Telescope of Theory: Radiative Transfer Studies of a Young Star - - PowerPoint PPT Presentation
Telescope of Theory: Radiative Transfer Studies of a Young Star Forming Object M. Yamada(ASIAA) M.N. Machida(NAOJ) S. Inutsuka(Nagoya-U.), K. Tomisaka Y. Kurono(NAOJ) I) young embedded outflow II)magnetic flux problem -
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I) young embedded outflow II)magnetic flux problem
diffusivity III) synthetic-observation towards ALMA era IV)LTR project - gallery
✦ Unresolved problems in (low-mass) Star Formation:
1) angular-momentum problem Jcore>>J* ⇒outflow launching that transfers J away 2) magnetic flux problem Φcore>>Φ*: how/when “extra” ΦB decreases by a factor of 104-105? 3) ... and so on
✦ Low-mass star formation site: center of the parent molecular core
✦
✦
evolution time scale~free fall time: rapid evolution at the central region (ρ∝r-2) ⇒need to probe the emission embedded in an infalling envelope
✦ 3D MHD model + line transfer simulation
Which line is the plausible tracer? How ALMA can reveal these problems realistically?
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✦ Unresolved problems in (low-mass) Star Formation:
1) angular-momentum problem Jcore>>J* ⇒outflow launching that transfers J away 2) magnetic flux problem Φcore>>Φ*: how/when “extra” ΦB decreases by a factor of 104-105? 3) ... and so on
✦ Low-mass star formation site: center of the parent molecular core
✦
✦
evolution time scale~free fall time: rapid evolution at the central region (ρ∝r-2) ⇒need to probe the emission embedded in an infalling envelope
✦ 3D MHD model + line transfer simulation
Which line is the plausible tracer? How ALMA can reveal these problems realistically?
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✦
interpreting data sets of Iν in terms
straightforward
✦
line RT can form a toolbox to decipher tangled “riddles” printed in observed line data cube
My dear Watson, circumstance evidence is a very tricky thing... and there is nothing more deceptive than an “obvious fact”. 3
✦ rate eq.: non-LTE in S.E.
✦
Bij (stimulated emission) & Cij (collisional transition) →dependent on Tkin & n [non-LTE]
✦ Radiative transfer eq. [ray tracing with long characteristics method]
✦
integrate RT eq. along sampling rays for each grid
✦
average Iν over all sampling rays
Hogerheijde&van der Tak(2000)
ni
1 4π ∞ IνdνdΩ + Cij
1 4π ∞ IνdνdΩ + njCji
Cij =
nXγij ≈
nXσijv dIν ds = −ανIν + jν jν = hν0 4π niAijφ(ν) αν = hν 4π
g2 n2 n1
ni & Iνij are solved iteratively until solution converges : emission coeff.
¯ J = 1 Nray
4
5
Belloche et al.2002
Dead region B dissipation
(1012cm-3<n<1015cm-3)
B amplification B amplification
Isothermal Phase Adiabatic Phase Second Collapse & Protostellar Phases
Adiabatic core (First core) Formation H2 dissociation (endoergic reaction)
To MS
protostar (second core)
Gas Temperature
Log T (K) 10 102 103 104
Log n (cm-3) 1010 1015 1020 105
Spatial Scale (AU)
104 100 1 0.1
Larson (1969) Tohline (1982) Masunaga & Inutsuka (2000)
Molecular Cloud Core Protostar
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✦ Magneto-Hydrodynamic simulations:
✦
3D nested grid, ideal MHD
✦
initial condition : rotating Bonnor-Ebert sphere (M=0.6Mo, R=2000AU, Tkin=10K)
✦
EOS: taken from 1D radiation hydro. simulation (Masunaga & Inutsuka, 2000) + some modification
✦
long evolution, and large spatial extent
✦
stop calculations shortly after the first core formation
✦ Radiative Transfer: [ray tracing with long characteristics method]
✦
non-LTE level population up to J=16 for each grid
✦
assume uniform chemical abundance distribution
✦
purely thermal velocity, no micro-turbulence
Hogerheijde&van der Tak(2000)
12CO
CS SiO ncrit ~102[1/cc] ~105[1/cc] ~105[1/cc] E10 5.5K 2.35K 2.08K
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500 1000 x[AU]
500 1000 z[AU]
5.81 6.75 7.69 8.63 9.57 10.5 11.5 log10(n[cm-3])
✦ we used a snap shot at very young protostellar object (YPO: t~4,000yrs)
that shows:
✦
bipolar outflow (~1.7 km s-1) launched in the vicinity of the first core [magneto- centrifugal force-driven flow by twisted B by rotation]
✦
rotation & magnetic field -> a geometrically thick disk-like structure (“protostellar disk”)
500 1000 x[AU]
500 1000 z[AU]
5.81 6.75 7.69 8.63 9.57 10.5 11.5 log10(n[cm-3])
density distribution first core (R~50AU, M~0.01Mo) protostellar disk
✦
dust continuum: provides higher angular resolution obs. than lines? NO!
