INTERPRETING EPSILON-AURIGAE

The eclipsing binary-epsilon Aurigae consists of an FO supergiant and a cool, mysterious eclipsing companion with an orbital period of 27.1 yr. The light curve of this system reveals tow sources of variability: the eclipses themselves and the variation of the supergiant. Photoelectric observations were made with the 38 cm reflector at the Villanova University Observatory. The bright star undergoes semiregular light variations both inside and outside of eclipse, with a characteristic time scale of a few months which are found to correlate extremely well with changes in color index. It appears that these light and color variations arise from pulsations of the supergiant. The light variations are similar to those found for other luminous A-F supergiants. The leading explanations of the nature of the eclipsing object have been the edge-on disk proposed by Huang and the tilted disk proposed by Wilson. The most recent data show a mid-eclipse brightening that can only be explained by a tilted disk with a central opening and possible transparency changes across the disk. We have developed a computer code to model the eclipse with these constraints, and explore possible configurations of the disk. The properties of the disk appear more consistent with an interpretation as a protoplanetary system than a remnant of mass transfer from the supergiant. This makes the epsilon-Aur an even more interesting system than was previously believed.