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Dynamical effects of stellar mass-loss on a Kuiper-like belt

Bonsor, Amy; Mustill, Alexander LU and Wyatt, Mark C (2011) In Monthly Notices of the Royal Astronomical Society 414(2). p.930-939
Abstract
A quarter of DA white dwarfs are metal polluted, yet elements heavier than helium sink down through the stellar atmosphere on time-scales of days. Hence, these white dwarfs must be the currently accreting material containing heavy elements. Here we consider whether the scattering of comets or asteroids from an outer planetary system, following stellar mass-loss on the asymptotic giant branch, can reproduce these observations. We use N-body simulations to investigate the effects of stellar mass-loss on a simple system consisting of a planetesimal belt whose inner edge is truncated by a planet. Our simulations find that, starting with a planetesimal belt population fitted to the observed main-sequence evolution, sufficient mass is scattered... (More)
A quarter of DA white dwarfs are metal polluted, yet elements heavier than helium sink down through the stellar atmosphere on time-scales of days. Hence, these white dwarfs must be the currently accreting material containing heavy elements. Here we consider whether the scattering of comets or asteroids from an outer planetary system, following stellar mass-loss on the asymptotic giant branch, can reproduce these observations. We use N-body simulations to investigate the effects of stellar mass-loss on a simple system consisting of a planetesimal belt whose inner edge is truncated by a planet. Our simulations find that, starting with a planetesimal belt population fitted to the observed main-sequence evolution, sufficient mass is scattered into the inner planetary system to explain the inferred heavy element accretion rates. This assumes that a fraction of the mass scattered into the inner planetary system ends up on star-grazing orbits, is tidally disrupted and is accreted on to the white dwarf. The simulations also reproduce the observed decrease in accretion rate with cooling age and predict accretion rates in old (>1 Gyr) white dwarfs, in line with observations. The efficiency we assumed for material scattered into the inner planetary system to end up on star-grazing orbits is based on a solar-like planetary system, since the simulations show that a single planet is not sufficient. Although the correct level of accretion is reproduced, the simulations predict a higher fraction of accreting white dwarfs than observed. This could indicate that the evolved planetary systems are less efficient in scattering bodies on to star-grazing orbits or that dynamical instabilities post-stellar mass-loss cause rapid planetesimal belt depletion for a significant fraction of systems. (Less)
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author
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Astrophysics - Earth and Planetary Astrophysics, Kuiper belt: general, circumstellar matter, planetary systems, planets and satellites: dynamical evolution and stability, white dwarfs
in
Monthly Notices of the Royal Astronomical Society
volume
414
issue
2
pages
930 - 939
publisher
Wiley-Blackwell
external identifiers
  • scopus:79958148379
ISSN
1365-2966
DOI
10.1111/j.1365-2966.2011.18524.x
language
English
LU publication?
no
id
8a6b15b0-9b56-4fd5-b3d9-7bc3a415098b (old id 4500291)
date added to LUP
2014-06-25 15:09:01
date last changed
2017-03-26 04:34:52
@article{8a6b15b0-9b56-4fd5-b3d9-7bc3a415098b,
  abstract     = {A quarter of DA white dwarfs are metal polluted, yet elements heavier than helium sink down through the stellar atmosphere on time-scales of days. Hence, these white dwarfs must be the currently accreting material containing heavy elements. Here we consider whether the scattering of comets or asteroids from an outer planetary system, following stellar mass-loss on the asymptotic giant branch, can reproduce these observations. We use N-body simulations to investigate the effects of stellar mass-loss on a simple system consisting of a planetesimal belt whose inner edge is truncated by a planet. Our simulations find that, starting with a planetesimal belt population fitted to the observed main-sequence evolution, sufficient mass is scattered into the inner planetary system to explain the inferred heavy element accretion rates. This assumes that a fraction of the mass scattered into the inner planetary system ends up on star-grazing orbits, is tidally disrupted and is accreted on to the white dwarf. The simulations also reproduce the observed decrease in accretion rate with cooling age and predict accretion rates in old (>1 Gyr) white dwarfs, in line with observations. The efficiency we assumed for material scattered into the inner planetary system to end up on star-grazing orbits is based on a solar-like planetary system, since the simulations show that a single planet is not sufficient. Although the correct level of accretion is reproduced, the simulations predict a higher fraction of accreting white dwarfs than observed. This could indicate that the evolved planetary systems are less efficient in scattering bodies on to star-grazing orbits or that dynamical instabilities post-stellar mass-loss cause rapid planetesimal belt depletion for a significant fraction of systems.},
  author       = {Bonsor, Amy and Mustill, Alexander and Wyatt, Mark C},
  issn         = {1365-2966},
  keyword      = {Astrophysics - Earth and Planetary Astrophysics,Kuiper belt: general,circumstellar matter,planetary systems,planets and satellites: dynamical evolution and stability,white dwarfs},
  language     = {eng},
  number       = {2},
  pages        = {930--939},
  publisher    = {Wiley-Blackwell},
  series       = {Monthly Notices of the Royal Astronomical Society},
  title        = {Dynamical effects of stellar mass-loss on a Kuiper-like belt},
  url          = {http://dx.doi.org/10.1111/j.1365-2966.2011.18524.x},
  volume       = {414},
  year         = {2011},
}