Modeling the Influence of Intrinsic Dipole Field Strength and Interplanetary Magnetic Field Orientation on Ion Escape from Weakly Magnetized Planets

Cessna, Julianna

Undergraduate Honors Thesis

Modeling the Influence of Intrinsic Dipole Field Strength and Interplanetary Magnetic Field Orientation on Ion Escape from Weakly Magnetized Planets Public Deposited

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Citeable URL: https://scholar.colorado.edu/concern/undergraduate_honors_theses/dn39x298q

Abstract

For a planet to be deemed habitable, it must have a substantial atmosphere. Planetary and stellar properties are common drivers for atmospheric loss in planets. A planetary property whose role in atmospheric loss has been called into question is the presence and strength of a planet's dipole magnetic field. A stellar property that interacts directly with this planetary property is the magnetic field that is embedded in the solar wind, called the interplanetary magnetic field (IMF). The orientation of the IMF (clock angle and cone angle) relative to the dipole field influences magnetospheric configuration and the importance of kinetic effects within the plasma. The interaction between the two fields determine the trajectories of atmospheric particles near the planet, thereby affecting atmospheric loss.

In this project, we use a global hybrid plasma model to simulate atmospheric ion loss from a Mars-like planet while changing the surrounding magnetic environment. We begin with a 'base case' of a magnetized planet with an IMF orientation that is perpendicular to the dipole field axis. The clock angle and cone angle of the base case are varied independently to determine the IMF orientation influence on ion escape. Then, the intrinsic dipole field strength of the planet is varied from nonmagnetized to magnetized to determine its dependence on ion loss through all explored IMF orientations. We find that the weakly magnetized planet is most influenced by IMF clock angle and the nonmagnetized and magnetized planets are most influenced by IMF cone angle.

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