Number 210 (Story #3), January 13, 1995 by Phillip F. Schewe and Ben Stein|
THE BEST EVIDENCE YET FOR A BLACK HOLE comes from observations of maser emissions (coherent microwave radiation analogous to laser light) from a dusty torus very near the center of galaxy NGC 4258. From the speed of the dust (900 km/sec) rotating around the galactic center, astronomers have calculated that the mass of the central gravitating body has a mass of almost 40 million solar masses, all within a radius of 0.13 parsec. This works out to a density of 100 million solar masses per light year, a density some 10,000 times greater than that of any known cluster of stars. James Moran of the Harvard-Smithsonian Center for Astrophysics, reporting the new results at the AAS meeting on behalf of his Japanese-American collaboration, believes that the profile of high-speed gas provides "compelling evidence" that the central object is a black hole. The high-resolution pictures of the heart of NGC 4258 were made with the Very Long Baseline Array, a network of radio telescopes located from Hawaii to the Virgin Islands.