Dissemin is shutting down on January 1st, 2025

Published in

American Geophysical Union, Geophysical Research Letters, 13(51), 2024

DOI: 10.1029/2023gl107689

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MESSENGER Observations of Mercury's Planetary Ion Escape Rates and Their Dependence on True Anomaly Angle

This paper was not found in any repository, but could be made available legally by the author.
This paper was not found in any repository, but could be made available legally by the author.

Full text: Unavailable

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Preprint: archiving allowed
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Postprint: archiving allowed
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Published version: archiving restricted
Data provided by SHERPA/RoMEO

Abstract

AbstractThis study investigates the escape of Mercury's sodium‐group ions (Na+‐group, including ions with m/q from 21 to 30 amu/e) and their dependence on true anomaly angle (TAA), that is, Mercury's orbital phase around the Sun, using measurements from MESSENGER. The measurements are categorized into solar wind, magnetosheath, and magnetosphere, and further divided into four TAA intervals. Na+‐group ions form escape plumes in the solar wind and magnetosheath, with higher fluxes along the solar wind's motional electric field. The total escape rates vary from 0.2 to 1 × 1025 atoms/s with the magnetosheath being the main escaping region. These rates exhibit a TAA dependence, peaking near the perihelion and similar during Mercury's remaining orbit. Despite Mercury's tenuous exosphere, Na+‐group ions escape rate is comparable to other inner planets. This can be attributed to several processes, including that Na+‐group ions may include several ion species, efficient photoionization frequency for elements within Na‐group, etc.