takeshi oka department of astronomy and astrophysics and department of chemistry the enrico fermi...
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Takeshi OkaDepartment of Astronomy and Astrophysics
And Department of Chemistry
The Enrico Fermi Institute, University of Chicago
University of Illinois, Nov. 15, 2005
H3+ in the Galactic Center;
Unifying Astronomy and Chemistry
Thomas R. Geballe Gemini Observatory Miwa Goto Max-Planck-Institut für Astronomie Tomonori Usuda Subaru Telescope Benjamin J. McCall University of Illinois, Urbana-Champaign
ApJ 632, 882 (2005)
A P C B
Johannes Kepler Galileo Galilei
Isaac Newton 1666
A P C BSpectroscopy
X-ray Crystallography,……
Joseph von Fraunhofer 1787 – 1826
Approximavit Sidera
"The most remarkable discovery in all of astronomy is that the stars are made of atomsof the same kind as those on the earth." Feynman Lectures on Physics I, 3-6 (1963)
Astronomy Chemistry
Nucleosynthesis
Ion chemistry H 3+
Stars, Galaxies, Universe Atoms, Molecules, Matter
H → He → C, N, O, Ne, Mg, Si, S,…..Fe…
Stars ← Molecular Clouds
1975 H–C≡C–C≡C–C≡N H–C≡C–C≡C–C≡C–C≡N H–C≡C–C≡C–C≡C–C≡C–C≡N
C60
H3+
H 2
H 2+
C H 3+
C H 5+
C H 4
C H2 3+
C H2 2
C H3+
C H3 3+
C Hm n
C H+
C H 2+
N H2
+
H C O+
O H+
H O2+
H O3
+H O2
O H
C H C N H2 5
+
C H C N H3
+
C H N H3 2
+
H C N2
+
H C N
C H N H3 2
C H N H2
C H C N3
C H C N2 5
C H
C H C O3
+
C H O H3 2
+
C H C O2
C H O H3
H C OC H O H
C H O C H
2
2 5
3 3
C H2 5
+C H2 4
H C O2 3
+C O3
C H2
H C N3 3
+H C N3
H C N5
H C N7
H C N9
H C N11
C H3
C 4
+
C H4+
C H4 2+
C H4 3+
C H4
C H3 2
cosm ic ray
H 2N 2
C OO
H 2
H 2
e
e
e
ee
e
e
N
N H 3
H C N
C H C N3
e
C O
H O2
C H O H , e3
C
H 2
H 2
H 2
e
e
C H 3
+e
e eH C N
C+
e
C+
H 2
e eC
+
H 2H 2
e
C O
C
H
+
e
e
The first spectrum of protonated ion
Unidentified Interstellar Microwave Line
D. Buhl & L. E. Snyder, Nature 228, 267 (1970)
Carrier of the Interstellar 89.190 GHz Line W. Klemperer, Nature 227, 862 (1970)
X-gen
HCO+
Salient features of H3+
Protonated H2 (P.A.=4.4 eV), simplest polyatomic molecule
Equilateral triangle, Infrared active 4μ band
Production H2 → H2+ + e H2
+ + H2 → H3+ + H rate = ζn(H2)
Destruction Dense cloud H3+ + CO → H2 + HCO+
Diffuse cloud H3+ + e → H + H + H
Simple chemistry
10-9
10-8
10-7
10-6
10-5
10-4
10-3
10-2
10-1
100
101
102
103
104
105
106
n(X
)
10-1
100
101
102
103
104
105
106
n(H)
Dense Clouds Diffuse Clouds
H2
HCO
C+H3
+
n(H3+) constant N(H3
+) → L cloud dimension
ζ
n(H3+) ∽ ζ N(H3
+) → ζL ioniozation rate
Ubiquity Dense cloud N(H3+) = 3.6 × 1012 cm-2 AV
Diffuse cloud N(H3+) = 4.4 × 1013 cm-2 AV
The most abundant molecular ion in the Universe
Initiator of interstellar chemistry H3+ + O → OH+ + H2 OH+ → H2O+ → H3O+ → H2O
2005 Hot and Diffuse Clouds near GC Probed by Metastable H3+
Oka, Geballe, Goto, Usuda, McCall, Astro-ph/0507464
1998 – 2002 Ubiquity, Dense and Diffuse Clouds McCall, Geballe, Hinkle, Oka
Historical sketch of H3+ observation
+
1951
1970
1996
1980 Oka, PRL. 45, 531Laboratory Spectrum
1996Geballe, Oka, Nature 384, 334
Interstellar H3+, Discovery
H
H2
H3+
1989 - 95
2002 Metastable H3+, Discovery
Goto, McCall, Geballe, Usuda, Kobayashi, Terada, Oka PASJ, 54, 951
1975
6
5
4
3
2
1
0
H3+
Col
umn
Den
sity
(10
14cm
-2)
50403020100
E(B-V) (mag)
AFGL2136
W33A
MonR2 IRS 3
AFGL961E
AFGL490
AFGL2591
8
6
4
2
0
H3+
Col
umn
Den
sity
(10
14cm
-2)
6543210
E(B-V) (mag)
OphP Cygni
HD 183143
WR 118
Cyg OB2 12
WR 104
Cyg OB2 5
WR 121
HD 168607
HD 194279
GC IRS 3
2 Ori
HD 20041
Dense clouds
McCall, Geballe, HinkleOka, ApJ 522,338(1999)
Diffuse clouds
McCall, Hinkle, Geballe, Moriarty-Schieven, Evans,Kawaguchi, Takano, Smith, Oka, ApJ 567, 391 (2002)
Per
Surprise!! H3+ more abundant in diffuse clouds!!
