Long-term photometric monitoring of the hybrid subdwarf B pulsator HS 0702+6043

摘要

Pulsating subdwarf B stars oscillate in short-period p-modes or long-period g-modes. HS 0702 +6043 is one of the three objects currently known to show characteristics of both types and hence is classified as hybrid pulsator. We briefly present our analysis of the g-mode domain of this star, but focus on the first results from long-term photometric monitoring in particular of the p-mode oscillations. We present a high-resolution frequency spectrum, and report on our efforts to construct a multi-season O C diagram. Additionally to the standard (although nontrivial) exercise in asteroseismology to probe the instantaneous inner structure of a star, measured changes in the pulsation frequencies as derived from an O C diagram can be compared to theoretical evolutionary timescales. Within the EXOTIME program, we also use this same data to search for planetary companions around extreme horizontal branch objects (``asteroseismic planets``).