κν = 0.1 × 0.25[mm] λ β
x[AU] 500 1000
500 1000 y[AU]
x[AU] 500 1000
500 1000 y[AU]
x[AU] 500 1000
500 1000 y[AU]
x[AU] 500 1000
500 1000 y[AU]
x[AU] 500 1000
500 1000 y[AU]
0.00e+00 1.00e-02 2.00e-02 3.00e-02 4.00e-02 5.00e-02 6.00e-02 Tb[K]
(a) 150GHz (d) 650GHz (b) 220GHz (c) 350GHz (e) 850GHz
Tb = Bν(1 − exp(−τν))
✴high column density at
disk - difficult to look further inside
✴emission from outflow
component is quite weak
1000 500
z 1000 500
x 1000 500
z 1000 500
x 1000 500
z 1000 500
x 1000 500
z 1000 500
x
✦
almost symmetric distribution of red/blue components
✦
in outflow & disk: red and blue contours show separate peaks
✦
not in perfect symmetry in red/blue contours due to optical thickness & velocity structure effects
✦
θ=30, 60deg.: almost circular envelope at the outer part ⇔infalling motion of envelope toward the center
✦
Δθ(10AU)=0.07” if D=140pc
θ=0, 30, 60, 90 deg. [SiO(J=7-6) E7=58K], barotropic
integrated intensity: full & blue/red
ALMA can resolve these structures (..and SMA as well?)
envelope
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✦
adopt “standard” mol. abundance y=3x10-4
✦
ncrit(1-0)~102 cm-3 , ncrit∝J3
✦
huge optical thickness (τ0 up to 4,000) and high density (106 cm-3 < n < 1011 cm-3) in the simulation box, pop. energy distribution becomes LTE even at high J (J=10-9) (Tex = Tkin~10K)
Tex[K] n[cm-3]
12 10 8 6 4 2 12 10 8 6 4 2 12 10 8 6 4 2 106107 108 1091010 1011 106107 108 1091010 1011 106107 108 1091010 1011
1-0 4-3 7-6 2-1 5-4 8-7 3-2 6-5 9-8
Tex[K] n[cm-3]
dominant: CO, 13CO, C18O are not good tracers
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✦
huge optical thickness ⇒the locations of photospheres are almost the same as the initial Bonnor-Ebert sphere
✦
qualitative characteristics are quite independent on viewing angle θ
(a) 12CO (b) 13CO (c) C18O
2000 4000 x[AU]
2000 4000 z[AU]
2000 4000 x[AU]
2000 4000 z[AU]
2000 4000 x[AU]
2000 4000 z[AU]
CO and its isotopologue lines are useless for a probe of very young protostellar object
12 10 8 6 4 2 12 10 8 6 4 2 12 10 8 6 4 2 106107 108 1091010 1011 106107 108 1091010 1011 106107 108 1091010 1011
1-0 4-3 7-6 2-1 5-4 8-7 3-2 6-5 9-8
n[cm-3] Tex[K]
✦
adopt “standard” mol. abundance y=2x10-8
✦
ncrit(1-0)~105 cm-3 ⇔ 106 cm-3 < n < 1011 cm-3
✦
low-J and in dense regime (n > 108 cm-3), pop. is LTE
✦
high-J and in tenuous regime (n < 108 cm-3), Tex decreases to ~ 5K ⇒non-LTE effects can be
(⇔12CO, 13CO, C18O)
n[cm-3] Tex[K] n[cm-3]
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✦
saturation
✦
<τ>SiO~0.01x<τ>CO: SiO will present inner structures that 12CO cannot
✦
non-LTE pop. & smaller τ ⇒double peak profile appears with respect to Vr=0 km sec-1
✦
qualitative characteristics are quite independent on viewing angle θ
