Intereclipse Spectroscopic Snapshot of epsilon Aurigae with the Hubble Space Telescope

Abstract

A single-epoch low-resolution Goddard High Resolution Spectrograph spectrum of the eclipsing binary epsilon Aurigae was obtained while the secondary was orbiting toward eclipse by the primary. The spectrum as recorded between 1175 and 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^-1, an overlying unresolved absorption component at -20 km s^-1, and a weaker blue emission bump at ~-92 km s^-1. We compare these observational results with known orbital properties of the epsilon 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.