Dynamical Mass of the Young Brown Dwarf Companion PZ Tel B
ASTRONOMICAL JOURNAL(2023)
摘要
Dynamical masses of giant planets and brown dwarfs are critical tools for empirically validating substellar evolutionary models and their underlying assumptions. We present a measurement of the dynamical mass and an updated orbit of PZ Tel B, a young brown dwarf companion orbiting a late-G member of the beta Pic moving group. PZ Tel A exhibits an astrometric acceleration between Hipparcos and Gaia EDR3, which enables the direct determination of the companion's mass. We have also acquired new Keck/NIRC2 adaptive optics imaging of the system, which increases the total baseline of relative astrometry to 15 yr. Our joint orbit fit yields a dynamical mass of 27(-9)(+25) M-Jup, semimajor axis of 27(-4)(+14) au, eccentricity of 0.52(-0.10)(+0.08), and inclination of 91.73(-0.32)(+0.36)degrees. The companion's mass is consistent within 1.1 sigma of predictions from four grids of hot-start evolutionary models. The joint orbit fit also indicates a more modest eccentricity of PZ Tel B than previous results. PZ Tel joins a small number of young (<200 Myr) systems with benchmark substellar companions that have dynamical masses and precise ages from moving group membership.
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Planetary Systems
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