Radar backscattering from a large-grain cometary coma: numerical simulation

Author： Dogra Shraddha Grynko Yevgen Zubko Evgenij Förstner Jens

E-ISSN： 1432-0746|608|issue|A20-A20

ISSN： 0004-6361

Source： Astronomy & Astrophysics, Vol.608, Iss.issue, 2017-11, pp. : A20-A20

Disclaimer: Any content in publications that violate the sovereignty, the constitution or regulations of the PRC is not accepted or approved by CNPIEC.

Previous Menu Next

Abstract

We numerically simulate the circular polarization ratio of the radar signal backscattered from a large-grain cometary coma and compare the simulation results with the radar measurements for seven comets. We apply the discrete dipole approximation method and a model of random irregular particles. Our results confirm water ice composition of the cm-sized chunks detected by the NASA Deep Impact space probe in the vicinity of the nucleus of Comet 103P/Hartley 2. The index of the power-law size distribution in this case can be constrained to the range n ≈ 3.3–4.3. For the other considered comets the circular polarization ratio can be reproduced with variations of the power index between 2 and 5.