A Spectroscopic Binary at the M/L Transition

Abstract

We report the discovery of a single-lined spectroscopic binary with an Ultra Cool Dwarf (UCD) primary with a spectral type between M8 and L0.5. This system was discovered during the course of an ongoing survey to monitor L dwarfs for radial velocity variations and is the first known small separation (a<1 AU) spectroscopic binary among dwarfs at the M/L transition. Based on radial-velocity measurements with a typical precision of 300 m/s we estimate the orbital parameters of this system to be P=246.73+/-0.49 d, a1 sin(i)=0.159+/-0.003 AU, M2 sin(i)=0.2062 (M1+M2)^(2/3)+/-0.0034 M_{\sun}. Assuming a primary mass of M1=0.08M_{\sun} (based on spectral type), we estimate the secondary minimum mass to be M2 sin(i)=0.054 M_{\sun}. With future photometric, spectroscopic, and interferometric observations it may be possible to determine the dynamical masses of both components directly, making this system one of the best characterized UCD binaries known.

11 pages, 2 figures. Accepted for publication in ApJ Letters

References in corpus (15)

• Evolutionary models for cool brown dwarfs and extrasolar giant planets. The case of HD 20945
• Precipitating Condensation Clouds in Substellar Atmospheres
• Line and Mean Opacities for Ultracool Dwarfs and Extrasolar Planets
• L' and M' Photometry of Ultracool Dwarfs
• Meeting the Cool New Neighbors V: A 2MASS-Selected Sample of Ultracool Dwarfs
• Clouds and Chemistry: Ultracool Dwarf Atmospheric Properties from Optical and Infrared Colors
• An Effective Temperature Scale for Late M and L Dwarfs, from Resonance Absorption Lines of CsI and RbI
• A Survey for Spectroscopic Binaries Among Very Low-Mass Stars
• The orbit of the brown dwarf binary Gl 569B
• First determination of the dynamical mass of a binary L dwarf
• Southern Infrared Proper Motion Survey I: Discovery of New High Proper Motion Stars From First Full Hemisphere Scan
• Multiepoch Radial Velocity Observations of L Dwarfs
• SDSS J080531.84+481233.0: An Unresolved L Dwarf/T Dwarf Binary
• Companions of old brown dwarfs, and very low mass stars
• 16-20 Jupiter mass RV companion orbiting the brown dwarf candidate ChaHa8

Cited by in corpus (37)

• Gaia Data Release 3: Stellar multiplicity, a teaser for the hidden treasure
• The NIRSPEC Ultracool Dwarf Radial Velocity Survey
• The Solar Neighborhood XLV. The Stellar Multiplicity Rate of M Dwarfs Within 25 pc
• SpeX Spectroscopy of Unresolved Very Low Mass Binaries. II. Identification of Fourteen Candidate Binaries with Late-M/Early-L and T Dwarf Components
• On the Distribution of Orbital Eccentricities for Very Low-Mass Binaries
• A Volume-Limited Sample of Ultracool Dwarfs. I. Construction, Space Density, and a Gap in the L/T Transition
• A Young Planet Search in Visible and IR Light: DN Tau, V836 Tau, and V827 Tau
• Kepler Monitoring of an L Dwarf I. The Photometric Period and White Light Flares
• The Hawaii Infrared Parallax Program. IV. A Comprehensive Parallax Survey of L0-T8 dwarfs with UKIRT
• Astrometric orbit of a low-mass companion to an ultracool dwarf
• Near Infrared Monitoring of Ultracool Dwarfs: Prospects for Searching for Transiting Companions
• The Ultracool SpeXtroscopic Survey. I. Volume-Limited Spectroscopic Sample and Luminosity Function of M7$-$L5 Ultracool Dwarfs
• WISE J072003.20-084651.2: An Old and Active M9.5 + T5 Spectral Binary 6 pc from the Sun
• Discovery of a Very Low Mass Triple with Late-M and T Dwarf Components: LP 704-48/SDSS J0006-0852AB
• A Search for Photometric Variability in L and T type Brown Dwarf Atmospheres
• Detectability of Transiting Jupiters and Low-Mass Eclipsing Binaries in Sparsely Sampled Pan-STARRS-1 Survey Data
• The MEarth project: searching for transiting habitable super-Earths around nearby M-dwarfs
• High Resolution Imaging of Very Low Mass Spectral Binaries: Three Resolved Systems and Detection of Orbital Motion in an L/T Transition Binary
• The 3-D Kinematics of the Orion Nebula Cluster: NIRSPEC-AO Radial Velocities of the Core Population
• Hubble Space Telescope Imaging and Spectral Analysis of Two Brown Dwarf Binaries at the L Dwarf/T Dwarf Transition
• T-Lyr1-17236: A Long-Period Low-Mass Eclipsing Binary
• The Orbit of the L dwarf + T dwarf Spectral Binary SDSS J080531.84+481233.0
• 2MASS J20261584-2943124: An Unresolved L0.5 + T6 Spectral Binary
• Radial Velocity Variability of Field Brown Dwarfs
• Improved radial velocity orbit of the young binary brown dwarf candidate ChaHa8
• An Age Constraint for the Very Low-Mass Stellar/Brown Dwarf Binary 2MASS J03202839-0446358AB
• Astrometric orbits of spectral binary brown dwarfs I: Massive T dwarf companions to 2M1059$-$21 and 2M0805$+$48
• CWISE J014611.20-050850.0AB: The Widest Known Brown Dwarf Binary in the Field
• Brown Dwarfs as Galactic Chronometers
• The 3D Kinematics of the Orion Nebula Cluster II: Mass-dependent Kinematics of the Inner Cluster
• Orbit of the young very low-mass spectroscopic binary CHXR 74
• The absolute magnitudes $M_J$, the binary fraction, and the binary mass ratios of M7 to M9.5 dwarfs
• CFBDS J111807-064016: A new L/T transition brown dwarf in a binary system
• The L dwarf/T dwarf transition: multiplicity, magnetic activity and mineral meteorology across the hydrogen burning limit
• The Brown Dwarf Kinematics Project (BDKP). V. Radial and Rotational Velocities of T Dwarfs from Keck/NIRSPEC High-Resolution Spectroscopy
• SpeX Spectroscopy of Unresolved Very Low-Mass Binaries. I. Identification of Seventeen Candidate Binaries Straddling the L Dwarf/T Dwarf Transition
• Testing Models with Brown Dwarf Binaries