JET-LIKE FEATURES NEAR THE NUCLEUS OF CHIRON

CONSIDERED as a comet, the object 2060 Chiron is unusual in two respec ts: it exhibits outbursts at very large distances from the Sun(1-3), a nd its nucleus is much larger than that of any other known comet(4,5). It is, however, similar in size to the recently discovered Kuiper-bel t objects(6)-a population of objects with orbits beyond Neptune, which are a possible source of short-period comets. This has led to the con jecture that Chiron is related to these objects, but its chaotic orbit has brought it much closer to the Sun(7). Here we report observations of a recent stellar occultation by Chiron which permit the identifica tion of several features associated with Chiron's coma. The observatio n of discrete, jet-like features provides evidence that the coma mater ial originates from just a few, small active areas, rather than from u niform sublimation, and that the particles in at least one of these fe atures have radii greater than 0.25 mu m. The observations also sugges t the presence of material in the plane of Chiron's orbit and are cons istent with a gravitationally bound coma, Finally, the present data, a nd those from a previous occultation(8), constrain the radius of Chiro n to lie between 83 and 156 km.