Hubble Space Telescope astronomers just released a new deep field image. Dubbed "Hubble Ultra Deep Field" (HUDF) compared to previously released 1995 and 1998 "Hubble Deep Field" (HDF), its two pictures -one in the visible, the other in the infrared- are showing farthest galaxies ever just at Dark Ages boundary. Previous Hubble Deep Fields were reaching a zone of the Universe at about 1 billion years after the Big Bang. Hubble Ultra Deep Field (HUDF) is now reaching a period 400-800 million years after the Big Bang (redshift 12 to 7). Such progress is due to the new Advanced Camera for Surveys (ACS) which was installed during the 2002 servicing mission. The ACS had twice the field of view and a higher sensitivity than the older Hubble workhorse camera, the Wide Field Planetary Camera 2 Field dating back to 1993. The Near Infrared Camera and Multi-object Spectrometer (NICMOS) was used too for furthest galaxies. It works in the near-infrared. HUDF field is just one-tenth full Moon and is located in constellation Furnace, below Eridan and the Whale. 10,000 galaxies are imaged. Picture needed a 12-day exposure. Infrared field is rotated right 90° relative to visible field and is part of the latter. Furnace constellation is accessible in winter months on southern horizon From left to right: Hubble Ultra Deep Field (ACS), Hubble Ultra Deep Field (NICMOS), Hubble Deep Field 1996 (WFPC2) Dark Ages is a period in the early Universe. Once the Big Bang occurred and developped, Universe eventually became filled with neutral hydrogen about 400,000 years after the initial bang. This is known as the "recombination epoch". Universe lets pass light as until know photons were bumping into hydrogen free protons and electrons. The famous CMB (Cosmic Microwave Background Radiation) is relic from this time. Soon after come the Dark Ages. First stars and galaxies form at that time. Although they are emitting strong radiation in the ultraviolet, these ages are dark for us however: light of these first objects is hampered by neutral hydrogen. As stars and galaxies becomes numerous, ultraviolet radiation eventually clears holes in hydrogen and 500 million years after the Big Bang (epoch known as the "re-ionization era") early Universe is cleared enough to be observed again in the visible light. Complete clearing does not occur until redshift 5, i.e. when Universe is 1.2 million years old Galaxies shown by Hubble Ultra Deep Field are far from orderly later spirals and ellipticals. Most of them are irregulars, which is mark of a more chaotic era. Few collisions are seen however. This new view of the early Universe confirms that stars and galaxies quickly formed and quickly evolved during first billion years after the Big Bang. Until now some studies mostly using gravitational lensing had yielded some oldest objects of the Universe. But this picture is the first to show such a plethora of objects so far away hence in a so young Universe Main aim of next generation astronomers' tools (like e.g. NASA-ESA James Webb Space Telescope (JWST), successor to Hubble) is towards Dark Ages. Such tools working mainly into the infrared will be able to reach deep into the period and see first stars and first galaxies at work
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