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(meteorobs) More Reasons to Keep Looking Up



In the latest issue of "Science News" (Jan. 31, 1998, Vol. 153 No. 5),
Astronomy Editor Ron Cowen reported on the recent meeting of the American
Astronomical Society.  Two of the papers which he mentioned are of some
interest to meteor observers.  Both deal with the possible causes of large
bodies impacting on Earth.

In the first paper, L. A. Molnar and R. L. Murtel of the University of Iowa
have looked at the possibility that passing stars might cause a disturbance
in the Oort Cloud sufficient to trigger a shower of comets.  Jet Propulsion
Laboratory (JPL) in Pasadena, CA, looked at possible disturbance from the
Algol system and the star Gliese.  Molnar and Mutel analyzed the same stars
and took into account the motion of the Sun orbiting the Milky Way, motion
of nearby stars, etc.  While their figures indicate that neither star came
close enough to cause such showers, they also plan to look for other
candidate stars.

In the second paper, Kenneth Brecher of Boston University speculates that a
gamma-ray burst of sufficient energy and close proximity might have
disturbed the Oort Cloud.  The numbers Brecher uses are a burst equivalent
to 10% of the Sun's mass coming within 300,000 light-years of our galaxy. 
Such a burst "...could vaporize the outer layers of myriad small comets
thought to lie in the Oort Cloud...".  The "...vaporized material could act
as a propellant, flinging some of the smallest, least massive comets --
those with a diameter of 1 km or less -- into the inner solar system."

The Science News web site, http://www.sciencenews.org contains references
and contact names concerning the article.

H C Titus