Friday, December 27, 2013

Studying the Mass Loss Rate of Exoplanet HD 209458b

On the sensitivity of extrasolar mass-loss rate ranges: HD 209458b a case study


Villarreal D'Angelo et al


We present a 3D hydrodynamic study of the effects that different stellar wind conditions and planetary wind structures have on the calculated Ly-α absorptions produced during the transit of HD 209458b. Considering a range of stellar wind speeds ∼[350-800] km s−1, coronal temperature ∼[3-7] ×106 K and two values of the polytropic index Γ ∼[1.01-1.13], while keeping fixed the stellar mass loss rate, we found a that a M˙p range between ∼[3-5] ×1010g s−1 give account for the observational absorption in Ly-α measured for the planetary system. Also, several models with anisotropic evaporation profiles for the planetary escaping atmosphere were carried out, showing that both, the escape through polar regions and through the night side yields larger absorptions than an isotropic planetary wind.

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