
under
the
flux dataeven
50 AU< r < 100 also
AU, consistent
withpredicts
the 880 µm dust
continuum
from A11. Similarly
10µm dustE-mailcontinuum contact:is primarily opticallythin at radii r < 50 AU, consistentwithchristine.ducourantat u-bordeaux.fr
with a reduced d:g. (3) The cavity gas mass is consistent with the surfacethe
density
profile
of
the
outer
disk
extended
SED fitting (Espaillat et al. 2008, 2010).
inwards to the sublimation radius (corresponding to mass Md ∼ 0.03 M" ), and masses
by a molecularfactor >10complex
appear and in particular the Lynds L1688 dark
The ρlower
Ophiuchito be ruled out.
in its richness in young stars and protostars, and in its youth (0.5 Myr). It
accessible from the ground to study the early phases of star-formation. Prop
Accepted by ApJ
separating members of clusters from field stars, but very few proper motion
http://arxiv.org/pdf/1609.05894
most of the young sources are deeply embedded in dust and gas. We aim
Fig. 3.— Models are compared to the folded spectrum with 1 RMS. The grey boxes indicate
velocity channels corresponding to the HCO line-wings. Top left: Empty inner cavity modelFig. 5.— Constraining the inner cavity mass by fitting the disk cavity emission, where thestellar objects (YSOs) in the ρ Ophiuchi F core and partially in the E corewith the dust continuum parameters from A11 (see Section 4.1.1). Top right: Determining
standard cavity mass M (0.029 M ) is in green, 0.1 ⇥ M (0.003 M ) is in red and 10 ⇥ M
the characteristic radius R with an empty inner cavity model (see Section 4.1.2). Bottom left:
motion program at the ESO New Technology Telescope (NTT) with the S(0.3 M ) is in blue (see Section 4.2.3).
Propermotionand kinematic analysis of the Rho Ophiuchi
embedded cluster
Empty inner cavity model with R = 250 AU andstandard ISM d:g=
10 (see Section survey
4.1.2).
years in the near-infrared. We complemented these observations with var
We note that models of the outer disk with an empty inner cavity and varying R and R
1,2
2,1
1
1
2
4
1
have not been able to produce the observed C.
HCO Ducouranthigh velocity line-wings. Bottom, R.right:
Teixeira , S. Bontemps , D. Despois , P. A. B.
Gallitime, H.
Bouy, fromJ.F.
Le Campion,fit theof
baseof observations
thetofield
investigation
to 0.5◦ ×0.5◦ . We de
Fig. 8.— Full-disk
modelsgenerated
an innermost anddisk model
inner
disk
Disk without an inner cavity and d:g= 10 (see Section 4.2). Even though
1 there is some
5and
J.C. Cuillandre
described in A11(radii 0.1 toFrom
10 AU; Section
4.1.1)
and aproper
two-component
disk modelwere
to fit derived from SOFI observat
HCO line-wing emission, the filled-cavity M.
models Rapaport
do not fit the high velocity
line-wing
objects.
these,
607
motions
the cavity (10 to 50 AU) and the outermost disk (50 to 400 AU). We show the best-fit cavity
emission present in the HCO spectrum either.
1567heightGeoffroy(60 AU at a reference
radius of 100 AU)
and d:g=
10 , 10 and 10 . Left:
Laboratoire d’astrophysique de Bordeaux, Univ. Bordeaux, CNRS, B18N,scalealléeSaint-Hilaire,
33615
Pessac,Full-disk SED models with the stellar spectrum (green), innermost disk (blue), disk cavity
France(red) and outer disk (grey). The dashed line depicts the two-disk model with a dust-to-gas
213
in the disk
cavity atRuad:g= 10red), the1226
solid line- isCidadeat d:g= 10 6 (red) and theInstituto de Astronomia, Geofı́sica e Ciências Atmosféricas, Universidade ratiode SãoPaulo,
do5 (darkMatão,dotted line is at d:g= 10 7 (light red). Right: HCO+ spectra produced from the two-disk
Universitária, 05508-900 São Paulo - SP, Brazil
models using d:g= 10 5 (dark red, dotted line), 10 6 (red, dashed line) and 10 7 (light red,3
solid line).
CENTRA/SIM, Faculdade de Ciências, Universidade de Lisboa, Ed. C8,
Lab. 8.5.02, Campo Grande, 1749-016,
Lisboa, Portugal
4
Centro de Astrobiologı́a, Dpto de Astrofı́sica, INTA-CSIC, PO BOX 78, E-28691, ESAC Campus, Villanueva de laCañada, Madrid, Spain
5
CEA/IRFU/SAp, Laboratoire AIM Paris-Saclay, CNRS/INSU, Université Paris Diderot, Observatoire de Paris, PSL
Research University, F-91191 Gif-sur-Yvette Cedex, France

E-mail contact: e.drabekmaunder at imperial.ac.uk

s

s

6

0

+

d

d

d

c

2

c

c

out

+

2

+

+

E-mail contact: christine.ducourant at u-bordeaux.fr
The ρ Ophiuchi molecular complex and in particular the Lynds L1688 dark cloud is unique in its proximity (∼130 pc),

new members are generally fainter than the known ones. We measured a m-24.3)±0.8 mas/yr for the L1688 dark cloud. A supervised classification wa
to allocate a spectral energy distribution (SED) classification to the unclassi
http://arxiv.org/pdf/1609.05894
that the 56 members that were known from previous studies of the ρ Oph
our survey are members of the cluster, and we added 26 new members.
Proper motion survey and kinematic analysis of the Rho Ophiuchi
embedded
unclassified
members of cluster
the cluster. We showed that a large part (23) o
1,2
2,1
1
1
2
4 multiplies the number
dwarfs,which
C. Ducourant , R. Teixeira , S. Bontemps , D. Despois , P. A. B. Galli , H. Bouy , J.F. Le Campion1 , of known substellar objects in the clu
A&A proofs: manuscript no. Ducour
M. Rapaport1 and J.C. Cuillandre5
Accepted by A&A main
1
Laboratoire d’astrophysique de Bordeaux, Univ. Bordeaux, CNRS, B18N, allée Geoffroy
Saint-Hilaire, 33615 Pessac,
http://arxiv.org/pdf/1609.04963
Francepositions. Th
InstitutodeFAstronomia,
Geofı́sica
YSOs	
  in	
  t2he	  ρ	  Oph	  
	
  and	  parBally	
  E	
   e Ciências Atmosféricas, Universidade de São Paulo, Rua do Matão, 1226 - Cidade
thesecatalogd
A photo-evaporative gap in the closest planet
forming
Universitária, 05508-900 São Paulo - SP, Brazil• Near	
  
I
R	
  
p
roper	
  
m
oBon	
  
p
rogram	
  
a
t	
  
t
he	
  
E
SO	
  
N
ew	
  
to
these
data
3
1,2
CENTRA/SIM, Faculdade de Ciências, Universidade de Lisboa, Ed. C8, Lab.Barbara
8.5.02, CampoGrande,1749-016,P. Rosotti3 , Giovanni Picogna1 , Le
Ercolano, Giovanni( ↵, )= (Technology	
  Telescope	
  (NTT)	
  with	  the	
  Son	  of	
  Lisboa, Portugal
1
Universitäts-Sternwarte München, Scheinerstr. 1, 81679 München,Germ4217) masforCentrode Astrobiologı́a,de9Astrofı́sica,
ESAC Campus, Villanueva de la
2
ISAAC	
  (SOFI)	
  instrument	  Dptoover	  	
  years.	
   INTA-CSIC, PO BOX 78, E-28691,
Excellence Cluster Origin and Structure of the Universe, Boltzmannstr.2
positions. AfCañada, Madrid, Spain
3
Institute of Astronomy, University of Cambridge, Madingley Road, Camb
5
• Public	  image	
  databases	
  to	
  enlarge	  the	
  Bme	  CEA/IRFU/SAp,
Laboratoire
AIM Paris-Saclay,
CNRS/INSU, Université Paris4Diderot, Observatoire de Paris, PSL
catalogue tha
European Southern Observatory, Garching bei München, Germany
Research
University,
Gif-sur-Yvette
France
base	
  
and	
  the	  ﬁeld	
  oF-91191
f	
  invesBgaBon	
  to	
  0Cedex,.5◦	
  ×0.5◦	  5INAF/Osservatorio Astrofisico di Arcetri, Largo E. Fermi 2MASS
5, I-50125posiFireat u-bordeaux.fr
PosiBons	
  E-mailand	
  pcontact:roper	
  christine.ducourant
moBons	  for	  2213	  objects.	
  	
  
and
the
whol
E-mail contact: ercolano at usm.lmu.deTheρ Ophiuchi
complexand in particular
Lynds L1688 dark cloud is unique in its proximity (∼130 pc),
An younga po• 607	
  
from	
  
SOFI	
  (molecular∼1.8	
  mas/yr	
  accuracy)	
  
+	
  13	
  ftherom	
  The dispersal of the circumstellar discs of dust and gas surrounding
in its richness in young stars and protostars, and in its youth (0.5 Myr). It is certainly
one
of
the
best
targets
currently
showedevidr
for the formation of planetary systems. Photo- evaporation from energetic
auxiliary	
  
data	
  
precision	
  ∼3	
  earlymas/yr).	
  	
