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Posted on 01/16/2003 12:01:01 PM PST by theFIRMbss
Three-star system ejects weakest link
Thu Jan 9, 7:59 AM ET
Dan Vergano USA TODAY
SEATTLE -- Astronomers report a first sighting of a round of Survivor set in space -- a weakling brown dwarf star being booted out of a triple-star solar system.
Brown dwarfs are ''failed'' stars with relatively low mass. They are huge, but they lack the heft needed to light up with the nuclear fusion that powers true stars.
Numerous brown dwarfs have been spotted in recent decades, even in regions of space not associated with star formation. Seeing one ejected from a solar system suggests one explanation for their origin. And the find points to a new way to look at stars in their earliest development.
The phenomenon was reported at the American Astronomical Society meeting here by astronomer Laurent Loinard of the National Autonomous University of Mexico. The ejected star, called T Taurus South b, appears to have orbited a pair of larger stars, known as T Taurus South a, in the constellation Taurus for a good part of its less-than-1-million-year lifetime.
By using archival data from the U.S. National Science Foundation (news - web sites)'s Very Large Array radio telescope as far back as 1983, Loinard's team discovered that the smaller star apparently lost a game of gravitational chicken with its bigger brethren sometime around 1998.
Before then, T Taurus South b appears to have looped around the bigger pair of stars, traveling about 6 miles per second, a normal orbital speed. But by 2001, the star, about one-tenth the size of the sun, appeared headed out of the system at twice its original speed.
''The most likely explanation is we're actually seeing an ejection,'' Loinard says. Most likely, the two larger inner stars produced a very sharp tidal tug, just at the time the dwarf was at its closest approach.
Ejected from the system in which it was born, a young star could be cut off from the gas and dust it needs to gain mass.
The odds against randomly spotting a 20-year ejection event during the million-year adolescence of a young star suggest that such events ''may be more common than we expected,'' says astronomer Charles Lada of the Smithsonian Astrophysical Observatory. Though Lada believes most brown dwarfs form on their own, he expressed ''great confidence'' in the ejection spotted by Loinard's team.
Some tin foil people
have wondered if Jupiter
and Saturn in our
solar system might
be brown dwarfs at some stage
of evolution.
If they ignited,
earth people might see first hand
this drama play out.
(That's assuming the
Velikovsky-type events
didn't do us in.)
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