On the kinematic age of brown dwarfs: Radial velocities and space motions of 43 nearby L dwarfs
Andreas Seifahrt, Ansgar Reiners, Khiria A. M. Almaghrbi, Gibor, Basri

TL;DR
This study measures radial velocities and space motions of 43 nearby L dwarfs to estimate their ages, finding a median age of about 5 billion years and identifying potential young moving group members.
Contribution
It provides the first comprehensive kinematic analysis of a sizable sample of L dwarfs, revealing their age distribution and potential group memberships.
Findings
Kinematic age of ~5 Gyr for the sample
Identification of 9 candidate young moving group members
Distribution of velocities suggests complex dynamical history
Abstract
We present radial velocity measurements of a sample of L0-L8 dwarfs observed with VLT/UVES and Keck/HIRES. We combine these measurements with distance and proper motion from the literature to determine space motions for 43 of our targets. We identify nine candidate members of young moving groups, which have ages of 50-600 Myr according to their space motion. From the total velocity dispersion of the 43 L dwarfs, we calculate a kinematic age of ~5 Gyr for our sample. This age is significantly higher than the ~3 Gyr age known for late M dwarfs in the solar neighbourhood. We find that the distributions of the U and V velocity components of our sample are clearly non-Gaussian, placing the age estimate inferred from the full space motion vector into question. The W-component exhibits a distribution more consistent with a normal distribution, and from W alone we derive an age of ~3 Gyr, which…
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