AAS 205th Meeting, 9-13 January 2005
Session 59 ISM: Dust and Molecules
Poster, Tuesday, January 11, 2005, 9:20am-6:30pm, Exhibit Hall

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[59.15] Molecules in Grains (MIGS) as the Source of the Unidentified Infrared Bands (UIRs)

L. S. Bernstein (Spectral Sciences, Inc.), D. K. Lynch (The Aerospace Corporation), A. Berk (Spectral Sciences, Inc.), R. W. Russell (The Aerospace Corporation)

We present a model for interstellar grains that is able to closely reproduce the observed UIR spectral features at 3.3, 6.2, 7.7, 8.6, and 11.3 Ám. The particles consist of highly porous "closed-cell" siliceous or carbonaceous foam that holds and retains molecules of H20, CH4, SiO and SiH4 in its interior. Surface interactions between the trapped molecules and interior grain surfaces result in pressure broadening and frequency shifts. The pressure broadening is sufficiently high to produce smooth spectral contours for the molecular vibration-rotation emission bands. The small grains (20 nm) are heated by absorbing single UV photons. The stability, lifetime, chemistry, composition and formation of MIGs are discussed in the context of astrophysical possibility.

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© 2004. The American Astronomical Society.