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H.H. Hsieh, D.C. Jewitt, Y.R. Fernandez (Inst. for Astronomy, U. Hawaii)
We present a new investigation of the comet-asteroid transition object 133P/(7968) Elst-Pizarro. As in 1996, when this object's comet-like activity first came to notice, observations in 2002 show a long, narrow dust trail in the projected orbit of the object. Observations over several months reveal changes in the structure and brightness of this trail, showing that it is actively generated over long periods of time. Finson-Probstein modeling is used to constrain the parameters of the dust trail. We find low ejection velocities (\leq 2 {\rm ~m~s-1}) and optically dominant particle sizes of ~10 microns released over a period of activity lasting at least 5 months. The lightcurve of the nucleus shows an aspherical shape (axis ratio b/a\geq0.69) and rapid rotation (P=3.471±0.001 hrs). This rapid rotation may be a significant factor in mass loss from the body. The 1996 trail has been previously explained as debris released by a chance impact, but our recent trail detection casts doubt upon this interpretation. Instead, our data suggest that Elst-Pizarro is a barely active comet that has somehow evolved into an asteroid-like orbit.
A paper describing this work has been submitted for publication in The Astronomical Journal.
The author(s) of this abstract have provided an email address for comments about the abstract: hsieh@ifa.hawaii.edu
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Bulletin of the American Astronomical Society, 35 #4
© 2003. The American Astronomical Soceity.