✦
double-peak structure even in pole-on [θ=90] view
Vr [km sec-1]
2 4 2 4 6 8 10 12 Tb[K] 50 100 150 200 250
τν Vr [km sec-1]
2 4 2 4 6 8 10 12 Tb[K] 50 100 150 200 250
τν Vr [km sec-1]
2 4 2 4 6 8 10 12 Tb[K] 50 100 150 200 250
τν
(a) (b) (c)
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v =
Tbdvr −1
500 1000 z[AU]
500 1000 x[AU]
500 1000 z[AU]
500 1000 x[AU]
0.0 0.5 1.0
Vr [km sec-1]
(a) (b)
vφ≠0 vφ=0 vφ=(vx2+vy2)1/2 ∇<v>≠0
✦
SiO(4-3) vel. 1st moment
✦
Δv~1km/sec, irrespective of transition [J] ←relatively large τ, velocity at the surface appears
✦
✦
rotation of outflow: one of characteristic features of magneto-centrifugal force-driven outflow
Strong B
Wide Opening Angle
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Tb[K]
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vφ=0 Tb[K]
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*fist detection of
*incl.=85deg. in CB26 (class I/II)
✦disk-wind like model
: rotation is the key
✦symmetric around the center (not to
the equator) will be observed unless EXACTLY edge-on view SiO(4-3), y=2x10-8 Launhardt et al. 2009 model
0.0 0.5 Vr[km sec-1] y[AU]
500 1000 x[AU]
500 1000
∇v
0.0 0.2 0.5 0.6 Vr[km sec-1] z[AU]
500 1000 x[AU]
500 1000
color: v first moment black contour: 12CO(2-1) white contour: 270GHz
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6 7 8 9 log(n[cm-3]) 10 11 0.0 0.5 1.0 |v|[km sec-1] 1.5
0.0 0.76 1.5 2.3 3.0 3.8 4.6 freq./104
(b)
✦
In a YPO embedded in infall envelope,
✦
✦
|vrot |~ |vinfall |~ |voutflow| [grav. potential]
✦
similar norm, but different directions -> VERY complicated vel. structure ⇔more evolved outflow/disk system (voutflow>>vinfall, vrot)
envelope
* more than one vel. components appear on a line-of-sight irrespective of viewing angle ⇒ careful identification of outflow is necessary
500 1000 x[AU]
500 1000 z[AU]
5.81 6.75 7.69 8.63 9.57 10.5 11.5 log10(n[cm-3])
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✦ “Magnetic flux problem”
Φcore >> Φ* stellar magnetic flux is ~10-4~10-5 compared with the parent core
✦ How & where has φB dissipated?
✦
dissipation: ambipolar diffusion, Ohmic dissipation ->dynamical evolution
✦
resistive MHD study: rapid diss. at the formation of outflows from the first core
ideal MHD resistive MHD Machida et al.2006+
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Can we observationally examine these expected differences in morphology of outflows? parameterize Cη・η (Nakano et al. 2002)
✦
Dissipation of B-field depends on resistivity coeff. η
✦
uncertainty in resistivity parameter (η) affects the launch of the outflows
✦
Difference in evolution paths of the young outflows - different emission signature (morphology)?
