14T. G. Bisbas, T. A. Bell, S. Viti, J. Yates and M. J. Barlow

3D-PDR: A new three-dime
THE STAR FORMATION NEWSLETTER: No.237 20 Sept 2012
担当: 塚越(茨城大)2012/10/12

3D-PDR: A new three-dimensional astrochemistry code for treating Photodissociation
Regions
T.G.Bisbas et al.
•これまで1Dが主流だったPDR計算を3Dに拡張。観測に合うような高分解能。
•thermal balance & 化学反応を解く•3つのケースで計算•uniform density spherical cloud interacting with a planet-parallel external radiation ﬁeld
•uniform density spherical cloud interacting with two-component external radiation ﬁeld
•cometary globule•基本的には1Dを再現。3Dの利点は観測の向きでの計算が可能な事
CII
CI
CO

Figure 8. Results of Application 2, in which we simulate the interaction of a spherically symmetric cloud as it interacts with a UV field consisting of aradial sampling and a plane-parallel component. The top four plots show emission maps for [C II ] 158 µm (top left), [C I ] 610 µm (top right), [O I ] 63 µm(middle left) and CO (1-0) (middle right). The colour bars are in units of (K km s−1 ). The bottom left image shows a cross section of the gas temperature(K). The bottom right image shows an RGB composite image of the emission maps of CO (1-0) (red), [C I ] (green) and [C II ] (blue). The values on the colour
bar correspond to the [C II ] emission. RGB colour bar ratios of 5:1:10 for CO(1-0):[C I ]:[C II ]. The white dotted line in the RGB image corresponds to thedirection along the “Equator” whereas the dashed is along the “Diagonal” direction (HEALPix ray ID=6,9 of the NESTED numbering scheme – see §4.2 forthe relevant discussion).

H2O line mapping at high spatial and spectral resolution: Herschel observations of the
Figure 9. Divergence of calculations between one-dimensional and fully
VLA1623 outﬂow
three-dimensional calculations of the PDR described in §4.2. The top panel
shows the attenuation of the UV field strength (in units of the Draine field)
P.Bjerkeli et al.
and the bottom the corresponding number densities of C+ , C, and CO (in•high-velocity gasのトレーサーであるH2O観測。アバンダンス比の比較を行う
cm−3 ). The solid line (1D calc.) is the one-dimensional calculation andthe dotted (Equator) & dashed (Diagonal) lines are the directions shown•H2OはCOより高温領域をトレース(T>=200K)
in the RGB composite image on bottom right of Fig.8. When effects of•H2Oアバンダンスはショックモデルの予想より低い
the three-dimensional structure of the PDR are taken into consideration,
discrepancies between
the calculations appear.
•COより高速度領域をトレースするが、モーメントやエネルギーなどはCO
outﬂowと同じ
On the massive young stellar object AFGL4176: High-spatial-resolution multi-wavelength
Gritschneder et al. 2009; Bisbas et al. 2011; Haworth & Harries
observations and modeling2012).
We take a snapshot at t = 0.12 Myr. A cross-section plot (atP.Boley et al.
z = 0) of the density structure of the clump at t = 0.12 Myr is•VLTI/MIDI(MIR interferometer), Herschel(PACS 70, 160µm), APEX(870µm)
shown at the bottom left of Fig.10 where the ionizing radiation is•大きな構造としては中心集中したspherical modelで構造とSEDを再現
impinging from bottom to top. At this time the cloud has attained a
V-shape structure which contains an approximately ellipsoidal core
•MIDIデータで非対称性構造あり(ビジビリティベース)。数百AUスケールの円盤と思われる。
of density nH ∼ 105 − 106 cm−3 located at its tip and directly ex•円盤を持つ天体で最も明るい大質量星
posed to the ionizing radiation. Although in the SPH simulation theradiation is emitted spherically symmetrically from the distant exciting source, the angular size of the clump is quite small (∼ 6o )and we therefore consider a plane-parallel radiation field here. The

B出現– 13 –I (mag)

