Death of the Great Attractor?Eight years ago, astronomers reported evidence that the Milky Way Milky Way, the galaxy of which the sun and solar system are a part, seen as a broad band of light arching across the night sky from horizon to horizon; if not blocked by the horizon, it would be seen as a circle around the entire sky. and a host of other galaxies and galaxy clusters This page lists some of the more interesting galaxy clusters and groups. Defining the limits of galaxy clusters is imprecise as many clusters are still forming. In particular, clusters close to the Milky Way tend to be classified as galaxy clusters even when they are much smaller are moving forward a distant superculuser in the constellations of Hydra and Centaurus. To supply the gravitational grav·i·ta·tion n. 1. Physics a. The natural phenomenon of attraction between physical objects with mass or energy. b. The act or process of moving under the influence of this attraction. 2. tug that might account for such motion, the team proposed, a huge concentration of matter, dubbed the Great Attractor Great Attractor Proposed concentration of mass, equivalent to tens of thousands of galaxies, that influences the movement of many galaxies, including the Milky Way Galaxy (see galaxy). , must lie at least 150 million light-years from Earth (SN: 12/92, p.408). But an astronomer now says that a key assumption used in calculating the velocities of elliptical galaxies in the Great Attractor study may harbor a fatal flaw. Elliptical galaxies in clusters are generally though to contain only elderly stars. But increasing evidence suggests that at least some ellipicals outside of clusters have more youthful populations, notes Rafael Guzman of the University of Durham (body, education) University of Durham - A busy research and teaching community in the historic cathedral city of Durham, UK (population 61000). Its work covers key branches of science and technology and traditional areas of scholarship. in England. In assuming that ellipticals only have old stars, the Great Attractor team may have consistently underestimated the true distances to these galaxies and overestimated their motion, he says. When Guzman applies an age-independent measure of distance to these galaxies the Great Attractor vanishes. Infrared observations should verify whether individual elliptical galaxies do contain substantial numbers of young starts, he adds. |
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