Abstract: Mercury is the planet closest to the Sun, which possesses a global intrinsic magnetic field that interacts with the solar wind to form a small magnetosphere. Unlike other planets in the solar system, Mercury lacks a significant atmosphere; instead, it has a surface-bounded exosphere. In this presentation, I will introduce our recent investigations of the escape of the most abundant heavy ions at Mercury, specifically the Na+-group ions, using MESSENGER’s measurements. Our findings show that the escape rates of the Na+-group ions are dependent on Mercury’s orbital phase around the Sun, exhibiting a seasonal effect with rates from 0.2 to 1 × 1025 atoms/s. This rate is comparable to the ion’s escape rates at other inner planets. We propose that this can be attributed to several processes such as efficient photoionization, solar wind sputtering, and solar wind momentum exchange at Mercury, and the Na+-group ions include several ion species such as Na+, aluminum ion (Al+), silicon ion (Si+) and magnesium ion (Mg+) etc. Additionally, we will also show our studies of solar wind-magnetosphere-surface coupling and how the magnetospheric dynamics influence the planetary ions during the flux transfer event “shower” intervals.
References:
https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2023GL107689
https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2022JA030280
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