[meteorite-list] Semi- on topic-- portable star

From: Darren Garrison <cynapse_at_meteoritecentral.com>
Date: Mon Mar 21 13:24:54 2005
Message-ID: <oarj2150l00hvurm9i9j3k75grhor4h0ku_at_4ax.com>

Very cool.

http://www.msnbc.msn.com/id/7081156/


  MSNBC.com
Newfound star smaller than some planets
Find sheds light on gray area in celestial definitions

By Robert Roy Britt
Senior science writer
Space.com
Updated: 6:01 p.m. ET March 3, 2005


Astronomers have found the tiniest full-fledged star known, an object just 16 percent bigger than
Jupiter. It is smaller than some known planets that orbit other stars.

The star is a companion to a sunlike star toward the center of our Milky Way galaxy. It was found
and measured by observing changes in the light output of the system when the smaller star passed in
front of the larger star from our vantage point.

The discovery helps astronomers better understand a gray area of definition concerning stars and
planets.

Between planets and stars, there exist odd objects called brown dwarfs. They're often referred to as
failed stars, because they don't have enough mass to trigger the thermonuclear fusion that powers
real stars, like the sun. A brown dwarf is typically several times the mass of Jupiter, but
astronomers haven't determined the exact size or mass cutoffs on either end.

The new discovery, announced Thursday, puts a firm diameter measurement on the smallest star that
does in fact shine normally.

The result shows that stars less than one-tenth the mass of the sun can generate thermonuclear
fusion while being barely bigger than Jupiter.

"Imagine that you add 95 times its own mass to Jupiter and nevertheless end up with a star that is
only slightly larger," Claudio Melo of the European Southern Observatory suggested. "The object just
shrinks to make room for the additional matter, becoming more and more dense."

The star is more than 50 times as dense as the sun. It is smaller than some extrasolar planets,
including one world that is 30 percent larger than Jupiter.

"This result shows the existence of stars that look strikingly like planets," said Frederic Pont of
the Geneva Observatory in Switzerland, another member of the study team.

The diminutive star was initially discovered as part of the Optical Gravitational Lensing
Experiment, or OGLE survey, which identified several dozen stars toward the center of our galaxy
that appeared to have something moving in front of them. The diameter measurements were done from
the ESO's Paranal Observatory in Chile.

The star is named OGLE-TR-122b. It orbits the larger star once every 7.3 days. Because of its
relatively low mass, the smaller star's nuclear energy production is low compared with a sunlike
star, the astronomers said.

? 2005 Space.com. All rights reserved. More from Space.com.
URL: http://www.msnbc.msn.com/id/7081156/
Received on Sat 05 Mar 2005 12:34:32 PM PST