OCCULTATION ECLIPSE EVENTS IN BINARY ASTEROID 1991 VH/

We present the results of photometric observations of the Apollo aster oid 1991 VH. Its lightcurve consists of two components: the first is t he rotational lightcurve with period P-s = (0.109327 +/- 0.000003) d a nd amplitude 0.09 mag, while the second, with period P-t = (1.362 +/- 0.001) d, shows two minima with depth 0.16-0.19 mag, each with a durat ion of about 0.10 d, and little or no variation at phases between them . We present a model of the occulting/eclipsing binary asteroid with t he secondary-to-primary diameter ratio d(s)/d(p) = 0.40 that explains the observed lightcurve, In this model, the primary's rotation is not synchronized with the orbital motion and produces the short-period lig htcurve component (P-s). The orbital period is P-1. The mutual orbit's semimajor axis is estimated to be a (2.7 +/- 0.3) d(p); the eccentric ity is 0.07 +/- 0.02. The similarity between the lightcurve of 1991 VH and those of 1994 AW(1) (Pravec and Hahn, Icarus 127, 431, 1997) and (3671) Dionysus (Mottola et al. 1997, IAU Circular 6680) suggests that binary asteroids may be common among near-Earth asteroids. Based on t he three known cases, we tentatively derive some typical characteristi cs of this new class of asteroids. They are mostly consistent with the hypothesis that binary asteroids are generated by tidal disruptions o f weak, gravitationally bound aggregates (so-called ''rubble piles'') during encounters with the Earth (Bottke and Melosh, Nature 281, 51, 1 996). A possible relationship between the population of binary asteroi ds and the belt of small near-Earth asteroids is discussed. (C) 1998 a cademic Press.