Resolving the pulsations of subdwarf B stars: HS 0039+4302, HS 0444+0458 and an examination of the group properties of resolved pulsators

ABSTRACT We continue our program of single-site observations of pulsating subdwarf B (sdB)stars and present the results of extensive time series photometry of HS 0039+4302and HS 0444+0458. Both were observed at MDM Observatory during the fall of2005. We extend the number of known frequencies for HS 0039+4302 from 4 to14 and discover one additional frequency for HS 0444+0458, bringing the total tothree. We perform standard tests to search for multiplet structure, measure amplitudevariations, and examine the frequency density to constrain the mode degree l.Includingthe two stars in this paper,23 pulsatingsdB stars have receivedfollow-up observations designed to decipher their pulsation spectra. It is worth an examina-tion of what has been detected. We compare and contrast the frequency content interms of richness and range and the amplitudes with regards to variability and diver-sity. We use this informationto examine observationalcorrelationswith the proposedκ pulsation mechanism as well as alternative theories.Key words:Stars: oscillations–stars: variables–stars: individual (HS 0039+4302,HS 0444+0857)– Stars: subdwarfs