   star-formation. Proper motionaccessible
from(mean	  the groundto study thephases ofanalysisisavery
efficienttool
for
to drive the dispersal in the majority of discs, by creating amations
gap whichdiwasmembersof clusters
field stars,
in theρ Ophiuchi
region thesinceouter disc from the inside-out, while thFrom	
  the	
  separating
kinemaBc	
  analysis	  we	
  dfromerived;	  	
   but very few proper motions are availableof the discandthen disperses
were
too
num
of the young sources are deeply embedded in dust and gas. We aim at performing
kinematic
censusof young
the star.a In
this Letterwe showthat the disc around TW Hya, thetoclosest• 68	
  mostmembers	
  
and	
  14	
  candidate	
  members,	  excl
stellar objects (YSOs) in the ρ Ophiuchi F core and partially in the E core of thefirst
L1688
dark
cloud.
Werun
a proper gap has been imaged cided
object where a photoevaporativearound the timcomprising	
  
2
6	
  
n
ew	
  
o
bjects	
  
w
ith	
  
a
	
  
h
igh	
  
mean
velocitmotion program at the ESO New Technology Telescope (NTT) with the Son of ISAAC
nineis consistent with the expectations ofdetected(SOFI)
gap ininstrument
the ALMAover
imagesyears in the near-infrared.
with various public
image
databasestoenlargetheThe photoevaporation model
plate-to-plate
membership	
  probability.	
  We
	
   complemented these observations
requiring the presence of a planet.
is also ctime base of observations and the field of investigation to 0.5◦ ×0.5◦ . We derived positions
andpropermotionsfor2213
of the TW Hya system, e.g. accretion rate and the locationbly
of cluster
the gap m
at• mean	  proper	
  
m
oBon	
  
	
  
(
μ
	
  
c
osδ,	
  
μ
)=(-­‐8.2,	
  α
δ were derived from SOFI observations with a ∼1.8 mas/yr accuracy while theobjects. From these, 607 propermotions
central, unresolved 870 µm continuum source might be produced by free f

Accepted by ApJ

1/2	

1.

2.
3.

•

-­‐24.3)±0.8	
  mas/yr	
  for	  the	
  L1688	
  dark	  cloud.	
  	  ρ	  Oph	  F	  cluster	
  
13
• 56	
  previously	
  known	
  members	
  in	
  our	
  survey	
  
area	
  –	
  kinemaBcally	
  conﬁrmed	
  • 26	
  new	
  members	
  added	
  with	  evoluBonary	
  status	  	
  • a	  large	
  part	  (23)	
  of	
  them	  are	
  probably	
  brown	
  dwarfs	
  =>	
  mulBplies	
  the	
  number	  of	
  known	
  substellar	
  objects	
  in	
  the	
  cluster	
  
by	
  a	
  factor	  of	
  3.3.	

We finall
objects sprea
Accepted by MNRAS Lettersarated into tw
http://arxiv.org/pdf/1609.03903
13.80 x 10.80
remaining ob
iliarydata. W
The link between turbulence, magnetic fields,
filaments,
Fig. 1: Areas coveredby the present
catalogue of our proper
tral MolecularZone proper
cloud motion
G0.253+0.016
overlaid on the C.
mapof the 1L1688
cloud 2from
Bontemps
Federrath, J. M.dark
Rathborne, S. N.
Longmore3 , J. The
M. sprea
D. K
1
8
9
10,11,12
et al. (2001). Red
lines
delimitate
the NTT-SOFI
observations
R. M.
Crocker, G. Garay, J. M. Jackson, L. Testimaterial
and
A
prop
and blue lines give
the
total
extensionofthecatalogue
including1
fromthis fig
Research School of Astronomy and Astrophysics, Australian
NationalUnauxiliary data. 2 CSIRO Astronomy and Space Science, P.O. Box 76, Epping
NSW, 1710,
tributionof S
3Astrophysics Research Institute, Liverpool John Moores University,
IC2, L
precise thant
Liverpool L3 5RF, United Kingdom
ple
benefitin
4
Astronomisches Rechen-Institut, Zentrum für Astronomie der Universität H
catalogue thadelberg,
Germany
where the absorptiondue
to dust is much lower and objects are
5
Max-Planck Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, G
detectable in the6 visible
wavelengths. For the vast majority of obCASA, University of Colorado, 389-UCB, Boulder, CO 80309, USA
jects, which are7only
detectablein theinfraredor NIR,
we 9513,
com-NL-2300 RA Leide
LeidenObservatory,
LeidenUniversity,
PO Boxbined the positions from 2MASS with those from the AllWISE
dust inside the gap.