N(H3+) ~ 3.6 ×1012 cm-2 AV
N(H3+) ~ 4.4 ×1013 cm-2 AV
Central Molecular Zone, the treasure house of H3+
M ~ 5 ×107 M⊙
Dominantly molecularDense clouds, n(H2) > 104 cm-4
Volume filling factor 0.1Hot gas T ~ 300 KHigh velocity dispersionLow dust temperature T ~ 20-30 K
Mezger, Duschl, Zylka, A&A Rev. (1996)
Morris, Serabyn, ARA&A (1996)
CMZ
Telescopes and spectrometers
UKIRT 3.8 m CGS4 8 km s-1 Mauna Kea
Subaru 8 m IRCS 15 km s-1 Mauna Kea
Gemini South 8 m Phoenix 5 km s-1 Cerro Pachon
Sightlines toward the CMZ
Extraordinary radio emission
• Radio Arc– Arched filaments– Nonthermal filaments
• Sgr A*Yusef-Zadeh, Morris, AJ (1987)
The central 30 pc of the CMZ
Yusef-Zadeh, Morris, AJ (1987)Nagata et al. (1990)Okuda et al. (1990)
The Quituplet
J
K32.9 K
361 K
(J, K)
The ideal energy levels of H3+
+ortho I = 3/2para I = 1/2
(3, 3) metastable level
(1, 1) ground level
Δk = ± 3 forbidden transitions
27.2 days (2, 2) unstable level
Watson, JMS (1971)
(1, 0)
Oka & Epp, ApJ 613, 349 (2004) 0 ±1 ±2 ±3 k
Ncrit ~ 200 cm-3
H3+ + H2 → (H5
+)* → H3+ + H2
Discovery of metastable H3+
Goto, McCall, Geballe, Usuda,Kobayashi, Terada, OkaPASJ, 54, 951 (2002)
(3, 3) metastable
Subaru telescope
(1, 1) ground levelCMZ and spiral arms
(3, 3) metastable level All CMZ
(2, 2) unstable level Neither
CO Mostly spiral arms
High temperature
Low density
The Expanding Molecular RingKaifu, Kato, Iguchi, Nature (1972)Scoville, ApJ (1972)
Whiteoak, Gardner, MNRAS (1979)
Dimension or the hot and diffuse clouds
ζ L = 2keN(H3+)(nC/nH)SVRX/f
= 3.7× 104 RX/f cm s-1
RX = (nC/nH)GC/(nC/nH)SV ~ 3 – 10, f ~ 1
COBE DIRBE Sodroski et al. ApJ 452, 262 (1995) Arimoto, Sofue, Tsujimoto, PASJ 48, 275 (1996)
ζ L = (1 – 4) × 105 cm s-1
If L = 20 pc, ζ = (2 – 6) × 10-15 s-1
Extremely high ionization rate
Liszt, A&A 398, 621 (2003)
Nagata, Hyland, Straw, Sato, Kawara, ApJ 406, 501 (1993)
Interstellar Space
Dense (molecular) clouds
Diffuse clouds New class of clouds?Galactic Center
Expanding molecular ring
Galactic nucleus New class of clouds?Extragalactic Object
Obscured AGN Magellanic cloudsCircumstellar Space
Planetary nebulae protoplanetary nebulaePlanet
Planets Proto-planet Exo-planet
Treasure hunting
Interstellar H3+
Cosmic Ray 0.6 primary particles cm-2s-1
H2 → H2+ + e- [H2] ~ 3 × 10-17
s-1
H2 H2 e
-H -H
H2+ + H2 → H + H3
+ kL [H2] [H2+]
H3+ + O → OH+ + H2 kL [H3
+] [O]
OH+ → H2O+ → H3O+ → H2O
kL~ 10-9 cm3 s-1
p
p
C.R.
Discovery of the infrared spectrum of H3+
T. Oka, Phys. Rev. Lett. 45, 531 (1980)
0
Ortho
ParaPara
H3+ emission from Jupiter
Maillard, Drossart, Watson, Kim, CaldwellApJ 262, L37 (1990)
Connerney, Satoh Phil. Trans. R. Soc. Lond. 358, 2359 (2000)
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