Trigonometric parallaxes of ten ultracool subdwarfs

Abstract

We measured absolute trigonometric parallaxes and proper motions with respect to many background galaxies for a sample of ten ultracool subdwarfs. The observations were taken in the H-band with the OMEGA2000 camera at the 3.5m-telescope on Calar Alto, Spain during a time period of 3.5 years. For the first time, the reduction of the astrometric measurements was carried out directly with respect to background galaxies. We obtained absolute parallaxes with mean errors ranging between 1 and 3 mas. With six completely new parallaxes we more than doubled the number of benchmark ultracool (>sdM7) subdwarfs. Six stars in the M_{K_s} vs. J-K_s diagram fit perfectly to model subdwarf sequences from M7 to L4 with [M/H] between -1.0 and -1.5, whereas 4 are consistent with a moderately low metallicity ([M/H]=-0.5) from M7 to T6. All but one of our objects have large tangential velocities between 200 and 320 km/s typical of the Galactic halo population. Our results are in good agreement with recent independent measurements for three of our targets and confirm the previously measured parallax and absolute magnitude M_{K_s} of the nearest and coolest (T-type) subdwarf 2MASS 0937+29 with higher accuracy. For all targets, we also obtained infrared J,H,K_s photometry at a level of a few milli-magnitudes relative to 2MASS standards.

Letter 4 pages 1 figure. accepted by Astronomy and Astrophysics

References in corpus (27)

• The Sloan Digital Sky Survey: Technical Summary
• Evolutionary models for cool brown dwarfs and extrasolar giant planets. The case of HD 20945
• Color Transformations for the 2MASS Second Incremental Data Release
• The SuperCOSMOS Sky Survey. Paper I: Introduction and Description
• The Solar Neighborhood XVII: Parallax Results from the CTIOPI 0.9m Program -- Twenty New Members of the RECONS 10 Parsec Sample
• Preliminary Parallaxes of 40 L and T Dwarfs from the U.S. Naval Observatory Infrared Astrometry Program
• The Spectra of T Dwarfs I: Near-Infrared Data and Spectral Classification
• M-Subdwarfs: Spectroscopic Classification and the Metallicity Scale
• Revised metallicity classes for low-mass stars: dwarfs (dM), subdwarfs (sdM), extreme subdwarfs (esdM), and ultra subdwarfs (usdM)
• The First Substellar Subdwarf? Discovery of a Metal-poor L Dwarf with Halo Kinematics
• A Method for Determining the Physical Properties of the Coldest Known Brown Dwarfs
• 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
• The Spectra of T Dwarfs. II. Red Optical Data
• 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
• Optical Spectroscopy of 2MASS Color-Selected Ultracool Subdwarfs
• Discovery of a Second L Subdwarf in the Two Micron All Sky Survey
• 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
• LSR1610-0040: the first early-type L subdwarf
• Discovery of the Coolest Extreme Subdwarf
• Parallax and Luminosity Measurements of an L Subdwarf
• Discovery of an ultra-cool subdwarf: LSR1425+7102, first star with spectral type sdM8.0
• Twenty-three new ultra-cool subdwarfs from the Sloan Digital Sky Survey
• SSSPM J1444-2019: an extremely high proper motion, ultracool subdwarf
• Trigonometric Parallaxes for Two Late-Type Subdwarfs: LSR1425+71 (sdM8.0) and the Binary LSR1610-00 (sd?M6pec)
• The Schizophrenic Spectrum of LSR 1610-0040: a Peculiar M Dwarf/Subdwarf
• Halo Stars Near the Hydrogen-Burning Limit: The M/L Subdwarf Transition

Cited by in corpus (41)

• The Hawaii Infrared Parallax Program. I. Ultracool Binaries and the L/T Transition
• Further Defining Spectral Type "Y" and Exploring the Low-mass End of the Field Brown Dwarf Mass Function
• Fundamental Parameters and Spectral Energy Distributions of Young and Field Age Objects with Masses Spanning the Stellar to Planetary Regime
• Discoveries from a Near-infrared Proper Motion Survey using Multi-epoch 2MASS Data
• The Hawaii Infrared Parallax Program. II. Young Ultracool Field Dwarfs
• The Solar Neighborhood XLV. The Stellar Multiplicity Rate of M Dwarfs Within 25 pc
• The Solar Neighborhood XXXV: Distances to 1404 M Dwarf Systems Within 25 pc in the Southern Sky
• The AllWISE Motion Survey and The Quest for Cold Subdwarfs
• Photometry and Proper Motions of M, L, and T Dwarfs from the Pan-STARRS1 3$\pi$ Survey
• A Volume-Limited Sample of Ultracool Dwarfs. I. Construction, Space Density, and a Gap in the L/T Transition
• Epsilon Indi Ba, Bb: a detailed study of the nearest known brown dwarfs
• The AllWISE Motion Survey, Part 2
• Primeval very low-mass stars and brown dwarfs. I. Six new L subdwarfs, classification and atmospheric properties
• The discovery of a very cool binary system
• The Hawaii Infrared Parallax Program. IV. A Comprehensive Parallax Survey of L0-T8 dwarfs with UKIRT
• Trigonometric parallaxes of young field L dwarfs
• Secondary eclipse observations for seven hot-Jupiters from the Anglo-Australian Telescope
• The Benchmark Ultracool Subdwarf HD 114762B: A Test of Low-Metallicity Atmospheric and Evolutionary Models
• Characterization of High Proper Motion Objects from the Wide-field Infrared Survey Explorer
• Parallax measurements of cool brown dwarfs
• WISEA J041451.67-585456.7 and WISEA J181006.18-101000.5: The First Extreme T-type Subdwarfs?
• 2MASS J06164006-6407194: The First Outer Halo L Subdwarf
• SDSS J125637-022452: a high proper motion L subdwarf
• CCD Parallaxes for 309 Late-type Dwarfs and Subdwarfs
• A spectroscopic and proper motion search of Sloan digital Sky Survey: red subdwarfs in binary systems
• On the Origin and Evolution of Life in the Galaxy
• GTC Osiris spectroscopic identification of a faint L subdwarf in the UKIRT Infrared Deep Sky Survey
• New ultracool subdwarfs identified in large-scale surveys using Virtual Observatory tools: Part I: UKIDSS LAS DR5 vs SDSS DR7
• The 5 GHz Arecibo Search for Radio Flares from Ultracool Dwarfs
• 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
• Characterization of the Very Low Mass Secondary in the GJ 660.1AB System
• A 1500 deg${}^2$ Near Infrared Proper Motion Catalogue from the UKIDSS Large Area Survey
• The first retrieval of a substellar subdwarf: A cloud-free SDSS J125637.13-022452.4
• Understanding Fundamental Properties and Atmospheric Features of Subdwarfs via a Case Study of SDSS J125637.13-022452.4
• A search for lithium in metal-poor L dwarfs
• A non-uniform distribution of the nearest brown dwarfs
• 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
• An ancient F-type subdwarf from the halo crossing the Galactic plane
• The Low-Mass Astrometric Binary LSR1610-0040
• Discovery of a Possible Early-T Thick-Disk Subdwarf from the AllWISE2 Motion Survey
• Optical and Near-Infrared Spectroscopy of the L Subdwarf SDSS J125637.13-022452.4