A new method to estimate the size and the surface temperature distribution of asteroids

Abstract

Among the most important physical parameters of asteroids are their size and albedo. The techniques currently used to determine these parameters from infrared and visible observations are based on the radiometric technique, which makes use of thermal models describing how the infrared radiation is emitted from the surface of the body. We propose a new method, alternative to the use of thermal models, to obtain sizes of asteroids and other atmosphere-less objects in the Solar System. Our approach is based on the numerical solution of the Inverse Black Body Radiation Problem (IBBRP) which allows the determination of the temperature distribution of a thermal radiator from its total radiated power spectrum. While classical thermal models make assumptions about the function describing the temperature distribution over the asteroid surface, our technique is able to derive this unknown from the observational infrared data alone. We discuss the results of the application of our method to a few ideal test cases.The application to real thermal infrared observations of 433 Eros is also presented.