(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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