June 20, 1997


Dr. Raghvendra Sahai of NASA's Jet Propulsion Laboratory, Pasadena, CA, is available for interviews about the new discovery of the coldest region in the universe. The cold region, found some 5,000 light years from Earth in the Boomerang Nebula, has a temperature of about 1 Kelvin, or minus 458 degrees Fahrenheit. It represents the outer regions of a cold wind being blown by a dying star.

"The Boomerang is a cloud of dust and gas being spewed out from an old star while its core collapses inward and becomes a white dwarf, a star which has used up its nuclear fuel," according to Sahai, who co-discovered the cold region. "The Boomerang Nebula is like a cosmic refrigerator, in which expanding gas cools very efficiently down to the very chilly temperatures we have found."

Sahai, had predicted the existence of such cold regions in a paper published in the Astrophysical Journal in 1990. He made the discovery along with Lars-Ake Nyman of the European Southern Observatory and Onsala Space Observatory, Sweden, after several observations between August and October of 1995. The work was done on a radio telescope at La Silla, Chile, by comparing signals received from carbon monoxide in the Boomerang Nebula with signals from cosmic microwave background radiation which pervades the whole universe. They discovered the cold region was absorbing some of that background radiation. The results have been submitted to Astrophysical Journal Letters.

Sahai believes the Boomerang Nebula is even colder than most other expanding nebulae because it is losing its mass about 100 times faster than other similar dying stars and 100 billion times faster than Earth's Sun. The nebula's dying star may represent our Sun's fate in 10 billion years, when it exhausts its nuclear fuel and becomes a white dwarf.

"Dying stars, like the one which produced the Boomerang Nebula, play a vital role in creating solar systems like ours," said Sahai. As these stars die, they synthesize and scatter elements like carbon and nitrogen and dust particles which sow the seeds for the birth of new suns, planets and life."

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