Abstract
The recent detection of the transit of very massive substellar companions (CoRoT-3b, Deleuil et al. 2008; CoRoT-15b, Bouchy et al. 2010; WASP-30b, Anderson et al. 2010; Hat-P-20b, Bakos et al. 2010) provides a strong constraint to planet and brown dwarf formation and migration mechanisms. Whether these objects are brown dwarfs originating from the gravitational collapse of a dense molecular cloud that, at the same time, gave birth to the more massive stellar companion, or whether they are planets that formed through core accretion of solids in the protoplanetary disk can not always been determined unambiguously and the mechanisms responsible for their short orbital distances are not yet fully understood. In this contribution, we examine the possibility to constrain the nature of a massive substellar object from the various observables provided by the combination of Radial Velocity and Photometry measurements (e.g. M_p, R_p, M_s, Age, a, e...). In a second part, developments in the modeling of tidal evolution at high eccentricity and inclination - as measured for HD 80 606 with e=0.9337 (Naef et al. 2001), XO-3 with a stellar obliquity >37.3+-3.7 deg (H\'ebrard et al. 2008; Winn et al. 2009) and several other exoplanets - are discussed along with their implication in the understanding of the radius anomaly problem of extrasolar giant planets.
Highlights
In order to quantify the radius anomaly of many ”Hot Jupiters” and study the possibility of such an anomaly for the more massive objects, we computed the radius predicted by our standard model (Rirrad), described in Baraffe, Chabrier & Barman (2008) and Leconte et al (2009), for detected transiting planets with Mp > 0.3MJ
The objects significantly above the R = Rirrad line suggest that a missing physical mechanism which is either injecting energy in the deep convective zone or reducing the net outward thermal flux is taking place in these objects
The recent transit detection of massive companions in the substellar regime (5 MJ ∼< Mp ∼< MHBMM = 0.075 M ), where MMMHB is the hydrogen burning minimum mass, in close orbit to a central star raises the questions about their very nature: planet or brown dwarf ?
Summary
Because the radius of a gaseous giant planet is not set only by its mass, but strongly depends on the object’s composition, age and irradiation history, the mass-radius diagram only gives a limited view of the constraints offered by the observation of transiting systems. In order to quantify the radius anomaly of many ”Hot Jupiters” and study the possibility of such an anomaly for the more massive objects, we computed the radius predicted by our standard model (Rirrad), described in Baraffe, Chabrier & Barman (2008) and Leconte et al (2009), for detected transiting planets with Mp > 0.3MJ (about a Saturn mass).
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