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Working ScienceQuasars: Really Far Out ScienceBy Robert E. Allen Princeton University announced the discovery of the most distant quasar detected, an estimated 13 billion light years from Earth. Quasars are mysterious objects that emit massive amounts of energy; an average quasar has the luminosity of 100 galaxies, although they appear to be compact objects, perhaps no larger than our solar system. Many astronomers think quasars are massive black holes at galactic centers. As surrounding stars are pulled into the black hole, they emit large amounts of radiation. The origin of quasars is not known. Most quasars are billions of years old. The host galaxy cannot be seen surrounding the most distant quasars, and they are quite rare in the nearby universe. One explanation for this lack of nearby young quasars is that they may have been formed shortly after the big bang. Once the stars in the immediate vicinity were pulled into the black hole, the radiation stopped. The distance and orbital speed of other stars in the galaxy kept them from being pulled into the black hole. Xiaohui Fan, a graduate student at Princeton University, discovered the quasar while analyzing initial data from the Sloan Digital Sky Survey. He credits the unique qualities of the Survey telescope and its associated sensors for the discovery. The survey telescope contains a 2.5-meter mirror and a wide-angle camera. It records the brightness of each object in five colors, with high accuracy, and for large segments of the sky at high speeda combination of capabilities that is unique to the Sloan instrumentation. The detailed color information allows researchers to identify possible quasars with a high degree of confidence. The suspected objects are then examined in greater detail with a nearby 3.5-meter telescope. The initial analysis identified 15 quasars. Astronomers calculate extreme distances by the redshift of light coming from distant objects. The wave length shifts toward the red end of the spectrum if the object is moving away from the observer; larger shifts indicate greater speeds, and greater speeds indicate greater distances in the expanding universe model. The three most distant quasars discovered by the Sloan Survey emitted the light seen by the researchers when the universe was less than one billion years old and one-sixth of its current volume. This research is supported by SC's Office of High Energy and Nuclear Physics. Contact: Michael Strauss, (609) 358-3808, strauss@astro.princeton.edu. Related article: Sloan Digital Sky Survey, Energy Research News, September-October 1998. |
![]() ![]() ![]() ![]() ![]() ![]() You guessed it! That's a quasar. |
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