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Events in Physics
Title: 290B Seminar    (Seminar)
Start Date: 02/05/2013
Time: 1:00 pm
Location: 325 Old LeConte Hall, Campus
Speaker: Matt Fillingim
Affiliation: SSL/UCB
Contact Person: Chadi Salem


Observations of Ionospheric Currents at Mars"

Abstract:  How the solar wind interacts with a planetary object depends upon the object's properties, such as the presence of a magnetic field or an atmosphere. An unmagnetized object cannot stand-off the solar wind unless it possess a substantial atmosphere. Currents can be induced in the ionosphere which act to cancel out the external solar wind magnetic field preventing it from reaching the surface. Here we present observations of such induced currents in the ionosphere of Mars. During aerobraking maneuvers, Mars Global Surveyor made several passes through the ionosphere in the unmagnetized northern hemisphere. From the observed changes in the local magnetic field, we calculate vertical profiles of (predominantly) horizontal ionospheric currents. Given an atmospheric model, we also calculate the ionospheric conductivity and the ionospheric electric fields associated with these currents. These results can give us insights into how external magnetic fields are effectively screened out by induced currents and how induced magnetospheres form around unmagnetized objects.