new members are generally fainter than the known ones. We measured a m-24.3)±0.8 mas/yr for the L1688 dark cloud. A supervised classification wa
A&A proofs: manuscript no. Ducourantv2
to allocate a spectral energy distribution(SED) classification to the unclassi
http://arxiv.org/pdf/1609.05894
that
the
56
members
that
were
known
from
of theρ Ophthe kinematic members. We observe that they are mostly located previous
We presentstudies
the distributionof theseH
ourare membersof thecluster, andadded
26 newinthe survey
region of highest
absorption where
star-formationis on- we
known
members(blackmembers.
dotted histog
going.
We alsoembedded
notethat class I objects
globally aligneda (red)that
in Fig. a13large.
Proper motion survey and kinematic analysis of the Rho Ophiuchi
unclassified
membersof cluster
thearecluster.
We on
showedpart (23) onorthwest-southeast axis, mostly located in the most embedded
As expected, most of the new me
1,2
2,1
1
1
2
4 multiplies
1to corresponddwarfs,which
thenumberofknown
substellar
objects
region,which
was
proposed
by
Motte
et
al.
(1998)
withM
rangingfrom5
toin
12.theSinceclu
theC. Ducourant , R. Teixeira , S. Bontemps , D. Despois , P. A. B. Galli , H. Bouy , J.F. Le Campion ,H
totheperpendiculartothedirectionofshock
propagation
by
the
and
BDs
occurs
at
M
⇠5
mag,
that
i
1
5
H
M. Rapaport and J.C. Cuillandre
Acceptedmain
Upper
Scorpiusby
OBA&A
association
onto the core of the ⇢ Oph cloud clusters (e.g., Bara↵e et al. 2015), virtu
ourant C. et al.: Kinematics in ⇢ Ophiuchi
A&A
proofs:manuscriptno.
Ducourantv2
1
fall in the substellar regime. The MH v
Laboratoire d’astrophysique de Bordeaux, Univ. Bordeaux, CNRS, B18N, allée complex.
Geoffroy
Saint-Hilaire, 33615 Pessac,
http://arxiv.org/pdf/1609.04963
troscopically confirmed BDs in ⇢ Ophiu
FranceFig 13 together with their spectral type.
2
find 23 new substellar members, which
Instituto de Astronomia, Geofı́sica e Ciências Atmosféricas, Universidade de São Paulo, Rua do Matão, 1226 - Cidade
previously
known BDsformingin the surveyeddAphoto-evaporative
gap
in
the
closestplanetKs bands (cenUniversitária, 05508-900 São Paulo - SP, Brazil
The weakest four new member
3297,0.275) µm)
1,23
BX162727602-24381862,
CENTRA/SIM, Faculdade de Ciências, Universidade de Lisboa, Ed. C8, Lab.Barbara
8.5.02, CampoGrande,1749-016,P. Rosotti244059.1,
Ercolano, Giovanni, Giovanni
Picogna1 , Leer objects of the244339.5,
and
2MASS-6X
J16265864Ducourant
C.
et
al.:
Kinematics
in⇢OphiuchiLisboa, Portugal
1
the Ks magnimag1,are81679
potentiallyvery low mass
BDs
Universitäts-Sternwarte München, Scheinerstr.
München,Germ
4Centrode Astrobiologı́a, Dpto de Astrofı́sica, INTA-CSIC, PO BOX 78, E-28691,
ESAC Campus, Villanueva de laphotometric data from Table 6. If there
are some contaminants
as cool as L0 (⇠2200K, see discussio2
list in Table 6
Excellence Cluster Origin and Structure of the
Universe,
Boltzmannstr.2
in our kinematic members sample, then they will be incorrectly2015). These cool young BDs are expe
Madrid,Spainin this work for
attributed to one of the three YSO Cañada,classes since we assume
here
3Institute of Astronomy, University of Cambridge,
Road, Cambof onlyMadingley
about 10 MJup (Chabrieret al. 2that each of the 82 members and 5candidates are young stellar
see next section
A&A
proofs:manuscriptno.
Ducourantv2
CEA/IRFU/SAp, Laboratoire AIM Paris-Saclay, CNRS/INSU, Université Paris4Diderot, Observatoire de Paris, PSL
objects.
We summariseGermany
the evolutionary stat
EuropeanSouthern
Observatory,
Garchingbei
München,Ducourant
C.
et
al.:
Kinematics
in⇢OphiuchiFor
theclassification
we
adoptedasupervised
learning
h the AllWISE
candidates in Table 4. Seven members
Research
University,
F-91191 Gif-sur-Yvette Cedex, France
5
method, whose principle is the following.
The method
considE. Fermi
5, I-50125
Fire
e one hand, it may also be interesting to test any
the classified
kinematic
members. We observe that they are mostly located We present the distribution of these INAF/Osservatorio
H absolute magnitudes forAstrofisico di Arcetri, Largo
are identified
BD (Alvesde Oliveiraet aers the various magnitudes of each previously
memberatalogue for its membership to the F/E cores al(J,H,K s ,w1,w2,w3,w4) and all theirE-mailcolourin
combinations(J-H,ofJ- highest
are BD candidates (Alves de Oliveira echristine.ducourant
u-bordeaux.fr
thecontact:regionabsorption where atstar-formationis on- known members (black dotted histogram) and new members
er motion is not of high accuracy to have a census
K s , J-w1, etc.) and searches for regions in this magnitude-colour
E-mail contact: ercolano at usm.lmu.decomplete as possible. This is why we performedWe
also(red) in Fig. 13 .
hyperspace that are occupied by membersgoing.
of a same
class(I, IInote that class I objects are globally aligned on a
two steps.
Table 4: Summary of evolutionary sta
Thenorthwest-southeast
ρ theseOphiuchicomplexparticular
L1688mostdarkismembers
unique arein itsproximity(∼130 pc),
regions are molecularlected the most reliable proper motions of and
our III). When the parameters characterisingaxis, mostly
located andin theinmostembedded the Lynds
As expected,
of cloudthe newTheweaksources
dispersalof thecircumstellar discs of dust members
and gasandsurroundingyoung
e to derive the kinematic properties of the clus“learned’, the algorithm considers the unclassified members andcandidates.
region,which
was
proposed
by
Motte
et
al.
(1998)
tocorrespondwithMranging
from
5
to
12.
Since
the
transition
betweenstars
inonits
in young stars and protostars, and in its youth H(0.5 Myr). It is certainly
oneformationof the best
targets
currently
field, using objects with at least a time baseattributesofa class to them depending
their richness
localisation in this
for
the
of
planetarysystems.
Photoevaporationfromenergeticr
five years, with a number of observations greater
hyperspace.
to the perpendicular
to the directionof shockby theand BDs occurs at ProperMH ⇠5 mag,that is,M J ⇠6 magyoungth 2mas/yr. From these, we excluded proper
accessible
fromthethe groundto study
thepropagation
early phasesof star-formation.
motionanalysis
isdispersal
afor
very
efficient
tool for of discs, by
StatusMembers
we adopted
than 45 mas/yr, which correspond to foreground Of the various supervised methods available,
to
drive
the
in
the
majoritycreating
a
gap
which
di
Upper
ScorpiusOB
association
onto
the
core
of
the
⇢
Oph
cloud
clusters(e.g.,
Bara↵eetal.
2015),
virtually
all
the
new
members
and successful data classification non-parametric
w1 − w4 [mag]56 known YSOs (CDS)
not belong to the ⇢ Ophiuchi complex. This well-known
left
separating
members of clusters fromfield stars, but veryfall
few
motions
areTheavailable
inoftheρsevenOphiuchiregion thesinceouter disc fromin proper
the substellar
regime.
Mvaluesthe
spec2001; Breiman et al.
ects with highly accurate proper motions. method called random forests (Breimancomplex.
ofH the
disc
and
then
disperses
inside-out, while 4th
ClasstheIership analysis led to the following mean proper2003), complemented by a Monte most
Carlo trialof
to accountfor
erFig.
10:
One
of
the
colourcolourdiagramsforkinematic
memFig. 9: K s are
distributionof known
objects referenced Class II
the young sources are deeply embedded in dusttroscopicallyand gas. confirmed
We aimBDs
at in
performinga In
kinematic
censusofstellar
young⇢ Ophiuchi
also indicatedin young
34
recisions for the cluster derived with 48 memrors in the observable quantities. We adopted the R language im- bers using 2MASS K s and WISE w1,w2, and w4 photometry.
the
star.
this
Letter
we
show
that
the
disc
aroundTW
Hya, the closest= (-7.4 -22.9) ±0.8 mas/yr (hereafter µ stands
atthe AboveCDS
andkinematic
members
or candidates of the Class III
Fig 13 together
withtheir spectraltype.
MH new= 5 mag,
we runplementation of random forests bystellar
Liaw & Wiener(2002), and
13
Objects withclassespreviously
known in the literaturethat andwere partiallyobjects(YSOs)
intheρ
Ophiuchi
F
core
in
the
E
core
of
the
L1688
dark
cloud.
Weaproperd for the field (µ , µ ) = (-3.5, -1.4) ± (0.4,0.3)
first object
where
photoevaporative gap has been
to take all the errors of the available measurements into account, used for the training of the method (train) are shown with filled
nematic values derived for field stars agree reafind 23 new substellar members, cluster.
which
is 3.3 times
moreathan
26 newimaged
YSOs around the tim
wefollowed
a
Monte
Carlo
approach,performing
30000
indemotion program attheandESO
New
Technology(NTT)knownwith BDs
theof ISAAC(SOFI)
instrument
overnine consistentClasssymbols
the objects
we classified
are shown withTelescope
ith predictions from the Besançon Galaxy model
8: Distribution
onempty
the sky ofpreviously
kinematic
members,
candidate
I the expectations of2
inSon
the surveyedarea.
detected
gap inonthe
ALMA
imageswithpendent classifications of the dataset. At each run the following symbols. Squares refer to Fig.
he direction of our field : (µ , µ )= (-2,-2) mas/yr.
class I, circles to class II, and trianFig.
12:
Distribution
the skyof objects
from ouris
proper mowas performed: first the magnitudes
ofin
eachthestar atnear-infrared.
each gles to class III.
d step, we considered all the objects from process
our
years
We
complemented
observations
withpublicimage
databasestoenlarge
the
Class
II
11
members(0.5<P<0.9)theseand field
starsThe
with weakest
indication
ofvarious
the new
local-members
four
(UGCS
J162746.78tions
cataloguethe(greypresencedots) and of ofthe a
82 planet.
kinematic members
andrequiring
The photoevaporation
model is also4c
catalogue that were excluded from previous analfilter are sampled from Gaussian probability distribution func◦◦ Red circles corClass III
isationof ofthe investigation
B, C, E, and F coresof⇢ Ophiuchi.
d those whose data were spread over five or more
244059.1,
UGCS
J162700.96tions with the mean equal to the measured
imputed,thetime (orbaseofseeobservations
and the
field
to
0.5
×0.5BX162727602-24381862,. We derived positions
motions2213
candidates
ofand
theHya⇢proper
Ophiuchicluster(colouredsymbols)
derived1
Fig. 4:main-sequencestars(-6.3±0.3)
kms for(Prato2007;rate
Guentherpochs with a time base of observations
longerDistribution on the sky of objects from our proper motion respond to the kinematic members (P>0.9) derived in this work,
of
the
TW
system,e.g.
accretionandthelocationof the gap at
Fig. 6:below)
Repartition
ofand
membershipprobabilitiesofthe936 ob- (orparagraph
value
the
sigma
equal
to
the
measured
244339.5,
and
2MASS-6X
J16265864-2443281)
with
M
11
in
work.
Red
squares2007;
designateclass al.
I, green
circlesclass IIH
and a precision better than 3.5 mas/yr. We thenjects.
The indication
filled blackcorresponds
tothenknown
objects.
From
these,
607
motions
derived
from
SOFI
observations
with∼1.8unresolved
mas/yraccuracytheet thisal.a 2007;
KurosawaJames2006).
We summarise
computed
basedproperon the angulardistance
the positions
imputed)magnitude
errorhistogramat theof
relevant
all youngthe possicatalogue
withtheirfilter;
magnitude
range.
mbership to the two distributions
and retained
blue
circlesbetween
towerecandidatemembers<0.9).
Filled870µmetwhile
continuum
source might be produced by free fstellar objects (detected by ISO (Bontemps et al. 2001) or Spitzer
mag(0.5<P
are potentiallyvery circles
low mass central,
BDs that reach
spectral types

Accepted by ApJ

2/2	

●

Class

I − Train● II − Train

7.5

III − Train

K − w2 [mag]I − New●● II − New

III − New

5.0

●

●
●●
●
●●
● ● ●● ●● ●● ●●●●● ●● ●●●●● ●●● ● ●●●
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●
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●
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●
● ● ● ●●●● ●●●●●●●●● ●● ●●●● ●● ● ●●●● ●●●●●●●● ●●
●●
●
●
●●●
●
● ●
● ●●
●
● ●●
●
●
●
●
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●
●
●
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●
● ●● ●
●●
●●
●
●●
●
●●
● ●
●
●
●

●

2.5

●

0.0

µ

0.0

⇤
↵

2.5

5.0

7.5

●

●

10.0

⇤
↵

f

⇤
↵

and blue triangles class III. The zones with few grey dots correof each object and the median position of all member objects
in Table 3 the kinematic properties of the ⇢ Ophiuchi (F core).
designateobjects
belongingcatalogue
and triangles(Fig.11). The median projected
radii andthe absolute
median to thespond to themost obscureregions. Crosses indicate the approx- 8. Conclusions
as SOFI
cool asL0 (⇠2200K,
see discussions
in Tottle& Mohanty
deviation for each type of object
shows
that
the
di↵erent
classes
identify known young stellar objects
detectedby ISOor Spitzer.
imative
centresthe E,F, anddotted line indicates2015).
These
cool
young
BDs
are
expected
to beofspatial
very
low
massB cores; thepresent di↵erent preferential projected radii and also di↵erent
Table
3:
Mean
and
propertiesof (1998).
the ⇢ Ophi-With our astrometric observations w
black dots
correspond0 to fieldobjects(P<0.1).
0of clumps and YSOs kinematic
identified byMotte et al.
Ducourant C. et al.: Kinematics in ⇢ Ophiuchi
spread: RI = 5.6 ± 3.1 0 , RTheof onlyabout
10 MJup (Chabrier ettheal.line2000).
II = 8.8 ± 4.5 , RIII = 10.7 ± 5.3 .
uchi
F
core
as
derivedfromthe68
kinematic
members with thepropermotions of 2213 stellar and s
These results indicate that the youngest objects are more concenWesummarisetheevolutionary
statusofthe82
membersand4.1. Comparison to PPMXL and 2MASS catalogues
trated in the central parts of the working zone (cores E and F),
highest membership probability (P>0.9).
Breiman,L., Last,We
M., &perform
Rice, J. 2003
⇢ Ophiuchi cluster
region.
(Springer New York), 243–254
candidates in Table 4. Seven members already known as YSOs
while more evolved objects are more spread towards the exterior.

