Multiperiodicities from the Hipparcos epoch photometry and possible pulsation in early A-type stars

A selection criterion based on the relative strength of the largest peaks i n the amplitude spectra, and an information criterion are used in combinati on to search for multiperiodicities in Hipparcos epoch photometry. The meth od is applied to all stars which have been classified as variable in the Hi pparcos catalogue: periodic, unsolved and microvariables. Results are asses sed critically: although there are many problems arising from aliasing, the re are also a number of interesting frequency combinations which deserve fu rther investigation. One such result is the possible occurrence of multiple periods of the order of a day in a few early A-type stars. The Hipparcos c atalogue also contains a number of these stars with single periodicities: s uch stars with no obvious variability classifications are listed, and infor mation about their properties (e.g., radial velocity variations) discussed. These stars may constitute a new class of pulsators.