Dust buster eyes fireworks in nearby galaxy.Ten million light-years from Earth lies the nearest galaxy with a heart of fire. Powered by a central black hole 1. black hole - An expression which depends on its own value or a technique to detect such expressions. In graph reduction, when the reduction of an expression is begun, the root of the expression can be overwritten with a black hole. If the expression depends on its own value, e.g. x = x + 1 then it will try to evaluate the black hole which will usually print an error message and abort the program. that sucks in stars and gas, the giant, radio-emitting galaxy Centaurus Centaurus (sĕntôr`əs), southern constellation located N and E of Crux, the Southern Cross. It is known especially for its bright stars Alpha Centauri and Hadar. It also contains Centaurus A, a radio galaxy, as well as a globular star cluster visible to the naked eye. A got a further jolt several hundred million years ago when it swallowed a disk-shaped galaxy. With such an example of cosmic violence close to home, astronomers should have a field day studying black holes and galactic mergers. However, a stripe of dust girdling the galaxy has clouded efforts to observe the maelstrom Maelstrom, whirlpool, Norway: see Moskenstraumen.. Partially penetrating the dust with a near-infrared camera, the Hubble Space Telescope has now recorded the first detailed portrait of the galaxy's nucleus. Images unveiled this week show that a disk of gas extending 130 light-years in diameter and coming within 7 light-years of the center encircles the black hole. Curiously, the disk is tilted with respect to the black hole's axis, like a loose wheel around an axle. The axis is defined by a jet shooting from the core. The newly found disk may be linked to an unseen, inner disk of gas that is aligned with the axis and fuels the black hole, notes study collaborator Ethan J. Schreier of the Space Telescope Science Institute in Baltimore. He and his colleagues presented the images May 14 at a briefing in Washington, D.C. They describe their study in the June 1 Astrophysical Journal Letters. If there are disks aligned in different directions, "it may mean that the gravitational pull of the ... galaxy is stronger than the gravitational pull of the black hole," says Schreier. If that's the case, the black hole, estimated to weigh as much as I billion suns, may have slightly less mass than predicted. An analysis of images taken by the Infrared Space Observatory Infrared Space Observatory: see infrared astronomy. may bolster that interpretation. Although the observatory, which ended its mission in April, had a lower-resolution telescope than Hubble, it recorded emissions at longer infrared wavelengths, which penetrate dust more easily. The images indicate that most of the radiation comes from the birth of stars rather than from material spiraling into the galaxy's black hole, notes I. Felix Mirabel of the Centre D'Etudes de Saclay in Gif-sur-Yvette, France. |
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