Surface Density Structure in Outer Region of Protoplanetary Disk Jul. 24th 2014 Nobeyama UM Eiji Akiyama (NAOJ) Munetake Momose, Yoshimi Kitamura, Takashi Tsukagosh, Shota Shimada, Masahiko Hayashi, Shin
Surface Density Structure in Outer Region of Protoplanetary Disk
Jul. 24th 2014 Nobeyama UMEiji Akiyama (NAOJ)
Munetake Momose, Yoshimi Kitamura, Takashi Tsukagosh, Shota Shimada, Masahiko Hayashi, Shin Koyamatsu
Importance of Outer Region of the Disk• How is disk gas cleared ?• How can planets form at a distant from a central star ?
Kalas et al. 2009
Fomalhaut
r = 119 AU
Power Law Disk Model
Power law description in surface density was introduced in the minimum mass solar nebula. (e.g. Kusaka et al. 1970, Weidenschilling 1977, Hayashi et al. 1985)
Discrepancy between Dust & Gas EmissionDiscrepancy in disk size has emerged between the extent of the dust continuum and molecular gas emission. Dust continuum: smaller size Gas emission: larger sizeExamples・ AB Aur (Pietu et al. 2005)
Continuum (2.8, 1.4mm) : 350±30 AU12CO(J=2-1) :
1050±10 AU
・ HD 163296 (Isella et al. 2007)Continuum (0.87-7mm) : 200±15 AU12CO(J=3-2) etc : 540±40 AU
Is the power law description really appropriate ?
Similarity Solution Disk Model Surface density is based on the theory of viscous evolution
(Lynden-Bell & Pringle 1974, Hartmann et al. 1998)
Radial temperature distribution Same as power-law disk model
power-law
similarity
x[AU]
y[A
U]
y[A
U]
x[AU]
log nH2
[1/cc]
Log r [AU]
Log
Σ(r
) [g
cm
-2]
rout
power-law
similarity
distance where Σ(r) starts decreasing exponentially
normalized surface density
C2
Examples of Similarity Solution
velocity [km s-1]
HD163296
R.A.
Dec
.
2 4 6 8 2 4 6 8 2 4 6 8
PowerSimilarity
Hughes et al. 2008
ALMA SVband7
color: CO(3-2)contour: continuum
10 100 1000r [AU]
CO(3-2)continuum
rc = 125 AU
de Gregorio-Monsalvo et al. 2013
10-2
10-3
10-4
10-1
10-1
10-2
10-3
10-0
CO
(3-2) [Jy/beam]
cont
inuu
m [
Jy/b
eam
]
10
8
6
4
2
Vel. [km
/s]
CO(3-2)
2
0
4
6
24
6
offs
et [
arcs
ec]
Gallery of Protoplanetary Disks (Radio)
Andrews et al. 2011 Mathew et al. 2012Brown et al. 2012 Cieza et al. 2012Isella et al. 2010
Object Details
distance [pc] SP type M* [M☉] Mdisk [M☉] inclination [deg.]
140 A2/3 2.3 0.029 38
• MWC 480 is bright Herbig Ae star with primordial disk.• Many people have observed and basic properties are well known.• No complex structures → easy to analyze the structure
Kusakabe et al. 2012 Acke & van den Ancker 2004
No complex structures
log λ[μm]
log
λFλ
[erg
cm
-2s-1
μm
]H-band
Subaru
Observation Details
TelescopeReciever
NRO45, ASTEBEARS, T100H/V, CATS345
Lines 12CO(1-0), 13CO(1-0), C18O(1-0), 12CO(3-2), 13CO(3-2)
Frequency 109 – 115 GHz, 330 – 345 GHz
Spatial res. ~ 15” (~2100 AU), ~ 23”(~3200 AU)
Velocity res. ~ 0.055 – 0.1 km/s
Integ. time 4.2h (2.0h on source)
System temp. 140 -350 K
Model Parameters・ Fixed parameters : The results obtained by other observations applied
・ Free parameters : Best fit parameters are searched
・ X ( 12CO) = 10000 ・ Local Thermal Equilibrium (LTE)
・ X ( 12CO) / X ( 13CO) = 60 ・ Hydrostatic Equilibrium
・ X ( 13CO) / X ( C18O) = 5
・ Outer radius : rout (C2)・ Temperature : T100 ・ Surface density : Σ100
(C1)
distance [pc]
M* [M☉]
inclination [deg.]
p q
HD163296 140 2.3 38 1.0 0.5
Model Fit Results
Similarity solution shows better fit in multi-CO line observation → It supports viscous evolution
Akiyama et al. 2013
Observation Details
Lines 12CO(2-1), 13CO(2-1), C18O(2-1)
Frequency 219 – 230 GHz
Spatial res. ~ 0.68” x ~ 0.55”
FoV ~ 27”
Proj. baseline 16 – 400 m
Velocity res. 0.3 – 0.66 km/s
Integ. time 4.2h (2.0h on source)
System temp. 60 -180 K (0.8mm water vapor)
ALMA SV band 6
Results (ALMA SV band 6)
12CO(2-1)
13CO(2-1)
C18O(2-1)
0th 1st 2nd
Akiyama et al. submitted
Vlsr [km s-1]
Flu
x D
ensi
ty [
Jy]
12CO(2-1) 13CO(2-1) C18O(2-1)
Successful Example of SS Model 2rout = 700AU, p=1.0, θ=45°
T100 [K]
Σ100 [gm s-1] 12CO(J =3-2) 13CO(J =3-2) 12CO(J =1-0) 13CO(J =1-0)
0.001
12CO(J =3-2) 13CO(J =1-0) 13CO(J =3-2)4030
20
100
0
0.15
0.312CO(J =1-0)
1.5
3
0
-100
10
20
30
Tm
b [K
]
3
1.5
0
-1.5
Tm
b [K
]
40
-0.15
0
0.15
0.3
201510
50
-5201510
50
-5-10
0 2 4 6 8 10 12 Vlsr [km s-1]
0 2 4 6 8 10 12 Vlsr [km s-1]
0 2 4 6 8 10 12 Vlsr [km s-1]
0 2 4 6 8 10 12 Vlsr [km s-1]
Summary
1. MWC 480 was selected for its simple disk structure.
2. Similarity solution model is based on the viscous evolution. → Surface density tapers off gradually with distance.
3. Similarity solution reproduces the observation ・ Verified by NRO45/ASTE (single dish) and ALMA SV (interferometry) and data. ・ Similarity solution model is more suitable than power law for describing disks. → The disk evolves via viscous diffusion