Document Type
Article
Publication Date
10-1-2021
Publication Title
Astronomy and Astrophysics
Abstract
Aims. We aim to demonstrate that the presence and mass of an exoplanet can now be effectively derived from the astrometry of another exoplanet. Methods. We combined previous astrometry of β Pictoris b with a new set of observations from the GRAVITY interferometer. The orbital motion of β Pictoris b is fit using Markov chain Monte Carlo simulations in Jacobi coordinates. The inner planet, β Pictoris c, was also reobserved at a separation of 96 mas, confirming the previous orbital estimations. Results. From the astrometry of planet b only, we can (i) detect the presence of β Pictoris c and (ii) constrain its mass to 10.04-3.10+4.53 MJup. If one adds the astrometry of β Pictoris c, the mass is narrowed down to 9.15-1.06+1.08 MJup. The inclusion of radial velocity measurements does not affect the orbital parameters significantly, but it does slightly decrease the mass estimate to 8.89-0.75+0.75 MJup. With a semimajor axis of 2.68 ± 0.02 au, a period of 1221 ± 15 days, and an eccentricity of 0.32 ± 0.02, the orbital parameters of β Pictoris c are now constrained as precisely as those of β Pictoris b. The orbital configuration is compatible with a high-order mean-motion resonance (7:1). The impact of the resonance on the planets' dynamics would then be negligible with respect to the secular perturbations, which might have played an important role in the eccentricity excitation of the outer planet.
Keywords
Astrometry, Instrumentation: high angular resolution, Instrumentation: interferometers, Planets and satellites: detection
Volume
654
DOI
10.1051/0004-6361/202141889
ISSN
00046361
Rights
© S. Lacour et al. 2021
Recommended Citation
Lacour, S.; Wang, J. J.; Rodet, L.; Nowak, M.; Shangguan, J.; Beust, H.; Lagrange, A. M.; Abuter, R.; Amorim, A.; Asensio-Torres, R.; Benisty, M.; Berger, J. P.; Blunt, S.; Boccaletti, A.; Bohn, A.; Bolzer, M. L.; Bonnefoy, M.; Bonnet, H.; Bourdarot, G.; Brandner, W.; Cantalloube, F.; Caselli, P.; Charnay, B.; Chauvin, G.; Choquet, E.; Christiaens, V.; Clénet, Y.; Coudé Du Foresto, V.; Cridland, A.; Dembet, R.; Dexter, J.; De Zeeuw, P. T.; Ward-Duong, K.; and al, et, "The Mass of β Pictoris C from β Pictoris b Orbital Motion" (2021). Astronomy: Faculty Publications, Smith College, Northampton, MA.
https://scholarworks.smith.edu/ast_facpubs/100
Comments
Archived as published.