First observations of the Na exosphere of Mercury with the high-resolution spectrograph of the 3.5M Telescopio Nazionale Galileo |
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Authors: | Cesare Barbieri Stefano Verani Ann Sprague Rosario Cosentino |
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Affiliation: | a Department of Astronomy, University of Padova, I-35122 Padova, Italy b Astronomical Observatory of Padova, INAF, Italy c Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721, USA d Center for Space Physics, Boston University, MA 02215, USA e Telescopio Nazionale Galileo, INAF, Italy |
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Abstract: | Analysis of three spectra of the exosphere of Mercury in the Na-D lines are presented. Spectra were secured with the high-resolution spectrograph (SARG) of the 3.5 M Telescopio Nazionale Galileo (TNG, located on the Roque de los Muchachos, Canaries) on the evenings of August 23 and 24, 2002. Spectra have resolution ; the slit length was 26.7”. The Na column abundances range from 4.3 to with the highest abundances being close to the illuminated limb. Our observations at true anomaly angles (TAA) from 171°to 174°show the traces of the emission lines to be strongly peaked at the illuminated limb, supportive of recent modeling that shows thermal desorption to be a strong factor in determining the distribution of Na about the planet. |
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Keywords: | Mercury Planetary exospheres Na emission atmospheres High-resolution planetary spectroscopy |
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