University Of Tasmania

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

journal contribution
posted on 2023-05-17, 14:36 authored by Dobbie, PD, Burleigh, MR, Levan, AJ, Barstow, MA, Napiwotzki, R, Holberg, JB, Hubeny, I, Howell, SB
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. Therefore, 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).


Publication title

Monthly Notices of the Royal Astronomical Society








School of Natural Sciences


Blackwell Publishing Ltd

Place of publication

9600 Garsington Rd, Oxford, England, Oxon, Ox4 2Dg

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Copyright 2005 RAS

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