Can we observationally examine these expected differences in morphology? Machida et al.2006+ decoupled coupled parameterize Cη・η
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✦ Hydrodynamic simulations:
✦
3D nest grid, resistive MHD
✦
initial condition: rotating Bonnor-Ebert sphere (M=0.3Mo, R=2000AU, Tkin=10K)
✦
EOS : taken from 1D radiation hydro. simulation (Masunaga & Inutsuka, 2000) + some modification
✦
long evolution, and large spatial extent
✦
stop calculations slightly after the first core formation
✦ Radiative Transfer: [ray tracing with long characteristics method]
✦
non-LTE level population up to J=16 for each grid
✦
assume uniform chemical abundance distribution
✦
purely thermal velocity, no micro-turbulence
Hogerheijde&van der Tak(2000)
HCO+ HCN SiO ncrit ~105[1/cc] ~105[1/cc] ~105[1/cc] E10 4.2K 4.1K 2.08K
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✦ density distribution - “hole” near the first core (launching point) for η>0
cases
✦
B-field dissipation at the center -> launching point of the magneto-centrifugal force goes OUTWARD
Cη=0 (ideal) Cη=1 Cη=10 Cη=100
x[AU] 100 200
z[AU] 100 200 12.80 11.80 10.80 9.80 8.80 7.80 6.80 log10n [cm-3]
x[AU] 100 200
z[AU] 100 200 12.80 11.80 10.80 9.80 8.80 7.80 6.80 log10n [cm-3]
x[AU] 100 200
z[AU] 100 200 12.80 11.80 10.80 9.80 8.80 7.80 6.80 log10n [cm-3]
x[AU] 100 200
z[AU] 100 200 12.80 11.80 10.80 9.80 8.80 7.80 6.80 log10n [cm-3]
(a) (b) (c) (d)
Strong B
Wide Opening Angle
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✦ density distribution - “hole” near the first core (launching point) for η>0
cases
✦
B-field dissipation at the center -> launching point of the magneto-centrifugal force goes OUTWARD
Cη=0 (ideal) Cη=1 Cη=10 Cη=100
x[AU] 100 200
z[AU] 100 200 12.80 11.80 10.80 9.80 8.80 7.80 6.80 log10n [cm-3]
x[AU] 100 200
z[AU] 100 200 12.80 11.80 10.80 9.80 8.80 7.80 6.80 log10n [cm-3]
x[AU] 100 200
z[AU] 100 200 12.80 11.80 10.80 9.80 8.80 7.80 6.80 log10n [cm-3]
x[AU] 100 200
z[AU] 100 200 12.80 11.80 10.80 9.80 8.80 7.80 6.80 log10n [cm-3]
(a) (b) (c) (d)
Strong B
Wide Opening Angle
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x[AU] 100 200
z[AU] 100 200 32.0 26.7 21.3 16.0 10.7 5.3 0.0 I [K km sec-1]
x[AU] 100 200
z[AU] 100 200 32.0 26.7 21.3 16.0 10.7 5.3 0.0 I [K km sec-1] 32.0 26.7 21.3 16.0 10.7 5.3 0.0 I [K km sec-1]
x[AU] 100 200
z[AU] 100 200 32.0 26.7 21.3 16.0 10.7 5.3 0.0 I [K km sec-1]
x[AU] 100 200
z[AU] 100 200
(a) (b) (c) (d)
✦ Integrated intensity distributions show differences in the widths of
“cavities” of outflows
✦
B-field dissipation at the center -> launching point of the magneto-centrifugal force goes OUTWARD
Cη=0 (ideal) Cη=1 Cη=10 Cη=100 H13CO+(4-3), y=2x10-10
✦ required
resolution ~10AU@140pc = 0.07”: resolvable 15
✦ required resolution
~10AU@140pc = 0.07”: resolvable
✦ pole-on ~ close-to-pole-on views show
morphology differences due to η
✦
filled cone (η=0) ⇔ “empty” cone (η≠0)
✦
significant difference in ideal/resistive MHD results
Cη=0 (ideal) Cη=1 Cη=0.1 H13CO+(4-3), y=2x10-10, θ=30deg
200 100 z[AU]
x[AU] 100 200 0.0 5.3 10.7 16.0 I [K km sec-1] 21.3 26.7 32.0 200 100 z[AU]
x[AU] 100 200 0.0 5.3 10.7 16.0 I [K km sec-1] 21.3 26.7 32.0 200 100 z[AU]
x[AU] 100 200 0.0 5.3 10.7 16.0 I [K km sec-1] 21.3 26.7 32.0
(a) (b) (c)
η=0 η≠0
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Strong B
Wide Opening Angle
eta=0(ideal MHD)
✦
Wider opening outflows from outer launching loci form “cavity” structure in (x, y, v) space
pole-on view
eta=1
磁気遠心力風モデル
Strong B
Wide Opening Angle
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✦ Shift in launching point → evolution of aspect ratio of outflow width/
length
✦
easier than direct detection of relatively small differences in the launching points from images
x[AU] 20 40 60
y[AU] 20 40 60 4.20 2.80 1.40 0.00
Vz [km s-1]
Rout Zout
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strong coll.
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✦ line transfer simulation of YSO outflow ✦ rotation of magneto-centrifugal-force driven
flow appears in velocity channel maps
Yamada, Machida, Inutsuka & Tomisaka, 2009
SiO(7-6), 30deg
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SMA
Y.Kurono & MY, private comm.
✦ diffuse component from the geometrically thick (pseudo-)disk: the
total power array is inevitably necessary in ALMA obs.
