The Radial and Rotational Velocities of PSO J318.5338$-$22.8603, a Newly Confirmed Planetary-Mass Member of the $\beta$ Pictoris Moving Group

Abstract

PSO J318.5338$-$22.8603 is an extremely-red planetary-mass object that has been identified as a candidate member of the $\beta$ 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, $-$6.0${}_{-1.1}^{+0.8}$ km s${}^{-1}$ and 17.5${}_{-2.8}^{+2.3}$ km s${}^{-1}$, respectively. We calculate the space velocity and position of PSO J318.5$-$22 and confirm that it is a member of the $\beta$ Pictoris moving group. Adopting an age of 23$\pm$3 Myr for PSO J318.5$-$22, we determine a mass of $8.3\pm 0.5$ $M_{\mathrm{Jup}}$ and effective temperature of $1127_{-26}^{+24}$ K using evolutionary models. PSO J318.5338$-$22.8603 is intermediate in mass and temperature to the directly-imaged planets $\beta$ Pictoris b and 51 Eridani b, making it an important benchmark object in the sequence of planetary-mass members of the $\beta$ Pictoris moving group. Combining our $v$ sin($i$) measurement with recent photometric variability data, we constrain the inclination of PSO J318.5$-$22 to $>29^{\circ }$ 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.

8 pages, 5 figures, 2 tables, ApJ accepted

References in corpus (11)

• The Evolution of L and T Dwarfs in Color-Magnitude Diagrams
• Discovery and spectroscopy of the young Jovian planet 51 Eri b with the Gemini Planet Imager
• A self-consistent, absolute isochronal age scale for young moving groups in the solar neighbourhood
• The fast spin-rotation of a young extrasolar planet
• Fundamental Parameters and Spectral Energy Distributions of Young and Field Age Objects with Masses Spanning the Stellar to Planetary Regime
• On the age of the $\beta$ Pictoris moving group
• Strong Brightness Variations Signal Cloudy-to-Clear Transition of Brown Dwarfs
• Lithium Depletion of Nearby Young Stellar Associations
• BANYAN. IV. Fundamental parameters of low-mass star candidates in nearby young stellar kinematic groups - Isochronal Age determination using Magnetic evolutionary models
• Variability in a Young, L/T Transition Planetary-Mass Object
• Magellan Adaptive Optics first-light observations of the exoplanet $\beta$ Pic b. I. Direct imaging in the far-red optical with MagAO+VisAO and in the near-IR with NICI

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