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The Non-Thermal Rotational
Distribution of Interstellar H3+
(ApJ, in press )
Takeshi Oka and Erik Epp,
Department of Astronomy and Astrophysics,
and Department of Chemistry,
The Enrico Fermi Institute,
The University of Chicago
59th Ohio State University In ternational Symposium on Molecular Spectroscopy, RI 05, 2:51 pm, June 24, 2004
8
6
4
2
0
N(H
3+)
in 1
01
4 cm
-2
16012080400Av
151050Av
8
6
4
2
0
Dense Clouds Diffuse Clouds
Diffuse CloudsGC
Dense cloudsMcCall, Geballe, HinkleOka, ApJ 522,338(1999)
Diffuse cloudsMcCall, Hinkle, Geballe, Moriarty-Schieven, Evans, Kawaguchi, Takano, Smith, Oka, ApJ 567, 391 (2002)
W33A
AFGL2136
AFGL 2591
AFGL 490
AFGL 961EMonR2 IRS3
Cygnus OB2 #12
WR 118
# 5WR 104
WR 121
HD 20041
183143
Ζ Per
Ubiquitous H3+
Dense Clouds
Diffuse Clouds
GC
Galactic plane
Quintuplet
H3+ toward the Galactic center
N(H3+) = 17.5(3.9) × 1014 cm-2 GC IRS 3
27.7(2.4) 1014 cm-2 GCS 3-2
Geballe, McCall, Hinkle, Oka, ApJ 510, 251 (1999)
GC IRS 3
Δk = 3 Forbidden Rotational Transitions in H3+
Interstellar NH3 Oka, Shimizu, Shimizu, Watson, ApJ 165, L15 (1971)
Interstellar H3+ Pan, Oka, ApJ 305, 518 (1986)
Theory H3+ Neale, Miller, Tennyson, ApJ 335, 486 (1988)
Metastable
27.2 days
20.4 days
μ
Critical Density
200 cm-3
R(3, 3)l
R(2, 2)l
(3, 3)
(2, 2)
Very Non-thermal
Radiation Collision Reaction
Rigorous Selection Rules Approximate Rules Random
+ - ΔJ = ± 1, 0
ortho para ΔI = 0 ortho para ΔI = 0 ΔItotal = 0
A
A
B
B
C
A
D
B
Ψ’
ψ
Trad 3 K « Tkin
Rate Equations
1' ' ' '2
' '
( ) exp( )2
J K JK JK J KJK JK
J K
g E Ek C
g kT
2
' '' '
' '
' '' '
' '
( )( ) ( )
( ' ') ( )
( ' ') ( )
( ) ( ) ( ) ( )
J K JKJK J K
J K
J K JKJK J K
J K
e XX
dn JKn H f JK
dt
A n J K A n JK
k n J K k n JK
k n e n JK k n X n JK
Production
Spontaneous emission 4 10-7 s-
1
Collision n(H2) 100 cm-3 10-7 s-1
Destruction 10-9 s-1
10-17 s-1
10-7 cm3 s-1 10-9 cm3 s-1
' '' '
' ' ' '
exp( )J KJK JK JK J KJKJ K J K
k g E E
k g kT
H3+ + H2 (H5
+)* H3+ + H2
Detailed balance
Cosmic ray ionization
Dissociative recombination Proton hop reaction
0 =
Steady State
n(3,3)/n(1,1)
n(3,3)/n(2,2)
Tex from n(1,0)/n(1,1)
Ortho-H3+
Para-H3+
Para-H3+
Para-H3+
T(H2) = 10 K
T(H2) = 60 K
032.86 K
151.33 K
249.26 K
Gemini South
Quasi-metastable
11.4 years
Summary
Metastable level (3, 3) populated
Unstable levels (2, 2) and (2, 1) unpopulated
Spontaneous emission, chemical collision
High Temperature (T> 200 K)
Low density (n< 100 cm-3)
Other metastable levels (4, 4), (5, 5), (6, 6)
More observations of unstable levels