Epsilon Aurigae Hydrogen Alpha Emission Line Variation: The Horn Dance (Abstract)

Volume 37 number 2 (2009)

Jeffrey L. Hopkins

Robert E. Stencel

Abstract

(Abstract only) The Hopkins Phoenix Observatory has been doing high resolution spectroscopy on the 3rd magnitude long period (27.1 year) eclipsing binary star system epsilon Aurigae since August 2008 using a Lhires III spectrograph with a 2,400 line/mm grating mounted on a 12-inch Meade LX200 GPS telescope. Observations have been in both the sodium D-line region of the spectrum and with near continuous observations of the hydrogen alpha region. The out-of-eclipse hydrogen alpha spectrum shows significant night-to-night variation. While many star systems exhibit a strong hydrogen alpha absorption line, like Be stars, epsilon Aurigae also shows strong blue and red shifted emission components sometimes called wings or horns bracketing the absorption line. Unlike the Be stars, in which the blue and red horns remain relatively constant, the hydrogen alpha horns of epsilon Aurigae seem to be in a wild dance with continuous motion up and down. This paper will discuss techniques and results of recent out-of-eclipse high-resolution spectroscopy of epsilon Aurigae.