UV transit observations of EUV-heated expanded thermospheres of Earth-like exoplanets around M-stars: testing atmosphere evolution scenarios
Authors: Lammer, H.1; Eybl, V.2; Kislyakova, K.3; Weingrill, J.4; Holmström, M.5; Khodachenko, M.4; Kulikov, Yu.6; Reiners, A.7; Leitzinger, M.8; Odert, P.8; Xiang Grüß, M.9; Dorner, B.10; Güdel, M.2; Hanslmeier, A.8
Source: Astrophysics and Space Science, Volume 335, Number 1, September 2011 , pp. 39-50(12)
Abstract:The detection and investigation of EUV heated, extended and non-hydrostatic upper atmospheres around terrestrial exoplanets would provide important insights into the interaction of the host stars plasma environment as well as the evolution of Earth-type planets their atmospheres and possible magnetic environments. We discuss different scenarios where one can expect that Earth-like planets should experience non-hydrostatic upper atmosphere conditions so that dynamically outward flowing neutral atoms can interact with the stellar plasma flow so that huge hydrogen coronae and energetic neutral atoms (ENA) can be produced via charge exchange. By observing the size of the extended upper atmospheres and related ENA-clouds and by determining the velocities of the surrounding hydrogen atoms, conclusions can be drawn in respect to the origin of these features. Due to the large number of M-type stars in our neighbourhood and their long periods of strong and moderate stellar activity in comparison to G-stars, we expect that M-type stars represent the most promising candidates for the detection of hydrogen ENA-clouds and the subsequent study of the interaction between the host star and the planets’ upper atmosphere. We show that the low mass of M-type stars also makes them preferable targets to observe extended hydrogen clouds around terrestrial exoplanets with a mass as low as one Earth mass. Transit follow-up observations in the UV-range of terrestrial exoplanets around M-type stars with space observatories such as the World Space Observatory-UV (WSO-UV) would provide a unique opportunity to shed more light on the early evolution of Earth-like planets, including those of our own Solar System.
Document Type: Research Article
Affiliations: 1: Space Research Institute, Austrian Academy of Sciences, Schmiedlstr. 6, 8042, Graz, Austria, Email: email@example.com 2: Institute for Astronomy, University of Vienna, Türkenschanzstr. 17, 1180, Vienna, Austria 3: N. I. Lobachevsky State University, University of Nizhnij Novgorod, 23 Prospekt Gagarina, 603950, Nizhnij Novgorod, Russia 4: Space Research Institute, Austrian Academy of Sciences, Schmiedlstr. 6, 8042, Graz, Austria 5: Swedish Institute of Space Physics, Box 812, 98128, Kiruna, Sweden 6: Polar Geophysical Institute, Russian Academy of Sciences, Khalturina Str. 15, Murmansk, 183010, Russia 7: Institut für Astrophysik, Universität Göttingen, Friedrich-Hund-Platz 1, 37077, Göttingen, Germany 8: Institut für Physik/IGAM, Universität Graz, Universitätsplatz 5, 8010, Graz, Austria 9: Institut für Theoretische Physik und Astrophysik, Christian-Albrechts-Universität zu Kiel, 24118, Kiel, Germany 10: Centre de Recherche Astrophysique de Lyon, Université Lyon 1, 9 Avenue Charles André, 69561, Saint Genis Laval Cedex, France
Publication date: September 1, 2011