Star	  Forma)on	
  Newsle0er	
  #266	
  1-­‐5本目	
麻生 有佑	

Gas particles were allowed to cool by employing a parametric cooling function(Λ), defined by Eqn. (3) below
and plotted in Fig. 2. The curve can be readily identified as the thermal equilibrium curve for gas in theinterstellar medium (e.g. Wolfire et al. 1995). We also
assume3a constant background source of heating definedby the heating function(Γ),

Unde
gas-s
are i
absen
dens
Formation of prestellar cores via non-isothermal gas fragmentation
the s
simil
gravi
Table 1 Physical parameters for the two cases.
!
" !
" !
"
−26
−1
to co
d
b
Γ = 2.0 × 10 erg s ,Pgravhavg eMgas f
Tgas
Ticm
Pext
h0 c
Ntot
PthermSerial n̄gas a
n̄icm
[K]
[K]
kB
kB
kB
[pc]
×105
[pc]
MJeanstwo r
1
2.5×102 125
40
131
1.0
0.63662 1.63662 0.572 6.4
0.044 1.4
direc
2
2.5×102 125
100
328
2.5
1.592
4.092
0.905 7.21
0.052 0.6
time
! −92 "
! −1.184 × 105 "3
2.5×102 125
150
491
3.75
2.388
6.138
1.108 7.61
0.055 0.36Λ(T )
tions
−2 √
7
+ 1.4 × 10
T exp
cm
= 10 exp
ΓT + 1000
T of tha Number density for gas and the ICM listed in columns 2 & 3 in units of [cm−3 ].
(3)becob Components of pressure listed in columns 6, 7 & 8 in units of 104 ×[K cm−3 ].
(Koyama&Inutsuka
2002;
Vázquez-Semadenietal.
c Scale-height for the slab
centrd Total number of particles including those representing the ICM.
2007).
this fie Average smoothing length for gas particles.
Identifying gas clumps
the t
fM
is
the
thermalJeans
masscalculated
fortheinitialgas
temperature,T.
gas
J eansWe employed
the robust HOP algorithm suggested by
At 3thFormation of prestellar cores via non-isothermal
gas fragmentation
Eisenstein & Hut (1998) to identify clumps within theture
The slab was characterised by radius, R =density
2.5 pc, field. The algorithm proceeds by first identialong−3
Pext
Physicalparameters for the two cases.
uniform initial number density, n̄ = 250Table
cm 1, fying
gas temICM
the
local
density
peaks
in a given density field,
Re
!
"
!
"
!
"
perature, Tgas , anda thickness, y =thescaleb
Pext
Pext
Mgas fTgas2h0 ,Twhere
grav
Pext
h0 ceachNtot
avg e
Pthermfollowed
by aPneighbour
search forof dthe hidentified
icm
ment
Serialn̄icm
gas slab has[K] below.kB
kB
kB
[pc]
×105
[pc]
MJeansheight,h0 , forn̄thebeen [K]calculated
Valdensity peaks.
For the purpose, we need threedensity2
that
2.5×10125parameters40
131
1.0 listed
0.63662 1.63662 0.572 6.4
0.044 1.4
ues of1the relevant
physicalhave beenR
thresholds
:
ρ
,
ρ
and
ρ
.
An
initialscan0.6of2
peaksaddleouter
that
2 1. For
2.5×10
100
328
2.5
1.592
4.092
0.905 7.21
0.052
in Tablea slab in 125
pressureequilibrium,
the pres2
thedensityfield
wascarriedout
andSPH
particles
with
y
125
491 the3.75
2.388
6.138
1.108 7.61
0.055 0.36 form
sure 3exerted 2.5×10
by the ICM, Pext ,150
balancesthermal4−3SLABdensitypressure, Ptherm , and the gravitational pressure,
Pgrav , higher than, ρpeak ∼ 10 cm , were identified
proc
asdensitypeaks,
orinotherwords,
theseed-particles
a Number−3
withinthedensity
slab soforthat
Pext
resou
gas and the ICM listed in columns 2 & 3 in units of [cm ].
−3b Components of pressure listed in columns 6, 7 & 8 for
4 ×[Kclumps.
This
choiceofthedensity
threshold
is
sufin
units
of
10
cm
].
tatio
2
c Scale-height
Pext
Pint
(1)
for=theslab+ Pgrav = Pint + GΣg ficiently
large
for
the
extantpurposeofstudyingtheShowdFigure 1. A sketch of the gas-slab of radius, R, and height, y,
Total number of particles including those representing the ICM.
e Averageof core-formation. The density at the edge of aconfined by the ICM has been shown in this cartoon. The small(e.g.
Whitworthetlengthal. 1994),
the gasonset
surfacesmoothingfor gas whereparticles.
rend
Anathpindika,SfM
ICM exerts pressure, pext , externally on all faces of the slab asthermalJeans
masscalculated forT
thegas temperature,gas . ρouter , and ρouter ∼ 0.2ρpeak .
J eansΣisfragment
is denotedTas,
density,= n̄µhgas
temperature,,initialcorreg the
0 . Thegas
mentdemonstrated by the direction of arrows.
sponds to sound-speed a, so that the scale heightfor
The density
field was then re-scanned with this densityof cluathe slab, h0 = √2πGn̄µ(Ledoux 1951; Lubow &Pringle to identify
threshold
immediateneighboursbyofradius,
the previThe slab
was characterised
R = 2.5dentapc,−32001). The length of the fastestPext
growing modea coolously
identified
densitypeaks.
Finally,twon̄clumps
were
uniform
initialnumberdensity,= 250 cm
, gas temthat
ICM in2 Initial conditions
ing medium
perature,Tgasa, andthickness,y = 2hmergedtogetherto form
contiguous
objectif 0a, whereparti-the scalePext is,
Pext
smal
height,
h
,
for
the
slab
has
been
calculated
below. curre
Val!
"
2
cle
and
its
nearestneighbour
appearedintwo
diﬀerent0
The set-up for our simulations is simple and consists ofγe πa 1/2
λf ast =
(2)
ues
of
the
relevant
physicalparameters
have
been
listeda uniform-density slab that is marginally gravitationclumps
and
if
the
averagedensity
of
these
two
particlesform
γGµn̄ R
Table
1. Forthana slabin pressure
equilibrium,
the presally super-critical in case 1 (slab mass approximately
turned out toinbe
greaterρsaddle∼ 0.1ρ
peak . Theappe
y polysure exerted
by the ICM, Prext , balances
the thermal(Vázquez-Semadeni et al. 1996); γe , is the eﬀective
1.4 times the initial thermal Jeans mass), and gravradiusof a clump
was calculatedas,clump = max(<
two,s
SLAB
tropic exponent, i.e. slope of the cooling curve shown inpressure, Ptherm , and the gravitational pressure, Pgrav
itationally sub-critical (slab mass only a fraction ofrc − ri >), i ∈ (1, Nclump) and c, the identifier of thewithin the slab so that
Fig. 2, which for our choiceof the initial gas density, n̄,Pext
the initial thermal Jeans mass) in the remaining two
seed-particle for a clump. Finally, the mass of a clump
3 Clumturns out to be ∼ 0.9 where as, γ = 5/3, is the adiacases (see Table 1). The slab is circular with radius,
2
2
P
=
P
+
P
=
P
+
GΣ
(1)
was
calculated
as,
M
=
Σ
r
;
Σ
,
befilam
ext
int
int
clump
clump grav
clump
g
clump
batic gas constant. The equilibrium pressure at density,

