AAS Meeting #193 - Austin, Texas, January 1999
Session 8. Galactic Morphology and Stellar Populations
Display, Wednesday, January 6, 1999, 9:20am-6:30pm, Exhibit Hall 1

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[8.07] Weighing the Stellar Content of NGC 5907's Dark Matter Halo

M. C. Liu (UC Berkeley), F. R. Marleau (Cambridge), J. R. Graham (UC Berkeley), S. Charlot (IAP/Paris), P. Sackett (Groningen), S. E. Zepf (Yale)

We have obtained deep HST NICMOS images of the edge-on spiral NGC~5907 to determine the composition of its stellar halo. Ground-based observations find very extended faint halo light, which roughly traces the isothermal profile required to reproduce this galaxy's notorious flat rotation curve. For a normal stellar population, we should have resolved many bright giant stars in our images, but we did not. Combined with previous ground-based measurements of the integrated optical/IR color of the halo, these results raise many puzzles about the nature and origin of the faint extended emission. We address the resulting constraints on the stellar metallicity and initial mass function and their implications for the baryon fraction of NGC~5907's dark matter halo.

The author(s) of this abstract have provided an email address for comments about the abstract: mliu@astro.berkeley.edu

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