Документ взят из кэша поисковой машины. Адрес оригинального документа : http://www.arcetri.astro.it/~palla/ANDREAIMMAGINI/Cosmologia/Visibile.txt Дата изменения: Sun Mar 4 19:00:30 2001 Дата индексирования: Sat Dec 22 08:55:12 2007 Кодировка: Поисковые слова: universe

EMBARGOED UNTIL: 10:00 AM (EST)/9:00 AM (CST) January 7, 1999

PHOTO NO.: STScI-PRC99-02


COMBINED DEEP VIEW OF INFRARED AND VISIBLE LIGHT GALAXIES

This narrow, deep view of the universe reveals a plethora of galaxies
(reaching fainter than 28th magnitude), as seen in visible and infrared
light by NASA’s Hubble Space Telescope. The reddish galaxies are glowing
in infrared light, and the bluish galaxies are glowing in visible light.
Several distinctive types of galaxies can be seen in these views: blue
dwarf galaxies, disk galaxies, and very red elliptical galaxies. A
bright, nearby face-on spiral galaxy appears at upper right. Some of the
brightest objects in the field are foreground stars in the halo of our
own Milky Way galaxy. By combining views in infrared light and visible
light astronomers have a better idea of the shapes of galaxies in the
remote universe, and of the fraction which are old or dust-obscured at
early epochs.

Galaxies could appear bright in the infrared (and thus red in this
picture) for several reasons. They might be dusty, or contain old
stars, or are at a very great distance. Several of the red galaxies in
this field have the colors and the smooth, symmetric shapes expected for
old elliptical galaxies. The existence of such objects in the early
universe and their numbers can set important limits on the era when the
earliest galaxies assembled and formed most of their stars. In
general, the image shows that the shapes and sizes of most faint
galaxies are similar in infrared and visible light, suggesting that
younger and older stars within distant galaxies are well mixed and that
dust is not completely distorting impressions of distant objects.

The image was taken in October 1998 as part of the Hubble Deep Field
South imaging campaign. It is in a small patch of sky in the
constellation Tucana. The false-color image is a composite of separate
images taken with the NICMOS and STIS cameras on board the Hubble Space
Telescope. The red and green colors correspond to infrared
wavelengths of 1.6 and 1.1 microns, respectively. The blue color
corresponds to the STIS view that covers the full range of visible
wavelengths.

Credit: R. Williams (STScI) and the HDF-South team, and NASA