Forma)on	
  of	
  prestellar	
  cores	
  via	
  non-­‐isothermal	
  gas	
  fragmenta)on	
  S.	
  Anathpindika	  (2015)	

• 分子雲中でのコアの形成過程をSPHで追った。	
  • 特に(a)熱的不安定(TI)と重力不安定(GI)の相互作用、(b)warm	
  gasとcool	
  gas、(c)これまで報告されたコアに矛盾しないかに興味がある。	
  • R=2.5	
  pc,	
  n=250	
  cm-­‐3の板を考える。加熱冷却も考慮。	
  • 初期に重力的にsuper	
  cri)calなcase	
  1は半径方向に収縮、subなcase	
  2,3はフラグメント。	
  • FIg.3を見るとフィラメントに見える大きな構造が分裂して小さなコアになるヒエラルキー。	
  4←FIg.3	
  case	  2	

R, and is in pressure-equilibrium with the inter-cloud
medium (ICM), that confines it. Note that particles
in the slab and the ICM were so distributed that the
number-density of particles across the slab-ICM inter-

Figure 1. A sketch of the gas-slab of radius, R, and height, y,−3n̄,confinedaccordingto ICMthe cooling
7500
K cm
. We
by thehas been curve
shown isin thiscartoon.
The
small
PASA
(2015) (e.g. Whitworth et al. 1994), where the gas surfaceperform
three
realisations
with diﬀerent
choiceofslabtheas
ICM exerts
pressure,
pext , externallyon all faces
ofdoi:10.1017/pas.2015.xxx
thedensity, Σg = n̄µh0 . The gas temperature, Tgas , corredemonstrated
by the directionof arrows. thermal pressure,initialgas temperature,and therefore,
sponds to sound-speed a, so that the scale height forAt this point a comparison of rates at which theequilibrium. The reduction
in t
proachin
1
TI and the GI grow, will prove useful in unravellingplotp
ωT I =. TI, as is visible from(8) theseismoreτT I picks-up as the slab continues tForma)on	  f	
  prestellar	
  cores	
  
via	
  nIt
on-­‐isothermal	
  as	
  fragmenta)on	  the ofragmentation
process.
will help us gunderstandthe slowS.	
  Anathpindika	  (2015)続き	
which of thetwo instabilities
areresponsibleforclumption
inthefragmentingslab
is dyw
The growth-rate, ωT I , given by Eqn. (8) above was calearlier,3
formation in a MC. During
fragmentation
it isthelikely,
adjustments
happenThfculatedby distributing
SPH particles
on a 256
grid quickly.
smallercooling at a given pressure
density,both
have densityaments
breaktemperup further as
they cin theandk-space.
The
averageweighted
following
TIとGIの成長率を調べた。ωとkの分散関係。	
  16Anathpindika, S
destabilising eﬀect on gas withincess thenthat issimultaneously
for theeachslab.
cell Inonthis
thiscase
grid wascalculated
icalassoc
prop
初期に重力的にsuperなcase	
  1ature
ではGIが発達。	
  [the TI grows approximatelyonthethermaltimescaleasrisingstrengthofgravity.
Thisiand followed by the evaluation of the cooling functhese sim
速度、密度の分布やMss-­‐size関係も調べている。	
  perturbations need not tion,
wait fora pressure
equilibrium
servedrise infor
the
(nΛ(T
) − Γ), forthat cell. The
expression
thegrowth-rate o	  to become unstable. Thegrowth-rate
thermal timescaleAlso,onit appears,
the TIof the GI- on the surfaceofoftime.
the slab,
the
Some
	
