EDP Sciences
Free access
Volume 404, Number 2, June III 2003
Page(s) 709 - 714
Section The Sun
DOI http://dx.doi.org/10.1051/0004-6361:20030505

A&A 404, 709-714 (2003)
DOI: 10.1051/0004-6361:20030505

Photometric signatures of highly nonconvex and binary asteroids

J. Durech1 and M. Kaasalainen2

1  Astronomical Institute, Charles University Prague, V Holesovickách 2, 18000 Prague, Czech Republic
2  Observatory, PO Box 14, 00014 University of Helsinki, Finland

(Received 7 February 2003 / Accepted 27 March 2003)

We present an analysis of synthetic lightcurves of highly nonconvex single or synchronous binary asteroids, paying particular attention to the connection between the available solar phase angles and the observable degree of asteroid nonconvexity. The measure of nonconvexity of an object is defined and computed for asteroids with known shapes. We discuss the possibility of recovering global nonconvexities or binary structure of an asteroid from its lightcurves. The importance of observations at high solar phase angles is emphasized. For main-belt asteroids only binary or bifurcated shapes can be resolved (at least in a qualitative sense) - topologically star-like asteroids can be modelled as convex bodies. Concavities can be revealed only if an asteroid is observed at sufficiently high solar phase angles ( $\alpha > 60^\circ$) when shadowing effects from nonconvexities become important. This can be fulfilled only for near-Earth asteroids. Reconstruction of local topographic details is in practice precluded by the uncertainty of the light-scattering properties of the surface and the scarcity of very large phase angles.

Key words: minor planets, asteroids -- techniques: photometric -- methods: numerical

Offprint request: J. Durech, durech@sirrah.troja.mff.cuni.cz

© ESO 2003