Astrometric Discovery of GJ 802b: In the Brown Dwarf Oasis?

Abstract

The Stellar Planet Survey is an ongoing astrometric search for giant planets and brown dwarfs around a sample of about 30 M-dwarfs. We have discovered several low-mass companions by measuring the motion of our target stars relative to their reference frames. The lowest mass discovery thus far is GJ 802b, a companion to the M5-dwarf GJ 802A. The orbital period is 3.14 +/- 0.03 y, the system mass is 0.214 +/- 0.045 Msolar, and the semi-major axis is 1.28 +/- 0.10 AU or 81 +/- 6 mas. Imaging observations indicate that GJ 802b is likely to be a brown dwarf with the astrometrically determined mass 0.058 +/- 0.021 Msolar (one sigma limits). The remaining uncertainty in the orbit is the eccentricity that is now loosely constrained. We discuss how the system age limits the mass and the prospects to further narrow the mass range when e is more precisely determined.

13 pages, 6 figures, accepted for publication in ApJ on May 9, 2005

References in corpus (13)

• Evolutionary models for cool brown dwarfs and extrasolar giant planets. The case of HD 20945
• Binarity in Brown Dwarfs: T Dwarf Binaries Discovered with the Hubble Space Telescope WPFC2
• Detection of Nine M8.0-L0.5 Binaries: The Very Low Mass Binary Population and its Implications for Brown Dwarf and VLM Star Formation
• The NIRSPEC Brown Dwarf Spectroscopic Survey. I. Low-Resolution Near-Infrared Spectra
• Beyond the T Dwarfs: Theoretical Spectra, Colors, and Detectability of the Coolest Brown Dwarfs
• Epsilon Indi Ba/Bb: the nearest binary brown dwarf
• T Dwarfs and the Substellar Mass Function. I. Monte Carlo Simulations
• Dynamical Masses of the Binary Brown Dwarf GJ 569Bab
• First determination of the dynamical mass of a binary L dwarf
• The Solar Neighborhood IX: Hubble Space Telescope Detections of Companions to Five M and L Dwarfs within 10 pc of the Sun
• An Adaptive Optics Survey of M6.0-M7.5 Stars: Discovery of Three Very Low Mass Binary Systems Including Two Probable Hyades Members
• Coronal X-ray emission from an intermediate-age brown dwarf
• Astrometric Discovery of GJ 164B

Cited by in corpus (23)

• The Hawaii Infrared Parallax Program. I. Ultracool Binaries and the L/T Transition
• Rotation Velocities for M-dwarfs
• The Field Substellar Mass Function Based on the Full-sky 20-pc Census of 525 L, T, and Y Dwarfs
• Taking the Measure of the Universe: Precision Astrometry with SIM PlanetQuest
• Mass constraints on substellar companion candidates from the re-reduced Hipparcos intermediate astrometric data: Nine confirmed planets and two confirmed brown dwarfs
• An empirical calibration to estimate cool dwarf fundamental parameters from H-band spectra
• The PHASES Differential Astrometry Data Archive. V. Candidate Substellar Companions to Binary Systems
• A Near-Infrared Spectroscopic Survey of 886 Nearby M Dwarfs
• Dynamical Mass of GJ 802B: a brown dwarf in a triple system
• The Ultracool SpeXtroscopic Survey. I. Volume-Limited Spectroscopic Sample and Luminosity Function of M7$-$L5 Ultracool Dwarfs
• An Ultracool Star's Candidate Planet
• Radio Interferometric Planet Search I: First Constraints on Planetary Companions for Nearby, Low-Mass Stars from Radio Astrometry
• Masses of Astrometrically-Discovered and Imaged Binaries: G 78-28AB and GJ 231.1BC
• Direct Detection of the Brown Dwarf GJ 802B with Adaptive Optics Masking Interferometry
• The GL 569 Multiple System
• An Astrometric Search for a Sub-stellar Companion of the M8.5 Dwarf TVLM 513-46546 Using Very Long Baseline Interferometry
• Astrometric detection of exoplanets from the ground
• Planets Around Low-Mass Stars (PALMS). II. A Low-Mass Companion to the Young M Dwarf GJ 3629 Separated By 0.2"
• Detection and Characterization of Planetary Systems with $\mu$as Astrometry
• The ESPRI project: astrometric exoplanet search with PRIMA I. Instrument description and performance of first light observations
• Astrophysics in 2005
• Detection of a low-mass stellar companion to the accelerating A2IV star HR 1645
• ExoDNN: Boosting exoplanet detection with artificial intelligence. Application to Gaia Data Release 3