Binary Star Differential Photometry Using the Adaptive Optics System at Mount Wilson Observatory

We present photometric and astrometric results for 36 binary systems observed with the natural guide star adaptive optics system of the Mount Wilson Institute on the 100 inch (2.5 m) Hooker Telescope. The measurements consist of diÜerential photometry in U, B, V , R, and I —lters along with astrometry of the relative positions of system components. Magnitude diÜerences were combined with absolute photometry found in the literature of the combined light for systems to obtain apparent magnitudes for the individual components at standard bandpasses, which in turn led to color determinations and spec- tral types. The combination of these results with Hipparcos parallax measurements yielded absolute mag- nitudes and allowed us to plot the components on an H-R diagram. To further examine the reliability and self-consistency of these data, we also estimated system masses from the spectral types.