  
was not iscomplete at the4time
of
other
hand,
Etherm(T )from the usual Jeans-analysis,
τT I ≡
,
(7)
・・・	
  
culations. However, in allAsthe
tes
we
1/2
(nΛ(T ) − Γ)ωJ ≡ (4πGµn̄) appear to be slowing(9) at higheraw	
  prestella
so
that
its
growth-rate,), as it shouldwh	
  (Jeans 1928), which is also similarspatial-scales
to that suggestedof its ot
proachingtheirequilibriumtem
1by Elmegreen& Elmegreen(1978) andLedoux(1951),
attention	  ωT I =.
(8)
is moreprominently
thethoughtheformersuggestgrowth-rate
higherby a fac- visible
sityinbefo
τ
TI
	
  
the andslow-down
is visibleat eachall wrtor of 2 than that given by Eqn. (9),therefore,isin
まとめると、	
  The growth-rate, ωT I , given by Eqn. (8) above was calearlier, we could not follow(1)theTlunlikely to alter conclusions
3 drawn here.
分子雲は安定で低温、安定で高温、不安定な3つが混ざって
culated by distributing the SPH particles on a 256 grid
smallerwould(PDF
likely) bO
Plotted on the upper, middle andthe fragments
lower panelinthek-space.
The
averagedensityweighted
temperいる。	
  following
section,we willmentatio
separateof Fig. 6 are respectively, the measured
growthrates]
ature for each cell on this grid was then calculated
ical
properties
of
the
gas
and
t
フラグメントは熱的不安定で始まりフィラメントができ、質量降for the TI and the GI for cases 1, 2 and 3. It is clear
typicallyand followed by the evaluation of the cooling funcsimulations.
着や合体で重力不安定を起こしてコアができる。	
  that in each of the three test casesthese
the slabfragments
scribe astion, (nΛ(T ) − Γ), for that cell. The expression for thevia a cconfluenceof the TI and the GI. A common feaat tempe
これらの不安定性によって、dense	
  oreなどでよく観測される
growth-rate of the GI on the surface of the slab, on theture visible in these plots for cases 42 and3 isdiagnostic
the sub- propertie
temperaような弱い速度場が得られる。	
  Someother hand, from the usual Jeans-analysis, isservience of the GI relative to the TI suggesting, theties of pAs
weareconcerned
with
1/2
is largely driven
the thedistrb
ωJ ≡fragmentation(4πGµn̄)(9) by the TI, the growthprestellar
it is crucial
to exof which is the strongest in case 3.
On thephase,contrary,
perature(Jeans 1928), which is thealsoGIsimilarthatstrongly
suggestedof its otherphysicalgrowstomore
as comparedto theTI in properties.
the lowe
by Elmegreen & Elmegreen(1978) and Ledoux (1951),
attention to the distribution of
3

2.5

log10(ω/[Myr-1])

2

1.5

1

(TI)t=0.01 Myr(GI)t=0.01 Myr(TI)t=2.2 Myr(GI)t=2.2 Myr(TI)t=4.1 Myr(GI)t=4.1 Myr

0.5

0

20

40

60

80
k/[pc-1]

100

2.2

120

140

(TI)t=0.01 Myr(GI)t=0.01 Myr(TI)t=2.21 Myrs
(GI)t=2.21 Myrs
(TI)t=6.1 Myrs
(GI)t=6.1 Myrs

2

ω/[Myr-1]

1.8

1.6

1.4

1.2

1

0.8

20

40

60

80
k/[pc-1]

100

3

120

140

(TI)t=0.01 Myr(GI)t=0.01 Myr(TI) t=4.51 Myrs
(GI) t=4.51 Myrs
(TI) t=8.3 Myrs
(GI) t=8.3 Myrs

2.8
2.6
2.4

log10(ω/[Myr-1])

Schmidt, W., Kern, S.A.W., Federrath, C & Klessen, R.,
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2.2

2

1.8
1.6
1.4
1.2

1

20

40

60

80
k/[pc-1]

100

120

140

Figure 6. Comparative plots of the growth rates of the gravitational and the thermal instability in cases 1, 2 and 3 have beenshown on respectively, the top, middle and the lower panel.

