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A wide binary trigger for white dwarf pollution
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Bonsor, Amy and Veras, Dimitri (2015) A wide binary trigger for white dwarf pollution. Monthly Notices of the Royal Astronomical Society, 454 (1). pp. 53-63. doi:10.1093/mnras/stv1913 ISSN 0035-8711.
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Official URL: http://dx.doi.org/10.1093/mnras/stv1913
Abstract
Metal pollution in white dwarf atmospheres is commonly assumed to be a signature of remnant planetary systems. Most explanations for this pollution predict a sharp decrease in the number of polluted systems with white dwarf cooling age. Observations do not confirm this trend, and metal pollution in old (1–5 Gyr) white dwarfs is difficult to explain. We propose an alternative, time-independent mechanism to produce the white dwarf pollution. The orbit of a wide binary companion can be perturbed by Galactic tides, approaching close to the primary star for the first time after billions of years of evolution on the white dwarf branch. We show that such a close approach perturbs a planetary system orbiting the white dwarf, scattering planetesimals on to star-grazing orbits, in a manner that could pollute the white dwarf's atmosphere. Our estimates find that this mechanism is likely to contribute to metal pollution, alongside other mechanisms, in up to a few per cent of an observed sample of white dwarfs with wide binary companions, independent of white dwarf age. This age independence is the key difference between this wide binary mechanism and others mechanisms suggested in the literature to explain white dwarf pollution. Current observational samples are not large enough to assess whether this mechanism makes a significant contribution to the population of polluted white dwarfs, for which better constraints on the wide binary population are required, such as those that will be obtained in the near future with Gaia.
Item Type: | Journal Article | ||||||||||
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Divisions: | Faculty of Science, Engineering and Medicine > Science > Physics | ||||||||||
Journal or Publication Title: | Monthly Notices of the Royal Astronomical Society | ||||||||||
Publisher: | Oxford University Press | ||||||||||
ISSN: | 0035-8711 | ||||||||||
Official Date: | 21 November 2015 | ||||||||||
Dates: |
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Volume: | 454 | ||||||||||
Number: | 1 | ||||||||||
Page Range: | pp. 53-63 | ||||||||||
DOI: | 10.1093/mnras/stv1913 | ||||||||||
Status: | Peer Reviewed | ||||||||||
Publication Status: | Published | ||||||||||
Access rights to Published version: | Restricted or Subscription Access |
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