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Session 19 - Source Surveys, Galaxy Surveys, Distance Scale II.
Display session, Wednesday, January 07
Exhibit Hall,
During 1996 and 1997 we have obtained 95 nights on the FLWO 1.2-meter telescope and 35 nights on the MDM 1.3-meter telescope to search for detached eclipsing binaries and Cepheids in the M31 and the M33 galaxies. This is a first step in the ongoing program to improve the direct distance estimate to two important galaxies in the cosmological distance ladder -- M31 and M33. Detached eclipsing binaries provide us with the potential to determine these distances with an accuracy better than 5% and possibly to better than 1%. The massive photometry provides us with good light curves for known and new Cepheid variables. These are essential to the parallel project to derive direct Baade-Wesselink distances to Cepheids in M31 and M33. With both Cepheids and eclipsing binaries the distance estimates will be free of any intermediate steps.
We present the lightcurves of the Cepheids found in M31 and M33 and discuss the period-luminosity relations derived in different regions of the disk. We study the effects of differential extinction and metallicity, as well as the distribution of Cepheids in different spiral arms.
The author(s) of this abstract have provided an email address for comments about the abstract: sasselov@cfa.harvard.edu
