Cosmic cuisine: Giant gas blob on menu for Milky Way's black hole
Scientists who spotted a giant gas blob orbiting the black hole at the center of the Milky Way say they'll get a first-ever close-up view of matter falling into a supermassive black hole.
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The supermassive black hole in the Milky Way's center is estimated to contain the mass of 4 million suns.Skip to next paragraph
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The team discovered the gas blob earlier this year as part of a larger effort to observe the region around Sagittaruis A* over long periods of time. The area remains puzzling, with so many young stars and a supermassive black hole that seems to have put itself on a diet.
Sagittarius A* appears in the constellation Sagittarius, which lies in the direction of the Milky Way's core as viewed from Earth. In 1951, radio astronomers reported having picked up radio emissions in that region, earning the source the A. Astronomers have since discovered stars orbiting a tight portion of the region with speeds greater that any found elsewhere in the galaxy. This led to the conclusion that the galaxy harbors a supermassive black hole at its center. The object was designated Sagittaruis A*.
The blob is about the size of the solar system but tips the scales at only about three times the mass of Earth. It orbits the black hole once every 137 years, give or take 11.
When the researchers examined radiation from the blob, its spectrum was extended in a way that indicated the blob was being stretched – the so-called spaghetti effect that theories envision for the impact of a black hole's gravity on matter as it approaches.
Looking back through archived images of the same region of space, the team was able to calculate the blob's orbit and track changes in its velocity with time.
In 2004 the blob was hurtling through space at about 2.7 million miles an hour, for instance. This year's observation clocked the blob at 5.2 million miles an hour.
The team notes that over the course of the 19 years during which the broader Sagittarius A* observing effort has been underway, two stars orbiting the black hole have make closer approaches than will the blob, or what's left of it. But because a star's gravity is so much greater than that of the blob, each of the two stars was able to hold itself together and keep on orbiting, Gillessen says.
When matter begins its final descent into a black hole, gravity compresses it, it heats, and emits radiation. If the team's orbital calculations are correct, the researchers say they anticipates a flare of radiation from the region of Sagittarius A* in 2013, when the fragments reach their point of closest approach.
If some of the gas gets drawn close enough to the event horizon to make the final plunge, the researchers anticipate observing a giant radiation flare from Sagittarius A* a few years later.
IN PICTURES: The Milky Way
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