ble colour combinations between the filters J, H, K, w1, w2, w3
obability greater than 50%.
(Evans et al. 2003)) that are present in our catalogue. For visibiland w4then thea randomclassifierassigns ad up with 82 objects with a membership probaity are
the ycomputed;
axis is truncated;peak thatforests
corresponds
to a probaster higher than 50%. We present the repartition
class bility
to allofthe
objects
with unknownclasses. Finally, after all the⇠0.05
culminates
at 800 objects.
probabilities for the 936 objects analysed hereindependentinruns, the frequency that each object was assigned torve in this figure two clear peaks that correspondeach class is computed and the class with the greatest frequency
ion (P<0.1) and cluster population (P>0.9) andis adopted as the object class.
ermediate probabilities. Sixty-eight objects have
>0.9 and are considered as members, while14 ob- A special approach had to be adopted because some data
embership probability 0.5<P<0.9 and are classipoints were missing in our dataset (e.g., many objects were obte members.
served or detected only in some, but not all, of the 2MASS or
p analyses are very sensitive to outliers (e.g.,
WISE filters). The approach adopted was to perform data imects from the Galaxy with high proper motion)
putation and Monte Carlo sampling of error distributions. The
excluded to derive realistic solutions (see disfirst step is to perform data imputation, but to avoid mixing the
he pruning of the data in Cabrera-Cano & Alfaro⇤
well-known objects with the most uncertain objects, we split
refore excluded objects with µ↵ or µ > 45 mas/yr
objects with proper motions beyond 2.5 of thethe missing data imputation into two phases: first, the data ims of the cluster and of field at the end of step two.
putation was performed using all the objects with previously
st of objects in Table 5 that are considered as outknown classifications; then, the missing data imputation was pereir high membership probability (P>0.9) because
formed considering all objects in our dataset. We adopted a nonotion di↵ers by more than 2.5 from that of thedust inside the gap.

13

Accepted by MNRAS Letters

http://arxiv.org/pdf/1609.03903

ship analysis andCabrera-Cano,derivedJ. a& Alfaro,
list E.ofJ. 1985,
82

Density

Cesarsky, C. J., Abergel, A., Agnese, P
et al. 2012) and 6 new
YSOs
For the optical part of our catalogue, the densest comparison cat- 5.2. New and known membersare identified BD (Alves de OliveiraProperty
Valuecandidate members,
26G., ofthem
are
Chabrier,
Bara↵e,I., Allard,F., &nHhms‘”
Cieza, L., Padgett, D. L., Stapelfeldt, K
are BD candidates (Alves de Oliveiraetal.
2010).
alogue is the PPMXL catalogue (Roeser et al. 2010). We notelishedinareliable
mean
kinD
(↵,
)
(
16
27
22.51
,
24
41
58.5
)
7. Nature of kinematic members and candidates
Cutri,way
R. M. &the
IPAC/WISE
Sciencemembers or candidate members derived in The
Abstracturbulence,magnetic
fields,
L1688 darkcloud tronomical(µfilaments,
cosSociety, µMeeting)=(-8.2
that the present work included some PPMXL propermotions as Of the 82 kinematic(µ↵ coslink, µ ) between( -8.2, -24.3)±
0.8 mas/yr
Class
0.075
ciety↵Meeting Abstracts 219, 401.06
the 82 ofkinematic
members and candidate members in the confirm that the velocity
Tableas4:
Summary
evolutionary
statusthe 82 kinematic
at CDS
young
stellar of
objects,
the Of(l,b)
Cutri, R. M.,of
Skrutskie,F., vanI
this M.
core
isD( 352.9816,16.5540)
starting point of the iterative reduction process but the final cata- this work, 56 are referenced
tral
Molecular
Zone
cloud
G0.253+0.016
Catalog, 2246, 0
weanalysed, we proposeda classificationfor 53 ob- the Upper Scorpius
II
members
and candidates.
26 others are new members
or newcandidates.
Of the known ob- region
association.
Cutri,
R. M., Wright, E. L., Conrow, T
(µ
cos
b,
µ
)
( -23.8,-10.7)±
0.8 mas/yrlblogue should be more or less independent of it. Another difficulty jects, 7 are brown IIIdwarfs (BDs) (Alves de Oliveira et al. 2012), jects. Six objects (2MASS-6X
theAllWISE
Data
Release
Products
J16271965-2441487,
2MASS
0.050
We assigned 3Dawson,
a,SED
class
toD.
the
5a
T. P., etPosition(X, Y, Z) 12MASS-15.6,+37.4) pc 2 ,2MASSC.
Federrath,( 126.9,
J. M.
Rathborne
S. N. Longmore
J.P., Scholz,
M.A., Ray,K
resultsparametricfrom thefact that the 239 objects common to our cata- 1 is a BD candidate (FHTWIR-Oph
J16272661-2440451,
de Zeeuw, P.usingT., Hoogerwerf,R., de Bru
StatusCandidates
80, Alves de Oliveira etMembers
al. J16272439-2441475,
or candidates
a non-pa
missing data imputation method called missForest
1-5.9±0.1, -14.2±0.3,
8 -8.1±0.4) km/s members
9
10,11,12
Velocity
(U,
V,
W)
(
A. 1999, AJ, 117, 354
J16273272-2445004,
2MASS
J16274161-2446447,
and
2MASS
R.
M.
Crocker
,
G.
Garay
,
J.
M.
Jackson
,
L.
Testi
and
A
PPMXL
are mostly
atonthe southern edge (2010)), and 26 were found by the(Stekhoven& Buehlmann2012). Thisconcentrated
method is also based
Do, T.,
Martinez,
G. D., Yelda, S.,et alng meankinematic properties
the cluster andaresupervised methodforclassifying
obje
major spatial
NIR-surveys
permotioncat- of logue
56 known
YSOs (CDS)
Dodson-Robinson, S. E. & Salyk, C. 2
random forests algorithm to predict continuous missing val3. We present the list of the members and canJ16273894-2440206) have been listed by Alves de Oliveira et al. tion of the (J, H, K,
of the aues
field,
which means that the cluster is almost0.025completely ISO (Bontemps et al. 2001) or Spitzer
Ducourant,& Rapaport,
M. 1991,A
w1,C.w2,
w3 andw4
et al. 2003).
1 4 The mean proper
Notes.
motionof the core given here
does
not accountClass(EvansI
0cataloguewhile
s with their astrometricsolution and their memfrom the observed values of all other objects in the dataset
Research
Schoolof
Astronomy
andAstrophysics,
Australian
NationalUn
Ducourant,
C.,
Teixeira,R.,
Chauvin,(2010) as potential brown dwarfs (BDs) based on their position colours. Nine objects are defined as clasG
ility in Table 7. Fig. 7 shows the excluded
vector plot anddi- from
the relation
the object whoseandvalue ismissingand brightest objects
fromthis ofcomparison
only
thethe probable systematic
error (⇠ 2 mas/yr) of our proper motion
Ducourant, C., Teixeira, R., Hambly, N
The kinematic members are mostly
located around the Oph for
Class
II
34
2
logue.
uster and indicates the membership probability,2
ina colour-magnitude diagramand
among
the faintest,
red objects.
Eckart, A., Mužić, K., Yazici, S., et al.
all other objects considering the entire parameter space of theSpace
Science,
P.O. Box76,
Epping
NSW, 1710,
objects
as class
III.
catalogue.
ws the distribution of field stars ofand ourof cluster
Erickson, K. L., Wilking, B. A., Meyecatalogue are concerned. Nevertheless, we performed
the F and E cores, with several new detections
0.000
Class III south to these cores. That
13CSIRO Astronomy
3
dataset.
andidate members across our field.
L. N.new2011, AJ,
142, 140
3 we can kinematically confirm that they are part of the clusWe
discovered
23
BDscandida
0
5
10
15
20
The
results
oftheclassification
performed
here
arerepreSome
previously
known
membersaround
Oph
B
core
are
also
Astrophysics
Research
Institute,
LiverpoolJohn
Moores
University,
Evans,II,
N. J., Allen, L. IC2,
E., Blake, G.L
comparison
of
both
sets
of
propermotions,
and
we
noted
a
sys26 new YSOs
ows that the repartition of the kinematic members
ter indicates that they are probably BDs.
Radius [arcmin]Fritz, T., Gillessen,S., Trippe, S.,sented in one of the many possible colour-colour planes in Fig.
potentially multiplying
the number
ofet al.
kular, as expected. The dispersion of their properWe
comparedthesevalueswiththekinematic
characteristics
classified
askinematic
members.
The
highconcentrationofkineFig.
7:
Vectorplot
diagram.
Red
circlescorrespondtothekineFritz, T. K., Chatzopoulos, S., Gerhard
Class
I
2
3
tematicdi↵erence
(in
the
sense
this
work
minus
PPMXL)
UsingthetypicalIR
excesses
in
J,
H,
and
K
bands
for
class
mas/yr) is larger than expected fromthe astro10 mean
which
shows
that
most
of
the
objects
lackingliterature
clasLiverpool
L3
5RF,
UnitedKingdommatic members (P>0.9) derived in this work,
blue circles
canthemD.mightbeM
Fig.
12: toDistribution
on the sky of objects
fromour propermo- part of the field covered by this of the Upper Scorpius (US) association since the ⇢ Oph clustercluster by 3.3. A few
Furlan,ofE., Watson,
M., McClure,of view (1-2to
mas/yr)and reflects the difficulties
members
centralFig. 11: Radial density plot.matic
The projected
densitiesinof theeach classsificationwere
assigneda<0.9).
classTheII black
status.
Ofcorrespondthe 53 unclassified
down
much
Gallagher, D. B., Irace, W. R., & We
didatemembers(0.5<P
dots
to
field
Class
II
11
5
II
and
class
III
YSOs
and
the
extinctionlawinnear-IR
as
in
4
of
(
µ
cos(
),
µ
)=(-1,+6)
mas/yr.
↵2roper motions in such obscured zones and themembers
re- objects
in the10 M(blacktions
catalogue
dots)
82ofkinematic
members
and of deep SOFI observations.
Jup regime.
Astronomisches
Rechen-Institut,
Zentrum
Astronomie
derUniversitätof YSOs
are andgivenofin thenumberobjects par arcmin
areOpticalInstrumentation EngineersHor(P<0.1).
candidates,
wereassigneda class
III status,
Filled 16
circlesdesignateobjects
belongingto the 32 a(greyFig. 13:
Distributionof (seeabsolute
Hfürmagnitudes
of known
is expected
thederived
Upper theSco
association
Wilking
study
corresponds
to andtheeachzone
uracy.andTwenty-six
members are YSOs that have SOFI catalogue and triangles identify known young stellar obBontemps
ettoal.be(2001),
absolute
J and
H maguereachesClass III
4
1part ofwe
Telescopes and Instruments,
versus cluster
theprojected
distance tosymbols)
the center [ofclassII, and 5 a class
I.origin of thecandidates
We wereconableGirard,
toSpaceestablisha seconda
dotted) and new (solid red) members.
Spectroscopicallyof the displayed⇢di↵erence
Ophiuchi(colouredderivedTomemdetermine
thelarge systematic(esby ISO or Spitzer. Field stars and cluster
T. M., van Altena, W. F., Zacha
1 the
et
al.
(2008)).
We
observethatthevelocity
derivedhere
forWe
present
in
Fig.
9
the
repartition
in
terms
of
K
magnitudes
jects
detectedbyISOor
Spitzer.
delberg,
Germanysclass.
nitudesforthekinematic
members
andcandidates
members.
firmed brown dwarfs by Alves de Oliveiraframe
et al. (2012)
are indiN.,
Yano, T., where
Yamada, Y.,refeted in Fig.7 by a layer of objects with intermediate To analyse how probable it was to find a young stellar obin the
NIRGouda,
inVol.a576,
regionin thiswork.
Redsquaresdesignate ofclass
circlesclass
sentially
inclasses
declination),
the
2MASS
catalogue
catedwetogetherwith theirspectraltype.
The Three-Dimensional
clusterisverysimilar
to
the
one
that
deriveforthesampleject ofI, II, or III at awe
givenconsidered
distancefrom
thecenterobabilities (candidates).
5
theI,56green
known
and 26
newIImembers.
1 Max-Planck Institut für Astronomie, Königstuhl
17,astrometric69117O’Flaherty,
Heidelberg,
G7& M. A. C.can
Perryman,
existing
catalogues
ha
One
new
member(WISE
J162702.05-243938.6)
wasdetected inthe ⇢ Ophiuchi
cluster F core,
weepochbuilt
probability
densitywith
on on the sky of which ofprovides
andbluetriangles
class
III.
The
zones
with
few
grey
dots
correof117
members
of
Upper
Sco
OB2
group
with
Hipparcos
meapositions
for⇠1999.3
errors⇠100
Guenther,E.
W.,
Esposito,M.,
Mundt,The new members appear essentially fainter (down to only
Article number, page 7 of 16
6 one near-IR band therefore we were unable to derive its absolute catalogue will undoubtedly
estimations using kernel density estimators.
The projected radii
This is also visible in Fig.12, which displays the distribution
a valuab
Gutermuth, R.USA
A., beMegeath,S. T., Mye
CASA,(deUniversity
Colorado,
Boulder,
CO 80309,
totheweremostandobscureCrosses
theknown
approxneous, as shown mas andsurements
Zeeuw et al.of
1999)(U,V,W)US389-UCB,= (-5.0 , -14.8,
D. J., Melo, C., Santos, N. C., &Ks=18.1)
thancatalogue
theand were revealed by the magnitudes.
compared
its positions
to
PPMXL
for theobjects classified
as members ofspondeachthe
SED
class
on
theto
skyourof regions.
thecataobjects ofour properindicate
motionand of members
8. Conclusions
ciations
young James,stars,
as2007,
Hipparcos
wS
view of the star-formation processes and toaccess theof
youngest
Kurosawa,
R.
in Multiplicity in7
imative centresof theE, F, and Bofcores;
dottedobservations
line indicates
-6.5
)
±
(0.1,
0.4,
0.2)
km/s.
ected where the logue, each transported to the 2MASS
deeptheNear-IR
performed
in
this
work.
LeidenObservatory,
LeidenUniversity,
PO
Box
9513,
NL-2300
RA
Leideclusters
(<
a
few
Myr),
infrared
astrometriccatalogues
willbeLada, C. J. & Lada,
E. A. 2003,
ARA&
epoch byapplication
Article number, page 9 of 16
the crucial tool, however. The future space infrared astrometric Lawrence, A., Warren, S. J., Almaini, O
With ourastrometricobservations
wenumber,have page
determinedthethe lineofclumpsand
YSOs
identified
by
Motte
et
al.
(1998).
Article
10
of
16
We
note
that
some
well-attributed
membersof⇢Ophiuchie with the clus- its own proper motions. We present
these comparisons in Fig. 5.
mission Jasmine (Gouda et al. 2005) may in this respect be the Liaw, A. & Wiener, M. 2002, R News,first object where a photoevaporative gap has been imaged around the tim
detected gap in the ALMA images is consistent with the expectations orequiring the presence of a planet. The photoevaporation model is also c
http://arxiv.org/pdf/1609.04963
of the TW Hya system, e.g. accretion rate and the location of the gap acentral, unresolved 870 µm continuum source might be produced by freeA photo-evaporative gap in the closest planet forming disc dust inside the gap.
Barbara Ercolano1,2 , Giovanni P. Rosotti3 , Giovanni Picogna1 , Leonardo
Testi2,4,5
Acceptedby MNRAS Letters

