Astrometric search for Planets orbiting the closest Y Dwarf
Abstract
Located at 2.2 pc, the ~250K Y2 (sub-)brown dwarf WISE J085510.83-071442.5 is the fourth closest known system to Earth. Studying this object provides unique insights into brown dwarf (and exoplanet) atmospheric properties, thermal evolution, multiplicity, and planet-hosting prospects.
We propose to use HST to obtain one the most accurate annual parallax of this - or any - planetary-mass brown dwarf to date, achieving an unprecedented accuracy of 200 micro-arcseconds, and constraining its absolute space motion to equivalent accuracy. More importantly, we will be able to search for faint companions co-moving with the target, either resolved or through astrometric perturbations of its linear motion, the latter probing down to a few Earth masses. HST is the optimal facility for precision astrometric measurement of WISE 0855-0714, as this source is too cool and faint at optical and near-infrared wavelengths to observe with ground-based facilities or Gaia. Our observations will improve current astrometric precision of this source by a factor of 40 and anchor future JWST measurements of this and other cold brown dwarfs, while providing high-precision distance and motion measurements and tight constraints on planetary-mass companions for one of the closest \`\`stellar object'' to the Sun.- Publication:
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HST Proposal
- Pub Date:
- August 2023
- Bibcode:
- 2023hst..prop17403B