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A transient enhancement of Mercury's exosphere at extremely high altitudes inferred from pickup ions

Jasinski, JM; Regoli, LH; Cassidy, TA; Dewey, RM; Raines, JM; Slavin, JA; Coates, AJ; ... Murphy, N; + view all (2020) A transient enhancement of Mercury's exosphere at extremely high altitudes inferred from pickup ions. Nature Communications , 11 (1) , Article 4350. 10.1038/s41467-020-18220-2. Green open access

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Abstract

Mercury has a global dayside exosphere, with measured densities of 10-2 cm-3 at ~1500 km. Here we report on the inferred enhancement of neutral densities (<102 cm-3) at high altitudes (~5300 km) by the MESSENGER spacecraft. Such high-altitude densities cannot be accounted for by the typical exosphere. This event was observed by the Fast-Imaging Plasma Spectrometer (FIPS), which detected heavy ions of planetary origin that were recently ionized, and "picked up" by the solar wind. We estimate that the neutral density required to produce the observed pickup ion fluxes is similar to typical exospheric densities found at ~700 km altitudes. We suggest that this event was most likely caused by a meteroid impact. Understanding meteoroid impacts is critical to understanding the source processes of the exosphere at Mercury, and the use of plasma spectrometers will be crucial for future observations with the Bepi-Colombo mission.

Type: Article
Title: A transient enhancement of Mercury's exosphere at extremely high altitudes inferred from pickup ions
Location: England
Open access status: An open access version is available from UCL Discovery
DOI: 10.1038/s41467-020-18220-2
Publisher version: https://doi.org/10.1038/s41467-020-18220-2
Language: English
Additional information: This work is licensed under a Creative Commons Attribution 4.0 International License. The images or other third party material in this article are included in the Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder to reproduce the material. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/
Keywords: Asteroids, comets and Kuiper belt, Atmospheric dynamics, Inner planets, Magnetospheric physics
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Space and Climate Physics
URI: https://discovery.ucl.ac.uk/id/eprint/10111712
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