# Evaporating planet at KIC 10449976?

## Evaporating planet at KIC 10449976?

An evaporating planet explanation for the photometric variation of the extreme helium subdwarf KIC10449976
http://arxiv.org/abs/1303.0999

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.

I don't really understand why the planet hypothesis is the favoured one. I wouldn't expect a planet at 8.3 AU to reflect that much light.
This will make for an interesting read.

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Sirius_Alpha

Number of posts : 3659
Location : Earth
Registration date : 2008-04-06

## Re: Evaporating planet at KIC 10449976?

Sirius_Alpha wrote:I don't really understand why the planet hypothesis is the favoured one. I wouldn't expect a planet at 8.3 AU to reflect that much light.
It probably wouldn't. Actually they mean an orbital radius of 8.3 solar radii (see equation 2), "AU" looks like a rather consistent typo that is present throughout the paper...

Lazarus
dF star

Number of posts : 2979
Registration date : 2008-06-12

## Re: Evaporating planet at KIC 10449976?

Indeed paper reports an orbital period of 3.9 days. I have some doubts about a "supersonic-spinning" Jovian planet...

Edasich
dM star

Number of posts : 1545
Location : Tau Ceti g - Mid Latitudes
Registration date : 2008-06-02

## Re: Evaporating planet at KIC 10449976?

Revised version of the paper:

Planetary influences on photometric variations of the extreme helium subdwarf KIC10449976
http://arxiv.org/abs/1303.0999v2

Lazarus
dF star

Number of posts : 2979
Registration date : 2008-06-12