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Signs of a faint disc population at polluted white dwarfs

Bergfors, C; Farihi, J; Dufour, P; Rocchetto, M; (2014) Signs of a faint disc population at polluted white dwarfs. Monthly Notices of the Royal Astronomical Society , 444 (3) 2147-2156 . 10.1093/mnras/stu1565. Green open access

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Abstract

Observations of atmospheric metals and dust discs around white dwarfs provide important clues to the fate of terrestrial planetary systems around intermediate-mass stars. We present Spitzer Infrared Array Camera observations of 15 metal polluted white dwarfs to investigate the occurrence and physical properties of circumstellar dust created by the disruption of planetary bodies. We find subtle infrared excess emission consistent with warm dust around KUV 15519+1730 and HS 2132+0941, and weaker excess around the DZ white dwarf G245-58, which, if real, makes it the coolest white dwarf known to exhibit a 3.6 μm excess and the first DZ star with a bright disc. All together our data corroborate a picture where (1) discs at metal-enriched white dwarfs are commonplace and most escape detection in the infrared (possibly as narrow rings), (2) the discs are long lived, having lifetimes on the order of 106 yr or longer and (3) the frequency of bright, infrared detectable discs decreases with age, on a time-scale of roughly 500 Myr, suggesting large planetesimal disruptions decline on this same time-scale.

Type: Article
Title: Signs of a faint disc population at polluted white dwarfs
Open access status: An open access version is available from UCL Discovery
DOI: 10.1093/mnras/stu1565
Publisher version: http://dx.doi.org/10.1093/mnras/stu1565
Language: English
Additional information: This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society (MNRAS) ©: 2014 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
Keywords: Circumstellar matter, Planetary systems, White dwarfs
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy
URI: https://discovery.ucl.ac.uk/id/eprint/1465562
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