High Cadence Measurement of Neutral Sodium and Potassium Absorption During the 2009-2011 Eclipse of epsilon Aurigae

Volume 40 number 2 (2012)

Robin Leadbeater: Three Hills Observatory, The Birches, CA7 1JF, UK; address email correspondence to R. Leadbeater at robin@threehillsobservatory.co.uk
Christian Buil: Castanet Tolosan Observatory, 6 Place Clemence Isaure, 31320 Castanet Tolosan, France
Thierry Garrel: Observatoire de Foncaude, Juvignac, France
Stanley A. Gorodenski: 9440 E. Newtown Avenue, Dewey, AZ 86327
Torsten Hansen: Reichau 216, D-87737, Boos, Germany
Lothar Schanne: Observatory for Stellar Spectroscopy Völklingen, Hohlstrasse 19, 66333, Völklingen, Germany
Robert E. Stencel: Department of Physics and Astronomy, University of Denver, 2112 East Wesley Avenue, Denver, CO 80208
Berthold Stober: Nelkenweg 14, 66791 Glan-Münchweiler, Germany
Olivier Thizy: Shelyak Instruments, Les Roussets, 38420 Revel, France

Abstract

The results of a spectroscopic survey of e Aurigae during eclipse using a network of small telescopes are presented. The spectra have a resolution of 0.35 to 0.65Å and cover the period 2008 to 2012 with a typical interval of four days during eclipse. This paper specifically covers variations in the KI 7699Å, Na D, and Mg II 4481Å lines. Absorption started increasing in the KI 7699Å line three months before the eclipse began in optical photometry and had not returned to pre-eclipse levels by the end of the survey in March 2012, seven months after the broadband brightness had returned to normal outside eclipse levels. The contribution of the eclipsing object to the KI 7699Å line has been isolated and shows the excess absorption increasing and decreasing in a series of steps during eclipse ingress and egress. This is interpreted as an indication of structure within the eclipsing object. The F star is totally obscured by the eclipsing object at the Na D wavelength during eclipse. The radial velocity of the F star and the mean and maximum radial velocity of the eclipsing material in front of the F star at any given time have been isolated and tracked throughout the eclipse. The quasi-periodic variations seen in the F star radial velocity (RV) outside eclipse continued during the eclipse. It is hoped that these results can be used to constrain proposed models of the system and its components.