Accepted by A&A main

1

Universitäts-Sternwarte München,
81679 München,
L4Scheinerstr.
Ercolano,1,Rosotti,
Picogna,Germany
Testi
http://arxiv.org/pdf/1609.03903
Excellence Cluster Origin and Structure of the Universe, Boltzmannstr.2, 85748 Garching bei München, Germany
3
TWofHyadisc – and/or
if the accretionrate
at the time of
Institute of Astronomy, University
Cambridge,
MadingleyRoad,
Cambridge,
UK
Photo-­‐	  evaporaBon	
  of	
  the	
  circumstellar	
  4
opening isbei
high– again a probablescenario in TW Hya
European Southern Observatory,gap
GarchingMünchen,Germany
The link between turbulence, magnetic fields, filaments
the strong X-ray flux from the central object whichdiscs	  of	
  d5ust	  and	
  gas	
  surrounding	
  
oung	
  
INAF/Osservatorio
Astrofisico ydigiven
Arcetri,
Largo E. Fermi 5, I-50125 Firenze, Italy
tral Molecular Zone cloud G0.253+0.016
21.

results in high photoevaporation rates. This lends credence2.

to the fact that we might indeed be able to observe the gap
low-­‐	
  mass	  stars	
  E-mailcontact: ercolano at usm.lmu.de
C. Federrath1 , J. M. Rathborne2 , S. N. Longmore3 , J. M. D. K
opening phase in the TW Hya disc.
1
8
R. stars
M. Crocker, G. Garay, J. M. Jackson9 , L. Testi10,11,12 and A
of the tcircumstellar
has important
implications• A	
  gTheap	
  ddispersal
isconnects	  he	
  outer	  fdiscsrom	
  of dust and gas surrounding young low- mass
1 from the central object is thought
the formation of planetary systems. Photo- evaporation from energetic radiation
Research School of Astronomy and Astrophysics, Australian National U
the	
  for
i
nner	
  
r
egions	
  
o
f	
  
t
he	
  
d
isc	
  
	
  
2 the outer from the inner regions
to drive the dispersal in the majorityofdiscs,
bycreating
a
gap
which
disconnects
CSIRO Astronomy and Space Science, P.O. Box 76, Epping NSW, 1710
4 GAS AND DUST SURFACE DENSITY• Outer	
  
disc	
  
	
  disperses	
  
from	
  the
the	
  
of thedisc–andthen disperses
outerdisc from UNDER
the inside-out,
while theinner3 disckeeps draining
viscously
ontoLiverpool John Moores University, IC2,
Astrophysics
Research
Institute,
EVOLUTIONVISCOSITYAND
the star. In this Letter we show that X-RAY
the discPHOTOEVAPORATION
around TW Hya, the closest protoplanetary
to Earth,may
be theLiverpooldisc
L3 5RF,
UnitedKingdom
inside-­‐out	
  4
first object where a photoevaporative
gap developed
has beenaimaged
aroundtime atmodel
which
it is being created.
Indeed theZentrum für Astronomie der Universität
Astronomisches
Rechen-Institut,
We have
simple 1D
viscousthe
evolution• Inner	
  
d
isc	
  
–
	
  
k
eeps	
  
d
raining	  detected gap in the ALMA images
is consistentwiththe expectations
photoevaporation
which
includes X-ray
photoevaporation
for a ofTWX-ray
Hya-likedelberg,
Germany models, thus not
5 with a broad range of properties
requiringotheof a planet.system.
The photoevaporation model is also consistentviscously	
  nto	
  presencethe	
  star	  Max-Planck Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, G
Our
1D
gas
surfacedensityevolutioncode,
Spock,
6is of dispersal. We show that theof the TW Hya system, e.g. accretion rate and the location of the gap at the onset
CASA, University of Colorado, 389-UCB, Boulder, CO 80309, USAThe	
  disc	  central,around	  TW	  Hya	  may	  be	
  the	
  ﬁrst	
  described
in detail in Ercolano & Rosotti (2015). At t =70
unresolved 870 µm continuum
sourcemight
beproduced
by
free
free
emissionfromthegasdriftand/orresidual
Figure1. Thetimescalesof the dust particles
of di↵erent
Observatory,
LeidenUniversity,
PO Box9513, NL-2300 RA Leid
disc has a mass of 0.15 M , a radius of 18 au and an Leiden
sizes are plotted at the location and at the time of gap opening.
object	  where	  a	
  photoevaporaBve	
  
gthe
ap	
  
dust inside
the gap.
accretion rate of 10
M /yr. We solve the viscous evoThe radial velocity of the gas is overplotted with a dashed linehas	
  been	  Accepted
imaged	  he	
  Bme	
  alutiont	
   equation, taking into account the photo-evaporative
byaround	  MNRAS tLettersand its zero value is marked with a grey line.
mass-loss, on a grid of 2500 points uniformly spaced in R
14
which	  it	
  ihttp://arxiv.org/pdf/1609.03903s	
  being	  created.	
  (i.e.,	  no	
  pextending
lanet	
   from 0.025 au to 2500 au.
In our model the gap opens between 1 and 2 au at
required)	
  	
