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O4b: Contributed Orals – Exoplanets and Habitability (continued)
Time: Tuesday, 05/Jul/2011: 5:45pm - 6:30pm
Session Chair: Victoria Meadows
Location: Auditorium Pasteur


Atmospheric chemistry driven by stellar flares on habitable planets around M dwarfs

Antigona Segura1,5, Lucianne Walkowicz2,5, Marisol Sánchez1, James Kasting3,5, Victoria Meadows4,5

1Universidad Nacional Autónoma de México, Mexico; 2University of California at Berkeley; 3Pennsylvania State University; 4University of Washington; 5Virtual Planeatry Laboratory, NASA Astrobiology Institute

Using 1-D models we studied the effect of flares on the atmospheric chemistry of planets in the habitable zone of the M dwarf AD Leonis, one of the most chromospherically active M stars. The simulated atmospheres were oxygen-rich present Earth type and high CO2 atmospheres. On rich O2 atmopsheres O3 is not affected by the UV emitted during the flare.

Tidal equilibrium and the habitability of extrasolar planets

René Heller1, Jérémy Leconte2, Rory Barnes3,4

1Astrophysikalisches Institut Potsdam, Germany; 2cole Normale Supérieure de Lyon, France; 3University of Washington, Seattle, USA; 4Virtual Planetary Laboratory, USA

The gravitational interaction between a planet and its host star induces a steady change in the physical parameters of the system. It will decrease the angle between the planetary equator and the orbital plane (the obliquity) to 0°. Because both the rotation rate and the obliquity strongly affect the planetary climate, we show that tidal synchronization, tidal coplanarization and tidal heating urge a revision of the traditional concept of the "habitable zone", especially for low-mass stars.

Habitability of super-Earths around M-dwarf stars: a case study of the Gliese 581 system

Robin Wordsworth1, François Forget1, Franck Selsis2, Ehouarn Millour1

1Laboratoire de Meteorologie Dynamique, Paris, France; 2Laboratoire d'Astrophysique de Bordeaux, Bordeaux, France

We discuss the potential habitability of planets in the GJ581 system. For the super-Earth GJ581d, we have found many atmospheric scenarios in which it could support surface liquid water. We discuss the other possibilities, and propose observational tests to distinguish them from habitable cases in the future. We assess the potential climates of other planets in the system (including the disputed candidate GJ581g), and consider the implications of our work for M-dwarf habitability in general.