Asteroseismology of theCephei starEridani: photometric observations and pulsational frequency analysis

We undertook a multisite photometric campaign for theCephei starEridani. More than 600 hours of differential photoelectric uvyV photometry were obtained with 11 telescopes during 148 clear nights. The frequency analysis of our measurements shows that the variability ofEri can be decomposed into 23 sinusoidal components, eight of which correspond to in- dependent pulsation frequencies between 5-8 cd 1 . Some of these are arranged in multiplets, which suggests rotational m-mode splitting of nonradial pulsation modes as the cause. If so, the rotation period of the star must be between 30 - 60 d. One of the signals in the light curves ofEri has a very low frequency of 0.432 cd 1 . It can be a high-order combination frequency or, more likely, an independent pulsation mode. In the latter caseEri would be both aCephei star and a slowly pulsating B (SPB) star.