Sedna Proves Oort Cloud?

"Richard Alexander" wrote in message
m...
I just read in SFGate that the newly discovered planetoid, Sedna, is
the first direct evidence of the Oort Cloud. There was also some blurb
about Sedna likely to have been pulled out of the Kuiper Belt by
receeding stars.

"The new discovery is the first hard evidence of an Oort Cloud object,
[Michael E.] Brown said.

"Sedna must have been one of millions of objects within the Kuiper
Belt but was flung out of that region by the gravitational pull of
other stars in the cluster that were moving outward in nearby areas of
the galaxy."

"Farthest object in sun's grip found: Sedna's 10,000-year solar orbit
proves existence of Oort Cloud, scientist says"
http://sfgate.com/cgi-bin/article.cg.../16/PLANET.TMP

How is Sedna evidence of the Oort Cloud, particularly if it came from
the Kuiper Belt? Does it even make sense to talk about distance stars
"flinging" objects out of the Kuiper Belt?

The proof of the Oort Cloud lies in the random directions and extremely long
periods of the orbits of long-period comets.

I doubt if a passing star had anything to do with flinging this object
anywhere.

There is a sort of transitional region hypothesized between the KB and Oort
Cloud, and this object might well fit into that. It's a question of the
origin, I suppose--OC objects were flung out of the region around Jupiter,
Saturn, and Uranus in all directions, while KBOs were left-over bits in the
outer system beyond Neptune. The high eccentricity may imply it was flung
out rather than being a left-over object.
I'm not sure that it qualifies as an Oort Cloud object by the usual
definition. But it would make a spectacular comet indeed if it ever got
perturbed into the inner solar system!

--
Mike Dworetsky

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