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Session 19 - Source Surveys, Galaxy Surveys, Distance Scale II.
Display session, Wednesday, January 07
Exhibit Hall,

[19.11] Removing the Influence of Companion Stars on Extragalactic Cepheid Distance Measurements

B. J. Rebel (Grinnell College), M. Krockenberger, N. Evans (SAO)

A method of correcting the light curves of extragalactic Cepheids for contamination from companion stars is described. The method uses a nonlinear fitting routine to find the Cepheid's amplitude and mean magnitude in the V and I filters, as well as the companion's magnitude in those bands. Both true binary companions and line of sight companions can be detected. The method was applied to a sample of Cepheids in M31, to find the true distance modulus to these stars, and the galaxy. The corrected modulus to M31 increases the distance to the galaxy, but does not show the dependence on the period of the Cepheids of previous measurements.

Program listing for Wednesday