MARSH K.A., WRIGHT E.L., KIRKPATRICK J.D., GELINO C.R., CUSHING M.C., GRIFFITH R.L., SKRUTSKIE M.F. and EISENHARDT P.R.
Abstract (from CDS):
We present astrometric measurements of 11 nearby ultracool brown dwarfs of spectral types Y and late-T, based on imaging observations from a variety of space-based and ground-based telescopes. These measurements have been used to estimate relative parallaxes and proper motions via maximum likelihood fitting of geometric model curves. To compensate for the modest statistical significance ( ≲ 7) of our parallax measurements we have employed a novel Bayesian procedure for distance estimation which makes use of an a priori distribution of tangential velocities, Vtan, assumed similar to that implied by previous observations of T dwarfs. Our estimated distances are therefore somewhat dependent on that assumption. Nevertheless, the results have yielded distances for five of our eight Y dwarfs and all three T dwarfs. Estimated distances in all cases are ≳ 3 pc. In addition, we have obtained significant estimates of Vtan for two of the Y dwarfs; both are <100 km/s, consistent with membership in the thin disk population. Comparison of absolute magnitudes with model predictions as a function of color shows that the Y dwarfs are significantly redder in J - H than predicted by a cloud-free model.
astrometry - brown dwarfs - stars: low-mass
In table 3: WISE 0359-5405 is a misprint for WISE 0359-5401.