THE RADIAL AND ROTATIONAL VELOCITIES OF PSO J318.5338-22.8603, A NEWLY CONFIRMED PLANETARY-MASS MEMBER OF THEβPICTORIS MOVING GROUP
K. N. Allers, J. F. Gallimore, Michael C. Liu, Trent J. Dupuy
2016
Astrophysical Journal
PSO J318.5338-22.8603 is an extremely-red planetary-mass object that has been identified as a candidate member of the β Pictoris moving group based on its spatial position and tangential velocity. We present a high resolution K-band spectrum of PSO J318.5338-22.8603. Using a forward-modeling Markov Chain Monte Carlo approach, we report the first measurement of the radial velocity and v sin(i) of PSO J318.5-22, -6.0^+0.8_-1.1 km s^-1 and 17.5^+2.3_-2.8 km s^-1, respectively. We calculate the
more »
... e velocity and position of PSO J318.5-22 and confirm that it is a member of the β Pictoris moving group. Adopting an age of 23±3 Myr for PSO J318.5-22, we determine a mass of 8.3±0.5 M_Jup and effective temperature of 1127^+24_-26 K using evolutionary models. PSO J318.5338-22.8603 is intermediate in mass and temperature to the directly-imaged planets β Pictoris b and 51 Eridani b, making it an important benchmark object in the sequence of planetary-mass members of the β Pictoris moving group. Combining our v sin(i) measurement with recent photometric variability data, we constrain the inclination of PSO J318.5-22 to >29^∘ and its rotational period to 5-10.2 hours. The equatorial velocity of PSO J318.5-22 indicates that its rotation is consistent with an extrapolation of the velocity-mass relationship for solar system planets.
doi:10.3847/0004-637x/819/2/133
fatcat:5pk2kka4vfbshjjwx6mwk7ique