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(meteorobs) SURPRISE METEOR SHOWER: the Ursids
Dear Lew,
No, as far as I know there is no precedent, other than the recent predictions
for the Leonid shower. The Ursid comet 8P/Tuttle is dynamically similar
to the Leonid comet 55P/Tempel-Tuttle, which makes this particular model
usefull for such forecast. The full story is in the attached paper.
That similarity makes the Ursid outburst meteors special. They can be
precisely dated (to 1405) and we think we know where the center of the
dust trail is. This makes differences in composition and morphology of
the grains (meteor lightcurves, early release of sodium, etc.), as
compared to the Leonids for example, meaningfull.
We are about to have a local ground campaign here in California carrying
some of the visible and near-IR spectrometers that were used on
the Leonid MAC missions. The Ursids are no Leonids in terms of rate and
leave seldom a persistent train, but a few detections could provide
important clues.
We are particularly interested in how the air plasma temperatures of
meteors may differ with different entry velocity, whether sodium is released
earlier as in Leonids, and whether the metal atom abundances are different
for this particular comet. We will also look at meteor lightcurves and orbits
with photographic camera batteries and measure the position and width of
any dust trails using intensified video cameras.
Currently the weather predictions are not so good for our prime sites
however. We are looking into traveling further south to find clear weather...
Best regards,
Peter Jenniskens
>Interesting release from NASA Ames... Are there any issues of precedence
>among the professionals for these "forecasts" of an Ursid outburst? Well,
>that's something we amateurs luckily needn't concern ourselves with! Also
>in the EVENT of an outburst, are the URSs really expected to be plentiful
>and bright enough to make collection of spectra that likely? Or does the
>mention of astrobiology results mean there's a dust collection mission??
>My but this "minor" shower is turning out to be interesting in 2000! :)
>Clear skies,
>Lew Gramer <owner-meteorobs@jovian.com>
Ursids.pdf
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