Locating the Trailing
Edge of the Circumbinary Ringin the2
Capeloet al.KH 15D System システム全
H.L.Capelo et al.
最後のB
体が隠れる
binary orbital plane with the KH 15D ring is believedtoinduceprecession
in
its
ring
and,
further,thesystem•Tタウリ型星バイナリKH15D(e=0.6, p=48.37days), ほぼ
14
exhibits distinctive eclipses due to this non-coplanaredge-on, outﬂowあり
arrangement.
15
Although identified as a variable star in the late 1960s•star A: K6/K7(Badalian & Erastova 1970), interest in KH 15D be16
•star B:ganearlierthanAwith thediscoveryin 1995 (Kearns & Herbst 1998)
that the star essentially winked on and off by several•2010-11に変光がなくなり暗くなる->2012に増光
magnitudes on a period of 48.37 days (Hamilton et al.
17
Aとopaque2005), now known to be the orbital period of the bi•2012以降の増光はBによるもの
nary (Johnson et al. 2004). These extreme brightness exringによる変光
18•変光/増光現象はopaqueringとA/Bの組み合わせによる
cursions started
then because precession of the ring had
moved one of its razor-sharp edges fully across the orbit
KH 15D•=>precessing
ring of the binary (star B), leaving the otherof one member
19

2. OBSERVATIONS AND DATA ANALYSIS•水の質量は1.5E-6 Msun

1995

2000

2005
Year

2010

Fig. 1.— The long-term light curve of KH 15D showing its dramatic re-brightening in 2012. The one measurement in 1995 showing the system at I = 14 mag was obtained near periastron, whenstar B made its last appearance above the leading edge of thescreen.

14
15
I (mag)(star A) to periodically rise and set with respect to thathorizon as seen from Earth. From 1995 to 2009, the winking continued, with the system being increasingly more“off” as star A spent more and more of each orbital cycle below the horizon (Hamilton et al. 2005; Herbst et al.
2010).
In 2010 vaporand 2011,inthe
system was fainterat allFirst detectionof watera pre-stellar
core
times because neither star appeared above either edge.
P.Caselli et al. Both stars are believed to be less massive than theSun, with star A having a spectral type of K6/K7•HIFI/Herschelによる星なしコアL1544のH2Oの観測(Hamilton et al. 2001; Agol et al. 2004). The prediction
thatproﬁleを示す=>
star B is slightly more
massive and of earlier type•inverse P-Cygni
infallhas heretofore only been inferred from the fact that it•H2Oアバンダンス(数1000AU以下で)> 1E-9is a brighter star, as evidenced
by archival photometry(Winn et al. 2003; Johnson & Winn 2004; Johnson et al.
•cosmic-rayによるFUV
2005) and by its oneﬁeldでH2Oが気化した
appearance in the modern photo•中心密度>1E6 metriccm-3 record (see Fig. 1) prior to 2012.

