Homogeneous comparison of directly detected planet candidates: GQ Lup, 2M1207, AB Pic

Abstract

We compile the observational evidence for the three recently presented planet candidates imaged directly and derive in a homogeneous way their temperatures and masses. For both AB Pic b and 2M1207 b, we derive a larger temperature range than in Chauvin et al. (2004, 2005b). AB Pic b appears to be quite similar as GQ Lup b, but older. According to the Tucson and Lyon models, all three companions could either be planets or brown dwarfs. According to the Wuchterl formation model, the masses seem to be below the D burning limit. We discuss whether the three companions can be classified as planets, and whether the three systems are gravitationally bound and long-term stable.