Quasars or quasi-stellar radio source are sources of electromagnetic
energy which are characterized with high red shifts, thus leading scientists to conclude that not only they are moving away
but are also at a great distance from us. Of the over 100,000 quasars identified to-date, the greatest proportion are over
one billion light-years away (the closest quasar identified to-date is 780 million light-years away whereas the most distant
quasar discovered so far is 13 billion light-years away). As a result, quasars represent entities from the universe's
Given their visibility (generally as point sources of light), it follows they must be associated with tremendous amounts of energy which is only exceeded in intensity by supernovae and gamma-ray bursts. Some examples of quasars also involve the centers of (active) galaxies and which has led to the suggestion that supermassive black holes at the galaxy center and the consequent accretion of material must fuel these quasars. The rapid change in luminosity observed for some quasars also suggests they must be relatively small entities.
Note: QSO 0957+561 lying at a distance of 7.8 billion light-years away has the distinction of being the first gravitationally lensed object identified (1979). Due to an intervening mass lying in the optical path between earth and the quasar, the light from the quasar is bent (as predicted by Einstein), thus yielding two images of the source with relative magnitudes of 16.7 (QSO 0957+561A) and 16.5 (QSO 0957+561B) and with an apparent separation of only 6 arc-seconds. The edge-on galaxy partially visible in the image below is NGC 3079 (mag 10.9). With a redshift value of z=1.414, this quasar is receeding away from us at nearly 71% the speed of light (ie. 210,000 km/sec).
Please click on the image below to display in higher resolution (1200 x 900)
RA / Dec:
10h 01m 21s /
55° 53' 52"
7.8 billion ly
0.15' x 0.10'
Mar 23-24, 2007
23:30 - 00:15 UT+2
AP 160 f/7.5 StarFire EDF
AP 1200GTO GEM
SBIG LRGB filters