Resolving the pulsations of the subdwarf B star KPD 2109+4401

Abstract

We present the results of extensive time series photometry of the pulsating subdwarf B star KPD 2109+4401. Our data set consists of 29 data runs with a total length of 182.6 hours over 31 days, collected at five observatories in 2004. These data are comprised of high signal-to-noise observations acquired with larger telescopes and wider time coverage observations obtained with smaller telescopes. They are sufficient to resolve the pulsation structure to 0.4 $\mu$Hz and are the most extensive data set for this star to date. With these data, we identify eight pulsation frequencies extending from 4701 to 5481 $\mu$Hz, corresponding to periods of 182 to 213 s. The pulsation frequencies and their amplitudes are examined over several time-scales with some frequencies showing amplitude variability.