Institute for Advanced Study Informal Astrophysics Seminar

Exoplanets orbiting close to their parent star are bombarded by intense radiation which heats and ionizes the upper atmosphere. This is thought to create an extended atmosphere of gas which may be probed spectroscopically during transits of the host star. At the high altitudes where atomic resonance lines are absorbed, many interesting effects due to the intrinsic planetary magnetic field, stellar tides, and interaction with the stellar wind and high energy radiation may have an important impact on gas flow in the atmosphere, and also mass loss from the planet. In this talk I'll discuss theoretical models for the upper atmosphere including these effects, and their possible imprint on the transit spectrum.