Volume 573, January 2015
|Number of page(s)||4|
|Section||Planets and planetary systems|
|Published online||08 December 2014|
The Mg i line: a new probe of the atmospheres of evaporating exoplanets
CNRS, UMR 7095, Institut d’astrophysique de Paris,
98bis boulevard Arago,
2 UPMC Univ. Paris 6, UMR 7095, Institut d’Astrophysique de Paris, 98bis boulevard Arago, 75014 Paris, France
3 Observatoire de l’Université de Genève, 51 chemin des Maillettes, 1290 Sauverny, Switzerland
Received: 17 December 2013
Accepted: 22 October 2014
Transit observations of HD 209458b in the UV revealed signatures of neutral magnesium escaping the planet’s upper atmosphere. The absorption detected in the Mg i line provides unprecedented information on the physical conditions at the altitude where the atmospheric blow-off takes place. Here we use a 3D model of atmospheric escape to estimate the transit absorption signatures in the Mg i line of their host stars. The detectability of these signatures depends on the brightness of the star and the escape rate of neutral magnesium. We identify a sample of potentially evaporating exoplanets that covers a wide range of stellar and planetary properties, and whose extended exospheres might be detected through Mg i line observations with current UV facilities, allowing further steps in comparative exoplanetology.
Key words: surveys / planets and satellites: atmospheres / methods: numerical
© ESO, 2014
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