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Chilean Observatory Glimpses Most Distant Novae Ever
By
Staff Writer
posted: 07:00 am ET
01 August 2000
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Chilean Observatory Glimpses Farthest Novae Ever Detected Nestled atop an 8,000-foot (2,435-meter) mountain in the Chilean Atacama Desert, the Very Large Telescope has just made a very large discovery. Astronomers working at the Very Large Telescope (VLT) recently managed to peek at the most far-flung "stella novae" distant cousins of much more powerful and well-studied supernova blasts ever seen. The astronomers, Massimo Della Valle of the Osservatorio Astrofisico di Arcetri and Roberto Gilmozzi and Rodolfo Viezzer of the European Southern Observatory, spotted the novae at a distance of 70 million light-years away in the dusty galaxy known as NGC 1316, 10 million light-years farther than the previous record for a nova. "We were very excited," said Gilmozzi. "We had done simulations of the observations a few years ago to determine if they were possible, but seeing the real thing is a whole different experience!" The astronomers observations took place over a span of eight nights from January 9 to 19, 2000. Images of four novae were captured by the VLTs FORS 1 multi-mode instrument, with the help of a charged-coupled device (CCD) camera. Like supernovae, stella novae are huge stellar explosions. But contrary to supernovae, which involve the complete demolition of a star, novae are formed when a red dwarf star in a binary or two-star system spits matter (mostly hydrogen) onto its partner, a nearly-dead white dwarf star. This added matter acts like a fan to a flame, forcing nuclear reactions to occur at the white dwarfs surface. As a result, the white dwarf releases tons of energy and eventually shines a million times brighter than before, thus turning into a stella nova. During the following few weeks, a stella nova will release about as much energy as our sun produces in 10,000 years. Finally, the nova cools off and dies out completely. ~ A Major FindAccording to researchers who study stellar phenomena, this latest nova find may well be the most significant in the area of stella nova research in 20 years. Previous studies of novae in far regions of the universe took place in the 1980s. At that time, said Gilmozzi, the longest recorded distance was about 60 million light-years away, 10 million light-years shy of the current record. However, although far-flung novae have not been well documented, stella novae are relatively common. For example, such novae occurring in our own Milky Way galaxy can be visible to the naked eye as often as once every two or three years. 
One nova from the group of four discovered in NGC 1316. But the novae seen by the VLT are so far away, they are nearly 100 million times fainter than whats visible with the naked eye. The astronomers were able to determine these latest novaes distances by comparing their brightness to similar objects of known distance. Although such distances may seem gargantuan, they are not particularly large when compared to other objects, which can lie billions of light-years away. The newly detected novae are "much farther than the farthest known pulsar," explained Sumner Starrfield, an astronomer at Arizona State University, "but we see supernovae at much larger distances." Scientists say their novae discovery will add a great deal to the study of galaxies, stars and our own solar system. For one thing, these objects "show promise as standard candles for measuring distances to other galaxies," said Howard Bond, a researcher at the Space Telescope Science Institute in Baltimore. In addition, these novae may someday help scientists learn a thing or two about life closer to home. Thats because nuclear reactions taking place inside stella novae are known to produce several rare chemical elements, including possibly aluminum 26. "This may tell us how some of the chemical elements in our own system were formed," said Starrfield.
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