[meteorite-list] Bumper Crop of New Objects Revealed Beyond Neptune

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu Apr 27 12:07:10 2006
Message-ID: <200604262053.NAA10960_at_zagami.jpl.nasa.gov>

http://www.newscientistspace.com/article/dn9056-bumper-crop-of-new-objects-revealed-beyond-neptune.html

Bumper crop of new objects revealed beyond Neptune
Jeff Hecht
New Scientist
April 26, 2006

Astronomers have found 45 previously unknown bodies of rock and ice
orbiting beyond Neptune in the Kuiper Belt. They range from about 50 to
500 kilometres wide.

The announcement is probably a record for the most new solar system
objects reported simultaneously, increasing the number of distant
objects with well defined orbits by nearly 10%.

But its real importance will be in measuring the distribution of distant
objects well enough to test theories of how the outer solar system
evolved. So says Joel Parker at the Southwest Research Institute in
Boulder, Colorado, US, a member of the team that found the new objects.

About 1100 small objects have been spotted in the outer solar system
since the discovery of the first Kuiper Belt Object in 1992. However,
astronomers have concentrated more on discovering objects than on
tracking them, so about half were never seen again after only brief
observation, says Brian Marsden of the Minor Planet Center at the
Harvard Smithsonian Center for Astrophysics.

The Minor Planet Center aids follow-up observers by calculating the
preliminary orbits they need to spot the objects again. But when the MPC
has only a few days' worth of data to work with, they have to assume the
objects follow common orbits that are circular or, alternatively, linked
with Neptune's orbit.

Telling tales

Those assumptions usually work, and the objects are seen again where
expected. But they can miss the paths of objects with less-common
orbits. "And it's those few unusual things that really tell you the
story of the solar system," Parker told New Scientist.

Different models of how the solar system evolved make different
projections of how many objects should occupy certain orbits, so knowing
the distribution of objects can support or eliminate some hypotheses.

Parker, lead researcher Brett Gladman at the University of British
Columbia, Canada, and others were concerned that objects in important
orbits might be escaping detection, so in 2003 they launched the Canada
France Ecliptic Plane Survey.

No snapshots

The researchers repeatedly scan regions of the sky where distant objects
are most likely to lurk, identify slow-moving candidate objects, then
track the objects themselves rather than relying on other groups. Taking
this extended data, rather than a brief snapshot, ensured that no
mistaken assumptions down the line could cause the objects to evade
future detection. "The study was to be as complete and free of 'recovery
bias' as possible," Parker explains.

In February, after more than two years of accumulating data, they began
feeding observations to Marsden at the Minor Planet Center. The 45 new
objects yielded by observations are described in the Minor Planet
Electronic Circular issued on Saturday.

Meanwhile, Gladman's group is now analysing the differences between the
orbital distributions recorded by its survey and in previous, more
conventional studies. They hope to uncover what the orbits of these new
objects will add to the early story of the solar system.
Received on Wed 26 Apr 2006 04:53:43 PM PDT