Astronomy: Sharpest View Yet of Galactic Core

"This portrait of the Milky Way's central region was made by combining images taken by Hubble's Near Infrared Camera and Multi-Object Spectrometer (NICMOS) between February and June 2008 and images previously taken by Spitzer's Infrared Astronomy Camera (IRAC). The region at lower left shows pillars of gas sculpted by winds from hot, massive stars in the Quintuplet cluster. At the centre of the image, ionised gas surrounding the supermassive black hole at the galactic centre is confined to a bright spiral embedded within a doughnut-shaped ring of gas and dust. (Hubble image: NASA/ESA/Q D Wang/UMass Amherst; Spitzer image: NASA/JPL/S Stolovy/Spitzer Science Center/Caltech)

The Milky Way came into unprecedented focus on Monday as astronomers released the sharpest infrared picture yet taken of the roiling furnace at the centre of galaxy. The new mosaic reveals massive filaments of gas as well as a new population of massive, rogue stars. The centre of the galaxy is full of hot gas and dust and is thought to harbour a black hole weighing about 4 million Suns. The area is not easily seen at visible wavelengths, which are largely absorbed and scattered by dust, but astronomers can image the centre using infrared light, which passes through intervening material more easily.

The picture, released at the American Astronomical Society meeting in Long Beach, California, combines images taken during 144 orbits of the Hubble Space Telescope with pictures taken by the Spitzer Space Telescope. The Hubble portion of the panorama is 10 times as sharp as Spitzer's map, and covers a 300- by 115-light-year area around the centre of the Milky Way. (Earth sits some 26,000 light years from the galactic centre.) The new map reveals some 600,000 stars, including a new population of about 200 massive stars. These stars illuminate the gas around them with strong blasts of radiation, and - curiously - seem to be loners. That is surprising, since most massive stars near the Milky Way's centre are found in one of three star clusters called Central, Quintuplet and Arches.

The newly found stars, on the other hand, are found in isolation, and researchers are not sure if they were born outside the clusters or were cast away from star clusters that were torn apart by gravitational forces in the violent region around the galaxy's central black hole."

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