A near-infrared spectroscopic search for very-low-mass cool companions to notable DA white dwarfs

P. D. Dobbie, M. R. Burleigh, A. J. Levan, M. A. Barstow, R. Napiwotzki, J. B. Holberg, I. Hubeny, S. B. Howell

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Abstract

We have undertaken a detailed near-infrared spectroscopic analysis of eight notable white dwarfs, predominantly of southern declination. In each case the spectrum failed to reveal compelling evidence for the presence of a spatially unresolved, cool, late-type companion. There-fore, we have placed an approximate limit on the spectral type of a putative companion to each degenerate. From these limits we conclude that if GD659, GD50, GD71 or WD2359-434 possesses an unresolved companion then most probably it is substellar in nature (M < 0.072 M⊙). Furthermore, any spatially unresolved late-type companion to RE J0457-280, RE J0623-374, RE J0723-274 or RE J2214-491 most likely has M < 0.082 M⊙. These results imply that if weak accretion from a nearby late-type companion is the cause of the unusual photospheric composition observed in a number of these degenerates then the companions are of very low mass, beyond the detection thresholds of this study. Furthermore, these results do not contradict a previously noted deficit of very-low-mass stellar and brown dwarf companions to main sequence F, G, K and early-M type primaries (a ≲ 1000 au).

Original languageEnglish (US)
Pages (from-to)1049-1058
Number of pages10
JournalMonthly Notices of the Royal Astronomical Society
Volume357
Issue number3
DOIs
StatePublished - Mar 1 2005

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Keywords

  • Binaries: spectroscopic
  • Stars: abundances
  • Stars: low-mass, brown dwarfs
  • White dwarfs

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Dobbie, P. D., Burleigh, M. R., Levan, A. J., Barstow, M. A., Napiwotzki, R., Holberg, J. B., Hubeny, I., & Howell, S. B. (2005). A near-infrared spectroscopic search for very-low-mass cool companions to notable DA white dwarfs. Monthly Notices of the Royal Astronomical Society, 357(3), 1049-1058. https://doi.org/10.1111/j.1365-2966.2005.08720.x