METEOR STREAM ACTIVITY .5. THE QUADRANTIDS, A VERY YOUNG STREAM

This paper presents the first large set of precisely reduced orbits of Quadrantid meteoroids. These orbits were ob-l rained from photographi c observations during the 1995 return of the Quadrantid stream. The or bits refer to the main peak of the activity curve, with an unidentifie d few being part of a broad background component. The measured dispers ion of orbits is less than from previous data obtained by less accurat e techniques.-In combination with existing stream models, we conclude that the main component is only about 500 years young, much less than the 5000-7500 year age that was widely assumed before. This main peak is now interpreted as an ''outburst'', with an evolution history simil ar to other near-comet type outbursts, while the background is thought to be the classical ''annual'' dust component. The stream does not or iginate from comet 96P/Machholz !. Rather? the parent object may be hi ding as an asteroid-like object in a high-inclination orbit. An estima te of that orbit is given.