number in a MC could possibly influence filament propboundary particles that prevent SPH particles fr
erties, we leave this aspect of the problem for future
caping. Unlike the gas and the ICM particles, theinvestigation. Other free parameters in the set-up were,ary particles are dead and do not contribute t
Stability	
  of	
  ﬁlaments	
  in	
  star-­‐forming	
  clouds	
  and	  the	
  fD=10,orma)on	  of	
  pTherestellar	
  cores	  in	
  them	   wa
the length of the cylinder, L= 5 pc, contrast, Stability
forces.
layer
ofthedeadboundaryof filaments
in star-forming
clouds andformationof prestellar particles
cores in themS.	
  Anathpindika	  and	  J.	
  Freundlich	  2015)	
betweenthe initial gas(density
within the cylinder andto simply hold the gas+ICM particles in the bits surrounding medium, the average initial gas density
prevent them from diﬀusing away. Particles wit
within the cylinder, n̄gas = 600 cm−3 andtheinitialset-up were initially stationary as no external v
8フィラメントの力学的安定性を他の論文より現実的に調べる。	
  mass line-density, (Ml )init . This choice of gas density
field was introduced.
isalso
consistentwithdensities
found
in
a
typicalstar(i) 等温一様密度ではなくcooling	
  func)onも含めたエネルギー方程式を解く。	
  by taking a transverse section through the mid-plane offorming cloud (e.g. André et al. 2013). The temperature
the filament. The
propagating
compressional(ii) 初めから動的ではなく、圧力平衡	
  3.2 inwardly
Numerical
method : Smoothed
Particof the confining medium is calculated by using the condisturbanceisevident
fromthedensity
plots
at
early
Hydrodynamics(SPH)
dition of pressure-balance at the surface of the cylinder.
(iii) 重力的にsupercri)calな必要があるか調べる。	
  epochsusingof the collapse. As the gas is steadily accumuThe initial radius of the cylinder was calculated
Simulations were performed using our well teste• 初期条件は、重力収縮せず一様密度で周囲と圧力平行にある筒。	
  lated condiin the central
plane of the cylinder, the density
Eqn. (4) above. Though simple, this set of initialalgorithm, SEREN, in its conservative energy
of gasFigure
there
rises
develops
profilethat
5. As inthe plot andshown ineventually
Fig. 1, this is the radial
disSameas the plot
in Fig. 3, buttions is suitable for the extant purposes of studyingthe• 筒は半径方向に収縮し、軸上にジーンズ長間隔でコア(105cm-­‐3)ができる。	
  (Hubber
et al. 2011).
The Figure
SPHa8.calculations
in thtribution of gas density within the collapsing filament at diﬀerent
form in the post-collapse filament in realis
origin of the density profile and the temperature
proepochs inrealisation
2.
matches
very
well
with
the
one
suggestedbyOstrikeralso
includecontributions
due
to
the
artificialcStability of filaments in star-forming clouds
and the formation of prestellar cores in them9
• R~0.1	
  pcになり、密度分布はOstriker	  1964)と合う。(Plummer-­‐like;	
  
p
=2)	
  
