English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

We present astrometric measurements of eleven nearby ultracool brown dwarfsof spectral types Y and late-T, based on imaging observations from a variety ofspace-based and ground-based telescopes. These measurements have been used toestimate relative parallaxes and proper motions via maximum likelihood fittingof geometric model curves. To compensate for the modest statisticalsignificance (<~ 7) of our parallax measurements we have employed a novelBayesian procedure for distance estimation which makes use of an a prioridistribution of tangential velocities, Vtan, assumed similar to that implied byprevious observations of T dwarfs. Our estimated distances are thereforesomewhat dependent on that assumption. Nevertheless, the results have yieldeddistances for five of our eight Y dwarfs and all three T dwarfs. Estimateddistances in all cases are >~ 3 pc. In addition, we have obtained significantestimates of Vtan for two of the Y dwarfs; both are <100 km/s, consistent withmembership in the thin disk population. Comparison of absolute magnitudes withmodel predictions as a function of color shows that the Y dwarfs aresignificantly redder in J-H than predicted by a cloud-free model

Parallaxes and Proper Motions of Ultracool Brown Dwarfs of Spectral Types Y and Late T