Spectroscopic classification and Gaia DR2 parallaxes of new nearby white dwarfs among selected blue proper motion stars

Abstract

AIMS: With our low-resolution spectroscopic observing program for selected blue proper motion stars, we tried to find new white dwarfs (WDs) in the solar neighbourhood. METHODS: We used the LSPM catalogue with a lower proper motion limit of 150mas/yr and the UCAC2 for proper motions down to about 90mas/yr. The LSPM and UCAC2 photometry was combined with Two Micron All Sky Survey (2MASS) near-infrared (NIR) photometry. Targets selected according to their blue optical-to-NIR and NIR colours were observed mainly at Calar Alto. The spectra were classified by comparison with a large number of already known comparison objects, including WDs, simultaneously observed within our program. Gaia DR2 parallaxes and colours were used to confirm or reject spectroscopic WD candidates and to derive improved effective temperatures. RESULTS: We found ten new WDs at distances between 24.4pc and 79.8pc, including six hot DA WDs: GD 221 (DA2.0), HD 166435 B (DA2.2), GD 277 (DA2.2), 2MASS J19293865+1117523 (DA2.4), 2MASS J05280449+4105253 (DA3.6), and 2MASS J05005185-0930549 (DA4.2). The latter is rather bright (G~12.6) and with its Gaia DR2 parallax of ~14mas it appears overluminous by about 3mag compared to the WD sequence in the Gaia DR2 colour-magnitude diagram. It may be the closest extremely low mass (ELM) WD to the Sun. We further classified 2MASS J07035743+2534184 as DB4.1. With its distance of 25.6pc it is the second nearest known representative of its class. With GD 28 (DA6.1), LP 740-47 (DA7.5), and LSPM J1919+4527 (DC10.3) three additional cool WDs were found. Gaia DR2 parallaxes showed us that four of our candidates but also two previously supposed WDs (WD 1004+665 and LSPM J1445+2527) are in fact distant Galactic halo stars with high tangential velocities. Among our rejected WD candidates, we identified a bright (G=13.4mag) G-type carbon dwarf, LSPM J0937+2803, at a distance of 272pc.

arXiv comment14 pages, 13 figures, accepted for publication in Astronomy and Astrophysics

References in corpus (58)

• The Sloan Digital Sky Survey: Technical Summary
• Gaia Data Release 2. Summary of the contents and survey properties
• Gaia Data Release 2: The astrometric solution
• The First Data Release (DR1) of the LAMOST general survey
• Gaia Data Release 1: Astrometry - one billion positions, two million proper motions and parallaxes
• The second US Naval Observatory CCD Astrograph Catalog (UCAC2)
• Revised Stellar Properties of Kepler Targets for the Quarter 1-16 Transit Detection Run
• A Catalog of Northern Stars With Annual Proper Motions Larger Than 0.15 Seconds of Arc (LSPM catalog - North)
• SDSS DR7 White Dwarf Catalog
• Spectroscopic Analysis of DA White Dwarfs: Stark Broadening of Hydrogen Lines Including Non-Ideal Effects
• A Spectroscopic Survey & Analysis of Bright, Hydrogen-Rich White Dwarfs
• The Sloan Digital Sky Survey Data Release 7 Spectroscopic M Dwarf Catalog I: Data
• New white dwarf and subdwarf stars in the Sloan Digital Sky Survey Data Release 12
• New white dwarf stars in the Sloan Digital Sky Survey Data Release 10
• Know Your Neighborhood: A Detailed Model Atmosphere Analysis of Nearby White Dwarfs
• All-Sky spectrally matched UBVRI-ZY and u'g'r'i'z' magnitudes for stars in the Tycho2 catalog
• The binarity of the local white dwarf population
• Cooling Models for Old White Dwarfs
• UCAC5: New Proper Motions using Gaia DR1
• The Gaia 20 pc white dwarf sample
• The Ages of the Thin Disk, Thick Disk, and the Halo from Nearby White Dwarfs
• The First U.S. Naval Observatory Robotic Astrometric Telescope Catalog (URAT1)
• Hot subdwarf binaries from the MUCHFUSS project - Analysis of 12 new systems and a study of the short-period binary population
• The ELM Survey. VII. Orbital Properties of Low Mass White Dwarf Binaries
• The Solar Neighborhood XLIV: RECONS Discoveries within 10 Parsecs
• Analysis of the carbon-rich very metal-poor dwarf G77-61
• Cool DZ white dwarfs I: Identification and spectral analysis
• The Solar Neighborhood. XXI. Parallax Results from the CTIOPI 0.9m Program: 20 New Members of the 25 Parsec White Dwarf Sample
• High-velocity white dwarfs: thick disk, not dark matter
• White Dwarf Cosmochronology in the Solar Neighborhood
• A survey for pulsating subdwarf B stars with the Nordic Optical Telescope
• Innocent Bystanders: Carbon Stars from the Sloan Digital Sky Survey
• Discovery of a Cool, Massive, and Metal-Rich DAZ White Dwarf
• Search for nearby stars among proper motion stars selected by optical-to-infrared photometry III. Spectroscopic distances of 322 NLTT stars
• The Gaia DR1 Mass-Radius Relation for White Dwarfs
• The nearest cool white dwarf (d~4pc), the coolest M-type subdwarf (sdM9.5), and other high proper motion discoveries
• The Solar Neighborhood. XXXIX. Parallax Results from the CTIOPI and NOFS Programs: 50 New Members of the 25 Parsec White Dwarf Sample
• The White Dwarfs within 25 Parsecs of the Sun: Kinematics and Spectroscopic Subtypes
• A study of high proper-motion white dwarfs I. Spectropolarimetry of a cool hydrogen-rich sample
• The Solar Neighborhood. XIX. Discovery and Characterization of 33 New Nearby White Dwarf Systems
• Toward a Spectroscopic Census of White Dwarfs Within 40 parsecs of the Sun
• Ultracool white dwarfs and the age of the Galactic disc
• White dwarfs and Galactic dark matter
• The sdA problem I: Physical Properties
• A Multi-Survey Approach to White Dwarf Discovery
• An Extreme-AO Search for Giant Planets around a White Dwarf --VLT/SPHERE performance on a faint target GD 50
• DA white dwarfs observed in LAMOST pilot survey
• Illuminating the darkness: More evidence from faint-star proper-motions for a cool and warm component to the local dark matter in the Galaxy
• Activity and Kinematics of White Dwarf-M Dwarf Binaries from the SUPERBLINK Proper Motion Survey
• The Core Composition of a White Dwarf in a Close Double Degenerate System
• A Spitzer Search for Substellar Companions to Low Mass White Dwarfs
• An ancient F-type subdwarf from the halo crossing the Galactic plane
• Distances of Dwarf Carbon Stars
• New nearby white dwarfs from Gaia DR1 TGAS and UCAC5/URAT
• Spectroscopic distances of 28 nearby star candidates
• The 1.17-day orbit of the double-degenerate (DA+DQ) NLTT 16249
• SSSPM J1549$-$3544 Is Not a White Dwarf
• Wolf 1465: Not a Bright Dwarf Carbon Star

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• The ELM Survey South. I. An Effective Search for Extremely Low Mass White Dwarfs
• The closest extremely low-mass white dwarf to the Sun