UF professor, team find what may be brightest star ever

Published: Tuesday, January 6, 2004 at 6:01 a.m.
Last Modified: Tuesday, January 6, 2004 at 12:40 a.m.
What may be the brightest star yet observed in the universe makes the sun look like a dim night light.
"It's probably at least 5 million times more luminous than the sun, and maybe as much as 40 million times brighter," said University of Florida astronomy professor Steve Eikenberry, who led a team of scientists who have found what they think is the brightest and most massive star ever discovered.
Their discovery of an almost incomprehensibly bright, and distant, star may lead scientists to rethink theories about the way stars are formed.
On Monday, Eikenberry presented some of his team's findings at the American Astronomical Society's national conference in Atlanta. He was the lead author of a paper on the star - named LBV 1806-20 - that is expected to be published in the coming weeks in Astrophysical Journal.
Ironically, this blindingly bright star cannot be seen from Earth with the naked eye or most telescopes.
"You have to look at it in infrared," said Jessica LaVine, one of two UF graduate students in astronomy who have worked with Eikenberry on the project. "There is so much dust in the plane of our galaxy that all optical light coming from the star is blacked out."
Its distance doesn't help either. The sun, the star nearest to Earth, is 93 million miles away. That's 8.3 light minutes - not years - distant. The star LBV 1806-20 is 45,000 light years away, on the opposite side of the galaxy.
A single light year - the distance light travels in one year - equals almost 6 trillion miles. The bright star also is estimated to be about 150 times the size of the sun.
Reached Monday by cell phone just before a news conference in Atlanta - where he hoped this weekend's Mars landing wouldn't outshine his bright-star announcement - Eikenberry acknowledged the enormity of the numbers associated with LBV 1806-20. One number that is comparatively small, however, is its age.
"It's only about 2 million years old, compared to the sun which is about 5 billion years old," he said. "And (LBV 1806-20) will last only a couple more million years. The sun should last another 5 billion years, because typical stars last about 10 billion years."
The bigger the star, the shorter its life, Eikenberry said. "The more mass you have, the more nuclear fuel you have, the faster you burn it up. They start blowing themselves to bits."
The LBV in its name stands for "luminous blue variable," a type of gigantic star that displays light and color variability in the infrared spectrum. Eikenberry said astronomers have known about LBV 1806-20 for four or five years, and actually were looking for another type of rare star "when we stumbled" on this one.
Eikenberry's team thinks LBV 1806-20 is at least as bright as the Pistol Star, which was discovered in 1997. The current record holder for brightest star, Pistol is 5 million to 6 million times as bright as the sun.
Eikenberry said further study may show LBV 1806-20 to be seven times brighter than the Pistol Star. He said astronomers are less interested in the star's brightness than what it means for understanding the formation of stars.
"The current theories of star formation say we shouldn't have one this big," he said. "Most stars we expect to quietly coalesce out of blobs of gas in space, but this one is very different from that . . . We may now have to rethink our theories of star-formation to understand what formed these beasts."
Bob Arndorfer can be reached at (352) 374-5042 or arndorb@gvillesun.com.

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