Long-term photometric monitoring of the hybrid subdwarf B pulsator HS0702+6043

TL;DR

This study analyzes the long-term pulsation behavior of the hybrid subdwarf B star HS 0702+6043, focusing on its p- and g-mode oscillations, to understand its internal structure and search for planetary companions.

Contribution

First long-term photometric monitoring of HS 0702+6043's p-mode oscillations, including frequency spectrum analysis and O--C diagram construction for evolutionary insights.

Findings

High-resolution frequency spectrum obtained

Constructed multi-season O--C diagram

Detected potential frequency changes over time

Abstract

Pulsating subdwarf B stars oscillate in short-period $p$-modes or long-period $g$-modes. HS 0702 + 6043 is one of currently three objects 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 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.