New ultracool and halo white dwarf candidates in SDSS Stripe 82

S. Vidrih, D. M. Bramich, P. C. Hewett, N. W. Evans, G. Gilmore, S. Hodgkin, M. Smith, L. Wyrzykowski, V. Belokurov, M. Fellhauer, M. J. Irwin, R. G. McMahon, D. Zucker, J. A. Munn, H. Lin, G. Miknaitis, H. C. Harris, R. H. Lupton, D. P. Schneider

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A 2°.5 × 100° region along the celestial equator (Stripe 82) has been imaged repeatedly from 1998 to 2005 by the Sloan Digital Sky Survey (SDSS). A new catalogue of ∼4 million light-motion curves, together with over 200 derived statistical quantities, for objects in Stripe 82 brighter than r ∼21.5 has been constructed by combining these data by Bramich et al. This catalogue is at present the deepest catalogue of its kind. Extracting ∼130 000 objects with highest signal-to-noise ratio proper motions, we build a reduced proper motion diagram to illustrate the scientific promise of the catalogue. In this diagram, disc and halo subdwarfs are well-separated from the cool white dwarf sequence. Our sample of 1049 cool white dwarf candidates includes at least eight and possibly 21 new ultracool H-rich white dwarfs (Teff < 4000 K) and one new ultracool He-rich white dwarf candidate identified from their SDSS optical and UKIDSS infrared photometry. At least 10 new halo white dwarfs are also identified from their kinematics.

Original languageEnglish (US)
Pages (from-to)515-525
Number of pages11
JournalMonthly Notices of the Royal Astronomical Society
Issue number2
StatePublished - Dec 2007

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


  • Catalogues
  • Stars: atmospheres
  • Stars: evolution
  • White dwarfs


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