file of a typical filament and (theformationofprestel(1964),
tivity prescribed by Price distribution(2008), oftogasavoid
density any
withinsptdrical cloud which, though remarka
lar cores along cthe
length ofS(r)で評価。	
  this filament. Parameters• 重力的な安定性をSturges	
  riterion	
  numerical artefacts
due to the creatio
shown in Fig. 2 for the isothermal fi
ρc possible
used in the realisations performed in this work haveshallow(Plummer-like;p = 2 in Eq
gap
betweenmulti-phasefluids.
An SPH (11)particle,;ρ(r)=! Anathpindika.
"#2S.,$p/2
àずっとsub-­‐cri)cal	
  beenS(r<R)<1で自由落下していない。	
  10Freundlich,variation ofJ.the stability factor, S(r)listed in Table
1. Sinusoidal density perturbationsrwork, had1 +a fixed numberingofcylinder
neighbours,
Nneibsfor this realisation
has b
r lat
along
the length
ofcoresthein theminitial distribution9 of gas were labelled
Stabilityof filaments in star-forming clouds andthe formationof prestellar
This plotis qualitatively
similar
to t
温度も一様ではない。	
6 and
7 respectively,
Table 1. As withtheGascooling
wasinfimplemented
bygas
employingthe
1 and shown earlier in F
2 that was subject to cooling,simulationin this case
imposed in five simulations; see Table 1. These pertur- in realisation
functionthatby theequation
below, the collaps
formerplot,
we observethe =initialof gascol- gas withinwith p =xp4., also,Hereρc ≡ given
ρ(rrfdistribution
being
the ralat ); rfcase
latalso always remains less than ubations were imposed by revising particle positions,lapsed radially to form a thin filament aligned!with the
5in"free-fal
suggestingthat
gas is not
′
dius
at
which
the
density
profiledevelops
a
knee.
The
Λ(Tgas) in Figs.
−1.184× 10
Shown
10 areto xp , such that the following expression was satisfied, central axis of the cylinder.
7 9inandthis case is assembled on a+
times
=
10
exp
the rendered
imagesfalls-oﬀ
of the post-collapse
filaments
that
that intheisothermal
realisation.
Tdensity of thisfilament
relatively
steeply
in
the
Γ
T
+
1000
CR
gas
form in realisations 6 and 7, those that havethedespite
best the gas-cooling, the ccause,
AL
Jeans
resolution
in thisset of calculations.
For gravitationallycomparison
which
is consistent
with
that
reported
byA direc
sub-critical.
xp = x′p +sin(kx′p ) outer regions
we haveshown
a plot of ofthe post-collapse
mass line-density,
M(R),
against th
Figure 6. Aspurposesin Fig. 2, shownin thisalso
plot isthe time-variation
l
2π
"
! −92
et
al.
(2012)
fortypicalfilamentary
cloudsin ot# bility,of(MFigure 5. As in the plot shown in Fig. 1, this is the radial dis- Malinen
Figure 8.
as theplot inFig.
3, butrealisation
now
the
cores
theSamestability
factor,S(r),calculated
forfordiﬀerent
at various
suggests
filamentfrom
4 radii
onthatthelower-panel
Fig.
l )max , however,3−2
tribution of gas density within the collapsing filament at diﬀerent
form in the
post-collapse
filamentfilament
in realisation2.
epochsof the collapsingin realisation
2. × 10Tcm
1.4
gasarecause,
implicita comparison of
The .physicalparameters for thisrealisation
the in shows,epochsetin realisation2.
the Taurus
Furthermore,
thisfigurealso(Hubberal. 2006),
where the wave-number,
k = 9.MCT
sumption
ofgas
isothermality and unifsame as those for realisation 6, but was developed
with
nπ
gas
withinof
the typpost-collapse
Figure 9.
Rendered
image showing
projectionofn Upper-panel:= 1, 2 forrespectively,
fundardistribution
∼
0.1
which
isalbeit
comparable
to theradiusadensityslightly
lower,
suﬃcient
to density
prevent
fa thelatof gaspc,
withinthecollapsing
cylin- resolution
LJeans , the integer,
the mid-plane of the post-collapse filament(t=1.) in realisation 6
Onthe contrary,
and as is evide(Koyama&Inutsuka
2002).
Constant
backgrounartificial
fragmentation(Truelove
criterion
satisfied).
Adricalcloud
which,
thoughremarkably
similartothatmental mode andA ical=ishasthe found in eight nearby star-forming(only thea smallsecond
volume of harmonic;
the medium confining
the 0.1,
filament
filaments
cloudsgas temperature within
the post-c
shown
Fig. 2 for comparison
the isothermaloffilament,is relatively
the
plots
on therays
two panelsof Fig. 9 by the heatin
been shown on this plot). Fine black blobs on topof theinimage
ing
due
to
cosmicisprovided
hardlyuniform.
The
cold central reamplitude of perturbations.
shallow(Plummer-like;p = 2littleinEqn.
(11)).
Thediﬀerence
radialsuggests
qualitative
betweentheoutrepresent the positions of cores in the post-collapse
filamentatinthe
Gould-Belt(e.g.
Arzoumanian
et
al.
2011;
Andre
is cocoonedby the relatively warm
Figure 5. As in the plot shown in Fig. 1, this is the radial disFigure 8. Same as the plot in Fig. 3, but now for the cores thatvariationof rethe stability
withintion,
ΓCR=the2collaps×
10−26 erg
s−1 .howThetemperatur
theof terminationof calculations.
Perturbations,
inare
this
comesfactor,
fromS(r),therespective
realisations.
We innermostmust,
The number
oftimegas
particlesin 2.length-scalea simulation
caltribution of gas density within the collapsing filament at diﬀerent
form in the post-collapse
filament
in realisation
regions of this filamentalisation,were
imposedontheL,
definedbying
cylinderfor
thisrealisation
has
been
shown
in
Fig.
6.
et
al.
2014).
J eansever, point
out
that
while
the
satisfactionoftheresoluepochs in realisation 2.
temperatureof 10 K whichis cons
SPH toparticle
is calculated
by revising
its inter
Eqn. (5).
atisthisThis plot
qualitatively
similarthe one produced
for above is suﬃcient
culated according
to Not- all density perturbations have condensedtion
criterion
definedby Eqn. (10)tobe
portedfromobservationsof filamen
Anotherinteresting
conclusion
that
can
drawn
epoch, but those that are relatively closely spacedsimulationareseparated
1 and shown
earlier
in
Fig.
3.
As
with
this
equilibrium
temperature,
Tregions
distributiononofa scalegas density
withinthecollapsing
cylineq , attaine
ensureergy.
there isTheno artificial
fragmentation,
as isstar-forming
indeedical(see for e.
on the orderof L
J eans" Same!∼ 0.08Vtopc.Lower-panel:
formerplot, asgas within the collapsing cylinder in thisdrical cloud
thatfor
Arzoumanian
2011; And
3shown inremarkably
1 thoughfrom
thisrealisation
is itthatabout
the 2013;
stabilityof etaal.filseen in
this
work,
is
unlikelytobesuﬃcient
to obtain
thewhich,
picturethe upper- similar
panel, butnow
the realisation
init
small
SPH
particlecorresponds
toequilibrium
case
also
alwaysremains
lessthanunity,
S(r
<
R)
<
1,
,
· thedeveloped· Nneibs
Ngas
=
shown
in Fig.
2 forisothermal
filament,
is relatively
nally, shownin Fig. 8 is the histor
4 thatwaswitha ·somewhat
lower resolution,
thoughconvergenceincalculationsofenergyandmomentumof3suggesting that gas is not in free-fall.
Also, bethe filament
8 to4πhavg(init)
can
seen
from
2whichthatthe isshallow (Plummer-like;p = artificial
2 in Eqn.
(11)).
The radialuoneqaIt,timescaleandthetimescale,τ ,inFig.
over
suﬃcient
avoid
fragmentation
along amentary
the length of the cloud.
this filament.
It isenergy
qualitatively
the collapsinggas (Federrathin this case is assembled
comparable et
to al. 2014). In fact, be100000

2

t=0.002 Myr
t=0.1 Myrt=0.2 Myrt=0.3 Myrt=0.4 Myrt=0.5 Myr
t=0.6 Myrt=0.8 Myr
p=2

1.8
1.6
1.4

n/[cm-3]

Mcore/[MSun]

10000

1000

1.2

1

0.8
0.6
0.4
0.2

100
0.01

0.1
r/[pc]

1

0
0.5

0.55

0.6

0.65

0.7
0.75
t/[Myr]