✦
exposure time: ~14 hours for SiO(7-6) @0.1”, 0.3K sensitivity w/ALMA
@140pc, dec=-30
26
SiO(7-6), 30deg
SMA
Y.Kurono & MY, private comm.
✦ diffuse component from the geometrically thick (pseudo-)disk: the
total power array is inevitably necessary in ALMA obs.
✦
exposure time: ~14 hours for SiO(7-6) @0.1”, 0.3K sensitivity w/ALMA
@140pc, dec=-30
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SiO(7-6), 30deg ALMA SiO(7-6), 30deg
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✦ “Observational Visualization” (K. Tomisaka)
⇒”Numerical Astronomy” (MY)
✦ Hydrodynamic simulations + Radiative Transfer -> pseudo obs. tool ✦ hydro. (theoretical models) : ρ(x), T(x), v(x), ymol(x) .... ✦ real observation : Iν(θ) ✦ currently we do not pay much
attention to TA⇔Tb, or response
simulation(Wada&Tomi saka2005)
radiation transfer
Members:(phase1)
Omukai, K.Saigo, MY.+..
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✦ Supersonic “turbulence”
✦
seen ubiquitously over a wide spatial scale as a broad line width (Δv>Δvtherm) → “supersonic” flow
✦
energy source to maintain “supersonic” flow against shock dissipation is still unclear (supernovae, YSO outflow, rotation of Galactic disk..)
✦ Multi-phase ISM by Thermal Instability (Koyama & Inutsuska 2002)
✦
diffuse cloud with Av~1 becomes thermally unstable
✦
motion of cold & dense clump in a warm & diffuse ambient form a broad line width MY, Koyama, Omukai, & Inutsuka(2007)
Vkin(cold)~Vth(warm) >>Vth(cold) ◎motion of cold clumps is SUBSONIC to the ambient, so that it can escape shock dissipation
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2-phase 1-phase
Sakamoto&Sunada(2003) CO(1-0) obs. of Taurus HCL2
✦ Clumpy structure of ~0.05pc in PV diagram naturally appear in 2-phase
model → transition from 1-phase (no UV heating) to 2-phase?
✦ in agreement with diffuse cloud observation w/ Av~1?
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✦
ISM is in general very inhomogeneous
✦
Rclump<O(10pc) : Δθ～ 0.1”@D=20Mpc in
✦
currently substructures in a compact nuclei might be smeared out in a obs. beam...
✦
.. but we can predict and prepare what we could expect in ALMA era
1kpc
VLT MELIPAL + VIMOS Kohno et al. 2003 PASJ, 55, L1
1 kpc
P.-Y. Hsieh et al., 2004
12CO(2-1) SMA
←CO obs. of NGC 1097 (Seyfert 1) ↓simulation (HCN)
31
✦
RHCN/HCO+>2 is observed in a number of galaxies, but results of rad. transfer suggest “RHCN/HCO+ =1 ceiling”
✦
In order to obtain RHCN/HCO+~2:
✦ HCN should be much abundant than HCO+
↑↓
✦ XDR/PDR models (yHCN<yHCO+ in XDR)
Imanishi et al. 2004, Kohno et al. 2005
HCN/HCO+ HCN/CO
Yamada, Wada, & Tomisaka, 2007
✦
ISM is in general very inhomogeneous
✦
What can we derive from substructures in an (finite) observation beam?
✦
relation between multi-phase ISM & beam (area) filling factor & volume filling factor
✦
validity of “mist model”..?
✦
τ<<1: Fν∝NH2
✦
τ>>1: Fν∝(surface area of photosphere)
1kpc
VLT MELIPAL + VIMOS Kohno et al. 2003 PASJ, 55, L1
1 kpc
P.-Y. Hsieh et al., 2004
12CO(2-1) SMA
←CO obs. of NGC 1097 (Seyfert 1) ↓simulation (HCN)
31
✦ Optically thin & low density limit (n<< ncrit)
✦
population distribution : balance of coll. excitation and spontaneous decay
✦
rate eq. in SE :
✦
✦
J-dependence of rot. transitions:
✦ LTE & thick limit :
A10n1 =
C0Jn0 AJ,J−1nJ =
C0J′n0 γ0J = γJ0 gJ g0 exp
kBTkin
γJ0(2J + 1) exp
kBTkin
J4 2J + 1 νJ,J−1 ∝ J
R43/10 ≈ hν43n4A43/(hν43)2 hν10n1A10/(hν10)2 ∝ 1 J
≈ 0.3
J=0 J=1 Jcrit Jmax
C0J AJ, J-1 ~1(hν<<kTkin) R43/10 = Tb(43) Tb(10) = Tkin Tkin = 1
32
✦ average ratio takes a value around 1 ⇔ peak-to-peak ratio >1 ✦ difference between (a)&(b)→clumpiness inside ✦ as y increases, R43/10 decreases below 1 ✦ one-zone analysis suggests R43/10->1 as tau increases ??
