Discovery of New Ultracool White Dwarfs in the Sloan Digital Sky Survey

Abstract

We report the discovery of five very cool white dwarfs in the Sloan Digital Sky Survey (SDSS). Four are ultracool, exhibiting strong collision induced absorption (CIA) from molecular hydrogen and are similar in color to the three previously known coolest white dwarfs, SDSS J1337+00, LHS 3250 and LHS 1402. The fifth, an ultracool white dwarf candidate, shows milder CIA flux suppression and has a color and spectral shape similar to WD 0346+246. All five new white dwarfs are faint (g > 18.9) and have significant proper motions. One of the new ultracool white dwarfs, SDSS J0947, appears to be in a binary system with a slightly warmer (T_{eff} ~ 5000K) white dwarf companion.

arXiv comment15 pages, 3 figures, submitted to ApJL. Higher resolution versions of finding charts are available at http://astro.uchicago.edu/~gates/findingcharts

References in corpus (21)

• The Sloan Digital Sky Survey: Technical Summary
• The Sloan Digital Sky Survey Photometric Camera
• The u'g'r'i'z' Standard Star Network
• The Second Data Release of the Sloan Digital Sky Survey
• Spectroscopic Target Selection in the Sloan Digital Sky Survey: The Quasar Sample
• The MACHO Project: Microlensing Results from 5.7 Years of LMC Observations
• The First Data Release of the Sloan Digital Sky Survey
• Astrometric Calibration of the Sloan Digital Sky Survey
• A photometricity and extinction monitor at the Apache Point Observatory
• A Catalog of Spectroscopically Identified White Dwarf Stars in the First Data Release of the Sloan Digital Sky Survey
• Direct Detection of Galactic Halo Dark Matter
• Pure hydrogen atmosphere for very cool white dwarfs
• Discovery of high proper motion ancient white dwarfs: nearby massive compact halo objects?
• A Very Low-Luminosity, Very Cool, DC White Dwarf
• Model Atmosphere Analysis of Two Very Cool White Dwarfs
• A New Very Cool White Dwarf Discovered by the Sloan Digital Sky Survey
• Observations of Ultracool White Dwarfs
• A new wide pair of cool white dwarfs in the Solar neighbourhood
• Cool White Dwarfs Revisited -- New Spectroscopy and Photometry
• Radiative transfer in the refractive atmospheres of very cool white dwarfs
• Discovery of an Ultracool White Dwarf Companion

Cited by in corpus (48)

• SDSS-III: Massive Spectroscopic Surveys of the Distant Universe, the Milky Way Galaxy, and Extra-Solar Planetary Systems
• The Sixth Data Release of the Sloan Digital Sky Survey
• SEGUE: A Spectroscopic Survey of 240,000 stars with g=14-20
• A Catalog of Spectroscopically Confirmed White Dwarfs from the Sloan Digital Sky Survey Data Release 4
• A $Gaia$ Data Release 2 catalogue of white dwarfs and a comparison with SDSS
• The White Dwarf Luminosity Function from SDSS Imaging Data
• On type Ia supernovae and the formation of single low-mass white dwarfs
• Cool DZ white dwarfs I: Identification and spectral analysis
• The Age of the Milky Way Inner Halo
• Cool White Dwarfs in the Sloan Digital Sky Survey
• Initial-Final Mass Relationship for Stars of Different Metallicities
• Fifteen new T dwarfs discovered in the UKIDSS Large Area Survey
• The spectrum of the recycled PSR J0437-4715 and its white dwarf companion
• Stars in the Hubble Ultra Deep Field
• Search for nearby stars among proper motion stars selected by optical-to-infrared photometry III. Spectroscopic distances of 322 NLTT stars
• The light curve of the companion to PSR B1957+20
• A Detailed Model Atmosphere Analysis of Cool White Dwarfs in the Sloan Digital Sky Survey
• On the Interpretation of High Velocity White Dwarfs as Members of the Galactic Halo
• The Most Massive White Dwarfs in the Solar Neighborhood
• A 1.05 $M_{\odot }$ Companion to PSR J2222-0137: The Coolest Known White Dwarf?
• Ultracool white dwarfs and the age of the Galactic disc
• Additional Ultracool White Dwarfs Found in the Sloan Digital Sky Survey
• New UltraCool and Halo White Dwarf Candidates in SDSS Stripe 82
• On the Nature of Ultracool White Dwarfs: Not so Cool Afterall
• Visitors from the Halo: 11 Gyr old White Dwarfs in the Solar Neighborhood
• On the Dissociation Equilibrium of H2 in Very Cool, Helium-Rich White Dwarf Atmospheres
• Spitzer Observations of the Oldest White Dwarfs in the Solar Neighborhood
• A Nearby Old Halo White Dwarf Candidate from the Sloan Digital Sky Survey
• The Mystery Deepens: Spitzer Observations of Cool White Dwarfs
• 11-12 Gyr old White Dwarfs 30 parsecs Away
• Extremely faint high proper motion objects from SDSS stripe 82 - Optical classification spectroscopy of about 40 new objects
• Structure and evolution of ultra-massive white dwarfs in general relativity
• Trigonometric parallaxes of high velocity halo white dwarf candidates
• Discovery of a nearby halo white dwarf with proper motion mu=2.55 arcsec/yr
• Infrared absorption of dense helium and its importance in the atmospheres of cool white dwarfs
• The First Mid-Infrared Spectra of Cool White Dwarfs
• Cool White Dwarfs Found in the UKIRT Infrared Deep Sky Survey
• Near-UV absorption in very cool DA white dwarfs
• The brightest pure-H ultracool white dwarf
• Photometric constraints on white dwarfs and the identification of extreme objects
• Spectroscopic confirmation of UV-bright white dwarfs from the Sandage Two-Color Survey of the Galactic Plane
• Cool White Dwarfs Identified in the Second Data Release of the UKIRT Infrared Deep Sky Survey
• New Halo White Dwarf Candidates in the Sloan Digital Sky Survey
• Cool Versus Ultracool White Dwarfs
• A New Ultracool White Dwarf Discovered in the SuperCOSMOS Sky Survey
• White dwarfs with hydrogen-deficient atmospheres and the dark matter content of the Galaxy
• An ultra-cool white dwarf serendipitously found with COMBO-17
• Search of nearby resolved neutron stars among optical sources