• DOI:10.1111/j.1365-2966.2010.16528.x
• Corpus ID: 55055925

Are debris discs self-stirred?

@article{Kennedy2010AreDD,
  title={Are debris discs self-stirred?},
  author={Grant M. Kennedy and Mark C. Wyatt},
  journal={Monthly Notices of the Royal Astronomical Society},
  year={2010},
  volume={405},
  pages={1253-1270}
}

• G. Kennedy, M. Wyatt
• Published 18 February 2010
• Geology, Physics
• Monthly Notices of the Royal Astronomical Society

This paper aims to consider the evidence that debris disks are self-stirred by the formation of Pluto-size objects. A semi-analytical model for the dust produced during self-stirring is developed and applied to the statistics for A stars. We show that there is no significant statistical difference between fractional excesses of A-stars .50Myr old, and therefore focus on reproducing the broad trends, the “rise and fall” of the fraction of stars with excesses that the pre-stirred model of Wyatt et al. (2007b) does not predict. Using a population model, we find that the statistics and trends can be reproduced with a self-stirring model of planetesimal belts with radius distribution N(r) / r 0.8 between 15–120AU, with width dr = r=2. Disks must have this 15AU minimum radius in order to show a peak in disk fraction, rather than a monotonic decline. However, the marginal significance of the peak in the observations means that models with smaller minimum radii also formally fit the data. Populations of extended disks with fixed inner and/or outer radii fail to fit the statistics, due mainly to the slow 70�m evolution as stirring moves further out in the disk. This conclusion, that debris disks are narrow belts rather than extended disks, is independent of the significance of 24�m trends for young A-stars. Although the rise and fall is naturally explained by self-stirring, we show that the statistics can also be reproduced with a model in which disks are stirred by secular perturbations from a nearby eccentric planet. Detailed imaging, which can reveal warps, sharp edges, and offsets in individual systems is the best way to characterise the stirring