Surveying nearby brown dwarfs with HGCA: direct imaging discovery of a faint, high-mass brown dwarf orbiting HD 176535 A

Yiting Li*, Timothy D. Brandt*, G. Mirek Brandt, Qier An*, Kyle Franson, Trent J. Dupuy, Minghan Chen, Rachel Bowens-Rubin, Briley L. Lewis, Brendan P. Bowler, Aidan Gibbs, Rocio Kiman, Jacqueline Faherty, Thayne Currie, Rebecca Jensen-Clem, Hengyue Zhang, Ezequiel Contreras-Martinez, Michael P. Fitzgerald, Benjamin A. Mazin, Maxwell Millar-Blanchaer

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Brown dwarfs with well-measured masses, ages, and luminosities provide direct benchmark tests of substellar formation and evolutionary models. We report the first results from a direct imaging survey aiming to find and characterize substellar companions to nearby accelerating stars with the assistance of the Hipparcos-Gaia Catalog of Accelerations (HGCA). In this paper, we present a joint high-contrast imaging and astrometric discovery of a substellar companion to HD 176535 A, a K3.5V main-sequence star aged approximately 3.59+−10.8715s Gyr at a distance of 36.99 ± 0.03 pc. In advance of our high-contrast imaging observations, we combined precision High Accuracy Radial velocity Planet Searcher (HARPS) Radial Velocities (RVs) and HGCA astrometry to predict the potential companion's location and mass. We thereafter acquired two nights of KeckAO/NIRC2 direct imaging observations in the L' band, which revealed a companion with a contrast of ΔL'p = 9.20 ± 0.06 mag at a projected separation of ≈0.35 arcsec (≈13 au) from the host star. We revise our orbital fit by incorporating our dual-epoch relative astrometry using the open-source Markov chain Monte Carlo orbit fitting code ORVARA. We obtain a dynamical mass of 65.9+−12.07MJup that places HD 176535 B firmly in the brown dwarf regime. HD 176535 B is a new benchmark dwarf useful for constraining the evolutionary and atmospheric models of high-mass brown dwarfs. We found a luminosity of log(Lbol/L⊙) = −5.26 ± 0.07 and a model-dependent effective temperature of 980 ± 35 K for HD 176535 B. We infer HD 176535 B to be a T dwarf from its mass, age, and luminosity. Our dynamical mass suggests that some substellar evolutionary models may be underestimating luminosity for high-mass T dwarfs. Given its angular separation and luminosity, HD 176535 B would make a promising candidate for Aperture Masking Interferometry with JWST and GRAVITY/Keck Planet Imager and Characterizer, and further spectroscopic characterization with instruments like the CHARIS/SCExAO/Subaru integral field spectrograph.

Original languageEnglish
Pages (from-to)5622-5637
Number of pages16
JournalMonthly Notices of the Royal Astronomical Society
Volume522
Issue number4
Early online date4 May 2023
DOIs
Publication statusPublished - 1 Jul 2023

Keywords / Materials (for Non-textual outputs)

  • astrometry
  • methods: data analysis
  • techniques: high angular resolution
  • techniques: image processing

Fingerprint

Dive into the research topics of 'Surveying nearby brown dwarfs with HGCA: direct imaging discovery of a faint, high-mass brown dwarf orbiting HD 176535 A'. Together they form a unique fingerprint.

Cite this