The 2003 eclipse of EE Cep is coming

A review of past eclipses

¹ Centre for Astronomy, ul. Gagarina 11, 87-100 Toruń, Poland e-mail: weganin@astri.uni.torun.pl; mamiko@astri.uni.torun.pl
² National Astronomical Observatory Rozeh, Institute of Astronomy, BAS, PO Box 136, 4700 Smolyan, Bulgaria

Corresponding author: D. Graczyk, darek.graczyk@astri.uni.torun.pl

Received: 18 December 2002
Accepted: 17 March 2003

Abstract

EE Cep is an eclipsing binary with a period of 5.6 years. The next eclipse will occur soon, in May–June 2003, and all available past eclipses were collected and briefly analysed. EE Cep shows very large changes of the shape and the depth of minima during different eclipses, however it is possible to single out some persistent features. The analysis suggests that the eclipsing body should be a long object surrounded by an extended semi-transparent envelope. As an explanation, a model of a precessing optically thick disc, inclined to the plane of the binary orbit, is invoked. The changes of its spatial orientation, which is defined by the inclination of the disc and the tilt, induced most probably by precession of the disc spin axis with a period of about 50 years, produce strange photometric behaviour of this star. The Hα emission, and possibly the NaI absorptions, show significant changes during several months outside of the eclipse phase.