Fig12_15 Einstein rings

Fig12_15 Einstein rings

Fig. 12.15 . When a background and foreground galaxy are perfectly aligned, the closer galaxy acts as a gravitational lens, bending and magnifying the light of the more distant galaxy and forming a glowing “Einstein” ring. A double ring is captured in this Hubble Space Telescope image, indicating an exceptionally rare alignment of a massive foreground galaxy with two background ones; the distances of the three galaxies are estimated at 3 billion, 6 billion and 11 billion light-years from Earth. (Courtesy of NASA/ESA/Raphael Gavazzi and Tommaso Trea, U. C. Santa Barbara and the SLACS team.)

Copyright 2010, Professor Kenneth R. Lang, Tufts University