16

17
We obtained images of KH 15D on over three hundred nights between October 2010 and March 2012, using
18
the ANDICAM instrument on the 1.3m telescope operated by the SMARTS consortium at Cerro Tololo InterAmerican Observatory (CTIO). The I−band photome19
try is in addition to an observing record from multiple
0.0
0.2
0.4
0.6
0.8
1.0
observatories dating back to 1995 and the V − I color
Phase
(P
=
48.37
d)
Fig. 2.— HIFI-HRS
spectrum of ortho-H2 O(110 -101 )hasCHESS
been on record
for nearlya decade. ofThethe protostellar
The Herschel information
and IRAM
spectralsurveysshock L1157-B1:
Fig. 2.— Light+ curves from 2010 and 2011 (x’s) and 2012 (solid
optical images consisted of four exposures, each lasting(110 -1) (intensity
dividedCaselli et a
2 D withcircles) H
phasedthe11orbital
period of 48.37
days. by
The30;
dramatic
fossil deuteration
150 seconds. We used IRAF scripts to flat field, sky subbrightening that occurred around apastron (phase = 0.5) in 2012 isshows
aninverseP-Cygni
profile,withemissiononapparent and represents the appearance of star B partially above
tract and combine dithered images, and the package phot
C.Codella et al.
the ringwateredge. in the bulk of the core is absorbing the far-infr
to complete the aperture photometry. The median error
is 0.01 mag for I < 17.5 mag and increases to 0.05 mag•ショック領域における重水素化度
byartifacts.
the core The
centralregions.
detector
detailsof the standard GNIRSat I = 18.5 mag.
reduction procedures are given in Winge et al. (2009).
•HIFI/Herschel, IRAM30m(80GHz-1THz):
H2O,HCN,NH3,CH3OH,H2COの同位体とD化物
We obtained cross-dispersed (XD)
spectroscopy with
The Astrophysical Journal Letters, 757:L9 (6pp), 2012 September 20
the Gemini Near Infrared Spectrograph (GNIRS) on UT
3. RESULTS•12(+2)本の輝線を検出(Eu=<63K):
CH2DOH,
HDCO,
DCNなど
January 5, 2011, when the stars were both near apas3.1.
Lightcurvetron but fully obscured, with I = 16.95
mag. The XD•H2O,H2CO,CH3OHは低アバンダンス->icy
mantleThe I−band light curve of KH 15D from 1995 todata were taken in the GNIRS short focal length camera•これらは氷生成期の情報を保有
present is shown in Fig. 1. Each vertical strip represents
mode with wavelength coverage from 0.9 to 2.5 µm, a
an annual observing season, culminating in Octoberslit width of 0.3!! , and a 31.7 line mm−1 grating (1600 !
•重水素化度: CH3OH,H2CO> H2O, HCN, NH3
March 2012. The full on-off eclipse behavior, caused
R ! 1700). The processing used the gemini.gnirs IRAF
by star A disappearing behind the leading edge of the
package Beta Version 1.11. The data products consist of•O(CO)との反応を考えた場合の分子生成の軌跡
occulting screen during each orbit, was present up until
a set of calibration images, a spectrum of KH 15D and•低密度(<<1E3
1/cc)->
反応の早いH2Oの生成
about 2006. The maximum system brightness then grada spectrumof HD 59374,
an F8 V star observed(~20K)
for theually diminished, because star A never fully rose above
purposes of characterizing the sensitivity function. The
•密度増加
3E4
1/cc
->
H2CO
&
CH3OH生成the screen edge. The system spent increasingly more
integration times were less than four seconds for all oftime in complete obscuration until 2010, when both stars
the calibration and standard exposures. The observawere fully occulted at all phases and the system never aptions of the target itself include 20 frames, each of 300Figure 3.
Deuteriumthan
fractionationof CHmag.
CO, H2 O, HCN, andNH3 aspearedbrighter
I = 16.3
evensecond duration. The spectra were flat-fielded, assigned
3 OH, H2Interestingly,
foundfully
towardocculted,
L1157-B1 (red)IRAS16293–2422
Loinardwhen
the andsystemvaried by(blue;
morefromthantwoet al.
a wavelength solution by comparison with an argon arcLAMP: The Long-term
Accretion
Monitoring
Program
of
T
Tauri
stars
in
Chamaeleon-I
2001; Parise eton
al. the2002,orbital
2004). Blackdiamonds
standbrighter
for the predictionofmagnitudes
period,being
near
lamp spectrum and corrected for spatial distortions and
3
4
5
6
−3
Taquet et al. (2012b) for pre-shock gas densities of 10 , 10 , 10 , and 10 cm

