EECep is an unusual long-period (5.6 yr) eclipsing binary discovered during the mid-twentieth century. It undergoes almost-grey eclipses that vary in terms of both depth and duration at different epochs. The observed depths range from about 2m in 1958 to about 0.6m in 1969, and the observed duration vary from about one month for the shortest eclipse in 1992 to maybe even somewhat above 2 months for the longest one observed in 1969.
The light curves of ten among the eleven eclipses of EE Cep observed since 1952 are shown (C.Galan et al. 2014).

The system consists of a Be type star and a dark dusty disk around an invisible companion. EECep together with the widely studied εAur are the only two known cases of long-period eclipsing binaries with a dark, dusty disk component responsible for periodic obscurations.

Two observational campaigns were carried out during the eclipses of EECep in 2003 and 2008/9 to verify whether the eclipsing body in the system is indeed a dark disk and to understand the observed changes in the depths and durations of the eclipses.

These observations confirm that the eclipsing object in EECep system is indeed a dark, dusty disk around a low luminosity object. The primary appears to be a rapidly rotating Be star that is strongly darkened at the equator and brightened at the poles. 

Some of the conclusions from last campaigns require verification in future studies: 
  • a complex, possibly multi-ring structure of the disk in EECep,
  • explanation of the “bump” observed during the last two eclipses in terms of the different times of obscuration of the hot polar regions of the Be star by the disk,
  • suggested period of the disk precession (∼ 11–12 Porb) and predicted depth of about 2. m for the forthcoming eclipse in 2014.

Continuing observational efforts from 2003 and 2008-2009 campaigns we organize a new observational campaign for the next eclipse of EE Cep which take place on August 23, 2014 (according to the ephemeris JD(Min) = 2434344.1 + 2049.94 × E)

If you would like to join the current campaign, please contact Piotr Wychudzki:

Clear Skies, 

Cezary Galan
Nicolaus Copernicus Astronomical Center, Poland