Identifying modes in KIC 5807616, a Pulsating sdB Star from Kepler Field

Abstract

KIC 5807616 is a pulsating B-type hot subdwarf, reported to harbor planets. Its Kepler spacecraft Q 2 and Q 5 -Q 8 light curves as well as spectroscopic data were already analyzed and parameters characterizing the star were derived. Since then, Kepler had collected 2 years of additional data (Q 9 -Q 16 and half of Q 17). One might think new data could improve previously derived parameters, but it doesn’t seem to be that easy. It appears that the Fourier transform amplitude spectra of the KIC 5807616 data do not show ”clear” multiplets. Therefore, in this work we performed the mode identification based mainly on the period spacing of g-modes, while the analysis of multiplet splitting relied on two p-modes with stable multiplet components. We also derived the rotational period of the star and analyzed the low frequency region of the FT, where signatures of two planets were found in the past, but we had difficulties confirming their existence.