Delta Scuti stars in the Praesepe cluster observed by the MOST satellite

摘要

The Praesepe cluster contains a number of Delta Sct and Gamma Dor pulsators.Asteroseismology of cluster stars is simplified by the common distance, age andstellar abundances. Since asteroseismology requires a large number of knownfrequencies, the small pulsation amplitudes of these stars require spacesatellite campaigns. The present study utilizes photometric MOST satellitemeasurements in order to determine the pulsation frequencies of two evolved (EPCnc, BT Cnc) and two main-sequence (BS Cnc, HD 73872) Delta Sct stars in thePraesepe cluster. The frequency analysis of the 2008 and 2009 data detected upto 34 frequencies per star with most amplitudes in the submillimag range. In BSCnc, two modes showed strong amplitude variability between 2008 and 2009. Thefrequencies ranged from 0.76 to 41.7 c/d. After considering the differentevolutionary states and mean stellar densities of these four stars, thedifferences and large ranges in frequency remain.