Properties of the young gas giant planet beta Pictoris b
Résumé
Young systems such as beta Pictoris are of great importance as they trace the formation and early evolution of planetary systems. They are also the only targets around which planets can be imaged today. We detected with NaCo a giant planet around beta Pictoris, roughly along the dust disk position angle (PA), with a semi-major axis (sma) between 8 and 14 AU. Its observed L' luminosity indicated a 1700 K, 7-11 MJup mass planet according to hot-start" models. We obtained the first images of the planet in the J (1.265 mum), H (1.66 mum), and M' (4.78 mum) bands between 2011 and 2012. We used these data to estimate build its 1-5 mum spectral energy distribution (SED) for the companion, and to consolidate previous semi-major axis (8-10 AU) and excentricity (e ~ 0.15) estimates. We compared the SED to 7 atmospheric models to derive Te f f = 1700 ± 100 K and log g = 4.0 ± 0.5. We used the temperature and the luminosity of beta Pictoris b to derive new mass estimate for the companion. We compared these estimate to independant mass measurments set by the orbital parameters and the radial velocities and use them to derive informations on the formation history of the object.