Direct confirmation of the radial-velocity planet beta Pictoris c

Nowak, M.; Lacour, S.; Lagrange, A.M.; Rubini, P.; Wang, J.; Stolker, T.; ... ; Woillez, J. (2020)

Article / Letter to editor

Context. Methods used to detect giant exoplanets can be broadly divided into two categories: indirect and direct. Indirect methods are more sensitive to planets with a small orbital period, whereas direct detection is more sensitive to planets orbiting at a large distance from their host star. This dichotomy makes it difficult to combine the two techniques on a single target at once.Aims. Simultaneous measurements made by direct and indirect techniques offer the possibility of determining the mass and luminosity of planets and a method of testing formation models. Here, we aim to show how long-baseline interferometric observations guided by radial-velocity can be used in such a way.Methods. We observed the recently-discovered giant planet beta Pictoris c with GRAVITY, mounted on the Very Large Telescope Interferometer.Results. This study constitutes the first direct confirmation of a planet discovered through radial velocity. We find that the planet has a temperature of T=125050 K and a dynamical mass of M=8.2 +/- 0.8 M-Jup. At 18.5 +/- 2.5 Myr, this puts beta Pic c close to a 'hot start' track, which is usually associated with formation via disk instability. Conversely, the planet orbits at a distance of 2.7 au, which is too close for disk instability to occur. The low apparent magnitude (M-K=14.3 +/- 0.1) favours a core accretion scenario.Conclusions. We suggest that this apparent contradiction is a sign of hot core accretion, for example, due to the mass of the planetary core or the existence of a high-temperature accretion shock during formation.

• All authors: Nowak, M.; Lacour, S.; Lagrange, A.M.; Rubini, P.; Wang, J.; Stolker, T.; Abuter, R.; Amorim, A.; Asensio-Torres, R.; Baubock, M.; Benisty, M.; Berger, J.P.; Beust, H.; Blunt, S.; Boccaletti, A.; Bonnefoy, M.; Bonnet, H.; Brandner, W.; Cantalloube, F.; Charnay, B.; Choquet, E.; Christiaens, V.; Clenet, Y.; du, Foresto, V.; Cridland, A.J.; de, Zeeuw, P.T. de; Dembet, R.; Dexter, J.; Drescher, A.; Duvert, G.; Eckart, A.; Eisenhauer, F.; Gao, F.; Garcia, P.; Lopez, R.G.; Gardner, T.; Gendron, E.; Genzel, R.; Gillessen, S.; Girard, J.; Grandjean, A.; Haubois, X.; Heissel, G.; Henning, T.; Hinkley, S.; Hippler, S.; Horrobin, M.; Houlle, M.; Hubert, Z.; Jimenez, -Rosales, A.; Jocou, L.; Kammerer, J.; Kervella, P.; Keppler, M.; Kreidberg, L.; Kulikauskas, M.; Lapeyrere, V.; Le, Bouquin, J.B.; Lena, P.; Merand, A.; Maire, AL.; Molliere, P.; Monnier, J.D.; Mouillet, D.; Muller, A.; Nasedkin, E.; Ott, T.; Otten, G.; Paumard, T.; Paladini, C.; Perraut, K.; Perrin, G.; Pueyo, L.; Pfuhl, O.; Rameau, J.; Rodet, L.; Rodriguez, -Coira, G.; Rousset, G.; Scheithauer, S.; Shangguan, J.; Stadler, J.; Straub, O.; Straubmeier, C.; Sturm, E.; Tacconi, L.J.; Dishoeck, E.F. van; Vigan, A.; Vincent, F. von; Fellenberg, S.D.; Ward-Duong, K.; Widmann, F.; Wieprecht, E.; Wiezorrek, E.; Woillez, J.
• Date: 2020-10-02
• Journal: Astronomy & Astrophysics
• Volume: 642
• Pages: L2
• DOI: doi:10.1051/0004-6361/202039039