The Physics Factbook™
Edited by Glenn Elert -- Written by his students
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|Bibliographic Entry||Result |
|Paranides, Nicholas A. Introduction to Astronomy. Massachusetts: Addison Wesley, 1979: 306.||"The red shift of 16 percent corresponds to a distance of two billion light years in the expanding universe."||2 billion light-years|
|"Quasars." McGraw Hill Encyclopedia of Science and Technology. 14 1997: 713.||"… their red shifts would ambiguously show them (quasars) to be the most distant known objects in the universe, ranging up to about 1010 light-years away."||10 billion light-years|
|Asimov, Isaac. Quasars, Pulsars, and Black Holes. Milwaukee: Gareth Stevens, 1988: 22.||"And as recently as 1987, British and American astronomers detected an object that may be 12 billion light-years away."||12 billion light-years|
|Howard, Neale E. The Telescope Handbook and Star Atlas. Toronto: Fitzhenry & Whiteside, 1975: 110.||"The shifts of some quasars suggest they are receding at about 90% of the speed of light, and if this is true they are about 12 billion light-years away."||12 billion light-years|
|Sagan, Carl. Cosmos. New York: Ballantine, 1980: 216.||"The nearest is perhaps half a billion light-years away. The farthest mat be ten to twelve or more billions."||12 billion light-years|
Quasar is short for quasi-stellar radio source. They are veryfaint, intensely blue galaxy-like formations that emit large amountsof energy and strong radio signals. In the late 1950s quasarswere first discovered with radio telescopes. Later on opticalimages that matched the positions of the radio sources were found.The brightest quasar is 3C 273 which lies at a distance of 2 billionlight-years away.
The properties of quasars are still very obscure. The suddenshift of the emission lines from blue to red (the longest wavelengths),discovered in 1963, puzzled astronomers. This radical red shifthas been interpreted as a Doppler effect, that is, and increasein wavelength due to motion. This increase indicates the quasarsare traveling away from us at incredible speeds. But a few astronomershave argued that the red shifts are not cosmological in originand do not indicate the distances of quasars.
On the other hand, these red shifts suggest that some quasarsare receding at a speed of 90 percent the speed of light. Accordingto Hubble's law of expansion of the universe, these large velocitiescorrespond to large distances. No quasars are found with 2 billionlight-years. Therefore, quasars are the most distant known objectsin the universe ranging from 2 billion to 12 billion light-yearsaway.
Ji Young Lee -- 1998
|Bibliographic Entry||Result |
|Astronomers Find the Most Distant Radio Galaxy. Lawrence Livermore National Laboratory (LLNL), 1 June 1999.||"The newly-discovered radio galaxy, TN J0924-2201, was found toward the southern constellation Hydra at a distance of nearly 11 billion light years from Earth."||11 billion |
|LLNL Astrophysicists Discover Most Distant Galaxy Known is not as Far Away as Once Believed. Lawrence Livermore National Laboratory (LLNL), 4 November 2000.||"With the estimated distance of 12.5 billion light years for STIS 123627+621755 no longer correct, the new title holder for the most distant object known belongs to a quasar, an active black hole at 12.4 billion light years."||12.4 billion |
|Hubble and Keck team up to find farthest known galaxy in the Universe, W.M. Keck Observatory press release, 15 February 2004,||"A team of astronomers may have discovered the most distant galaxy in the universe. Located an estimated 13 billion light-years away, the object is being viewed at a time only 750 million years after the big bang, when the universe was barely 5 percent of its current age …. Analysis of a sequence of Hubble images indicate the object lies in between a redshift of 6.6 and 7.1, making it the most distant source currently known. However, long exposures in the optical and infrared taken with spectrographs on the 10-meter Keck telescopes suggests that the object has a redshift towards the upper end of this range, around redshift 7."||13 billion |
|VLT Smashes the Record of the Farthest Known Galaxy, ESO Press Release 04/04, 1 March 2004.||"Named Abell 1835 IR1916, the newly discovered galaxy has a redshift of 10  and is located about 13,230 million light-years away. It is therefore seen at a time when the Universe was merely 470 million years young, that is, barely 3 percent of its current age."||13.23 billion |
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