Interpreting Epsilon Aurigae

The eclipsing binary Epsilon Aurigae consists of an F0 supergiant and a cool, mysterious eclipsing companion with an orbital period of 27.1 yr. The light curve of this system reveals two 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 the 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. A computer code has been developed to model the eclipse 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.