face-on edge-on
✦ Model multi-phase torus with a simple isothermal two-phase ISM
✦
2 phases = (dense clumps + tenuous ambient), & optically thin over a whole region
✦
If we assume optically thin, average line ratio becomes :
✦
in dense clumps : nJ~thermalized in tenuous ambient : n0~1 (balance between
spontaneous decay)
R′
43/10 ≃
ν10 ×
=(A)
G(Tkin, J) ≡
γJ,0
pxpxpxpxpxpx
(A) = ξ43(nH2f4A43)d + (1 − ξ43)(nH2f4A43)t ξ10(nH2f1A10)d + (1 − ξ10)(nH2f1A10)t ≃ ξ44 exp
kBTkin
H2G(Tkin, J = 4)f0)t
ξ(nH2f1A10)d + (1 − ξ)(n2
H2G(Tkin, J = 1)f0)t
✦ Numerical evaluation of <R43/10> in isothermal two-phase model
✦
If we assume optically thin, average <R43/10>(ξ,Tkin,nave) takes a value from 0 to 64
✦
<R43/10> can become two-value function
✦
η(inhomogeneity index) strongly influence line ratio ⇒
internal density structure should be taken into account for excitation analysis nave =100[cm-3] nave =1000[cm-3] nave =104[cm-3]
200 400 600 800 10001200 Tkin[K] 10-5 10-4 10-3 10-2 10-1
ξ
200 400 600 800 10001200 Tkin[K] 10-5 10-4 10-3 10-2 10-1
ξ
200 400 600 800 10001200 Tkin[K] 10-5 10-4 10-3 10-2 10-1
ξ
16.00 13.33 10.67 8.00 5.33 2.67 0.00 R43/10
nave=102[cm-3] nave=103[cm-3] nave=104[cm-3]
✦ Fitting formula for <R43/10> in isothermal two-phase model
データベースを用いて、数値計算した結果を図 に示す。図 中、斜線をかけた領 域は、式 で求めた の密度が負になる領域で、物理的に意味のない解に対 応する。図 より、輝度温度比 は系の運動温度、平均密度 、 の に応じて最大 近くまでの値を取ることが分かる。この図から、温度を固定す ると、比 は の値と共に増加し、また固定 に対しては比は基本的 に温度とともに上昇することが分かる。ただし、 の条件を満たさない低温領域 では、比は温度の増加関数ではない。これは、 での比が のファ クター分だけ下がる効果が無視できなくなり、この項を に置き換えられなくなるためである。 図 式を用いて計算した 輝度温度比に直してある の分布。 枚の図は、それぞれ異な る に対応する。パネル では 、パネル では 、パネル では である。 図 に表示された輝線比 は、下のような関数で近似的に記述できる
r4310(η, Tkin, nave) = a exp −(η − b)c d
= 1.19118 − | log10(Tkin) − 4.484386|8.83371 14580.1 b = log10 (nave) − 5.0 c = 215.238 T c2
kin
− 6.29 × 105 log10 (nave) c2 = −0.001 log10 (nave)4.96 + 1.14 dex(d) = −2.1 log10(nave) + 11.8 Tkind2 + 8009.14Tkin−6.9129 + 0.169 log10(nave) − 1.83 d2 = −0.07 log10(nave) + 0.116
上式 は、図 に表示された値と最大 倍程度の範囲内で一致する。下に、式 と式 の評価の相対誤差 を表示する。図 で、低温領域で特に誤差が大きくなるのは、ガスの温度が上のレベル を十分励起できるほど高くないため、式 等の評価の精度が悪くなるためである。
η
10
10
10
10
10 Tkin[K] 0 200 400 600 8001000 1200
η
10
10
10
10
10 Tkin[K] 0 200 400 600 8001000 1200
η
10
10
10
10
10 Tkin[K] 0 200 400 600 8001000 1200
1.00 0.50 0.00
(a) (b) (c)
☆agree with numerically evaluated <R43/10>(HCN) within a factor of 2 nave =100[cm-3] nave =1000[cm-3] nave =104[cm-3]
33
✦ examine if <R43/10> in two-phase model can
fit isothermal simulation results
✦
isothermal simulation: line transfer calc. w/ Tkin=const. data [density & vel. same as the
✦ <R43/10> in two-phase model can correctly
derive ξ ⇒two-phase modelling captures the density structure effect \
Tkin=350K 220K 150K 75K 35K 15K
