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New quasar most distant object yet.

New quasar most distant object yet

A quasar dubbed 1208 1011 is the most distant object yet discovered in the universe, according to a report in the July 3 NATURE. Discovered and investigated by a team of astronomers from the United States and the United Kingdom, the quasar--a galaxy with an especially bright, compact center--lies at a distance about 90 percent of the way to the edge of the observable universe.

The astronomers measured the quasar's relative distance by examining how the light it emits changes as it travels to earth. "In a sense, light expands as the universe expands,' says astronomer Wallace Sargent of Palomar Observatory in Pasadena, Calif. As the quasar travels away from earth, the wavelengths of light it emits grow longer, shifting toward the infrared region of the spectrum. This phenomenon, called redshift, indicates the speed at which the quasar travels away from us. By knowing how fast the quasar travels, scientists can estimate its distance.

The numeric value of the redshift indicates how far toward the infrared the quasar's spectrum has shifted as its light travels to earth; the higher the redshift, the more distant the object. The new quasar's redshift value of 3.8 is the highest ever found; four other quasars discovered concurrently in the same region of the sky all have redshifts greater than 3.5.

"High redshift quasars are all very bright,' Sargent says. According to Sargent, quasars' brightness gives rise to the possibility that quasars may have formed when matter fell into black holes--very small regions of enormous gravitational pull. As the black hole sucked up the matter--probably galactic gas and dust left over from the formation of the galaxy--the black hole's gravity excited the matter into emitting light. Such a possibility may indicate that black holes in the early universe were all very large, and that distant quasars such as the recent discoveries are all very young. At the other end of the time scale, according to astronomer Alexei Filippenko of the University of California at Berkeley, perhaps 10 percent of nearby galaxies may be the dim remains of old quasars whose black holes are slowly starving.

Such galaxies, says Filippenko, emit light characteristic of quasars, but at levels too faint for easy detection.

Says Filippenko, "We think we can find even more distant quasars. It seems unlikely that we've had the good fortune to find the only one with a redshift as high as 3.8.'
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Author:Kleist, Trina
Publication:Science News
Date:Jul 12, 1986
Words:408
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