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White dwarf–main sequence binaries identified within SDSS DR7 and UKIDSS DR5

  1. Cheng Liu1,2,3,*,
  2. Lifang Li1,3,
  3. Fenghui Zhang1,3,
  4. Yu Zhang1,2,3,
  5. Dengkai Jiang1,3,
  6. Jinzhong Liu4

Article first published online: 3 JUL 2012

DOI: 10.1111/j.1365-2966.2012.21285.x

Issue

Monthly Notices of the Royal Astronomical Society

Monthly Notices of the Royal Astronomical Society

Volume 424, Issue 3, pages 1841–1851, 11 August 2012

Additional Information

How to Cite

Liu, C., Li, L., Zhang, F., Zhang, Y., Jiang, D. and Liu, J. (2012), White dwarf–main sequence binaries identified within SDSS DR7 and UKIDSS DR5. Monthly Notices of the Royal Astronomical Society, 424: 1841–1851. doi: 10.1111/j.1365-2966.2012.21285.x

Author Information

  1. 1

    National Astronomical Observatories, Yunnan Observatory, Chinese Academy of Sciences, Kunming, China

  2. 2

    Graduate University of Chinese Academy Sciences, Beijing, China

  3. 3

    Key Laboratory for the Structure and Evolution of Celestial Objects, Chinese Academy of Sciences, Kunming, China

  4. 4

    National Astronomical Observatories/Xinjiang Observatory, Chinese Academy of Sciences, Urumqi, China

*E-mail: liucheng@ynao.ac.cn

Publication History

  1. Issue published online: 1 AUG 2012
  2. Article first published online: 3 JUL 2012
  3. Manuscript Accepted: 9 MAY 2012
  4. Manuscript Received: 3 MAY 2012

Funded by

  • Natural Science Foundation. Grant Numbers: 11073049, 10773026, 11103054
  • Chinese Academy of Sciences. Grant Number: KJCX2-YW-T24
  • Xingjiang National Science Foundation. Grant Number: 2011211A104
  • China's Western Region (LCWR). Grant Number: XBBS201022
  • Beyond The Horizons. Grant Number: 100020101

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Keywords:

  • binaries: close;
  • binaries: spectroscopic;
  • stars: fundamental parameters;
  • white dwarfs

ABSTRACT

We develop optical and near-infrared colour-selection criteria based on the model colours of binaries consisting of a white dwarf and a main-sequence star. Using our colour-selection algorithm, we present a catalogue of 523 white dwarf–main sequence (WDMS) binaries from the spectroscopic Sloan Digital Sky Survey Data Release 7 (SDSS DR7), most of them previously identified. Among them, we identify 86 objects as new WDMS binaries. 95 WDMS candidates are also found from the photometric SDSS DR7, cross-matched with the United Kingdom Infrared Telescope (UKIRT) Infrared Sky Survey Data Release 5 (UKIDSS DR5). Based on a χ2 minimization technique, we derive independent stellar parameters such as the effective temperatures, surface gravities, masses and distances of the white dwarfs and secondary stars and the metallicities of the secondaries. Meanwhile, we determine the cooling age via interpolation through evolutionary models for the effective temperature and surface gravity of each DA white dwarf. Distributions of these stellar parameters have been used to study both the general properties and the completeness of WDMS binaries. A comparison between the distances measured to the white dwarfs and the secondary stars shows a clear trend towards higher distances for the white dwarf component. It is found that the mean cooling age of the WDMS sample is inline image yr and our sample contains at least 11 per cent old systems, which were formed about 1.0 × 109 yr ago. The new and updated WDMS binaries will improve the completeness of the catalogue of WDMS binaries.

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