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Title: Dynamical Mass of the Young Brown Dwarf Companion PZ Tel B

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 theβPic 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 of279+25MJup, semimajor axis of274+14au, eccentricity of0.520.10+0.08, and inclination of91.730.32+0.36°. The companion’s mass is consistent within 1.1σof 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.

Publication Date:
Journal Name:
The Astronomical Journal
Page Range or eLocation-ID:
Article No. 246
DOI PREFIX: 10.3847
Sponsoring Org:
National Science Foundation
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