VARIABILITY INVESTIGATIONS OF POSSIBLE MAIA STARS

Series of spectrograms and a limited number of photometric measurement s of selected early-type stars have been used to search in the measure d radial velocities and light curves for stellar pulsations with times cales of a few hours. For these stars, located in the HR diagram betwe en the beta Cep and the delta Scu stars and designed sometimes as Maia variables, the presence of pulsations is claimed to be a common prope rty. In our sample we found no hints for a general existence of such p ulsations. RV-variations with the expected short-term scale could be o bserved for only two of the program stars, gamma UMi and gamma CrB. Th e variations are highly irregular in amplitude and frequency. On the o ther hand, for both stars a typical mean timescale of the RV-variation of about 2.4 hr has been found which gives some hints to possibly com mon physical causes of short-term variations of stars in this part of the HR diagram. The RV-variation of gamma CrB in the years 1992/93 cou ld be attributed to a rotational splitting of nonradial pulsations.