2003 EH1Is the Quadrantid Shower Parent Comet

Abstract

The Quadrantid meteor shower in early January is our most intense annual shower. Until now, the parent was thought to have evolved away from the observable part of an old, widely dispersed meteoroid stream. A few years ago, it was found from a small dispersion in a new set of precisely reduced Quadrantid orbits that the stream was only about 500 years old. It was predicted that the parent was still to be found among the meteoroids. I now find that the shower originated from 2003 EH1, a minor planet discovered by LONEOS on March 6, currently passing 0.213 AU outside of Earth orbit in a high-inclination, comet-like orbit with a Tisserand invariant with respect to Jupiter of only 2.064. The orbit agrees with that of the Quadrantids. Small discrepancies in node (~03) and perihelion distance (~0.23 AU) are consistent with the differential evolution of comet and debris that was released from 2003 EH1 about 500 years ago into slightly longer orbits. I conclude that object 2003 EH1 is an intermittently active comet. The large total mass in the shower (~1013 kg) is only consistent with a young age if the meteoroids were shed during a breakup. Comet C/1490 Y1 was observed in about the right time frame for such a breakup and might be a prior sighting when the Quadrantid meteoroid stream was created, but efforts to construct a common orbit that links 2003 EH1 and comet C/1490 Y1 show that nongravitational perturbations or close encounters with Earth may need to be considered.