Excitation and ionization of sodium in meteoroid impacts on the Moon

¹ Department of Physics, University of Parma, Parco Area delle Scienze 7A, 43100 Parma, Italy e-mail: albino@fis.unipr.it
² INAF – Osservatorio Astronomico Padova, Vic. Osservatorio 5, 35122 Padova, Italy e-mail: cremonese@pd.astro.it

Corresponding author: A. Carbognani, albino@fis.unipr.it

Received: 19 April 2002
Accepted: 6 August 2002

Abstract

After a brief historical review about the Moon sodium exosphere and lunar impacts, the attention is focused on the lack of enhancements of the sodium emissions by meteor showers different from Leonids. In order to contribute to the solution of this problem we perform an order-of-magnitude calculation of the physical conditions of sodium atoms during meteoroid impacts. This calculation suggests that the lack of sodium emission enhancements during different meteor showers could be caused by the different ionization degree of the sodium atoms which, in turn, depends on the meteoroid impact velocity.