Effects of Orbital Eccentricity and IMF Cone Angle on the Dimensions of Mercury's Magnetosphere

We investigate the influence of orbital eccentricity and interplanetary magnetic field (IMF) direction on the dimensions of Mercury's magnetosphere using four Earth years of data collected by the MErcury Surface, Space ENvironment, GEochemistry, and Ranging spacecraft. The variations in magneto...

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Bibliographic Details
Published in:The Astrophysical journal 2020-03, Vol.892 (1), p.2
Main Authors: Zhong, J., Shue, J.-H., Wei, Y., Slavin, J. A., Zhang, H., Rong, Z. J., Chai, L. H., Wan, W. X.
Format: Article
Language:English
Subjects:
Aerospace environments
Astrophysics
Compressibility
Earth magnetosphere
Eccentric orbits
Environmental conditions
Geochemistry
Interplanetary magnetic field
Interplanetary magnetic fields
Magnetic fields
Magnetopause
Mapping
Mercury
Mercury (planet)
Mercury surface
MESSENGER Mission
Perihelions
Planetary magnetic fields
Planetary magnetosphere
Planetary magnetospheres
Solar magnetic reconnection
Solar wind
Solar-planetary interactions
Spacecraft
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Summary:We investigate the influence of orbital eccentricity and interplanetary magnetic field (IMF) direction on the dimensions of Mercury's magnetosphere using four Earth years of data collected by the MErcury Surface, Space ENvironment, GEochemistry, and Ranging spacecraft. The variations in magnetopause subsolar distance, flank distance, and tail radius are compared to determine the global dimensions and compressibility of the magnetosphere. As Mercury moves from perihelion (aphelion) to aphelion (perihelion) its magnetosphere expands (contracts) globally by ∼15% on average. After mapping all of the magnetopause crossings to a fixed radial distance from the Sun, we find that IMF cone angle changes lead to reconfigurations of the magnetosphere of comparable magnitude to radial solar distance effects. Furthermore, the magnetosphere is found to expand globally under the quasi-radial IMF, while contracting under the quasi-perpendicular conditions. A new Mercury magnetopause model parameterized by the heliocentric distance and IMF cone angle was constructed. Unlike Earth, the model gives a closed magnetopause for the nightside in most cases, and its flaring decreases with the contraction of the magnetosphere. The results demonstrate the highly variable reconfigurations of Mercury's magnetosphere under its extreme environmental conditions.
ISSN:0004-637X
1538-4357
DOI:10.3847/1538-4357/ab7819