G.Costigan et al.
(see labels) and temperatures of 10 (dashed line) and 20 K (solid).
•VLTを使ったHa,HeI,CaIIの15ヶ月モニタリング観測。25天体。
(Benedettini et al. 2012). This is consistent with our methanol•降着有り10個、降着無し15個を検出
HIFI observations (Codella et al. 2010), which give Trot = 12 K
for Eu ! 50 K and Trot = 106 K for Eu between 50 and 220 K.
•星のrotation period程度の降着率の変動あり->関係有り
This discussion is out of the scope of the present Letter, and will
•Haの変動は他ラインより大きく、降着のindicatorとしてふさわしくない
not be further pursued, but it justifies a posteriori the selectionof only the 13 C-isotopologues transitions at the same excitation as those of the deuterated species observed. Given the Trot
uncertainties, the formaldehyde deuteration is 5–8 × 10−3 .
4. DEUTERATION IN THE SHOCKED GAS
The analysis in the previous section (Table 2) shows thatthe deuteration of H2 O (0.4–2 × 10−3 ) and HCN (∼10−3 )is lower than that found for formaldehyde (5–8 × 10−3 ) andmethanol (0.2–2 × 10−2 ). Figure 3 shows the deuteration
fraction for the five species studied here toward L1157-B1(Table 2) together with the corresponding values found in theMichiel Cottaar et al.: Characterizing a cluster’s dynamic state
Characterizing a clusterʼs dynamic stateusing a single epoch of radial velocitiesdN
4.8
M.Cottaar etwithal.
(for q < 0.6) and a binary fraction of 22%. Thisdq ⇠ qbinaryfraction
is much lower than that observed for solar-type•バイナリなどのorbital periodにdisturbされないようにクラス
stars in the field, although the e↵ect per binary on the velocity
ターのradial distribution
velocityを導出する
is much larger, because they tend to be on closer
orbitsand tend to be equal-mass.
•intrinsicな速度+バイナリによる速度ズレの効果を考慮してフィIn our simulations the masses range from 0.1 to 1 M .
ットする
Although recent results (Janson et al., 2012) suggest a smoothtransition
betweenbinary properties of the very low mass•period,mass
ratio,theeccentricity等の仮定が必要
and solar-type stars, we will use a sharp transition between these•NGC188へ適用してテスト。intrinsicなradial
velocityを再現
regimes for this numerical test. For the low mass
stars (< 0.2 M ,single starのみ⇠34% of all stars) we use the semi-major axis log-normal distri•solid:
best ﬁt model
bution, the mass ratio power-law distribution (for q between 0.1
and 1), intrinsic
and the binary
fractiondist.
found by Burgasser et al. (2007).
•dashed:velocity

For the higher mass stars we use the binary properties observed
for the solar-type field stars (Sec. 3) with a binary fraction of
46%. We once again fit these radial velocities under the (inaccurate) assumption that all stars still have the same binary fraction and follow the solar-type field binary period, mass ratio, andeccentricity distributions. These simulations are repeated for a
Fig. 5. Histograms of the three single-epoch radial velocity disbroad range of input velocity dispersions.
tributionfrom NGC 188 we consider in the top left, top right andInterstellar matterand star
W5-E- A Herschelview
The measured
velocityformation
dispersion is inshown
in Figure4 asbottom left panels, with the probability distribution of the best
green
L.Deharveng
etdots.
al. Although the assumed solar-type field binary prop- fitting model overplotted as the solid line for a star of 1 M anderties are inaccurate for a third of the ’observed’ stars, the o↵seta measurement error of 0.4 km s 1 . The intrinsic velocity distri•PACS+SPIRE/Herschel(100,160,250,350,500mum)によるYSO同定とHII領域の影響の調査
between the measured and input velocity dispersion is still atbutions (eq 8) are plotted as dashed lines. InL.thebottomthe inDeharveng
et al.:rightStar Formation
most 4%.
•SEDの作成、温度見積りと柱密度見積り
histogram of the velocities of the single stars identified in Geller
These two examples (Sec. 4.2.1 and 4.2.2) are meant to il- et al. (2008) is plotted. The intrinsic velocity distributions (renorsity in these•50個の点源->多くはclass0/I天体で温度16K程度
to allustrate the e↵ect of incorrect binary assumptions on the mea- malized to the smaller population) computed from the threeenoughdataproces
lapse
sured intrinsic velocity distribution. For reasonable di↵erences sets have been overplotted. All three of these intrinsic velocity•outﬂow起源もある
that the coll2
between the true and assumed binary properties, the e↵ect on distributions are consistent with the velocity distribution ofabout
the6⇥10•これらはHII領域の境界部に多く存在->triggered
starformationthe b
the intrinsic velocity dispersion turns out to be fairly small. For single stars from Geller et al. (2008) according to a KS-testaround(see dens
L. Deharveng et al.: Star Formation in W5-E
columnthe cases discussed above only a few percent. It would require text). In all panels the fraction of every bin expected to consist
is observed.
ofobservations of thousands of stars, before this systematic o↵set non-members (Platais et al., 2003) have been made yellow.theThe
nebula.
dense
becomes significant compared to the statistical error. However, color coding of the lines corresponds to the data set used to fitparendate Class 0
if the binary properties are very uncertain, it might still be useful the model. The first observed epoch has been shown in blue,lected
themateroutflows areto check how much the intrinsic velocity distribution might vary second epoch in green, and the last epoch in red.
sources, pro
for several reasonable assumptions about the binary properties
or candidate(Odenkirchen et al., 2002).
S201-s1-s2)

