Published in

Oxford University Press (OUP), Monthly Notices of the Royal Astronomical Society, 4(496), p. 5233-5242, 2020

DOI: 10.1093/mnras/staa1688

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The dust never settles: collisional production of gas and dust in evolved planetary systems

Journal article published in 2020 by Andrew Swan ORCID, Jay Farihi ORCID, Thomas G. Wilson ORCID, Steven G. Parsons ORCID
This paper was not found in any repository, but could be made available legally by the author.
This paper was not found in any repository, but could be made available legally by the author.

Full text: Unavailable

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Postprint: archiving allowed
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Published version: archiving allowed
Data provided by SHERPA/RoMEO

Abstract

ABSTRACT Multi-epoch infrared photometry from Spitzer is used to monitor circumstellar discs at white dwarfs, which are consistent with disrupted minor planets whose debris is accreted and chemically reflected by their host stars. Widespread infrared variability is found across the population of 37 stars with two or more epochs. Larger flux changes occur on longer time-scales, reaching several tens of per cent over baselines of a few years. The canonical model of a geometrically thin, optically thick disc is thus insufficient, as it cannot give rise to the observed behaviour. Optically thin dust best accounts for the variability, where collisions drive dust production and destruction. Notably, the highest infrared variations are seen in systems that show Ca ii emission, supporting planetesimal collisions for all known debris discs, with the most energetic occurring in those with detected gaseous debris. The sample includes the only polluted white dwarf with a circumbinary disc, where the signal of the day–night cycle of its irradiated substellar companion appears diluted by dust emission.

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