Wednesday, September 22, 2010

An Elegant Galaxy in an Unusual Light

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This striking new image, taken with the powerful HAWK-I infrared camera on ESO's Very Large Telescope at Paranal Observatory in Chile, shows NGC 1365. This beautiful barred spiral galaxy is part of the Fornax cluster of galaxies, and lies about 60 million light-years from Earth. The picture was created from images taken through Y, J, H and K filters and the exposure times were 4, 4, 7 and 12 minutes respectively.    Credit: ESO/P. Grosbol

NGC 1365 is one of the best known and most studied barred spiral and is sometimes nicknamed the Great Barred  because of its strikingly perfect form, with the straight bar and two very prominent outer spiral arms. Closer to the centre there is also a second spiral structure and the whole galaxy is laced with delicate dust lanes.
This galaxy is an excellent laboratory for astronomers to study how spiral galaxies form and evolve. The new infrared images from HAWK-I are less affected by the dust that obscures parts of the galaxy than images in visible light and they reveal very clearly the glow from vast numbers of  in both the bar and the spiral arms. These data were acquired to help astronomers understand the complex flow of material within the galaxy and how it affects the reservoirs of gas from which new stars can form. The huge bar disturbs the shape of the  of the galaxy and this leads to regions where gas is compressed and star formation is triggered. Many huge young star clusters trace out the main spiral arms and each contains hundreds or thousands of bright young stars that are less than ten million years old. The galaxy is too remote for single stars to be seen in this image and most of the tiny clumps visible in the picture are really star clusters. Over the whole galaxy, stars are forming at a rate of about three times the mass of our Sun per year.

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