The First Substellar Subdwarf? Discovery of a Metal-poor L Dwarf with Halo Kinematics

Abstract

We present the discovery of the first L-type subdwarf, 2MASS J05325346+8246465. This object exhibits enhanced collision-induced H${}_2$ absorption, resulting in blue NIR colors ($J-K_s=0.26\pm 0.16$). In addition, strong hydride bands in the red optical and NIR, weak TiO absorption, and an optical/J-band spectral morphology similar to the L7 DENIS 0205$-$1159AB imply a cool, metal-deficient atmosphere. We find that 2MASS 0532+8246 has both a high proper motion, $\mu$ = 2$\farcs60\pm0\farcs$15 yr${}^{-1}$, and a substantial radial velocity, $v_{rad}=-195\pm 11$ km s${}^{-1}$, and its probable proximity to the Sun (d = 10--30 pc) is consistent with halo membership. Comparison to subsolar-metallicity evolutionary models strongly suggests that 2MASS 0532+8246 is substellar, with a mass of 0.077 $\lesssim$ M $\lesssim$ 0.085 M$_{\sun}$ for ages 10--15 Gyr and metallicities $Z=0.1-0.01$ $Z_{\sun}$. The discovery of this object clearly indicates that star formation occurred below the Hydrogen burning mass limit at early times, consistent with prior results indicating a flat or slightly rising mass function for the lowest-mass stellar subdwarfs. Furthermore, 2MASS 0532+8246 serves as a prototype for a new spectral class of subdwarfs, additional examples of which could be found in NIR proper motion surveys.

arXiv comment9 pages, 3 figures, accepted to ApJ

References in corpus (29)

• The Sloan Digital Sky Survey: Technical Summary
• The u'g'r'i'z' Standard Star Network
• Local stellar kinematics from Hipparcos data
• The Theory of Brown Dwarfs and Extrasolar Giant Planets
• Astrometry and Photometry for Cool Dwarfs and Brown Dwarfs
• New Neighbors from 2MASS: Activity and Kinematics at the Bottom of the Main Sequence
• Towards Spectral Classification of L and T Dwarfs: Infrared and Optical Spectroscopy and Analysis
• The Spectra of T Dwarfs I: Near-Infrared Data and Spectral Classification
• M-Subdwarfs: Spectroscopic Classification and the Metallicity Scale
• Infrared Spectra and Spectral Energy Distributions of Late-M- and L-Dwarfs
• An Effective Temperature Scale for Late M and L Dwarfs, from Resonance Absorption Lines of CsI and RbI
• L Dwarfs and the Substellar Mass Function
• Spectral Energy Distributions for Disk and Halo M--Dwarfs
• Line Intensities and Molecular Opacities of the FeH $F^4{\Delta }_i-X^4{\Delta }_i$ Transition
• Spectroscopy of New High Proper Motion Stars in the Northern Sky. I. New Nearby Stars, New High Velocity Stars, and an Enhanced Classification Scheme for M Dwarfs
• High resolution spectroscopy of ultracool M dwarfs
• L Dwarfs Found in Sloan Digital Sky Survey Commissioning Imaging Data
• The Galactic disk mass-budget : II. Brown dwarf mass-function and density
• New High Proper Motion Stars from the Digitized Sky Survey. I. Northern Stars with proper motion between 0.5 and 2.0 arcsec/yr at Low Galactic Latitudes
• The 2MASS Wide-Field T Dwarf Search. I. Discovery of a Bright T Dwarf Within 10 pc of the Sun
• Revised Coordinates and Proper Motions of the Stars in the Luyten Half-Second Catalogue
• FeH Absorption in the Near-Infrared Spectra of Late M and L Dwarfs
• Probing the LHS Catalog. I. New Nearby Stars and the Coolest Subdwarf
• K-Band Spectra and Narrowband Photometry of DENIS Field Brown Dwarfs
• An Improved Red Spectrum of the Methane or T-dwarf SDSS 1624+0029: Role of the Alkali Metals
• Discovery of an ultra-cool subdwarf: LSR1425+7102, first star with spectral type sdM8.0
• M Subdwarfs: The Population II Luminosity Function
• L-Band Photometry of L and T Dwarfs
• Near-Infrared Spectroscopy of Brown Dwarfs: Methane and the Transition between the L and T Spectral Types

Cited by in corpus (126)

