Radiation-induced torques on spheroids
Astronomical Observatory, A. Mickiewicz University, Słoneczna 36, 60-286 Poznań, Poland e-mail: firstname.lastname@example.org
2 Institute of Astronomy, Charles University, V Holešovičkách 2, 18000 Prague, Czech Republic e-mail: email@example.com
3 Department of Space Studies, Southwest Research Institute, 1050 Walnut St., Boulder, CO 80302, USA
Accepted: 24 May 2007
Radiation-induced torques on ellipsoids of revolution are discussed. Exact formulae for the thermal YORP torques are given in terms of elliptic integrals. It is demonstrated that in the absence of thermal inertia, the average values of dynamically significant projections of these torques are zero if a spheroid rotates around the axis of maximum inertia and if there are no resonances between rotation and orbital motion. The thermal lag leads to a systematic drift in the obliquity, but it does not affect the rotation period. The direct radiation pressure torques on spheroids are shown to be zero.
Key words: methods: analytical / celestial mechanics / minor planets, asteroids
© ESO, 2007