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

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

26 Citations (Scopus)


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
Pages (from-to)515-525
Number of pages11
JournalMonthly Notices of the Royal Astronomical Society
Issue number2
Publication statusPublished - Dec 2007
Externally publishedYes


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