Hubble Space Telescope astrometry of the closest brown dwarf binary system -- I. Overview and improved orbit

Abstract

Located at ~2pc, the L7.5+T0.5 dwarfs system WISE J104915.57-531906.1 (Luhman16AB) is the third closest system known to Earth, making it a key benchmark for detailed investigation of brown dwarf atmospheric properties, thermal evolution, multiplicity, and planet-hosting frequency. In the first study of this series -- based on a multi-cycle Hubble Space Telescope (HST) program -- we provide an overview of the project and present improved estimates of positions, proper motions, annual parallax, mass ratio, and the current best assessment of the orbital parameters of the A-B pair. Our HST observations encompass the apparent periastron of the binary at 220.5+/-0.2 mas at epoch 2016.402. Although our data seem to be inconsistent with recent ground-based astrometric measurements, we also exclude the presence of third bodies down to Neptune masses and periods longer than a year.

19 pages, 9 figures, 9 tables. Accepted for publication in MNRAS on 2017 May 9

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Cited by in corpus (5)

• TESS Observations of the Luhman 16AB Brown Dwarf System: Rotational Periods, Lightcurve Evolution, and Zonal Circulation
• Individual, Model-Independent Masses of the Closest Known Brown Dwarf Binary to the Sun
• Chrono-chemodynamical analysis of the globular cluster NGC 6355: Looking for the fundamental bricks of the Bulge
• Weather on Other Worlds. VI. Optical Spectrophotometry of Luhman 16B Reveals Large-amplitude Variations in the Alkali Lines
• Gaia and VLT astrometry of faint stars: Precision of Gaia DR1 positions and updated VLT parallaxes of ultracool dwarfs