High latitude peaks in Mercury's sodium exosphere: Spectral signature using THEMIS solar telescope

We present the first combined intensity and temperature maps of sodium in Mercury's exosphere, made possible by the use of the THEMIS solar telescope on Tenerife in the Canary Islands. The intensity maps clearly show high-latitude peaks, and temperatures inferred from spectral line widths suggest that these regions are either slightly hotter than the rest of the exosphere or much smaller than observed. These brighter, warmer regions are also observed, for the first time, to appear within few Earth hours which strongly suggest that they are produced by solar wind sputtering. This highly capable instrument obtained these data during daylight, highlighting the unique potential for THEMIS to undertake continuous multi-hour and multi-day datasets in conjunction with the MESSENGER mission to Mercury.