• Near-Infrared Photometry and Spectroscopy of L and T Dwarfs: the Effects of Temperature, Clouds, and Gravity
• The 2MASS Wide-Field T Dwarf Search. III. Seven New T Dwarfs and Other Cool Dwarf Discoveries
• Discoveries from a Near-infrared Proper Motion Survey using Multi-epoch 2MASS Data
• Meeting the Cool Neighbors. IX. The Luminosity Function of M7-L8 Ultracool Dwarfs in the Field
• The Brown Dwarf Kinematics Project (BDKP) I. Proper Motions and Tangential Velocities for a Large Sample of Late-type M, L and T Dwarfs
• The Brown Dwarf Kinematics Project (BDKP). III. Parallaxes for 70 Ultracool Dwarfs
• A Sample of Very Young Field L Dwarfs and Implications for the Brown Dwarf "Lithium Test" at Early Ages
• Discovery of a Very Young Field L Dwarf, 2MASS J01415823-4633574
• Revised metallicity classes for low-mass stars: dwarfs (dM), subdwarfs (sdM), extreme subdwarfs (esdM), and ultra subdwarfs (usdM)
• A Method for Determining the Physical Properties of the Coldest Known Brown Dwarfs
• Spitzer/IRAC Photometry of M, L, and T Dwarfs
• The Spectra of T Dwarfs. II. Red Optical Data
• The Planetary Mass Companion 2MASS1207-3932 B: Temperature, Mass and Evidence for an Edge-On Disk
• Discovery of Two Nearby, Peculiar L Dwarfs from the 2MASS Proper Motion Survey: Young or Metal-Rich?
• 2MASSJ035523.51+113337.4: A Young, Dusty, Nearby, Isolated Brown Dwarf Resembling A Giant Exoplanet
• The Extreme Microlensing Event OGLE-2007-BLG-224: Terrestrial Parallax Observation of a Thick-Disk Brown Dwarf
• VIRAC: The VVV Infrared Astrometric Catalogue
• The AllWISE Motion Survey and The Quest for Cold Subdwarfs
• Clouds, Gravity and Metallicity in Blue L dwarfs: The Case of 2MASS J11263991-5003550
• New H2 collision-induced absorption and NH3 opacity and the spectra of the coolest brown dwarfs
• A Cross-Match of 2MASS and SDSS: Newly-Found L and T Dwarfs and an Estimate of the Space Densitfy of T Dwarfs
• Dust in brown dwarfs and extra-solar planets II. Cloud formation for cosmologically evolving abundances
• Photometry and Proper Motions of M, L, and T Dwarfs from the Pan-STARRS1 3$\pi$ Survey
• Atmospheres from very low-mass stars to extrasolar planets
• Clouds in the Coldest Brown Dwarfs: FIRE Spectroscopy of Ross 458C
• Finding benchmark brown dwarfs to probe the IMF as a function of time
• Optical Spectroscopy of 2MASS Color-Selected Ultracool Subdwarfs
• 2MASS J05185995-2828372: Discovery of an Unresolved L/T Binary
• Discovery of a Second L Subdwarf in the Two Micron All Sky Survey
• Physical Properties of Young Brown Dwarfs and Very Low-Mass Stars Inferred from High-Resolution Model Spectra
• A Possible Brown Dwarf Companion to the White Dwarf GD1400
• Deep ACS Imaging in the Globular Cluster NGC 6397: The Cluster Color Magnitude Diagram and Luminosity Function
• Atmospheres of Brown Dwarfs
• Discovery of an Unusually Red L-type Brown Dwarf
• The NIRSPEC Brown Dwarf Spectroscopic Survey II: High-Resolution J-Band Spectra of M, L and T Dwarfs
• Spectroscopic Constants, Abundances, and Opacities of the TiH Molecule
• CFBDSIR2149-0403: a 4-7 Jupiter-mass free-floating planet in the young moving group AB Doradus ?
• Ultracool Dwarfs Observed with the Spitzer Infrared Spectrograph. II. Emergence and Sedimentation of Silicate Clouds in L Dwarfs, and Analysis of the Full M5--T9 Field Dwarf Spectroscopic Sample
• Finding ultracool brown dwarfs with MegaCam on CFHT: method and first results
• Nearby M, L, and T Dwarfs Discovered by the Wide-field Infrared Survey Explorer (WISE)
• The discovery of a very cool binary system
• Primeval very low-mass stars and brown dwarfs. I. Six new L subdwarfs, classification and atmospheric properties
• Spectroscopic classification of red high proper motion objects in the Southern Sky
