Inter-Eclipse Spectroscopic Snapshot of Epsilon Aurigae with HST

A single-epoch low resolution GHRS spectrum of the eclipsing binary Epsilon Aurigae was obtained while the secondary was orbiting towards eclipse by the primary. The spectrum as recorded between 1175—1461 Å is rich with emission and absorption lines which include stellar and interstellar components. The emission line profiles have the appearance of double-peaked emission with a stronger red component at a radial velocity of +108 km s, an overlying unresolved absorption component at −20 km s and a weaker blue emission bump at ca. −92 km s. We compare these observational results with known orbital properties of the ǫ Aur binary system, and propose that the emission originates at the inner radius of the disk surrounding the enigmatic secondary. We interpret the kinematic data as a possible means to uncover the underlying stellar masses and we speculate about the binary’s relationship to other “high-mass” models. Subject headings: binaries: eclipsing — line: profiles — stars: individual (ǫ Aur) — techniques: radial velocities — ultraviolet emission