Poster Abstracts

Name/Affiliation:  A. Uribe, A. Koenigl, T. Matsakos (University of Chicago)

Title:  Simulations of magnetized outflows from close-in gas giant exoplanets

Abstract:
Gas giant exoplanets in close-in orbits are exposed to strong stellar irradiation, leading to a possible photoevaporative outflow from the outer planetary atmosphere. For transiting planets, spectroscopy can probe the planet's atmosphere by measuring the absorption of stellar light during transits. In the case of the exoplanet HD 209458b, the measured Ly-alpha absorption implies velocities as high as ~100 km/s away from line center, which were suggested to correspond to outflowing planetary gas. We present 2.5D magnetohydrodynamic models of the photoevaporative wind from a magnetized hot Jupiter. We study the 2D structure of the outflow from equator to pole and the dependence of the wind properties on the relevant physical parameters, including the irradiating flux and the planet's magnetic field strength and rotation rate, but we neglect the possible influence of a stellar wind. We investigate whether the observed high velocities can in fact originate in a planetary wind and consider other potential observational signatures of the planetary magnetosphere and outflow.