While spectroscopically characterizing nearby ultracool dwarfs discovered in
the Gaia Second Data Release with the TripleSpec spectrograph on the Palomar
200'' telescope, we encountered a particularly cool, nearby, new member of the
solar neighborhood: Gaia DR2 3106548406384807680 = WISE J064336.71-022315.4 =
2MASS J06433670-0223130. The Gaia parallax corresponds to a distance of
13.9 ± 0.3 pc. Using our TripleSpec spectrum we classify W0643 as spectral
type L8, and measured a heliocentric radial velocity of 142 ± 12 km
s−1. When combined with Gaia astrometry, we determine a Galactic
velocity (heliocentric; U towards Galactic center) of U,V,W = -109, -91,
-12 (±10, 5, 3) km s−1. We estimate that W0643 passed within ∼1.4
pc away from the Sun ∼100,000 years ago