  	
  
an age of 5.7 Myr. At this point the mass accretion rate
onto
themagnetic
star is 3.6 ⇥ 10
M /yr.
3.5 ⇥ 10 years
link
between turbulence,
fields,filaments,
andlaterstar formation in the Cen• The	  The
X-­‐ray	
  photoevaporaBon	
  
m
odel	
  
of the global disc lifetime and 17% of the transition
tral Molecular Zone cloud(4.6%
G0.253+0.016
phaseolifetime)the mass accretion rate has already droppedis	
  consistent	
  w1ith	  a	
  broad	  range	  f	
  2 ⇥ 103 gap outer radius is out to 4,5
to 8.6/yr and the
C. Federrath , J. M. Rathborne, S. N. M
Longmore, J. M. D. Kruijssen , J. Bally6 , Y. Contreras7 ,properBes	
  of	
  the	  1 TW	  Hya	
  s8ystem:	
  10,11,12
13
implies9 that
expects
4.6%andof theA.
globalproR. M. Crocker, G. Garay , J.6 au.
M.ThisJackson, L. one
Testi
J. Walsh
toplanetary disc population and 17% of transition discs toe.g.,	
  1 	
  Research School of Astronomy andAstrophysics,
Australian
University,
be observedin this earlyclearing National
phase . These
numbers Canberra, ACT 2611, Australia
2
show
that
a
small,
but
notnegligible
fractionof
young
proCSIRO
Astronomy
andSpace
Science,
P.O.
Box
76,
Epping
NSW,
1710,
Australia• accreBon	
  rate	  3nearby star
forming regions
should be Science Park, 146 Brownlow Hill,
Astrophysics Research Institute, toplanetary
Liverpool disks
JohninMoores
University,
IC2, Liverpool•Liverpool
locaBon	  of	
  the	
  gap	  at	  the	  in this evolutionary phase.
L3 5RF, United Kingdom
In order to verify the timescales for dispersal of dust
4
onset	  of	
  dispersal.	
  	
   particles
Astronomisches
Rechen-Institut,
Zentrum
Astronomie
Universität
of fürvarioussizes from der
the innerdisc onceHeidelberg,
the gap is Mönchhofstraße 12-14, 69120 Heidelberg,
Germany• The	
  5 central,	
  unresolved	
  870	
  μopened,m	
   we have used the gas surface density distributions
obtainedwith Spock17,
as an
inputHeidelberg,
to the fargoGermanyhydro code
Max-Planck Institut für Astronomie,Königstuhl
69117
6
conBnuum	  source	  mbe	
   389-UCB,(Masset 2000)
modified COby Picogna& USA
Kley (2015). We model
CASA, Universityof ight	  Colorado,
Boulder,
80309,
the dust as individual particles, sampling the evolution of a
7
Leiden b
Observatory,
LeidenUniversity,
PO Box 9513, NL-2300 RA Leiden, the Netherlands
produced	  y	
  free	  free	  emission	
  larger ensemble of single dust particles and their interaction
the surrounding environment.
from	
  the	
  gas	
  and/or	
  residual	
  dwithust	
  In Figure 1 we show the drift timescales for particles ofsizes between 100 µm and 1 mm just after the opening of theinside	  the	
  gap.	
Figure 2. The 2D dust distribution for 870 µm size particles is
14
8

1/2

10

5

11

3

gap in the dust distribution (as it is shown in the 2D dust
distribution for 870 µm size particles in Figure 2), when thegas mass accretion rates is 3.7 ⇥ 10 10 M /yr. In the inner
regions (⇠ 0.5 au) particles of 870 µm have a drift timescaleof 2 ⇥ 106 yr.

shown at the time of gap opening.

(overplotted with a dashed line) is directed outwards anddrags with it the dust particles. Inside 1 au the gas radialvelocity PDF typical for turbulence. We measure the total and turbulent velocity dispersion, 8.8 ±0.1 km s−1 , respectively. Using magnetohydrodynamical turbulence simulations, we find that G0.
magnetic field Bturb = 130 ± 50 µG is only <http://arxiv.org/pdf/1609.03903∼1/10 of the ordered field component. Combining
we reconstruct the dominant turbulence driving mode in G0.253+0.016 and find a driving param
indicating solenoidal (divergence-free) driving. We compare this to spiral-arm clouds, which typic
The link between turbulence, magnetic fields,compressive
filaments,and starformation
Cen(curl-free)drivingcomponentin(b the> 0.4).
Motivated by previous reports of strong shtral Molecular Zone cloud G0.253+0.016
CMZ, we speculate that shear causes the solenoidal driving in G0.253+0.016 and show that
rate(SFR) by4,5a, factorof 6.9nearby clouds.
6 compared to typical
C. Federrath1 , J. M. Rathborne2 , S. N. Longmore3 ,formation
J. M. D.
Kruijssen
J. Bally, Y. Contreras7 ,Accepted by MNRAS Letters

1/2	

R. M. Crocker1 , G. Garay8 , J. M. Jackson9 , L. Testi10,11,12
and
J. Walsh13
Accepted
byA.
ApJ

1.
2.

3.

4.

4

1

http://adsabs.harvard.edu/pdf/2016arXiv160905911F
Research School of Astronomy and Astrophysics, Australian
National
Federrathet al.University, Canberra, ACT 2611, Australia

2
turbulence,	
  magneBc	
  
ﬁeld	
  and
and	
  Spaceﬁlamentary	  structure	
  CSIRO
Astronomy
Science, P.O.
Box 76, Epping NSW, 1710, Australia
3
Astrophysics
Research
Institute,
LiverpoolJohn
Moores University, IC2, Liverpool Science Park, 146 Brownlow Hill,in	
  the	
  central	
  molecular	
  zone	  (CMZ)	
  cloud	  Spitzer Observations of Long Term Infrared Variability Among Young
Liverpool L3 5RF, United Kingdom
inUniversität
Chamaeleon
I Mönchhofstraße 12-14, 69120 Hei4
G0.253+0.016	
  Astronomisches Rechen-Institut, Zentrum für Astronomie derHeidelberg,
1, Lindsay DeMarchi2,8 , James Muzerolle3 , Zoltan Balog4 , W
delberg, mGermany
Dust-­‐conBnuum	
  ap	
  with	  ALMA+Herschel:	
  ﬁlaments	
   Kevin M. Flaherty
5
5ThomasMegeath,Elise
Furlan6 , Robert Gutermuth7
Max-Planck Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
and	
  at	
  least	  6 one	
  dense	
  core	  along	  them	
  1
CASA, University of Colorado, 389-UCB, Boulder, CO 80309,
USA
Van
Vleck Observatory, Astronomy Dept., Wesleyan University, 96 Foss Hill Drive, Middletow
7
2
LeidenObservatory,
University,
RAofLeiden,
Netherlands• ﬁlament	
  width	  Wﬁl	
  =	  0Leiden
.17	
  ±	
  0
.08	
  pc	
   PO Box 9513, NL-2300
Dept.
PhysicstheandAstronomy, Colgate University, 13 Oak Drive, Hamilton, NY 13346, US
3
Space
Telescope
Science
Institute, 3700 San Martin Drive, Baltimore, Maryland, 21218, USA• sonic	
  scale	  of	
  turbulence	
  λsonic	
  =	
  0.15	
  ±	
  0.11	
  pc	
  4
Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany(the	
  transiBon	
  scale	  from	  supersonic	
  to	
  subsonic	
  14 5 Ritter Astrophysical Research Center, Dept. of Physics and Astronomy, University of ToledUSA
turbulence)	
  =>	
  	
  Wﬁl	  ≈	
  λsonic	  	
  6Infrared Processing and Analysis Center, California Institute of Technology, 770 S. Wilson Ave,
HNCO	
  intensity-­‐weighted	
  velocity	
  maps	
  obtained	
  USA
7
Department of Astronomy, University of Massachusetts, Amherst, MA 01003, USAwith	
  ALMA+Mopra	
  8Department of Physics, Syracuse University, Syracuse, NY, 13244, USA•
Velocity	
  gradient:	
  large-­‐scale	
  shear	
  E-mail contact: kflaherty at wesleyan.edu•
Turbulence:	
  nearly	
  Gaussian	
  velocity	
  PDF	
  Infrared variability is common among young stellar objects, with surveys finding daily to we•
Velocity	
  dispersion:	
  8.8	  ±	  0.2	
  km/s	  (total),	
  	
  few tenths of a magnitude. Space-based observations can produce highly sampled infrared light
limited to total baselines of about a month due to the orientation of the spacecraft. Here we
3.9	
  ±	
  0.1	
  km/s	  (turbulence)	
  of the Chameleon I cluster whose low declination makes it observable by the Spitzer space tele
Comparison	
  with	  MHD	
  turbulence	
  simulaBons	
  period. We observe 30 young stellar objects with a daily cadence to better sample variability on•
Bturb	  =	  130	
  ±	
  50	
  μG	
  is	
  only	  <∼1/10	
  of	
  the	  We find such variability is common, occurring in ∼80% of the detected cluster members. The
color
over 200 days for many of the sources falls between that expected for extinction and fluctua
ordered	
  ﬁeld	  component	  	
  With our high cadence and long baseline we can derive power spectral density curves covering tw•
Driving	  parameter	
  b	
  =	
  0.22	
  ±	
  0.12	
  indicates	  in frequency and find significant power at low frequencies, up to the boundaries of our 200 dsolenoidal	
  (divergence-­‐free)	
  driving	
  	