1

1000002

t=0.002 Myr
t=0.1 Myrt=0.2 Myrt=0.3 Myrt=0.4 Myrt=0.5 Myr
t=0.6 Myrt=0.8 Myr
p=2

1.8

0.8

1.6
1.4

10000

1000002

t=0.002 Myr
t=0.1 Myrt=0.2 Myrt=0.3 Myrt=0.4 Myrt=0.5 Myr
t=0.6 Myrt=0.8 Myr
p=2

S(r)

n/[cm-3]

Mcore/[MSun]

0.6

1.2

1

0.4

0.8

1000
1.8

0.6

1.6

0.4

1.4

0.2

0.2

10000

n/[cm-3]

Mcore/[MSun]

0

1.2
100
0.01
1

0.1
r/[pc]

0
0.5

1

0.55

0

0.05

0.6

0.1

0.65

0.15

0.2

0.7
0.75
t/[Myr]0.25
r/[pc]
0.8

0.3

0.85

0.35

0.9

0.4

0.45

0.95

0.8

1000

0.6
0.4

100

1 0.2

90

100
0.01

t=0.01 Myr
t=0.2 Myrt=0.4 Myrt=0.9 Myr0.1
r/[pc]

0
0.5

1

0.8

0.55

0.6

0.65

0.7
0.75
t/[Myr]

0.8

0.85

0.9

0.95

t=0.002 Myr
t=0.1 Myrt=0.3 Myrt=0.5 Myr
t=0.7 Myrt=0.9 Myr80

Temp(r)/[K]

70

S(r)

0.6

1

0.4

0.8

0.2

60
50
40
30
20

t=0.01 Myr

S(r)

0.6

variation ofpost-collapse
the stabilityfilament.
factor, S(r), withint=0.2
theMyrcollapsthe isothermal
t=0.4 Myrlow realisation.
wecomparetheis sink-formationand the filament plotted in F
that in the10isothermal
This
probablybe- 0.7 timescales
t=0.9 Myr
0
0.1
0.2
0.3
0.4
0.5
0.6
0.8
ing0 cylinder for this realisation has been shownin Fig. 6.
following the formation of the first c
PASA (2015)r/[pc]
magnitude theof gas-velocity
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
cause, despite the gas-cooling,collapsing
gasinisthe
stillradial direction within
This plot is qualitatively similar
to the one produced forcores form relatively quickly. Also,r/[pc]

centrally assembled, post-collapse dense filament at theepoch when calculations for this realisation were termi-

Figure 14. Radial distribution of the density averaged gas temperature within the post-collapse globule in realisation 8 at thetime of termination of calculations (t = 2.5 Myrs).

Stability	
  of	
  ﬁlaments	
  in	
  star-­‐forming	
  clouds	
  and	  the	
  forma)on	
  of	
  prestellar	
  cores	
  in	
  them	
  S.	
  Anathpindika	  and	  J.	
  Freundlich	
  (2015)	
• ガスの温度を上げて初期にsub-­‐cri)calな場合も調べた。	
  à細くなるのではなく押しつぶされた。	
  • 高密度フィラメントを作るためには少なくともcri)cally	
  stable	
  (S(R)~>1)でなければなら
Figure 15.
A rendered density image showing a projection of
the mid-plane of the elongated globule in simulation 8. Time inない。	
  the top left-hand corner of the image is marked in Myrs (t = 2.5
Myrs ).
• S(R)~1の状態は10	
  Kの等温一様密度を仮定すると重力的にsuper-­‐cri)calに見える。	
  • 自由落下していなくても軸上にコアはできる。	
  • フィラメントで観測されるPlummer密度分布は地場なしでも作れる。	
  • 解析的にもPlummer密度分布から自由落下しないとわかる。	
  • 観測的にもフィラメントで自由落下でないインフォールを示すフィラメントの例がある(DR21,	
  Perseus	
  MC,	
  Serpens	  MC)。	
  • 自由落下でないとすると、極端に強い減光を示すフィラメントがないことや、フィラメン
トの幅がどの領域でも同じことを説明できる。	
0.4

0.2

V(r)/[km/s]

0

-0.2

-0.4

-0.6

-0.8

0

0.5

1

1.5

2

2.5

r/[pcs]Figure 16. Gas within the post-collapse globule shown in Fig.
14 exhibits a weak velocity field. The inwardly directed gas in theouter regions of the globule as it is being squashed has negative
velocity on this plot.

PASA (2015)
doi:10.1017/pas.2015.xxx

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Mopra	  CO	
  Observa)ons	
  of	
  the	
  Bubble	
  HII	
  Region	
  RCW120	
  Loren	  Anderson	
  et	
  al.	  (2015)	
••••

よく知られたHII	
  regionの円状バブル構造は一様膨張を示す。	
  しかし、球殻では説明できず<10	
  pcの薄いシート内でできた2次元のリングとするものも。	
  バブルの幾何は誘発的星形成の理解にとって重要(2Dリングではあまりできない)。	
  – 28 –RCW	
  120	  (d=1.3	
  kpc)は20のClass	
  I/IIを含むがバブル(D=3.8	
  pc)の中心に2個しかないà2Dリングか?	
  • Mopraで12CO,	
  13CO,	
  C17O,	
  C18O。速度分解能は0.7	
  km/s。	
  • Hαで見える吸収は手前にあるはずで、球状膨張していれば青方偏移しているはず。	
  • 吸収部(Absorp)on)、吸収なし(No	  Absorp)on)、両方(Interior)、PDRでスペクトルを比較。	
  – 22 –

