[meteorite-list] re: meteor velocity

From: Marco Langbroek <marco.langbroek_at_meteoritecentral.com>
Date: Thu Apr 22 10:27:45 2004
Message-ID: <011c01c3a6b3$c2a69640$4fc0ea3e_at_HAL>

Hello Jose,

All fast meteors will be of cometary origin. The speed of a meteor is
determined by its type of orbit, i.e. most notably by its semi-major axis.
If you have meteors in the, say 40-70 km/s speed class they are bound to
have an orbit with a large semi-major axis. A large semi-major axis means
its aphelion is beyond the asteroid belt. In other words: that is a typical
cometary kind of orbit, not an asteroidal type of orbit.

By contrast objects of asteroidal origin will typically not have their
aphelion beyond Jupiter, and therefore will have an orbit with a relatively
small semi-major axis, leading to a slower meteor velocity.

But at the down end of the cometary orbit range (short-period comets) there
is a range in semi-major axis where the smallest of the cometary orbits
overlap with the semi-major axis typical of asteroids. Comet Encke is an
example.

- So if you have a fast meteor: it is bound to be of cometary origin
- If you have a slow meteor: it can be either cometary or asteroidal, with
the
latter likely
- If you have a very slow meteor: it is very likely to be of asteroidal
origin.

So indeed it is not clear-cut, except for the fast domain and the very slow
domain. The "muddle in the middle" needs either a known parent body (e.g. as
with the Taurids - but then there still is the discussion whether some
inactive short-period comets might 'pose' as an asteroid) or dynamic data on
the meteor to determine whether it is of cometary or asteroidal origin.

- Marco Langbroek
  Dutch Meteor Society

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Dr Marco Langbroek
Leiden, the Netherlands
52.15896 N, 4.48884 E (WGS 84)

meteorites_at_dmsweb.org
http://home.wanadoo.nl/marco.langbroek
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Received on Sun 09 Nov 2003 06:19:56 AM PST