  
•
cf.	
  b	
  >	
  0.4	  in	
  spiral-­‐arm	
  clouds:	
  signiﬁcant	  15compressive	
  (curl-­‐free)	
  driving	
  component	  •SpeculaBon:	  	
  shear強い=>	
  solenoidal	
  driving	
  =>	
  SFR低い	  Figure 1. H2 column density maps of G0.253+0.016 from Herschel (Longmore et al. 2012) (left-hand panel) and ALMA+Herschel(Rathborne et al. 2014b) (right-hand panel). The Herschel map traces the large-scale structure well, while the combined ALMA+Herschelmap reveals the internal structure of G0.253+0.016. Using the DisPerSE algorithm we identify 11 filaments in the ALMA+Herschel map,
which are highlighted and labelled by artificially increasing the column density by a factor of 5 for each pixel belonging to a filament. The

PDFsive),typicalturbulence.
We measure
total and turbulent
velocity dispersion, 8.8 ±thefordriving
parameter
can varythe
continuously
in theis defined as (Federrath & Klessenvelocity
2012; −1
Accepted by2003).
MNRASItLetters
0.1
km
s
,
respectively.
Using
magnetohydrodynamical
turbulencesimulations,
we find that G0.
range 1/3 ! b ! 1. An increasing b value corresponds
Federrath 2016)23<
magnetic
field
B
=
130
±
50
µG
is
only
1/10
of
the
orderedfieldcomponent.
Combiningtoanincreasing
fractionofcompressive
modes
in
the
turb
http://arxiv.org/pdf/1609.03903∼!
"
turbulent
drivingturbulencemechanism.
Themodespecialcase called and find a driving param
we reconstruct
the dominant
driving
in G0.253+0.016
λsonic = LM−2 1 + β −1 ,(5)‘natural (divergence-free)mixture’ is close tosolenoidal
driving andindicating solenoidal
driving.
We compare
this refers
to spiral-arm clouds, which typic
tothesituation
where
theturbulent
driving
modes
where
L,
M
=
σ
/c
and
β
are
the
cloud
scale
v,3D s magnetic fields,compressive
The link between turbulence,
filaments,and starformation
Cen(curl-free)drivingcomponentin(b the> 0.4).
Motivated byare
previous reports of strong sh
randomly distributed in all three dimensions (see Fig. 8(diameter),the cloud
3D turbulent
sonic Mach number,andwe speculate
tral MolecularZone
G0.253+0.016
CMZ,
that
shear
causesthesolenoidal
drivingin
G0.253+0.016
and show thatin Federrath et al. 2010).
the ratio of thermal to magnetic pressure, plasma
β =
(SFR)
by
a
factorof
6.9
comparedtotypicalnearbyclouds.
1
2 2
3 formation rate Given
4,5
6
7
2
our measurementsof σContreras
C. Federrath, J./pM.
Rathborne, J. M. D. Kruijssen, J. Bally , Y.
, 0.5, M =ρ/ρ0 = 1.3 ±pthermal= 2cs /v,AS.ofN.theLongmore
cloud. Inserting
magnetic11±
and β 13= 0.34 ± 0.35 in G0.253+0.016 from theL = 14.7± Garay
0.1 pc, 8M
11Jackson± 3, and9 , βL.=Testi
0.3410,11,12± 0.35andR. M. Crocker, G.
, J.=M.
J.3Walsh
Accepted
byA.
ApJ
previous sections and summarized in Table 1, we can
The CMZ cloud G0.253+0.016
based5 on our measurements
and values taken from the8Federrath et al.
1
http://adsabs.harvard.edu/pdf/2016arXiv160905911F
Research Schoolof Astronomy
andAstrophysics,
Australian
National
University,
Canberra,
2611, Australia
solve Equation(7) forACT
the turbulence
driving parameter
literaturesummarized
in
Table
1,
we
find
a
sonic
scale
of
ution to a high column-density
2
CSIRO Astronomy and Space Science, P.O. Box 76, Epping NSW, 1710,
Australiaal. (2014b).
andfindameter of the water maser and3
λsonic Liverpool= 0.15 ± 0.11
(6) IC2, Liverpool Science −1
Astrophysics Research Institute,
JohnpcMoores University,
Park, 146−1Brownlow
Hill,
dates is 0.09 pc with a variab = σρ/ρ0 M(1 + β Term
)1/2 =Infrared
0.22 ± 0.12.Variability(9)
2. The filling fraction of these
Spitzer
Observationsof LongAmong Young
Liverpool L3for5RF,
UnitedKingdom
0011 ± 0.0001 of the total area
G0.253+0.016.
This
is
in
excellentagreementwithinChamaeleonIing inefficient dense-core and4This
resultmeans
thatturbulenceinG0.253+0.016
isAstronomisches
Rechen-Institut,für Astronomie
der Universität Heidelberg, Mönchhofstraße 12-14, 69120 HeiKauffmann et al. 2013). The
the filament
width thatZentrum
we measured
for G0.253+0.016
2,8dense-core candidates are loby a solenoidal
drivingmechanism.
Kevin
Flaherty1caused, Lindsay
DeMarchi, JamesMuzerolle3 , Zoltan Balog4 , W
delberg, Germanyin Figure 2. It supports the idea that the sonic scaleof M. primarily
2 and 4. Dense cores are of56
7
5
ments and their intersections,magnetizedturbulencegivenbyEquation(5)
may
conThomas
Megeath,Elise
Furlan,RobertGutermuth
Max-Planck Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
6.1. The density dispersion–Mach number relation
uds in the spiral arms of the6trol the widthof interstellar
filaments,
not CO
only80309,
in1nearbyl. 2012; Polychroni et al. 2013;
CASA, Universityof Colorado,
389-UCB,
Boulder,
USA
Van
Vleck Observatory,
Astronomy
Dept.,
Wesleyan University,
96 Foss Hill Drive, Middletow
s suggests that filaments may
Figure 6 showsa graphicalrepresentationof the den2016),
but
also
in
the
CMZ.
clouds(Federrath7
blocks of molecular clouds, ir2
LeidenObservatory,
LeidenUniversity,
PO
Box
9513,
NL-2300
RA
Leiden,the
Netherlands
sity
dispersion–Machnumberrelationgiven
byEquaDept.
ofPhysics
andAstronomy,
ColgateUniversity,
13
Oak
Drive,
Hamilton, NY 13346, US
clouds are located along spiral
We have to add the caveat that Equation (5) is generCenter.
3
tion
(7).
In
order
to
put
our
result
for
the
CMZ
cloud
Space
Telescope
Science
Institute,
3700
San
MartinDrive,
Baltimore,
Maryland, 21218, USA
ally
only
applicableforcloudswherethemagnetic
field
isthe right-hand panel of Figd large-scale magnetic field di4 seem
G0.253+0.016
in context, Königstuhl
we include 17,
three
spiral-arm
primarily
turbulent,
i.e.,
B
>
B
.
This
does
not
Max-Planck-InstitutfürAstronomie,
69117
Heidelberg,
Germanyturb
0polarization measurements byclouds in Figure
6, Center,
for whichthe ofdensity
dispersion–
5 so weurther analysed in Pillai et al.
to
be
the
case
in
G0.253+0.016(see
Section
3.3),
RitterAstrophysicalResearch
Dept.
Physics
andAstronomy,
University of Toled
14
filaments are mainly parallel
Mach number relation was measured in previous works.
have to perform a more careful analysis of the orientationd 5), while others are primarUSA
Measurements in Taurus were obtained in Brunt (2010),.g., filaments 2 and 4). We doof the filaments with respect to the large-scale ordered6s have a preferred orientation
Infrared Processing
and Analysis
California
Instituteof Technology,
770 S. Wilson Ave,
with corrections
to Center,
the Mach
numberestimateincale magnetic field. In the folmagnetic field component B0 . In Figure 2 we found thatwidth of these filaments andUSA
Kainulainen&Tan(2013),
andcombined
here
with
an
filaments parallel to B0 are somewhat wider than
filaarily parallel or perpendicular7
Alfvén
Mach numberof MA
1 estimated forthe gasMA 01003, USA
ther the width depends on the
Departmentof Astronomy,
Universityof >Massachusetts,
Amherst,ments perpendicular to B0 , however, this is merelya24
8
insidethecloud(Heyer&Brunt2012).
The
Galac- USA
Department of Physics, Syracuse University, Syracuse, NY, 13244,
trend that is not statistically significant given the uncerlament profiles
tic Ring Survey molecular cloud GRSMC43.30-0.33 data
tainties in the measured filament width. So whileE-mailEqua-contact:e characteristic width of the
kflaherty
at wesleyan.edu
6, we construct radial profiles
are from
Ginsburg
et al. (2013) and the IC5146 data aretion (5) only takes the turbulent magnetic pressure into
al filament in Figure 1. The
from Padoan
et al. among(1997a).young
For GRSMC43.30-0.33
andsurveys finding daily to we
at applied in previous studies
account
and
would
thus
theoretically
only
apply
to
the
Infraredvariability
iscommonstellar objects, with
Federrath 2016). The radial
we hadSpace-based
to neglect themagnetic canfieldproduce(assumed
filaments perpendicular to B0 , it seems to providefew
a goodselecting all pixels belonging
tenths ofIC5146,
a magnitude.
observations
highly sampled infrared lightacing the column density cells
MA → ∞), because there are no measurements of Bturb
match to the measured filament widths, irrespectiveof to totale r to the filament as in previlimited
baselines
of
about
a
month
due
to
the
orientation
available for these clouds. However, we emphasize thatof the spacecraft. Here weh 2016, and references therein).
the filament orientation.
of the Chameleon
I clusterwhosemagnetic
low declination
makes itBobservableby the Spitzer space telemn density and column density
includinga realistic
field strength
turb > 0
distance r from each filament
period. We observe
30 young
stellarwitha daily
cadenceto better sample
will
alwaysleadtohighervaluesofthedriving
parameThe
CMZ objects
cloudG0.253+0.016
13 variability on
6. THE EFFECTIVE TURBULENT DRIVING
ment profile of G0.253+0.016
Figure 2.
Top panel: Average radial profile of all the
Figure 4. Top panels: maps of the HNCO intensity-weighted
velocity
invariability
theG0.253+0.016,
beforesubtracting
thelarge-scale velocity
ter
b.
The
data
pointsfor
GRSMC43.30-0.33
andIC5146
We
find
such
is
common,occurring
in
∼80%
of
the
detectedclustermembers. The
G0.253+0.016
filaments
inFigure1.
Middlepanel:
sameas
top
age profile and the shaded regradient (left-hand panel) and after subtracting it (right-hand panel). The middle panel shows the fitted gradient across G0.253+0.016,
panel, but only for the filaments that are primarily parallelTheoreticalto theon). In order to determine theand numericalstudieshave motions,shownwhich is likely associatedwith systematic
such thatas large-scale
shear
or rotationofFigure
thecloud. Thissystematic
contribution
must
be lower that
shown
in
6
therefore
represent
limitsofb.
large-scale magnetic field (B ). Bottom panel: same as top panel,
color
over
200
days
for
many
of
the
sourcesfalls
betweenexpectedfor
extinction
and fluctua
ply two fits, one with a Gaussubtracted in order to isolate the turbulent motions in the cloud. The coordinates and field of view of the maps are identical to Figure 1.
but only for the filaments that are primarily perpendicular to B .
density fluctuations(σρ/ρHNCO) invelocity
a turbulent
medium
We
see
that
all
three
available
spiral-arm
cloudshave density curves covering tw
Bottom panels:
PDF before subtracting
the large-scale gradient(left-handpanel)
andafter subtracting
it (right-hand
h a Plummer profile.
In all panels, the shaded region shows the 1σ-dispersionthe
about the
0
With
our
high
cadenceandlongbaselinewecanderivepower
spectralpanel).
The
velocity
PDF
after
subtractionisconsistentwiththetypicalGaussiandistribution(dottedline)ofaturbulentmediumwithaverage
profile.
Plummerfits
withEquation(2)
andaGaussianrofile (shown as the dotted line
a significant compressive driving component, i.e., theycorrelatewith the aMach
number(M) ofandthelines, refits with Equation (1) are shown as dashed and dotted
one-dimensional
velocity dispersion
σv,1D =
3.9 ± 0.1
km s−1 .
in drivfrequency
and find significant power at low frequencies, up to the boundaries of our 200 dspectively. The beam size is shown as a ruler. Both Gaussian and"!
have b parameters exceeding the natural driving mixture,
Plummer fits yield consistent beam-corrected filamenting
widthsofof the turbulence, which is controlled by the turbur2
W
=
0.17
±
0.08
pc
for
all
filaments,
W
=
0.19
±
0.09
pc
for
the
+ Σoffset ,
(1)
− 2
Here
we
use
the
HNCO
line
emissionofG0.253+0.016
This
velocityby
gradient
likely associatedfilaments primarily parallel to B , and W = 0.13 ± 0.07
pc for the driving parameter b (Federrath et al. 2008b, 2010;b >large-scale
0.4, given
the isblue
dotted withline (Federrath et al.
lence
2σGaussby Rathborne et al. (2015), in order to obtain global
systematic rotation or shearing of the cloud. By confilaments mainly perpendicular to B .
2010).
G0.253+0.016(shownas the red cirPrice et al. 2011; Konstandin
et al.velocity
2012;
Nolan
et al.
kinematics (large-scale
gradient
and dispersion)
trast,
stellarHowever,feedback or gravitational
infall would
pro(0) and σGauss . The filament
15 disperthat we will 2015),
then correlate with the global gas density
duce
ainshock,i.e.,6)a discontinuity,
but we see a rather
auss ≈ 2.355 σGauss is definedwith the fit parameters Σ(0), p and Rflat , where
the lat- Federrath & Banerjee
cle
Fig.
has
a
significantly
lowerdensity2015;
dispersion obtained in the previous section. The final
smooth gradient, which is most likely associated withussian. The constant column
ter is related to the filament width Wfil ≈ 3 Rflat for
sion
σ
and
thus
significantly
lower
b
than
any of the× 1023 cm−2 was chosen to be
goal
is
to
determine
the
sonic
scale
and
the
turbulence
shear(Kruijssen
et
al.,
in
preparation).
Suchlarge-scale
ρ/ρ0
p = 2 (Arzoumanian et al. 2011). Arzoumanian et al.
" mixed, or compressive). The! (solenoidal,
ge column density inside thedriving modesystematic motions must be subtracted in order to iso(2011), Contreras et al. (2013), Federrath
Smith et al. (2014)
and−1 −1/2
et
al.
σ
=
b
M
1
+
β
,
(7)
G0.253+0.016, providing highFederrath (2016) experimented with the power p andρ/ρ0 HNCO line measurements from Rathborne et al. (2015)
late24the turbulent motions on scales smaller or equal tos.
profile (shown as the dashedas$(1−p)/2
2/Rflat )+ Σoffset , (2)

