Background
Comet D/1819 W1 (Blanpain) was observed for 2 months in 1819-1820 and promptly lost, despite having a short orbital period that should have provided many opportunities for re-observation at subsequent returns. Its disappearance suggested to some that it might have disintegrated, or run out of gas.

Recently, planet crossing asteroid 2003 WY25 (the Tisserand Parameter is a comet-like 2.81) was shown by Jenniskens and others to have an orbit consistent with that of Blanpain. A dynamical association between the comet and the asteroid was drawn. An old conjecture that Blanpain might be the source of the Phoenicid meteor stream was revived.

Still, 2003 WY25 showed no direct evidence of being a comet.

The New Result
The new result here is that 2003 WY25 is definitely a comet, consistent with its orbital character. We know this because deep images taken in 2004 at the University of Hawaii 2.2-m show a faint coma around the object.

The faintness of the coma is consistent with a very low rate of production of dust: I estimate that 2003 WY25 releases about 10 grams per second (yes, grams!). This is far too small to supply the Phoenicid meteor stream mass (10^11 kg) on any reasonable timescale, showing that the latter stream must have been created impulsively, probably by the partial disintegration of the nucleus of Blanpain, leaving 2003 WY25 behind as a remnant.

All of this explains how D/Blanpain earned its "D" (for Defunct): it has come back from the dead as a Zombie Comet.

Summary

The sum of the data suggest that 2003 WY25 is a fragment of D/Blanpain, perhaps the largest one remaining from the disruption event that produced the Phoenicids.

A paper describing this in more detail is linked here as a pdf file from Astronomical Journal 131, 2327-2331.

David Jewitt. Last updated Apr 2006

Comet	Jewitt	Kuiper