Fundación Galileo Galilei - INAF Telescopio Nazionale Galileo 28°45'14.4N 17°53'20.6W 2387.2m A.S.L.

Seminars at FGG

Mercury Sodium Exosphere Observations

Speaker: Valeria Mangano (INAF, Instituto di Fisica dello Spazio Interplanetario)

Date and time: 2009-04-20 11:00

A long term plan of observations of the sodium exosphere of Mercury began in 2002 by using the high resolution echelle spectrograph SARG and a devoted sodium filter at the 3.5 m Galileo National Telescope (TNG) located in La Palma, Canary Islands. This program is meant to investigate the variations of the sodium exosphere appearance under different conditions of observations, namely Mercury’s position along its orbit, phase angle and different solar conditions. Here I will report about data taken in June/July 2005, when Mercury’s true anomaly angle (TAA) was in the range 124–130 deg. The spectra show particularly intense sodium lines with a distinctive peak in emission localized in the southern hemisphere at mid-latitudes. This seems to be a persistent feature related to consecutive favorable IMF conditions inducing localized enhancements of surface sodium density.