into massivein the act, inin our model the masses only a↵ect the binary orbital motions,
H ii region.
which have a negligible e↵ect on the very broad velocity distrioperating is
Triggerebution of the fore- and background stars.
These fore- and background stars will a↵ect the intrinsictions:ve• In thelocity distribution. Following Geller et al. (2008) we modelAsthediscussed
structures
radial velocity distribution of the field star population witha se
the central e
Gaussian. Choosing the same distribution to fit the field stars
alSome low-m
lows us to make direct comparison with the results from Geller
structures, w
Low-mass
et al. (2008). We can add this Gaussian to the model for thein- clars, which atrinsic velocity distribution (eq. 2) to get
We suggest
0
1
tion of lowBBB (vdyn µc )2 CCC
cess possibl
1
B
C
Ldyn, i (vdyn ) = fc q
exp B@C+
Gritschnede
2 + 2) A2(
2
2
provides a gci
2⇡( i + c )lence in the
0
1(8)
2 C decay with
B
(v
µ
)
1
B
dyn
f C
CCC , main at wor(1 fc ) q
exp BBB@A • In the2( 2i + 2f ) clouds.
BRC
2⇡( 2i + 2f )5. Case study: NGC 188

As a test for the procedure described above, we will here consider the case of the old (7 ± 0.5 Gyr; Sarajedini et al., 1999)
open cluster NGC 188. The dynamical state of the cluster was
extensively studied by Geller et al. (2008, 2009) and Geller &Mathieu (2011). Based on 9166 radial velocity measurements of1108 stars in the direction of this cluster, Geller et al. (2008)
identified a large number of stars with significant radial velocity variations. Based on the remaining (seemingly single) 640
stars, they derive a velocity dispersion of 0.64±0.04 km s 1 . Thisvalue is still inflated by unidentified binaries. Geller & Mathieu(2011) found that these unidentified binaries would inflate an1
intrinsic velocity dispersion of 0.49+0.07
to the observed
0.08 km s
10.64 ± 0.04 km s . In this section we will show that we can reproduce their intrinsic radial velocity distribution using only aFig. 2. Composite colour image of the W5-E field observed by Herschel. Red is the 250 µm Herschel-SPIRE data, which traces coldFig. 17. Scenario of star formation in the W5 region. Top: The
harbor clust
single
epoch
their
data.
dust emission,greenofis the100 µmHerschel-PACS data, which traces emission mainly from dust at higher temperature located in
exciting stars of Sh 201, W5-E and W5-W formed in a dense bly di↵eren
the PDRs, and blue is the DSS2-red survey, which traces the H↵ emission of the ionized gas. The yellow cross lies at the positionWe
estimatethemassesoftheobserved
stars
to
be
given
where
f
is
the
probabilityofanobserved
stars
to
be
a
clus- a mc filament. The exciting star of Sh 201 formed in the middle of the encloseof HD 18326, the exciting star of W5-E.
filament
whereasthose ofof
W5-E
and W5-W
formed onits borClassbytheclosest
point
on
the
7
Gyr
Padovaisochrone(Marigotermember(i.e.
thefractionclustermembers)andandµfI YSOf
The Lesser Role of Shear in Galactic Star Formation: Insight fromthe Galactic
Ring
expanding H ii regions
have bursted out of the bright rims hand a simple
model
of modified
emission.
especiallyuncertain.
Temperatures in the range
K–20 Kder. Middle:
etSPIRE
al.,data
2008)
with
E(B
V)blackbody= 0.09and areDM=
11.44(following
are 17
respectively
the Thevelocity
dispersion andmean velocity of
the(i.e. by the
While AND12 fitted simultanously for the dust temperature and are observed in zones of high column density such as the fila-filament. In Sh 201 the ionized gas flows away of the filament inSurveythefituseoftheSarajedini
