AAS 199th meeting, Washington, DC, January 2002
Session 91. Stellar Populations and Galactic Structure
Display, Wednesday, January 9, 2002, 9:20am-6:30pm, Exhibit Hall

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[91.05] The Milky Way: A Significant Asymmetric Distribution of Faint Halo/Thick Disk Stars

J.E. Parker, R.M. Humphreys (University of Minnesota), J.A. Larsen (University of Arizona, Lunar Planetary Laboratory)

We present a star count analysis of the faint stars on either side of the Sun-Center line, from l = ±20 to ±75 and b = +20 to +50 with data from 40 POSS I fields. Larsen and Humphreys [1996] found a significant asymmetry in the number of faint blue stars on either side of the line to the Galactic center with significantly more stars observed in the first quadrant. We sample stars of different color ranges to distinguish between halo/thick disk and old disk stellar populations using a galactic model. Our analysis shows that the observed stellar excess increases with fainter magnitudes and is comprised of mainly halo/thick disk stars. It is possible the excess in star counts could be due to a bar-induced ''wake'', a disk interaction from a merger or that the asymmetry is an indication that the thick disk/inner halo is triaxial. A ''wake'' would suggest that the asymmetry is also present below the plane, so we are investigating 40 additional fields below the galactic plane.


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

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