Optical effects of irregular cosmic dust particle U2015 B10

Abstract

The radiation effects of nonspherical really shaped cosmic dust particles are studied in this paper. A correlation between particle shape and estimated lifetime of a particle in the solar system was studied also. The discrete dipole approximation is utilized to calculate efficiency factors for scattering, absorption, extinction and radiation pressure, respectively, and scattering phase functions. Chemical and physical properties of our sample particle U2015 B10 are obtained by laboratory analyses. The model of particle constructed using computer techniques is compared with the real photos. Results of calculations show that Poyinting–Robertson drag used to simulate the particle motion in interplanetary space leads to incorrect results because the spherical shape of particle is proposed here. Therefore, for instance, a stability of zodiacal cloud cannot be explained in this manner. On the other hand, any asphericity or irregularities in particle shape will be reflected in the increase of energy scattered in nonradial (non forward) direction. This fact is directly connected with the lifetime of the particle in solar system — i.e. the smaller the energy scattered forwardly the greater possibility of increasing the particle lifetime. Stability of zodiacal cloud could be then explained also by particle shape — e.g. if zodiacal cloud consists mainly of particles similar to our sample (which is very probable). The mean bulk density of our particle (about 1.83 g cm -3) correlates well with material of carboneous chondrites of density about 2.1 g cm -3 (from asteroids or comets, too). This particle could belong also to the debris (remnants) of Population I, i.e. to large grains with density approx. 2–3 g cm -3.