Observations of the minor species Al and Fe in Mercury's exosphere

A simple model for zenith column abundances of the neutral species yields 1.9−5.2 × 107 Al cm−2, and 8.2 × 108 Fe cm−2. The observations appear to be consistent with production of these species by impact vaporization, with a large fraction of the Al ejecta in molecular form, and that for Fe in mixed atomic and molecular forms. The scale height of the Al gas is consistent with a kinetic temperature of 6100-8000 K. The apparent high temperature and low density of the Al gas would suggest that it may be produced by dissociation of molecules.