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Search for planets around M dwarfs: New statistical properties and first habitable Super Earths

Xavier Bonfils

The characteristics of M dwarfs bear many observational advantages. They allow to probe for new statistical properties of planetary systems. They allow the detection (and possibly the characterisation) of habitable Super Earths, a planetary regime not yet accessible around Sun-like stars.

I will present the results of our search for planets around M dwarfs, with a particular attention for some remarkable detections obtained in 2007. The case of GJ 674 will illustrate both the detection of a low-mass exoplanet (m sin i = 11 Mearth) and the limitation imposed to the radial-velocity method by the magnetic activity that occasionally spot the stellar surface. With GJ 581, we will talk about a system made of three planets, including 2 Super Earths (m sin i ~ 5 & 8 Mearth) located inside or close from the habitable zone. Finally, with GJ 436 we will see that M dwarfs are privileged targets to measure the radius of the smallest exoplanets.

All these detections are not only interesting individually, they also built up a statistical picture of the planetary formation. For the end of my talk, I will therefore focus on the statistical properties we derive from our observations and how they mesh up with the theory of planet formation.

2008 February 14, 13:30

Centro de Astrofísica da Universidade do Porto (Auditorium)
Rua das Estrelas, 4150-762 Porto

Faculdade de Ciências da Universidade de Lisboa Universidade do Porto Faculdade de Ciências e Tecnologia da Universidade de Coimbra
Fundação para a Ciência e a Tecnologia COMPETE 2020 PORTUGAL 2020 União Europeia