Planetary influences on photometric variation of the extreme helium subdwarf KIC10449976

Abstract

We propose that the unstable 3.9days photometric periodicity of the hot subdwarf (sdO) KIC10449976 results from a tidally locked planet that is heated to 5000K by the UV radiation from the hot sdO star. Although the bolometric radiation from the planet is very small relative to that of the star, in the visible band the planet contributes 0.07% of the light, sufficient to explain the observed periodic behavior. In our proposed scenario the stochastic variations in period and light amplitude are attributed to weather on the planet. Namely, streams on the surface and thermal variations in the planet's atmosphere that are driven by the heating and by the planet rotation lead to stochastic changes in the amount of radiation emitted by the planets. We predict that a careful monitoring will reveal a gas giant planet at an orbital separation of 8.3Rsun from KIC10449976.