Takeshi Oka Department of Astronomy and Astrophysics And Department of Chemistry The Enrico Fermi Institute, University of Chicago University of Illinois, Nov. 15, 2005 H 3 + 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)

APCB Johannes KeplerGalileo Galilei Isaac Newton 1666

APCB Spectroscopy 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 atoms of the same kind as those on the earth." Feynman Lectures on Physics I, 3-6 (1963)

Astronomy Chemistry Nucleosynthesis Ion chemistry H３＋H３＋ Stars, Galaxies, UniverseAtoms, 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 C 60 H3+H3+

The first spectrum of protonated ion Unidentified Interstellar Microwave Line D. Buhl & L. E. Snyder, Nature 228, 267 (1970) Carrier of the Interstellar GHz Line W. Klemperer, Nature 227, 862 (1970) X-gen HCO +

Salient features of H 3 + Protonated H 2 (P.A.=4.4 eV), simplest polyatomic molecule Equilateral triangle, Infrared active 4μ band Production H 2 → H e H H 2 → H H rate = ζn(H 2 ) DestructionDense cloud H CO → H 2 + HCO + Diffuse cloud H e → H + H + H Simple chemistry n(H 3 + ) constant N(H 3 + ) → L cloud dimension ζ n(H 3 + ) ∽ ζ N(H 3 + ) → ζL ioniozation rate Ubiquity Dense cloud N(H 3 + ) = 3.6 × cm -2 A V Diffuse cloud N(H 3 + ) = 4.4 × cm -2 A V The most abundant molecular ion in the Universe Initiator of interstellar chemistry H O → OH + + H 2 OH + → H 2 O + → H 3 O + → H 2 O

2005 Hot and Diffuse Clouds near GC Probed by Metastable H 3 + Oka, Geballe, Goto, Usuda, McCall, Astro-ph/ – 2002 Ubiquity, Dense and Diffuse Clouds McCall, Geballe, Hinkle, Oka Historical sketch of H 3 + observation Oka, PRL. 45, 531 Laboratory Spectrum1996 Geballe, Oka, Nature 384, 334 Interstellar H 3 +, Discovery H H2H2 H3+H Metastable H 3 +, Discovery Goto, McCall, Geballe, Usuda, Kobayashi, Terada, Oka PASJ, 54,

Dense clouds McCall, Geballe, Hinkle Oka, ApJ 522,338(1999) Diffuse clouds McCall, Hinkle, Geballe, Moriarty-Schieven, Evans, Kawaguchi, Takano, Smith, Oka, ApJ 567, 391 (2002)  Per Surprise!! H 3 + more abundant in diffuse clouds!! N(H 3 + ) ~ 3.6 ×10 12 cm -2 A V N(H 3 + ) ~ 4.4 ×10 13 cm -2 A V

Central Molecular Zone, the treasure house of H 3 + M ~ 5 × 10 7 M ⊙ Dominantly molecular Dense clouds, n(H 2 ) > 10 4 cm -4 Volume filling factor 0.1 Hot gas T ~ 300 K High velocity dispersion Low dust temperature T ~ 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 K 32.9 K 361 K (J, K) The ideal energy levels of H ortho I = 3/2 para 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 N crit ~ 200 cm -3 H H 2 → (H 5 + )* → H H 2

Discovery of metastable H 3 + Goto, McCall, Geballe, Usuda, Kobayashi, Terada, Oka PASJ, 54, 951 (2002) (3, 3) metastable Subaru telescope

(1, 1) ground level CMZ 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 Ring Kaifu, Kato, Iguchi, Nature (1972) Scoville, ApJ (1972) Whiteoak, Gardner, MNRAS (1979)

Dimension or the hot and diffuse clouds ζ L = 2k e N(H 3 + )(n C /n H ) SV R X /f = 3.7 × 10 4 R X /f cm s -1 R X = (n C /n H ) GC /(n C /n H ) 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) × 10 5 cm s -1 If L = 20 pc, ζ = (2 – 6) × 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 clouds Circumstellar Space Planetary nebulae protoplanetary nebulae Planet Planets Proto-planet Exo-planet Treasure hunting

Interstellar H 3 + Cosmic Ray 0.6 primary particles cm -2 s -1 H 2 → H e -  [H 2 ]  ~ 3 × s -1 H2H2 H2H2 e -H H H 2 → H + H 3 + k L [H 2 ] [H 2 + ] H O → OH + + H 2 k L [H 3 + ] [O] OH + → H 2 O + → H 3 O + → H 2 O k L ~ cm 3 s -1 p p C.R.

Discovery of the infrared spectrum of H 3 + T. Oka, Phys. Rev. Lett. 45, 531 (1980) 0 Ortho Para

H 3 + emission from Jupiter Maillard, Drossart, Watson, Kim, Caldwell ApJ 262, L37 (1990) Connerney, Satoh Phil. Trans. R. Soc. Lond. 358, 2359 (2000)