MIT-led Team Zooms in on Massive Black Hole at Center of Milky Way
September 12, 2008 at 5:28 pm
Astronomers linked together radio dishes in Hawaii, Arizona and California to create a virtual telescope more than 2,800 miles across that is capable of seeing details more than 1,000 times finer than the Hubble Space Telescope.
The key to making these observations is a technique called very long baseline interferometry, or VLBI, which links simultaneous observations from several radio telescopes that can be thousands of miles apart. The signals from these radio dishes are combined to create a “virtual” telescope with the same resolving power as a single telescope as large as the distance between the participating dishes. As a result, VLBI can reveal exquisitely sharp details.
The cosmic target of the observations was the source known as Sagittarius A* (“A-star”), long thought to mark the position of a black hole whose mass is 4 million times that of the sun. http://www.dailygalaxy.com/my_weblog/2008/09/mit-led-team-zo.html
Milky Way’s Core Black Hole Sent Out Massive Flares 300 years ago
Our galaxy’s central black hole let loose a powerful flare three centuries ago. The finding helped resolve a long-standing mystery: why is the Milky Way’s black hole so quiescent? The black hole, known as Sagittarius A-star (A*), is a certified monster, containing about 4 million times the mass of our Sun. Yet the energy radiated from its surroundings is thousands of millions of times weaker than the radiation emitted from central black holes in other galaxies.“We have wondered why the Milky Way’s black hole appears to be a slumbering giant,” says team leader Tatsuya Inui of Kyoto University in Japan. “But now we realize that the black hole was far more active in the past. Perhaps it’s just resting after a major outburst.”
Entry filed under: Astronomy Notes on the Web. Tags: black hole, milky way.