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Most astrophysical objects are not very bright in infrared. Stars and galaxies are too hot to emit much radiation here, but planets and other cool objects do. The near-infrared region is particularly interesting for cosmologists and astrophysicists studying some of the most distant and oldest objects in the universe, however. Although most objects radiate brightly at much lower wavelengths, extreme redshifting can move the lines from ultraviolet into the NIR. 2.1 THE HIGHEST-REDSHIFT GALAXIES 
« J-dropout object identified in the Hubble Deep Field North » This object is visible only in the NICMOS F160W (H) image. The U, B, V, and I images were obtained with WFPC2, the J and H images with NICMOS. Similar objects could be found in large numbers by WFC3 by searching a large area for sources bright in the H band and faint in the J band (M. Dickinson). There are hundreds of thousands of faint, distant galaxies per square degree of sky. Many of these galaxies are so distant that they have significant redshifts. For redshifts above z=3 the bright Lyman region (912 Å up to 1216 Å) is shifted into the infrared. WFC3 will conduct NIR surveys of discovery to find these bright distant sources which date back to the very early universe. 2.2 WATER AND ICES ON MARS AND THE OUTER PLANETARY SATELLITES 
« Water in Martian rocks as revealed by WFPC2 (left) and NICMOS (right) » The bluer shade along the edges of the Martian disk in the left panel is due to atmospheric haze and water ice clouds. The large reddish region in the right panel identifies an area of water-rich minerals known as Mare Acidalium. The search for life on extraterrestrial planets is focused on the detection of water. A key indicator of water vapor is located at 1.4nm. Special filters on WFC3 are optimized for this region.. Other filters permit detection of a variety of ices , from H2O in the satellites of Jupiter and Saturn, to CH4 (Uranus) and CO and N2 (Neptune's Triton).
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Curator: Lori Tyahla Content Manager: Lori Tyahla NASA Official: Randy Kimble Last Updated: March 22, 2007 + Contact WFC3 Webmaster |
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