The nearest cool white dwarf (d~4pc), the coolest M-type subdwarf (sdM9.5), and other high proper motion discoveries

Abstract

We report the discovery of seven high proper motion stars with proper motions between about 0.7 and 2.2 arcsec/yr. They were detected in an archival search using multi-epoch positions in the optical SuperCOSMOS Sky Surveys and in the near-infrared sky surveys 2MASS and DENIS. The star with the largest proper motion, is spectroscopically classified as a very nearby (d=8pc) M5.5 dwarf with Galactic thin disk kinematics. A second star with about 2 arcsec/yr proper motion, is still lacking spectroscopic confirmation but can be classified from photometry as thick disk M3.5 dwarf. Three objects turn out to be cool subdwarf members of the Galactic thick disk or halo, including the first sdM9.5 object, which represents the currently coolest known M subdwarf, another ultra-cool subdwarf, of spectral type sdM7.0 as well as an earlier type (sdM1.5) star. The latter has an extremely large space velocity with clear halo kinematics. Two objects show featureless spectra typical of cool white dwarfs. One of them is probably a very nearby (d~4pc) thin disk object and may be the nearest isolated white dwarf, the other one has thick disk kinematics.

arXiv comment9 pages, 4 figures, accepted for publication in Astronomy and Astrophysics

References in corpus (21)

• Kinematics of Metal-Poor Stars in the Galaxy. III. Formation of the Stellar Halo and Thick Disk as Revealed from a Large Sample of Non-Kinematically Selected Stars
• The SuperCOSMOS Sky Survey. Paper I: Introduction and Description
• M-Subdwarfs: Spectroscopic Classification and the Metallicity Scale
• Direct Detection of Galactic Halo Dark Matter
• The SuperCOSMOS Sky Survey. Paper II: Image detection, parameterisation, classification and photometry
• The First Substellar Subdwarf? Discovery of a Metal-poor L Dwarf with Halo Kinematics
• The SuperCOSMOS Sky Survey. Paper III: Astrometry
• Epsilon Indi Ba/Bb: the nearest binary brown dwarf
• 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
• Epsilon Indi B: a new benchmark T dwarf
• Meeting the Cool Neighbors III: Spectroscopy of Northern NLTT Stars
• Discovery of high proper motion ancient white dwarfs: nearby massive compact halo objects?
• The Solar Neighborhood VIII: Discovery of New High Proper Motion Nearby Stars Using the SuperCOSMOS Sky Survey
• Discovery of a New Nearby Star
• Probing the LHS Catalog. I. New Nearby Stars and the Coolest Subdwarf
• LSR1610-0040: the first early-type L subdwarf
• Discovery of an ultra-cool subdwarf: LSR1425+7102, first star with spectral type sdM8.0
• The Subdwarf Luminosity Function
• M Subdwarfs: The Population II Luminosity Function
• A new wide pair of cool white dwarfs in the Solar neighbourhood
• Discovery of an M8.5 Dwarf With Proper Motion mu=2.38 arcsec/yr

Cited by in corpus (51)

• The Hawaii Infrared Parallax Program. I. Ultracool Binaries and the L/T Transition
• Revised metallicity classes for low-mass stars: dwarfs (dM), subdwarfs (sdM), extreme subdwarfs (esdM), and ultra subdwarfs (usdM)
• 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
• Optical Spectroscopy of 2MASS Color-Selected Ultracool Subdwarfs
• A Volume-Limited Sample of Ultracool Dwarfs. I. Construction, Space Density, and a Gap in the L/T Transition
• Discovery of a Second L Subdwarf in the Two Micron All Sky Survey
• The AllWISE Motion Survey, Part 2
• 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
• New insight into the magnetism of degenerate stars from the analysis of a volume limited sample of white dwarfs
• Spectroscopic classification of red high proper motion objects in the Southern Sky
• Primeval very low-mass stars and brown dwarfs. I. Six new L subdwarfs, classification and atmospheric properties
• An Infrared High Proper Motion Survey Using 2MASS and SDSS: Discovery of M, L and T Dwarfs
• Search for nearby stars among proper motion stars selected by optical-to-infrared photometry III. Spectroscopic distances of 322 NLTT stars
• New Neighbors: Parallaxes of 18 nearby stars selected from the LSPM-north catalog
• Discovery of the Coolest Extreme Subdwarf
• The Benchmark Ultracool Subdwarf HD 114762B: A Test of Low-Metallicity Atmospheric and Evolutionary Models
• A high resolution spectroscopic atlas of M subdwarfs - Effective temperature and metallicity
• New High Proper Motion Stars from the Digitized Sky Survey. IV. Completion of the Southern Survey and 170 Additional Stars with pm>0.45 arcsec/yr
• Twenty-three new ultra-cool subdwarfs from the Sloan Digital Sky Survey
• Trigonometric parallaxes of ten ultracool subdwarfs
• The First High-Resolution Spectra of 1.3 L Subdwarfs
• SSSPM J1444-2019: an extremely high proper motion, ultracool subdwarf
• The Solar Neighborhood XV: Discovery of New High Proper Motion Stars with mu >= 0.4"/yr between Declinations -47 degrees and 00 degrees
• Primeval very low-mass stars and brown dwarfs - IV. New L subdwarfs, Gaia astrometry, population properties, and a blue brown dwarf binary
• Primeval very low-mass stars and brown dwarfs - II. The most metal-poor substellar object
• The Solar Neighborhood XII: Discovery of New High Proper Motion Stars with 1.0"/yr > mu >= 0.4"/yr between Declinations -90 degrees and -47 degrees
• CCD Parallaxes for 309 Late-type Dwarfs and Subdwarfs
• New ultracool subdwarfs identified in large-scale surveys using Virtual Observatory tools: Part I: UKIDSS LAS DR5 vs SDSS DR7
• A spectroscopic and proper motion search of Sloan digital Sky Survey: red subdwarfs in binary systems
• Optical spectroscopy of high proper motion stars: new M dwarfs within 10 pc and the closest pair of subdwarfs
• A Reanalysis of the Fundamental Parameters and Age of TRAPPIST-1
• 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
• Spectroscopic Follow-Up of Discoveries from the NEOWISE Proper Motion Survey
• Extremely faint high proper motion objects from SDSS stripe 82 - Optical classification spectroscopy of about 40 new objects
• Halo Stars Near the Hydrogen-Burning Limit: The M/L Subdwarf Transition
• Parallaxes of southern extremely cool objects III: 118 L \& T dwarfs
• Understanding Fundamental Properties and Atmospheric Features of Subdwarfs via a Case Study of SDSS J125637.13-022452.4
• Stars Outside the Hipparcos List Closely Encountering the Solar System
• 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
• Spectroscopic confirmation of UV-bright white dwarfs from the Sandage Two-Color Survey of the Galactic Plane
• Astrophysics in 2005
• An extremely wide and very low-mass pair with common proper motion. Is it representative of a nearby halo stream?
• SSSPM J1549$-$3544 Is Not a White Dwarf
• One of Everything: The Breakthrough Listen Exotica Catalog
• Spectroscopic classification and Gaia DR2 parallaxes of new nearby white dwarfs among selected blue proper motion stars
• Metal-Depleted Brown Dwarfs
• Optical and Near-Infrared Spectroscopy of the L Subdwarf SDSS J125637.13-022452.4
• 2MASS J06562998+3002455: Not a Cool White Dwarf Candidate, but a Population II Halo Star