When modeling the density and grain size distribution in debris disks, the
minimum particle size is often significantly larger than the corresponding
blowout size. While the dust particles are usually modeled as compact,
homogenous spheres, we instead investigate the impact of porosity. The optical
properties of porous particles are determined, and the influences of porosity
on the blowout size and dust temperatures investigated. Using the method of
discrete dipole approximation, we calculate the scattering and absorption cross
sections of porous particles and derive the blowout size and the behavior of
the dust temperature. We investigate the influence on the beta-ratio. Blowout
sizes are calculated for various stellar luminosities and porosities, and an
approximation equation is derived to estimate the blowout size as a function of
these parameters. Furthermore, we investigate the influence of the porosity on
the dust equilibrium temperature. The blowout size increases with the particle
porosity and stellar luminosity. The dust temperature of porous particles is
lower than the one of the compact spheres, in particular the temperature of
blowout grains decreases for porous particles.Comment: 10 pages, 18 figure