Fig. 1.— H↵ emission of RCW 120 from SuperCosmos (Parker et al. 2005). The map covers
the same area as our Mopra observations, and is 200 square, centered at (`, b) = (348.282 ,0.498 ), and oriented in Galactic coordinates. The north and west directions are indicated.
The location of the ionizing source (from Martins et al. 2010) is identified with a small green
cross and the location of “Condensation 1” is identified with a green circle. Absorption↑Hαで黒く吸収が見える。	

sive evidence of expansion in the Mopra molecular data. This suga two-dimensional
structure,or thatoit
spherical
but
expanding
Mopra	  CO	
  O
bserva)ons	
  f	
  tishe	
  Bubble	  HII	
  Region	
  RCW120	  hat detectable in our data. The presence of absorption across theLoren	  Anderson	
  et	
  al.	  (2015)続き	material associated with the region, however, implies that the twocannot be correct. It is also possible that RCW 120 is only half a
km/sの凹みはセンスとしては逆)。	
  duce à❌4つとも似ていた(-­‐10	  our estimated expansion by a factorof two. Below, we assess•
チャネルマップでは、blueからredで内側、PDR、内側と明るいはず。à❌	
  on rate of RCW 120, assuming spherical symmetry.

• moment	
  2で内側ほど速度分散が大きいはずà❌	  ved an expression for the time evolution of an H II region:• PV図で環状に見えるはずà❌	
  
✓
◆4/7
7ci t
=– R
,
(3)
S 1+
• R(t)
しかし、吸収が見えるので2Dではないはずで、速度分解能が足りないのだろう。	
  
29 –
4RS

• Stromgren半径を用いた球殻膨張の解析解。膨張速度は~1.2-­‐2.3	
  km/s。	  on radius,
RS is the initial Strömgren radius, ci is the sound speed in
m/s、膨張速度1.0	
  km/sのモデルが合う(1.5	  km/sでは合わない)。	
  d t is •the 乱流速度1.5	  elapsed time sincektheStrömgren radius formed,
in seconds.
– 31 –✓◆ 3/7✓ ◆3/4dR
7ci t
RS= ci 1 +
= ci
.
(4)
dt
4RS
R
the initial equilibrium– 30 –size between ionization and recombination, is:✓◆1/3
3 NLycRS =,(5) – 33 –4⇡ n20 2

pectra from the four apertures defined in the text and in Figure 7. So thecan be better seen, we normalized all spectra to a peak corrected antennaTA⇤ , of 1 K.

Mopra	  CO	
  Observa)ons	
  of	
  the	
  Bubble	
  HII	
  Region	
  RCW120	
  Loren	  Anderson	
  et	
  al.	  (2015)続き	
• 8.0	
  µmで見るとPDRの外にダスト温度がエンハンスされた場所がいくつもある。	
  • 東西のエンハンスは-­‐8.9	
  km/s	  (青コントア)のCOの隙間に、南は-­‐6.0	
  km/s	  (赤コントア)のCOのクランプの間にある。	
  • 北東に開いている部分も-­‐6	
  km/s	  (赤コントア)のCOがないところに合う。	
  • 北東も含め、バブルは多孔質になっていて光子が漏れている。(Anderson	
  et	
  al.	  2010の確認)。	

g. 14.— (Left) Dust temperature map of RCW 120 derived from Herschel data, showg temperature enhancements outside the PDR. Red contours show 13 CO emission a
6.0 km s 1 (antenna temperature values of 1.4 and 2.0 K), while blue contours show 13 CO

down to V ≃ 12.6 .

Hardie (1964). The results of our measurements are presented in Tabl

2 Observations
and results
Resolved	
  photometry	
  of	
  the	
  binary	  components	
  of	
  RW	
  Aur	  Table 1: U BV RI photometry of RW Aur
U
B
V
Rc
S.	
  
An)pin	  et	
  al.	  of(2015)	
Multicolor
imaging
RW Aur was performed on November 13/14,
2014
with
a
newly
RW Aur A 14.26 ± 0.3 14.50 ± 0.06 13.80 ± 0.05 13.18 ± 0.0

•
•
•
•
•
•

installed 2.5 meter telescope (Fequiv = 20 m) of the Caucasus observatory
RW Aur of
B Lomonosov
14.97 ± 0.3 14.26 ± 0.05 12.92 ± 0.03 11.97 ± 0.0
Moscow State University at the mount Shatzhatmaz1 in course of test precommissioning
新しい望遠鏡のテスト観測が上手くいったというレポート。	
  observations aimed at checking the image quality provided by the instrument.
The results The
are telenon-trivial, as follows from the comparison of ou
scope
was
equippedwithamosaicCCD
cameramanufactured
by
Niels
Bohr
Instituteof White & Ghez (2001) obtained 20 years ago (see Fig. 2). FirstRW	  Aur:	
  Aも伴星(B)もCTTS。変光星。	
  based on two E2V CCD44-82 detectors (pixel size 15 µm) and aobservations
set of standard
BesselRW Aur
A became ≃ 3m fainter in all spectral bands (theShatzhatmaz山にあるCaucasus	  observatory	
  
