AAS 207th Meeting, 8-12 January 2006
Session 64 ISM outside the Milky Way
Poster, Tuesday, 9:20am-6:30pm, January 10, 2006, Exhibit Hall

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[64.16] Dust Chemistry in Galactic and Extragalactic Environments

Y. J. Pendleton (NASA Ames Research Center), J. V. Keane (University of Hawaii), H. Spoon (Cornell University), R. Mason (NOAO/CTIO), L. J. Allamandola, A. G. G. M. Tielens (NASA Ames Research Center)

The near and mid-IR spectrum of the IRAS bright galaxy, IRAS 08572 +3915 is dominated by hydrocarbon dust similar in composition to the diffuse ISM in our own galaxy. For the first time, moderately high S/N data with good spectral profile information are provided for the near and mid IR hydrocarbon bands compared towards the same line of sight. Dust composition and powerhouse mechanisms are implicated as a result. The lack of detectable ice suggests the dense cloud fraction in the diffuse to dense ratio for this galaxy is minimal at best. A long standing debate concerning the origin of the energy source in such galaxies has suggested AGN or Starburst activity. The lack of dense clouds, and hence star forming regions, may offer support of an obscured AGN as the energy source in this case. In contrast, the strong crystalline substructure in the deep silicate absorption band may indicate recent Starburst activity. IRAS 08572 is a deeply obscured ultra-luminous infrared galaxy, emitting the bulk of its luminosity in the infrared. As such, it may serve as a beacon for understanding the chemistry in ULIRGs and galaxy mergers in general, and give insight into the relative importance of a combination of central energy sources.

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