EGU23-6215, updated on 14 May 2024
https://doi.org/10.5194/egusphere-egu23-6215
EGU General Assembly 2023
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.

The Yearly Variability of the Sodium Exosphere of Mercury: a Toy Model

Alessandro Mura1, Christina Plainaki2, Anna Milillo1, Valeria Mangano1, Tommaso Alberti1, Stefano Massetti1, Stefano Orsini1, Martina Moroni1, Elisabetta De Angelis1, Rosanna Rispoli1, and Roberto Sordini1
Alessandro Mura et al.
  • 1INAF, IAPS, Rome, Italy (alessandro.mura@inaf.it)
  • 2ASI, Rome, Italy

Observations of the sodium exosphere of Mercury show a peculiar yearly variability, with two intensity maxima at aphelion and perihelion. Here we present an analytical model for the total Na exosphere content, and we compare our results with ground-based observations. The model is able to reproduce the observed data, both in magnitude and in the seasonal variability. The combined effect of the planetary rotation with the modulation of sources and losses magnitude along the orbit, is able to produce a source of Na at dawn, which is needed to explain the observed maximum at aphelion. Also, we demonstrate that a process producing a consistent Na supply rate at the nightside, which can either be plasma or micrometeoroid precipitation, is needed as well. With the help of the model, we also propose a possible explanation for the dusk enhancement of Na that was seen in the MESSENGER data during the inbound leg of Mercury's orbit.

How to cite: Mura, A., Plainaki, C., Milillo, A., Mangano, V., Alberti, T., Massetti, S., Orsini, S., Moroni, M., De Angelis, E., Rispoli, R., and Sordini, R.: The Yearly Variability of the Sodium Exosphere of Mercury: a Toy Model, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6215, https://doi.org/10.5194/egusphere-egu23-6215, 2023.