o
f	
  
L
omonosov	  Moscow	
  State	  Universityに
UBV Rc Ic filters from Asahi Spectra Co.
at the left panel of the figure) which may be interpreted as gray ext
In course of observations the image quality with
FWHM between
0.7 arcsec
fit can0.5
beand
obtained
assuming thatBthe
is a sum of two co
新しく作られた2.5m望遠鏡でRW	  Aurをマルチカラーイメージング。U,	  ,	
  Vextinction,	
  Rc,	
  Icフィル
was routinely obtained confirming the excellent optics quality of the
instrument,
extinction withdelivered
AV = 2.87 and a selective standard one (Savage & Mター。	
  by the REOSC company of Safran group, France (Poutriquet et al.
Thebinarywas= 0.44– see
opencircles in the panel. It seems natural to explain
AV2012).
clearly
resolved
(see
Fig.
1):
the
wings
of
a
brightercomponent
image
contribute<
7 % of an eclipse of the star by dust particles, w
A dimming as a result
分解能は0.5-­‐0.7”で、連星を分解。	
  to the central intensity of a fainter component in all bands. Thislarge
timeenoughof year sizeat ther tositeproduce gray extinctions up to at least 0.7 µm,
Aは20年前より3等暗いßAv=2.87とAv=0.44の2成分gray	  ex)nc)on。ダストによる食だis known to be characteristic of exceptionally stable atmosphericconditions
r >turbulence
1 µm (Krügel2003).
(Kornilov et al. 2014), so this result was not unexpected. The exposure time varied fromろう。	
  5 sec in the Ic band to 300 sec in the U band, the middle date of measurements is JD
Bは0.7等明るい。Bは94年に食があり、Aとは逆センス。	
  2456975.56.

Figure 1. Images of RW Aur binary in the U BV RI photometric bands. The primary component, RW
Aur A, is placed in the origin of the coordinate system.

Aが左上、Bが右下。	

Primary data processing and PSF photometry were performed in a standard way in the
Figure2. U BV
RI-photometryfor A and B components of RW Aur for two epoc
ESO-MIDAS environment with the DAOPHOT program package(Stetson1987).
Stars
for R
HST
(Nov. 1994), the thick lines are for our observation. The
127 and 129 from the AAVSO chart for RW Aur were used as BV
photometricc Ic observationmm

Forma)on	
  of	
  complex	
  organic	
  molecules	
  in	
  cold	  objects:	
  the	
  role	  of	
  gas	
  phase	  reac)ons	
  Nadia	  Balucani,	
  Cecilla	
  Ceccarelii	  and	
  Vianney	
  Taquest	  (2015)	

• 複雑な有機分子(COMs)の生成は、水素を含む分子が<20	
  Kの粒子表面でできて加熱されて気相へ出て反応する”warm	
  gas-­‐phase”から、~30	
  Kなった粒子表
面でCOMsもできる”grain	
  surface”が主流になった。	
  • しかし、観測は30	
  K以下でCOMsを検出ß高密度コア内でできると説明ßL1544
ではコアの外側(~10	
  K,	
  3x104	  cm-­‐3)で検出。↓	  • 蟻酸メチル(MF)とジエチルエーテル(DME)を低温下気相反応で作る新しいモデルを提唱。	  
• 既存のchemical	
  networkにMF,	
  DME,	
  メトキシ基を追加。	
  
• 10	
  K,	
  6x104	  cm-­‐3を基準に比較。	
  • L1544観測に対して他のモデルでは大きく出てしまうメトキシ基、MF、DMEの上2 Balucani et-­‐10al.
限(2x10 ,	
  2x10-­‐10,	
  2x10-­‐9)に合う。	
  • DMEとMFは別の観測で6桁に渡る相関が示されており、今回加えた反応で説and O. Briefly, GRAINOBLE couples the gas-phase andgrain-surface chemistry with the rate equations approach
明できる。	
Complex organic molecul

introduced by Hasegawa et al. (1992), and takes into account the multilayer and porous natureof the ice mantles.
Reaction
Rate coefficient
References &3Species accrete on the grain surfaces
are10 desorbed(cm ands 1 atK)
Notesbycosmic ray-induced heating of grains (Hasegawa& Herbst(1) OH + CH3 OH ! CH3 O + H2 O
3.0⇥10 10
11993)
and by a non-thermal process 3.0⇥10that injects
into
the
10
(2) CH
see text
3 O + CH3 ! CH3 OCH3 + photon
10
phase
1%
the species
the surface, 2,
follow(3) Ogas
+ CH
HCOOCH
2.0⇥10
3
3 OCH
2 !of
3 + Hformed on
10(4) Fing+ CH
OCH3 !called
CH3 OCH
2.0⇥10 (Garrod
2 et al.
a 3process“chemical
desorption”
2 + HF(5) Cl+ CH3We
OCH
OCHchemical
2.0⇥10 10evolution
4 of a3 ! CH3the2 + HCl composition
2007).
followed
43
gas with a H density of 6 ⇥ 10 cm
and a temperature
Table 1. List of the added reactions that form DME, MF and methoxy. References: 1- Shannon et al. 2013of 10 K (to simulate the conditions in L1544; Vastel et al.
1996; 3- Song et al. 2005; 4- Wallington et al. 1988.
2014). We started with a gas having the initial abundances
quoted by Wakelam & Herbst (2008) for the di↵use cloudsForma)on	
  of	
  complex	
  organic	
  molecules	
  in	
  cold	  objects:	
  the	
  role	  of	
  gas	
  phase	  reac)ons	
  Nadia	
  Balucani,	
  ecilla	  Ceccarelii	  and	
  Vianney	
  Taquest	  (2015)続き	
4 Balucani
etCal.