The pulsating sdB+dM binary 2M1938+4603 revisited combining asteroseismology and eclipse timing

We present the analysis of 2M1938+4603 (KIC 9472174), a hot hybrid pulsating subdwarf B (sdB) star with a strong reflection effect. This analysis attempts to combine seismic modeling and investigation of variations in eclipse minima (O-C diagram) of this system, based on the full set (37 months) of available Kepler data. For asteroseismology, we focus on the 22 highest amplitude pulsation modes detected in the 2000-4500 μHz range (mostly p-modes), assuming the sdB star rotation period is locked to the orbital period (tidal synchronization). The seismic modeling provides in particular a constraint on the primary mass. We fit Lorentzian function to the detrended folded Kepler light curve for each individual eclipse to calculate eclipse minimum times, considering primary and secondary minima. We find the O-C curve has cyclic change, which could be explained as light-travel time effect via the presence of a planet with period 418(4) days and minimum mass 2.43 ± 0.073 MJ.We present the analysis of 2M1938+4603 (KIC 9472174), a hot hybrid pulsating subdwarf B (sdB) star with a strong reflection effect. This analysis attempts to combine seismic modeling and investigation of variations in eclipse minima (O-C diagram) of this system, based on the full set (37 months) of available Kepler data. For asteroseismology, we focus on the 22 highest amplitude pulsation modes detected in the 2000-4500 μHz range (mostly p-modes), assuming the sdB star rotation period is locked to the orbital period (tidal synchronization). The seismic modeling provides in particular a constraint on the primary mass. We fit Lorentzian function to the detrended folded Kepler light curve for each individual eclipse to calculate eclipse minimum times, considering primary and secondary minima. We find the O-C curve has cyclic change, which could be explained as light-travel time effect via the presence of a planet with period 418(4) days and minimum mass 2.43 ± 0.073 MJ