• The ultracool-field dwarf luminosity-function and space density from the Canada-France Brown Dwarf Survey
• Molecular astronomy of cool stars and sub-stellar objects
• Cool Subdwarf Investigations (CSI) I: New Thoughts for the Spectral Types of K and M Subdwarfs
• The nearest cool white dwarf (d~4pc), the coolest M-type subdwarf (sdM9.5), and other high proper motion discoveries
• SDSS J141624.08+134826.7: A Nearby Blue L Dwarf From the Sloan Digital Sky Survey
• The 2MASS Wide-Field T Dwarf Search. II. Discovery of Three T Dwarfs in the Southern Hemisphere
• Surface Gravities for 228 M, L, and T Dwarfs in the NIRSPEC Brown Dwarf Spectroscopic Survey
• Extending the Canada-France brown Dwarfs Survey to the near-infrared: first ultracool brown dwarfs from CFBDSIR
• New, nearby bright southern ultracool dwarfs
• Discovery of the Coolest Extreme Subdwarf
• The Ultracool SpeXtroscopic Survey. I. Volume-Limited Spectroscopic Sample and Luminosity Function of M7$-$L5 Ultracool Dwarfs
• SDSS J080531.84+481233.0: An Unresolved L Dwarf/T Dwarf Binary
• A Targeted Search for Peculiarly Red L and T Dwarfs in SDSS, 2MASS, and WISE: Discovery of a Possible L7 Member of the TW Hydrae Association
• The sub-stellar birth rate from UKIDSS
• Parallax and Luminosity Measurements of an L Subdwarf
• Photometric brown-dwarf classification. II. A homogeneous sample of 1361 L and T dwarfs brighter than J = 17.5 with accurate spectral types
• Proper motions of field L and T dwarfs
• Discovery of a nearby L-T transition object in the Southern Galactic plane
• A high resolution spectroscopic atlas of M subdwarfs - Effective temperature and metallicity
• Blue not brown: UKIDSS T dwarfs with suppressed K-band flux
• Radii of 88 M Subdwarfs and Updated Radius Relations for Low-Metallicity M Dwarf Stars
• Photometric brown-dwarf classification. I. A method to identify and accurately classify large samples of brown dwarfs without spectroscopy
• Twenty-three new ultra-cool subdwarfs from the Sloan Digital Sky Survey
• Trigonometric parallaxes of ten ultracool subdwarfs
• Primeval very low-mass stars and brown dwarfs - VI. Population properties of metal-poor degenerate brown dwarfs
• WISEA J041451.67-585456.7 and WISEA J181006.18-101000.5: The First Extreme T-type Subdwarfs?
• The First High-Resolution Spectra of 1.3 L Subdwarfs
• Discovery of a 66 mas Ultracool Binary with Laser Guide Star Adaptive Optics
• Retrieval of SDSS J1416+1348AB
• SSSPM J1444-2019: an extremely high proper motion, ultracool subdwarf
• Primeval very low-mass stars and brown dwarfs - II. The most metal-poor substellar object
• Primeval very low-mass stars and brown dwarfs - IV. New L subdwarfs, Gaia astrometry, population properties, and a blue brown dwarf binary
• A Search for Photometric Variability in L and T type Brown Dwarf Atmospheres
• Brown dwarf census with the Dark Energy Survey year 3 data and the thin disk scale height of early L types
• Trigonometric Parallaxes for Two Late-Type Subdwarfs: LSR1425+71 (sdM8.0) and the Binary LSR1610-00 (sd?M6pec)
• 2MASS J06164006-6407194: The First Outer Halo L Subdwarf
• A Brown Dwarf Census from the SIMP Survey
• SDSS J125637-022452: a high proper motion L subdwarf
• GTC Osiris spectroscopic identification of a faint L subdwarf in the UKIRT Infrared Deep Sky Survey
• A spectroscopic and proper motion search of Sloan digital Sky Survey: red subdwarfs in binary systems
• New ultracool subdwarfs identified in large-scale surveys using Virtual Observatory tools: Part I: UKIDSS LAS DR5 vs SDSS DR7
• The Schizophrenic Spectrum of LSR 1610-0040: a Peculiar M Dwarf/Subdwarf
• Mapping the Local Halo: Statistical Parallax Analysis of SDSS Low-Mass Subdwarfs
