Gravitational Lensing by Galaxy in Cluster IRC 0218
These Hubble Space Telescope images reveal the most distant cosmic lens yet found, a massive elliptical galaxy whose powerful gravity is magnifying the light from a faraway galaxy behind it.
The giant elliptical is the red object in the enlarged view at left. Its red color comes from the light from older stars. The galaxy is seen as it appeared 9.6 billion years ago and is one of the brightest members in a distant cluster of galaxies, called IRC 0218. The background image shows the entire region surrounding the galaxy.
In the enlarged view, the lighter-colored blobs at upper right and lower left are the distorted and magnified shapes of a more distant spiral galaxy behind the foreground elliptical. The giant elliptical is so massive that its enormous gravitational field deflects light passing through it, much as an optical lens bends light to form an image. This phenomenon, called gravitational lensing, magnifies, brightens, and distorts images from faraway objects that might otherwise be too faint to observe even with the largest telescopes.
Astronomers needed spectroscopy to determine that the blobby features were two images of the same distant galaxy, located 10.7 billion light-years from Earth. In the enlarged view at right, astronomers have subtracted the image of the giant red elliptical to show the more distant spiral galaxy. The glow of young stars makes the galaxy appear blue. The white area at upper right is probably a region of star formation.
The images were made by combining visible-light observations from the Advanced Camera for Surveys and near-infrared exposures from the Wide Field Camera 3.