[Prev][Next][Index][Thread]

(meteorobs) Re: Leonid 'gusts' -the 1997 Japanese video!!



Marco,
Those are fair points.  While small scale breakups could be part of the
overall phenomenon, and potentially bias the rates, the Japanese object
was almost certainly *not* of a "fresh" meteoroid (no young dust trails
near enough the Earth in 1997).  Certainly, small scale events like that
could contaminate the results, but if it were more common in fresh
meteoroids present in storms from young dust trails I still feel is would
have been specifically commented as something other than a flurry.  There
are probably (at least) two ways the breakups could be noticed

a) breakup in the near-Earth environment.  In this case, all the fragments
would necessarily be very closely spaced in the sky and in time.  For
Leonids this would imply near simultaneity and within a few degrees,
unless unrealistic high velocities of separation are assumed

b) systematic breakup during their lifetime in orbit by whatever
mechanism.  In this case, only those that have a breakup shortly before
(months?) entry into the Earth's atmosphere are likely to be recognisable
(consciously and statistically) as non random.

Presumably this has all been studied before and the consequences explored.
I could imaging aging effects to operate either way in increasing or
decreasing the likelyhood of breakup depending on what mechanism is
involved.  It is an important issue that I would wish to know thw answer
to.  In assuming it is insignificant, this could bias the rates
predictions based on the dust trail density model in two ways: the data
used in the  model may require correction for breakup, and the predictions
likewise.  It affects the dust trail density model through both the
increased flux AND the changed mass index.

One point I've made informally for many years, and might be well known, is
that in looking for non uniformity in occurance due to breakup, the
important quantity to test, is not just the time gap between meteors, but
their physical closeness in 3-D space.  The observations are converted to
a 3-D column through the stream and examined for clumping.

Cheers, Rob

Robert H. McNaught
rmn@aaocbn.aaodot gov.au


To UNSUBSCRIBE from the 'meteorobs' email list, use the Web form at:
http://www.tiacdot net/users/lewkaren/meteorobs/subscribe.html

References: