The Y dwarf population with HST: unlocking the secrets of our coolest neighbours — I. Overview & First astrometric results. (arXiv:2011.13873v1 [astro-ph.SR])
<a href="http://arxiv.org/find/astro-ph/1/au:+Fontanive_C/0/1/0/all/0/1">Clemence Fontanive</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bedin_L/0/1/0/all/0/1">Luigi R. Bedin</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Gagliuffi_D/0/1/0/all/0/1">Daniella C. Bardalez Gagliuffi</a>
In this paper we present our project that aims at determining accurate
distances and proper motions for the Y brown dwarf population using the Hubble
Space Telescope. We validate the program with our first results, using a single
new epoch of observations of the Y0pec dwarf WISE J163940.83$-$684738.6. These
new data allowed us to refine its proper motion and improve the accuracy of its
parallax by a factor of three compared to previous determinations, now
constrained to $varpi = 211.11 pm 0.56$ mas. This newly derived absolute
parallax corresponds to a distance of $4.737 pm 0.013$ pc, an exquisite and
unprecedented precision for faint ultracool Y dwarfs.
In this paper we present our project that aims at determining accurate
distances and proper motions for the Y brown dwarf population using the Hubble
Space Telescope. We validate the program with our first results, using a single
new epoch of observations of the Y0pec dwarf WISE J163940.83$-$684738.6. These
new data allowed us to refine its proper motion and improve the accuracy of its
parallax by a factor of three compared to previous determinations, now
constrained to $varpi = 211.11 pm 0.56$ mas. This newly derived absolute
parallax corresponds to a distance of $4.737 pm 0.013$ pc, an exquisite and
unprecedented precision for faint ultracool Y dwarfs.
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