The Effect of Dust Composition and Shape on Radiationpressure Forces and Blowout Sizes of Particles in Debris Disks
Abstract
The light scattered from dust grains in debris disks is typically modeled as compact spheres using the LorenzMie theory or as porous spheres by incorporating an effective medium theory. In this work we examine the effect of incorporating a more realistic particle morphology on estimated radiationpressure blowout sizes. To calculate the scattering and absorption crosssections of irregularly shaped dust grains, we use the discrete dipole approximation. These crosssections are necessary to calculate the βratio, which determines whether dust grains can remain gravitationally bound to their star. We calculate blowout sizes for a range of stellar spectral types corresponding with stars known to host debris disks. As with compact spheres, more luminous stars blow out larger irregularly shaped dust grains. We also find that dust grain composition influences blowout size such that absorptive grains are more readily removed from the disk. Moreover, the difference between blowout sizes calculated assuming spherical particles versus particle morphologies more representative of real dust particles is compositionally dependent as well, with blowout size estimates diverging further for transparent grains. We find that the blowout sizes calculated have a strong dependence on the particle model used, with differences in the blowout size calculated being as large as an order of magnitude for particles of similar porosities.
 Publication:

The Astronomical Journal
 Pub Date:
 April 2019
 DOI:
 10.3847/15383881/ab095e
 arXiv:
 arXiv:1902.10183
 Bibcode:
 2019AJ....157..157A
 Keywords:

 circumstellar matter;
 planetary systems;
 protoplanetary disks;
 radiation: dynamics;
 scattering;
 Astrophysics  Earth and Planetary Astrophysics
 EPrint:
 25 pages, 11 figures, Accepted for publication in AJ