TY - JOUR
AU - S. Lacour
AU - J. Wang
AU - L. Rodet
AU - M. Nowak
AU - J. Shangguan
AU - H. Beust
AU - A.-M. Lagrange
AU - R. Abuter
AU - A. Amorim
AU - Jason Dexter
AU - et al.
AB - We aim to demonstrate that the presence and mass of an exoplanet can now be effectively derived from the astrometry of another exoplanet. 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. 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+4.53−3.10MJup. If one adds the astrometry of β Pictoris c, the mass is narrowed down to 9.15+1.08−1.06MJup. The inclusion of radial velocity measurements does not affect the orbital parameters significantly, but it does slightly decrease the mass estimate to 8.89+0.75−0.75MJup. 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.
BT - Astronomy & Astrophysics
DA - 2021-10
DO - 10.1051/0004-6361/202141889
N2 - We aim to demonstrate that the presence and mass of an exoplanet can now be effectively derived from the astrometry of another exoplanet. 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. 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+4.53−3.10MJup. If one adds the astrometry of β Pictoris c, the mass is narrowed down to 9.15+1.08−1.06MJup. The inclusion of radial velocity measurements does not affect the orbital parameters significantly, but it does slightly decrease the mass estimate to 8.89+0.75−0.75MJup. 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.
PB - EDP Sciences
PY - 2021
EP - L2
T2 - Astronomy & Astrophysics
TI - The mass of β Pictoris c from β Pictoris b orbital motion
UR - http://dx.doi.org/10.1051/0004-6361/202141889
VL - 654
SN - 1432-0746
ER -