Investigating Possible Binarity for GJ 229B

Abstract

GJ 229B, the first type-T brown dwarf to be discovered, has presented a tension between comparisons with evolutionary models and the larger-than-expected mass and radius values derived from spectroscopic and astrometric observations. We examine the hypothesis that GJ 229B is actually a binary sub-stellar object by using two grid-based fits using evolutionary models to explore the range of mass ratios of the possible binary components. We find that the best-fit component values are most consistent with a roughly 2:1 binary mass ratio and an age range of 2-6 Gyr. The observed temperatures, masses, and apparent radii match expected values from evolutionary models for a binary much better than a single-object model, but more detailed observations and modeling are needed to definitively confirm the binary hypothesis.

arXiv comment9 pages, 3 figures, 2 tables, accepted for publication in ApJL

References in corpus (19)

• First Light for GRAVITY: Phase Referencing Optical Interferometry for the Very Large Telescope Interferometer
• A Unified Near Infrared Spectral Classification Scheme for T Dwarfs
• Binarity in Brown Dwarfs: T Dwarf Binaries Discovered with the Hubble Space Telescope WPFC2
• Individual Dynamical Masses of Ultracool Dwarfs
• Bayesian search for low-mass planets around nearby M dwarfs. Estimates for occurrence rate based on global detectability statistics
• Uniform Atmospheric Retrieval Analysis of Ultracool Dwarfs I: Characterizing Benchmarks, Gl570D and HD3651B
• The Spectrum of the Brown Dwarf Gliese 229B
• Uniform Atmospheric Retrieval Analysis of Ultracool Dwarfs II: Properties of 11 T-dwarfs
• Dynamical Masses of the Binary Brown Dwarf GJ 569Bab
• The Near-infrared Spectrum of the Brown Dwarf Gliese 229B
• 3-D selection of 167 sub-stellar companions to nearby stars
• Improved Dynamical Masses for Six Brown Dwarf Companions Using Hipparcos and Gaia EDR3
• Retrieval of SDSS J1416+1348AB
• Search for Nearby Earth Analogs. II. detection of five new planets, eight planet candidates, and confirmation of three planets around nine nearby M dwarfs
• WISE2150-7520AB: A very low mass, wide co-moving brown dwarf system discovered through the citizen science project Backyard Worlds: Planet 9
• Precise Dynamical Masses of Epsilon Indi Ba and Bb: Evidence of Slowed Cooling at the L/T Transition
• Hubble Space Telescope astrometry of the closest brown dwarf binary system -- I. Overview and improved orbit
• Physical Properties of Gliese 229B Based on Newly Determined Carbon and Oxygen Abundances of Gliese 229A
• Discovery of a nearby young brown dwarf binary candidate

Cited by in corpus (3)

• The cool brown dwarf Gliese 229 B is a close binary
• Discovery of the Binarity of Gliese 229B, and Constraints on the System's Properties
• Atmospheric abundances and bulk properties of the binary brown dwarf Gliese 229 Bab from JWST/MIRI spectroscopy