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Session 27 - Variable Stars, Novae, & Supernovae.
Display session, Tuesday, June 10
South Main Hall,

[27.03] New Insight into the Spatial Distribution of Novae in M31

K. Hatano, D. Branch, A. Fisher (U.Oklahoma), S. Starrfield (Arizona.S.U.)

We use a modified version of our Monte Carlo technique (Fisher et al., 1997, MNRAS submitted; Hatano et al., 1997 MNRAS submitted), together with a simple model for the distribution of dust in M31, to investigate the observability and spatial distribution of classical novae in M31. Observed novae within the apparent bulge of M31, which has been well searched for novae, show only a mild top--to--bottom asymmetry in the sense that more novae have been found on the top than on the bottom. If we assume that M31 novae are produced mainly by the bulge population, our model novae show a much stronger top--to--bottom asymmetry, because novae in the bottom of the bulge are obscured by dust in the foreground disk. Therefore, we conclude that most M31 novae come from the disk population, rather than from the bulge population as has been thought. Our results indicate that the M31 bulge--to--disk nova ratio is as low as, or lower than, the M31 bulge--to--disk mass ratio. It is important, now, to search more carefully for novae well out in the disk, where there can be no ambiguity concerning whether the nova comes from the disk or from the bulge.

Program listing for Tuesday