etderiveal.,a 1999).
The
massesthe BRC12,
non-members.
Thesethree parameters
will
be fitted
in Aaddition
the photometriccolumn density, we here
Herschel fluxes toments in thevicinityof Sh 201ofor inside
BRC13, andtwo opposite
directions,forming a bipolar
H ii region.
Bottom:tors:
temperature at each location, leaving the column density as a free BRC14. The PDR regions, adjacent to the IFs, are at an interme-new generation of stars is forming in the densest condensations,in tothismannervary
between0.8
to the binary fraction ( fbin ), the cluster velocity dispersion ( c ),parameter. Westars
smoothedestimatedthe Herschel images
the same
reso- diate
temperatureof 21 K–22
K. andS.Dib et al. observed
adjacent to the first generation H ii regions.
1. The mor
lutiona two-dimentional
representing the
SPIREcontains
The knowledgeof the dust temperature
us toestimate
1.1
Musing. The
sampleGaussianof observedstars
a significant
con- allows
andthemean velocity (µc ) of the cluster.
ing starbeam at 500 µm and reprojected the data to a uniform pixel spac- the column density of the gas. With the same assumptions, we
ing of the 500 µm
data. Fig.
3 shows
the temperature
map and stars.
can estimate
H2 columnstars
density wefrom the surfaceBecause
brightness•銀河のshearが星形成に与える影響を調査
taminationfromforeandbackground
Forthe these
multiple epochs of data are available for nearly2. all
The comsome iso-temperature contours; cold dust appears in white, hot F⌫ , using the formula:tionradiationactingonaturbulentmedium;4)
radiation-driven
the rims
doexpectthecomputedmasses
of
the
1108
stars
we
are
able
to
run
the
procedureonthreesingledustnot
in black.
The contours
correspondto 18 K, 20
K, 22 K, 24toK be accurate. Fortunately
100 F⌫•星形成率・星形成効率との相関性が言われているがよく分かっていない
and 26 K. The temperature does not vary strongly over the field:
T dust lies in the range 17 K to 31 K. Temperatures higher than
26 K are observed in the central cavities of W5-E and W5-W,
direction of Sh 201, in the direction of the small A and B
8 inH iitheregions
lying between W5-E and W5-W, and in the direction of the IR sources inside BRC14. Due to the relatively low
fluxes, the temperatures in the direction of the interior of W5-E

N(H2 ) =⌫ B⌫ (T dust ) 2.8 mH ⌦beam,(3)compression of pre-existing dense clumps (the RDI process). It

is often difficult to prove that star formation has been triggered
because the age di↵erence between two stellar populations is•Galactic Ring Survey@FCRAOの13CO(1-0)のデータでgravitational
instabilityに対するshear
where F⌫ is expressed in Jy beam , B⌫ in Jy, the factor of 2.8
is the mean molecular weight, mH is the hydrogen atom mass,difficult to estimate with accuracy (for example Martins et al.
and ⌦beam is the beam solid angle. The visual extinction can be2010), and we are often left with only morphological arguments.
parameter(Sg)の見積り
estimated from the column density. From the classical relations,
N(H + H2 )/E(B V) = 5.8 ⇥ 1021 particles cm 2 mag 1 (BohlinFurthermore it may be difficult to identify the processes at the•銀河内の位置、星形成効率、クランプ質量、等、どれもSgとの相関無し origin of the triggering. What can we learn from the Herschelobservations of W5-E?
5
Neutral material has been collected around the W5-E H ii re•銀河内においてshearは星形成活動に主要な役割を果たしていない
gion, about 8000 M according to AND12. It is observed forexample in the direction of PDR1 and PDR2, at the south borderof BRC13, and at the periphery of BRC12. The column den1

22vations,
ionizedusing SCthe dens
BRCs. Thigher th
BRC14.
its assoc
compres
tions for3. The obs
vicinity