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HUBBLE'S DEEP VIEW OF THE UNIVERSE UNVEILS EARLIEST GALAXIES

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  • uforaport@wp.pl
    http://observe.arc.nasa.gov/stsci/hubbledev/db/2004/07/images/a/formats/print.jpg HUBBLE S DEEP VIEW OF THE UNIVERSE UNVEILS EARLIEST GALAXIES Astronomers
    Message 1 of 1 , Mar 9, 2004
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      HUBBLE'S DEEP VIEW OF THE UNIVERSE UNVEILS EARLIEST GALAXIES

      Astronomers today unveiled the deepest portrait of the
      visible universe ever taken. A one million second long exposure
      taken by NASA's Hubble Space Telescope (HST) may reveal the
      first galaxies to emerge from the so-called "dark ages" shortly
      after the big bang.

      The new image, called the Hubble Ultra Deep Field (HUDF),
      should offer new insights into what types of objects reheated
      the cold, dark universe about one billion years after the big
      bang, when stars first started to shine, about 13 billion years
      ago. The image reveals some galaxies at distances until now too
      faint to be seen even in Hubble's previous faraway looks,
      called the Hubble Deep Fields (HDFs), taken in 1995 and 1998.

      "Hubble takes us to within a stone's throw of the big bang
      itself," said Massimo Stiavelli of the Space Telescope Science
      Institute (STScI) in Baltimore, and the HUDF project lead. A
      key question for HUDF astronomers is whether the universe
      appears the same at this very early time as it does when the
      cosmos was between one and two billion years old.

      The HUDF field contains an estimated 10,000 galaxies. In
      ground-based images, the patch of sky in which the galaxies
      reside is largely empty, just one-tenth the diameter of the
      full moon. Located in the constellation Fornax, the region is
      below the constellation Orion.

      This new view is actually two separate images taken by Hubble's
      Advanced Camera for Surveys (ACS) and the Near Infrared Camera
      and Multi-object Spectrometer (NICMOS). The combination of ACS
      and NICMOS images will be used to search for galaxies that
      existed between 800 and 400 million years after the big bang.

      The ACS field is studded with a wide range of galaxies of
      various sizes, shapes, and colors. In vibrant contrast to the
      image's rich harvest of classic spiral and elliptical galaxies,
      there is a zoo of oddball galaxies littering the field. Some
      look like toothpicks, others like links on a bracelet. A few
      galaxies appear to be interacting. These oddball galaxies, that
      existed 800 million years after the big bang, chronicle a
      period when the universe was chaotic, when order and structure
      were just beginning to emerge.

      The NICMOS reveals the farthest galaxies ever seen, perhaps
      just some 400 million years after the birth of the cosmos.
      That's because the expanding universe has stretched their light
      into the near-infrared portion of the spectrum, where NICMOS
      observes.

      "The images will also help us prepare for the next step from
      NICMOS on Hubble to the forthcoming James Webb Space Telescope.
      The NICMOS images reach back to the distance and time that Webb
      is destined to explore at much greater sensitivity," explained
      Rodger Thompson of the University of Arizona and the NICMOS
      principal investigator.

      The entire HUDF was observed with the advanced camera's "grism"
      spectrograph, an instrument used to measure distances to these
      distant objects. "The grism spectra have already yielded the
      identification of about a thousand objects. Included among them
      are some of the intensely faint and red points of light in the
      ACS image, prime candidates for distant galaxies," said
      Sangeeta Malhotra of the STScI and Principal Investigator for
      the Ultra Deep Field's ACS grism follow-up study. "Based on
      those identifications, some of these objects are among the
      farthest and youngest galaxies ever seen. The grism spectra
      also distinguish among other types of very red objects, such as
      old and dusty red galaxies, quasars and cool dwarf stars," he
      said.

      The ACS picture required a series of exposures taken over the
      course of 400 HST orbits around Earth from Sept. 24, 2003, to
      Jan. 16, 2004. The size of a phone booth, ACS captured ancient
      photons of light that began traversing the universe even before
      Earth existed. Photons of light from the very faintest objects
      arrived at a trickle of one photon per minute, as opposed to
      millions of photons per minute from nearer galaxies.

      The STScI is operated by the Association of Universities for
      Research in Astronomy, Inc. under contract with NASA's Goddard
      Space Flight Center, Greenbelt, Md. The HST is a project of
      international cooperation between NASA and the European Space
      Agency.

      For information about NASA and agency projects on the Internet,
      visit:

      http://www.nasa.gov/formedia

      For HST images and information on the Internet, visit:

      http://hubblesite.org/news/2004/07



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