Three-dimensional Hydrodynamical Simulation of the Exoplanet HD 209458b

SCHNEITER, E. MATIAS; VELÁZQUEZ, PABLO F.; ESQUIVEL, ALEJANDRO; RAGA, ALEJANDRO C.; BLANCO-CANO, XÓCHITL

ASTROPHYSICAL JOURNAL

Año: 2007 vol. 671 p. 57 - 57

0004-637X

D 209458b is a Jovian planet orbiting around a star with characteristics similar to the Sun, which has repeated transits across the stellar disk. The orbital period is of 3.5 days, with a mean distance to the star of 0.045 AU. The peculiar characteristic of this system is that the planet shows a larger apparent size when observed in Lyα (1214-1217 Å) than at optical wavelengths. This discrepancy is thought to be due to the existence of an extended upper atmosphere and/or a cometary wake. In this work we present 3D numerical simulations of this system, and study the absorption produced by the extended atmosphere. This ``exosphere´´ is modeled as a wind outflowing from the planet at the escape velocity (60 km s-1), which interacts with the stellar wind. Four runs where carried out with planetary mass loss rates in the 1.5 × 10-17 to 1.5 × 10-14 Msolar yr-1 range. By comparing the Lyα absorption predicted from