Meteoroid bombardment as a source of the exosphere of Mercury

Meteoroid impacts lead to the appearance of metal atoms as well as metal oxides and hydroxides in the Hermean exosphere. The abundances of the main Na-, K-, Ca-, Fe-, Al-, Mg-, and Mn-containing species delivered to the exosphere of Mercury by impacts were estimated. Impacts can be considered as a main source of Fe, Mg, and Mn atoms in the Hermean exosphere. Meteoroid impacts lead to the formation of hot metal atoms (0.2-0.4 eV) produced directly during impacts. Photolysis of metal oxides and hydroxides gives an additional energy to metal atoms in the Hermean exosphere. Na, K, Mn, and Fe atoms are delivered to the exosphere directly by impacts while Ca, Al, Mg, and O atoms are produced in the exosphere mainly by photolysis of oxides and hydroxides. Condensation of dust grains can significantly reduce the content of atoms of several elements such as Ca, Mg, Al, Fe, O in the exosphere