11-12 Gyr old White Dwarfs 30 parsecs Away

Abstract

We present a detailed model atmosphere analysis of two of the oldest stars known in the solar neighborhood, the high proper motion white dwarfs SDSS J110217.48+411315.4 (hereafter J1102) and WD 0346+246 (hereafter WD0346). We present trigonometric parallax observations of J1102, which places it at a distance of only 33.7 +- 2.0 pc. Based on the state of the art model atmospheres, optical, near-, mid-infrared photometry, and distances, we constrain the temperatures, atmospheric compositions, masses, and ages for both stars. J1102 is an 11 Gyr old (white dwarf plus main-sequence age), 0.62 Msol white dwarf with a pure H atmosphere and Teff = 3830 K. WD0346 is an 11.5 Gyr old, 0.77 Msol white dwarf with a mixed H/He atmosphere and Teff = 3650 K. Both stars display halo kinematics and their ages agree remarkably well with the ages of the nearest globular clusters, M4 and NGC 6397. J1102 and WD0346 are the closest examples of the oldest halo stars that we know of.

MNRAS Letters, in press

References in corpus (15)

• Found: The missing blue opacity in atmosphere models of cool hydrogen white dwarfs
• Discovery of HE 1523-0901, a Strongly r-Process Enhanced Metal-Poor Star with Detected Uranium
• The initial-final mass relationship of white dwarfs revisited: effect on the luminosity function and mass distribution
• Know Your Neighborhood: A Detailed Model Atmosphere Analysis of Nearby White Dwarfs
• The White Dwarf Cooling Sequence of NGC6397
• Hypervelocity Stars: From the Galactic Center to the Halo
• The spectrum of the recycled PSR J0437-4715 and its white dwarf companion
• First Results from Pan-STARRS1: Faint, High Proper Motion White Dwarfs in the Medium-Deep Fields
• A Deep, Wide-Field, and Panchromatic View of 47 Tuc and the SMC with HST: Observations and Data Analysis Methods
• Parallax and Distance Estimates for Twelve Cataclysmic Variable Stars
• Additional Ultracool White Dwarfs Found in the Sloan Digital Sky Survey
• A Nearby Old Halo White Dwarf Candidate from the Sloan Digital Sky Survey
• Direct Distance Measurement to the Dusty White Dwarf GD 362
• The First Mid-Infrared Spectra of Cool White Dwarfs
• The Pseudo-continuum Bound-free Opacity of Hydrogen and its Importance in Cool White Dwarf Atmospheres

Cited by in corpus (21)

• Co-formation of the Galactic disc and the stellar halo
• The Ages of the Thin Disk, Thick Disk, and the Halo from Nearby White Dwarfs
• A New Generation of Cool White Dwarf Atmosphere Models. IV. Revisiting the Spectral Evolution of Cool White Dwarfs
• The Age of the Galactic Stellar Halo from Gaia White Dwarfs
• Uncertain Times: The Redshift-Time Relation from Cosmology and Stars
• Probing primordial non-Gaussianity via iSW measurements with SKA continuum surveys
• A 1.05 $M_{\odot }$ Companion to PSR J2222-0137: The Coolest Known White Dwarf?
• The Gaia DR2 halo white dwarf population: the luminosity function, mass distribution and its star formation history
• Ultracool white dwarfs and the age of the Galactic disc
• The sdA problem I: Physical Properties
• Using Gaia DR2 to solve differential color refraction and charge transfer efficiency issues
• Constraints on Relic Magnetic Black Holes
• The ultracool helium-atmosphere white dwarf companion of PSR J0740+6620?
• Near-UV absorption in very cool DA white dwarfs
• First discovery of an ultra-cool white dwarf benchmark in common proper motion with an M dwarf
• A Hierarchical Model for the Ages of Galactic Halo White Dwarfs
• An Astrometric Approach to Measuring the Color of an Object
• The Next Generation Virgo Cluster Survey. XXVIII. Characterization of the Galactic White Dwarf Population
• One of Everything: The Breakthrough Listen Exotica Catalog
• Complex hydrogen chemical equilibrium and Gaia low mass problem in cool white dwarfs
• Revisiting constraints on asymmetric dark matter from collapse in white dwarf stars