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

doi:10.1111/j.1365-2966.2005.08720.x

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 language	English (US)
Pages (from-to)	1049-1058
Number of pages	10
Journal	Monthly Notices of the Royal Astronomical Society
Volume	357
Issue number	3
DOIs	https://doi.org/10.1111/j.1365-2966.2005.08720.x
State	Published - Mar 1 2005
Externally published	Yes

Keywords

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

ASJC Scopus subject areas

Astronomy and Astrophysics
Space and Planetary Science

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10.1111/j.1365-2966.2005.08720.x

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

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).",

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AU - Dobbie, P. D.

AU - Burleigh, M. R.

AU - Levan, A. J.

AU - Barstow, M. A.

AU - Napiwotzki, R.

AU - Holberg, J. B.

AU - Hubeny, I.

AU - Howell, S. B.

PY - 2005/3/1

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N2 - 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).

AB - 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).

KW - Binaries: spectroscopic

KW - Stars: abundances

KW - Stars: low-mass, brown dwarfs

KW - White dwarfs

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

Abstract

Keywords

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