@article{36f2a5be7a5b4aaf99cbcda60b08b3d1,
title = "Dust production and depletion in evolved planetary systems",
abstract = "The infrared dust emission from the white dwarf GD56 is found to rise and fall by 20 per cent peak-to-peak over 11.2 yr, and is consistent with ongoing dust production and depletion. It is hypothesized that the dust is produced via collisions associated with an evolving dust disc, temporarily increasing the emitting surface of warm debris, and is subsequently destroyed or assimilated within a few years. The variations are consistent with debris that does not change temperature, indicating that dust is produced and depleted within a fixed range of orbital radii. Gas produced in collisions may rapidly re-condense onto grains, or may accrete onto the white dwarf surface on viscous timescales that are considerably longer than Poynting-Robertson drag for micron-sized dust. This potential delay in mass accretion rate change is consistent with multi-epoch spectra of the unchanging Ca II and MgII absorption features in GD56 over 15 yr, although the sampling is sparse. Overall, these results indicate that collisions are likely to be the source of dust and gas, either inferred or observed, orbiting most or all polluted white dwarfs.",
keywords = "Circumstellar matter, planetary systems, stars: individual: GD56, white dwarfs",
author = "J. Farihi and {van Lieshout}, R. and Cauley, {P. W.} and E. Dennihy and Su, {K. Y.L.} and Kenyon, {S. J.} and Wilson, {T. G.} and O. Toloza and G{\"a}nsicke, {B. T.} and {von Hippel}, T. and S. Redfield and Debes, {J. H.} and S. Xu and L. Rogers and A. Bonsor and A. Swan and Pala, {A. F.} and Reach, {W. T.}",
note = "Funding Information: The authors acknowledge useful conversations with R. Rafikov, and thank an anonymous reviewer for a careful reading of the manuscript. This work is based in part on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology under a contract with NASA. This publication makes use of data products from the Wide-field Infrared Survey Explorer, which is a joint project of the University of California, Los Angeles, and the Jet Propulsion Laboratory/California Institute of Technology, funded by the NASA. Some of the data presented herein were obtained at the W. M. Keck Observatory from telescope time allocated to NASA through scientific partnership with the California Institute of Technology and the University of California. This work was supported by a NASA Keck PI Data Award, administered by the NASA Exoplanet Science Institute. Some of the observations presented here were made with ESO Telescopes at the Paranal Observatory. JF acknowledges support from STFC grant ST/R000476/1. RvL was supported by the DISCSIM project, grant agreement 341137 funded by the European Research Council under ERC-2013-ADG. TGW wishes to acknowledge funding from a STFC studentship, and OT was partially supported by a Leverhulme Trust Research Project Grant. Research leading to these results has received funding from the ERC under the European Union's 7th Framework Programme no. 320964 (WDTracer). TvH was supported by the National Science Foundation Award AST-1715718, and AB acknowledges the support of a Royal Society Dorothy Hodgkin Fellowship. Funding Information: of the University of California, Los Angeles, and the Jet Propulsion Laboratory / California Institute of Technology, funded by the NASA. Some of the data presented herein were obtained at the W. M. Keck Observatory from telescope time allocated to NASA through scientific partnership with the California Institute of Technology and the University of California. This work was supported by a NASA Keck PI Data Award, administered by the NASA Exoplanet Science Institute. Some of the observations presented here were made with ESO Telescopes at the Paranal Observatory. JF acknowledges support from STFC grant ST/R000476/1. RvL was supported by the DISCSIM project, grant agreement 341137 funded by the European Research Council under ERC-2013-ADG. TGW wishes to acknowledge funding from a STFC studentship, and OT was partially supported by a Leverhulme Trust Research Project Grant. Research leading to these results has received funding from the ERC under the European Union{\textquoteright}s 7th Framework Programme no. 320964 (WDTracer). TvH was supported by the National Science Foundation Award AST-1715718, and AB acknowledges the support of a Royal Society Dorothy Hodgkin Fellowship. Publisher Copyright: {\textcopyright} 2018 The Author(s).",
year = "2018",
month = dec,
day = "1",
doi = "10.1093/MNRAS/STY2331",
language = "English (US)",
volume = "481",
pages = "2601--2611",
journal = "Monthly Notices of the Royal Astronomical Society",
issn = "0035-8711",
publisher = "Oxford University Press",
number = "2",
}