2006/06/13 by I. Neill Reid, I. N. Reid, E. Lewitus +4 · 154 citations
Mathematics · Physics and Astronomy · #Angular diameter #Astronomy and Astrophysical Research #Astrophysics #Binary number #Brown dwarf #Gamma-ray bursts and supernovae #Logarithm #Mathematical analysis #Mathematics #Physics #Stars #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1086/505626
published in The Astronomical Journal 132(2), 891-901 (Institute of Physics) · 29 pages, 4 tables, 8 figures; accepted for publication in AJ
arxiv created 2006/06/13 · openalex publication_date 2006/07/10 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/06
We have used the Near-Infrared Camera and Multi-Object Spectrometer NIC1 camera on the Hubble Space Telescope to obtain high angular resolution images of 52 ultracool dwarfs in the immediate solar neighborhood. Nine systems are resolved as binary, with component separations from 1.5 to 15 AU. Based on current theoretical models and empirical bolometric corrections, all systems have components with similar luminosities and, consequently, high mass ratios, q > 0.8. Limiting analysis to L dwarfs within 20 pc, the observed binary fraction is 12% . Applying Bayesian analysis to our data set, we derive a mass-ratio distribution that peaks strongly at unity. Modeling the semimajor axis distribution as a logarithmic Gaussian, the best fit is centered at log a 0 = 0.8 AU (∼6.3 AU), with a (logarithmic) width of ±0.3. The current data are consistent with an overall binary frequency of ∼24%.