• A Reanalysis of the Fundamental Parameters and Age of TRAPPIST-1
• The discovery of a T6.5 subdwarf
• New ultracool subdwarfs identified in large-scale surveys using Virtual Observatory tools: II. SDSS DR7 vs UKIDSS LAS DR6, SDSS DR7 vs UKIDSS LAS DR8, SDSS DR9 vs UKIDSS LAS DR10, and SDSS DR7 vs 2MASS
• Early results from GLASS-JWST. XIII. A faint, distant, and cold brown dwarf
• Characterization of the Very Low Mass Secondary in the GJ 660.1AB System
• Extremely faint high proper motion objects from SDSS stripe 82 - Optical classification spectroscopy of about 40 new objects
• Infrared and kinematic properties of the substellar object G 196-3B
• Halo Stars Near the Hydrogen-Burning Limit: The M/L Subdwarf Transition
• Resolved Spectroscopy of M Dwarf/L Dwarf Binaries. IV. Discovery of an M9 + L6 BInary Separated by Over 100 AU
• Primeval very low-mass stars and brown dwarfs - III. The halo transitional brown dwarfs
• The HST large programme on $\omega$ Centauri -- V. Exploring the Ultracool Dwarf Population with Stellar Atmosphere and Evolutionary Modelling
• The first retrieval of a substellar subdwarf: A cloud-free SDSS J125637.13-022452.4
• Physical properties and trigonometric distance of the peculiar dwarf WISE J181005.5$-$101002.3
• Beyond the Local Volume. I. Surface Densities of Ultracool Dwarfs in Deep HST/WFC3 Parallel Fields
• Parallaxes of southern extremely cool objects III: 118 L \& T dwarfs
• Resolved Spectroscopy of M Dwarf/L Dwarf Binaries. III. The "Wide" L3.5/L4 Dwarf Binary 2MASS J15500845+1455180AB
• Understanding Fundamental Properties and Atmospheric Features of Subdwarfs via a Case Study of SDSS J125637.13-022452.4
• Hunting for Brown Dwarfs in the Globular Cluster M4: 2nd epoch HST NIR observations
• Deep near-IR observations of the Globular Cluster M4: Hunting for Brown Dwarfs
• HE 0017+0055 : A probable pulsating CEMP-rs star and long-period binary
• A search for lithium in metal-poor L dwarfs
• Primeval very low-mass stars and brown dwarfs -- VII. The discovery of the first wide M + L extreme subdwarf binary
• The Solar Neighborhood XLII. Parallax Results from the CTIOPI 0.9-m Program --- Identifying New Nearby Subdwarfs Using Tangential Velocities and Locations on the H-R Diagram
• Beyond the Local Volume. II. Population Scaleheights and Ages of Ultracool Dwarfs in Deep HST/WFC3 Parallel Fields
• Silicate Precursor Silane detected in Cold Low-Metallicity Brown Dwarf
• A Comparative L-dwarf Sample Exploring the Interplay Between Atmospheric Assumptions and Data Properties
• Primeval very low-mass stars and brown dwarfs - V. A halo L3 subdwarf with prograde eccentric orbit in the Galactic plane
• Brown Dwarfs as Galactic Chronometers
• Discovery of a Possible Early-T Thick-Disk Subdwarf from the AllWISE2 Motion Survey
• Primeval very low-mass stars and brown dwarfs -- VIII. The first age benchmark L subdwarf, a wide companion to a halo white dwarf
• Optical constraints on the coldest metal-poor population
• Optical Properties of Metal-poor T Dwarf Candidates
• The brown dwarf population in the star forming region NGC2264
• Large Scale Searches for Brown Dwarfs and Free-Floating Planets
• Probing Late-type T dwarf J-H Color Outliers for Signs of Age
• The L dwarf/T dwarf transition: multiplicity, magnetic activity and mineral meteorology across the hydrogen burning limit
• A review on substellar objects beyond the deuterium burning mass limit: planets, brown dwarfs or what?
• Metal-Depleted Brown Dwarfs
• Optical and Near-Infrared Spectroscopy of the L Subdwarf SDSS J125637.13-022452.4
• SpeX Spectroscopy of Unresolved Very Low-Mass Binaries. I. Identification of Seventeen Candidate Binaries Straddling the L Dwarf/T Dwarf Transition