Photometric and Spectroscopic Monitoring of the SDBV Star PG 1605+072:

Abstract

A small fraction of sdB stars show short-period, multiperiodic light variations and form the new class of pulsating star known as EC 14026 variables, after the prototype, or, alternately, as sdBV stars. Until recently, time-series observations of pulsating sdB stars have been limited to photometry (for a review see Charpinet et al., 2001). While emphasizing the great potential of asteroseismology with sdB variables (sdBV), Charpinet et al. also clearly demonstrate that the difficult process of mode identification, necessarily required for an asteroseismological study, is even more complicated for sdBV stars than for objects such as pulsating white dwarfs. While the latter tend to show a nearly equidistant mode pattern for consecutive overtones, no such relation is evident for sdBV stars. Consequently, observational methods beyond photometry alone are needed to further progress the interpretation of the sdBVs’ pulsational behaviour.