The Yarkovsky thermal force on small asteroids and their fragments

Choosing the right albedo

¹ Institute of Astronomy, Charles University, V Holešovičkách 2, 180 00 Prague 8, Czech Republic
² Southwest Research Institute, 1050 Walnut St, Suite 426, Boulder, CO 80302, USA e-mail: bottke@boulder.swri.edu

Corresponding author: D. Vokrouhlický, vokrouhl@mbox.cesnet.cz

Received: 13 February 2001
Accepted: 12 March 2001

Abstract

Thermal (Yarkovsky) forces acting on small bodies in the solar system have been shown to play an important role in the the delivery of meteoroids and km-sized asteroids to Earth. So far, several aspects of the Yarkovsky force have been studied in some detail, including non-linear effects of the heat diffusion problem, non-sphericity and the layered-structure of the objects. In this paper, we address the concept of optical absorptivity. We find that the best formulation of the Yarkovsky effect uses the first two moment-integrals of an object's hemispheric albedo. A useful approximation of these albedo parameters is an object's Bond albedo.