03/31/2021
By Ofer Cohen
The Kennedy College of Science, Department of Physics & Applied Physics, invites you to attend a master's thesis defense by Chen Li entitled “Stellar Wind–Magnetosphere Interaction and Ionospheric-Magnetosphere Coupling in Exoplanets.”
The defense will be held on April 19 at 9 a.m. via Zoom. Please contact Ofer Cohen (ofer_cohen@uml.edu) for meeting information if you are interested in attending.
Abstract: The magnetized solar wind carries a magnetic fi eld, Bsw, with a velocity, vsw. In the MHD description, assuming an infinite conductivity, a motional electric field, is introduced in the frame of the planet. The mapping of this electric field along the planetary open field lines introduces a potential across the polar cup, which is known as the cross polar cap potential (CPCP). During geomagnetic storms, the solar wind driver, and in particular, the z component of Bsw increases and so does Esw. As a result, the CPCP increases as well. However, at some point, the CPCP saturates. The solar wind driver and the CPCP response should occur on exoplanets as well. Previous studies have indicated that radio emissions from exoplanets can be strong due to a strong stellar wind-magnetosphere interaction and the power of radio emission is positively related to CPCP. Since the radio emission is the observable signal, a large radio emission, and hence a large CPCP, are expected on exoplanets which are surrounded by extreme stellar wind conditions. However, due to the CPCP saturation effect, the radio emission power may saturate as well, and may not be detectable. This research investigated the behavior of CPCP, as well as current density and Joule Heat, under extreme magnetic field conditions which might be the case of an exoplanet. It aims to find out whether CPCP also saturates under extreme magnetic field conditions and whether the relevant radio emissions are strong enough to be detected.