Wednesday, March 6, 2013

1303.0999 (Ealeal Bear et al.)

An evaporating planet explanation for the photometric variation of the extreme helium subdwarf KIC10449976    [PDF]

Ealeal Bear, Noam Soker
We propose that the unstable periodic variation of the extreme helium hot subdwarf star KIC10449976 is caused by the stochastic evaporation process of a planet orbiting the star with a period of 3.9 days. KIC10449976 shows evidence for photometric periodic modulation of P=3.9days. The period is not stable, neither in time nor in amplitude. In our model the UV radiation from KIC10449976, whose effective temperature is T_eff = 40000 K, heats the planet and causes its envelope to swell and lose mass where dust might be formed. The estimated mass outflow rate is 10^{-9} M_J yr^{-1}. Stochastic variations in the outflow rate and in dust formation rate lead to the variation in the amount of reflected light, hence to the unstable periodic behavior. Self-shielding of the dust and the behavior on the day-night boundary might lead to the stochastic outflow rate. We predict the presence of a sub-stellar companion to KIC10449976 with a mass of M_J < m_p < 20 M_J at an orbital separation of a_p=8.3AU.
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