0.0 0.2 0.4 0.6 0.8 1.0 1.2 <I43>/<I10>(sim.) 20 40 60 80 θ(deg)
(a) (b)
0.0 0.2 0.4 0.6 0.8 1.0 <I43>/<I10>(func.) 50 100 150 200 250 300 350 Tkin[K]
face-on edge-on
✦ We examined the emission signatures of very young objects w/ 3D MHD
+nonLTE simulations
✦
magneto-centrifugal force driven flow: rotation of outflows appears as vel. grad./ velocity channel maps
✦
complicated velocity (rot, infall, outflow)
✦ degree of resistivity shifts the launching point of the outflows
✦
“thickness” of the outflows (Rout/Zout) v.s. Rout would be an indicator of eta
✦
..or velocity moment map also helps rather than integrated intensity maps
✦ Opacity of surrounding envelope is quite severe (⇔necessary to examine
the VERY young stage)
✦
high-J lines having high ncrit, or low abundance isotopologue mid-J lines could probe the compact & embedded signatures
✦
e.g., HCO+(7-6) (624GHz), H13CO+/HC18O+ (4-3) (356GHz) are good candidate
✦
ALMA can resolve the structure (at least in nearby low-mass star formation regions)
✦
required observational time - ~8 hours(0.07”) for J=4-3, & ~40 hours for J=7-6 lines 34
✦ サブミリバンドにあるlineを使うべき
✦
非常に若いYPOのemission signatureを3次元MHD/nonLTE計算で調べた
✦
星形成の最初期段階はどう見えるか?
✦
envelopeの光学的厚みを通して見るには、critical densityが高い輝線を使う必要あり
✦
ミリ波ではほぼ無理、サブミリバンドにあるlineを使うべき
✦
HCO+(4-3), SiO(7-6) -> ~350GHz(Band 8) ~10-15hrs
✦
HCO+(7-6) -> ~624GHz(Band 9) ~40hrs
✦
COはisotopeでも freeze-outしていたとしても難しい
✦
vinfall~vrot~voutflow ⇒ 3つのcomponentの切り分けが難しく、irregularな形状になる
✦
現在観測されている双極分子流とは似ても似つかない! [天体同定に注意が必要]
✦
rotation of outflow, ..⇒ a possible evidence for ”disk-wind”-like models for outflow launching mechanism mean vel. map & channel mapに回転がよく現れる
✦
疑似観測simulation: ALMAではtotal power arrayが必須
✦
Future :
✦
boundary condition→envelope would not be negligible
✦
nested grid RT scheme is necessary [Tomisaka, preliminary]
✦
realistic comparison of simulation and observation...
✦
RT simulation data : standard FITS
✦
非常に若いYPOのemission signatureを3次元MHD/nonLTE計算で調べた
✦
星形成の最初期段階はどう見えるか?
✦
envelopeの光学的厚みを通して見るには、critical densityが高い輝線を使う必要あり
✦
ミリ波ではほぼ無理、サブミリバンドにあるlineを使うべき
✦
HCO+(4-3), SiO(7-6) -> ~350GHz(Band 8) ~10-15hrs
✦
HCO+(7-6) -> ~624GHz(Band 9) ~40hrs
✦
COはisotopeでも freeze-outしていたとしても難しい
✦
vinfall~vrot~voutflow ⇒ 3つのcomponentの切り分けが難しく、irregularな形状になる
✦
現在観測されている双極分子流とは似ても似つかない! [天体同定に注意が必要]
✦
rotation of outflow, ..⇒ a possible evidence for ”disk-wind”-like models for outflow launching mechanism mean vel. map & channel mapに回転がよく現れる
✦
疑似観測simulation: ALMAではtotal power arrayが必須
✦
Future :
✦
boundary condition→envelope would not be negligible
✦
nested grid RT scheme is necessary [Tomisaka, preliminary]
✦
realistic comparison of simulation and observation...
✦
RT simulation data : standard FITS
any radio observers can do it!