Characterizing Mars' magnetotail topology with respect to the upstream
interplanetary magnetic fields
Abstract
The canonical picture of the magnetotail of unmagnetized planets
consists of draped interplanetary magnetic fields (IMF) forming
opposite-directed lobes, separated by the current sheet.
\citet{DiBraccio2018twisted} showed that Mars’
magnetotail has a twist departing from this picture. Magnetohydrodynamic
(MHD) results suggest that open field lines connected to the planet that
populate portions of the tail cause the apparent twist. To validate this
interpretation, we compare the tail topology determined from MHD
simulations to that inferred from data collected by the Mars Atmosphere
and Volatile EvolutioN (MAVEN) spacecraft, in particular how each
topology responds to the upstream IMF orientation. The occurrence rates
for open topology from both data and MHD varies with IMF polarities in a
similar fashion as the tail twisting. This suggests that Mars’ crustal
fields have a global effect on the magnetosphere configuration,
supporting the picture of a “hybrid” magnetotail that is partly
induced/draped and partly intrinsic/planetary in origin.