2/2	

0

0

fil

fil
fil

0

0

found that the best fits to the filament profiles were

provide the best available correlation with the ALMA

As a reasonable estimate of M

in Taurus, we adopt MA = 2

A2000;
the size of the cloud (e.g., Burkert & Bodenheimer

6 thehorizontal
andetplot
in Fig.
obtained with p ≈ 2. Here we find p = 2.1 ± 1.0 for
dust emission and also provide the best available spatialSur
al. 2010;
Federrathet al.
2011b). In error
order tobars
iso- from the lower limit(Arzoumanian et al. 2011;
Benedettini
et al.
23 2.Note that the definition
G0.253+0.016
from the Plummer
fit shown in with
Figure(Mthe1) to motions,
4 times(Mwithof theEq. (45)inA =A =cloud coverage,
so wesonicuse it scale
here to in
determine
the turbulate
turbulent
we thisfit thevalue
gradienta 4). Given the lowFederrath2016).
(2016) provided
a eventheoretical modelforp=lainen et al. 2016; FederrathItis
AlfvénMach
numbertheandperipheryof Taurus(MA ∼ 0.5; see
Hopkins (2013a) issimilarours
and yields
the same dependence
lent tovelocity
dispersionof G0.253+0.016(cf. Sec. 2.2).
plane,
shownin themiddle inpanel,
then subtractit
2, which is given by the radial dependence of the den1/3:
purelysolenoidal
drivingfromtheoriginal
velocitymap(showninthe
toprighton M, but it does not incorporate the magnetic pressure contriHeyer & Brunt 2012), it is unlikely that MA could reach values
kable that we find here a filament width of
hand
panel
of
Figure4).
This
gradient-subtracted
veloc3.2.1.
Velocitymaps
0.4 : naturalb=(8)bution that
we include
here andmixture
first introduced as the ’magnetohigher than M = 4 inside Taurus. We further include the uncer± 0.08 pc for the CMZ cloud G0.253+0.016,
ity map depicts theAturbulent gas motions along the line (22) inThesonic’ scale in Eq.
tainty of the sonic Mach number into the horizontal error bars.
Federrathtop
panels&ofKlessen
Figure4 (2012).
show maps of the HNCO
of sight (LOS), centered on v = 0.
1 : purelycompressive
driving.
with Wfil in the solar neighborhood. We canintensity-weighted velocity (centroid velocity). The lefthand
panel
shows
a
strongandprominent
velocity
grasimilar widths of the filaments in both envidient
the long axisof G0.253+0.016,
which6. hadtheacrossmagneticpressurecontribution
Equation (7) includes
3.2.2.
Velocity
PDF (σρ/ρ ) and the combination of sonic Mach number (M) and plasma β.
FigureRelation between the turbulent
densityfluctuations
ith the following theoretical model.
been seen in earlier works (e.g., RathborneThis
et al.
2015).given by Equation (7), defines the turbulence driving parameter b (Federrath et al. 2008b, 2010). The three dotted lines
relationthroughthethermal-to-magnetic
pressure
ratio,
plasmashow Eq. (7) for three representative driving cases: purely solenoidal driving (b = 1/3, gold), naturally-mixed driving (b ∼ 0.4, blue),del, the filament width is determined by theand Note
purely compressive driving (b = 1, purple); see Eq. (8). Numerical simulations are shown as symbols (with the color indicating theβ (Padoan & Nordlund 2011; Molina et al. 2012).appliedof the turbulence (Arzoumanian et al. 2011;driving mode: sol, mix or comp): from Federrath et al. (2008b, 2010) (diamonds), Price et al. (2011) (pentagon), Molina et al.
0