Emeline Bomont (Obs. de Bordeaux)
Jeudi 13 Décembre - 11 h 00
Salle Manuel Forestini - IPAG
I will show the results of the study the tidal evolution of close-in planets around 0.1 M-dwarfs and Sun-like stars. Contrary to BDs, the rotation of these objects is braked by stellar winds, so after decreasing slightly after the protoplanetary disk dispersal, the corotation radius increases with time. I found that assuming an initially slow rotating M-dwarf or Sun-like star affects only the very close-in planets. The planets initially inside corotation tend to fall on the central object. For M-dwarfs, an analogy can be made with what is happening around brown-dwarfs : if the fate of the planets depend only on the M-dwarf tide, it would be possible to constrain M-dwarfs dissipation factor from an statistic population of planets. If the planet survived the first few million years of evolution after protoplanetary disk dissipation, it will survive for Gyr timescales. For Sun-like stars, the planets surviving the first few million years can still be doomed after a few Gyrs due to the still large radius of the star and the shrinking corotation radius. The late mergers of Jupiter mass planets onto Sun-like stars cause a noticeable acceleration of the spin of the star thus creating a population of old fast rotating stars. In light of this, the age of young stars determined by gyrochronology should be tested against other techniques so verify their youth because it could be old stars that experienced a merger with a massive planet.
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