(meteorobs) Meteor showers from comet disintegration
Petrus Jenniskens
pjenniskens at mail.arc.nasa.gov
Tue Jun 28 03:49:03 EDT 2005
Hello Mikhail,
I missed much of the discussion and I appologize if I
repeat what has been
said since.
The original paper is posted as a preprint at:
http://www.seti.org/site/apps/nl/content2.asp?c=ktJ2J9MMIsE&b=362179&ct=1016671
Although the idea has been around for a long time, only
now are
we finding comet fragments in the streams that are
evidence that
disintegration played a role in creating our normal meteor
shower activity.
Interestingly enough, the total amount of dust generated
in the breakup of a Jupiter-family comet is not necessary
much more
than in a normal return of the comet. The paper gives some
examples
that imply that the total amount of mass is only equal to
about one
remaining fragment and not always much more than generated
in a normal
return to perihelion.
If showers are created by fragmentation, then the showers
become a tracer
of possible comet fragments, which are an impact hazard.
That is important,
as well as the fact that the "ejection" speeds and time of
ejection would be
different.
-Peter
---
Hello,
Just like a joke, cncerning different variants of probe
impact into 9P.
Besides an expected crater or the comet's breaking apart,
the probe also
can break 9P through, make a hole in it and fly from the
back side of
the comet, especially if its material is not such dense as
expected,
or the probe impacts somethere near the edge of the comet
body.
On the main article topic: The way of meteor dust
formation through
comets disruption is known for very long time. It is less
usual comparing to
melting and vaporation, but more productive. I don't quite
understand
the phrase "it now appears that many meteoroid streams are
caused by wholesale
disintegration of comets, which are loose assemblages of
cometesimals
and are known to frequently break apart". The usual life
of comets is
a number of perihelions and final desintegraion or gradual
"cooling",
i.e. their turning into asteroids. In the second case the
dust is completely
vaporation product, in the first case it is the mix of
vaporation and
desintegration results. So we can't speak that meteor
showers are
caused by desintegration, which only make the last
material injection
into already existing streams, that begins to diffuse
gradually
afterwards.
Of course, desintegration give much more material than
usual
perihelion passage, so some strong historical meteor
outbursts (noted
in the acticle) were or could be caused by desintegration
clouds. But
we know many other cases (Drakonids, Leonids, J. Bootids)
when usual
dust trails gave strong enhancements and storms. One way
doesn't
disturb another one. I think, desintegration is
distinguished too much
in the article, more than it deserves.
Best regards, Mikhail Maslov
GB> Interesting article. Does anyone have thoughts, ideas
or criticism related
GB> to this article? I would love to read a discussion
about this topic on
GB> meteorobs!
GB> Regards,
GB> Geert
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