domingo, 18 de diciembre de 2011

Astrophysics - First Look at a Black Hole’s Feast

A true heart of darkness lies at the center of our galaxy: Sagittarius A* (pronounced “A-star”) is a supermassive black hole with the mass of four million suns packed into an area only as wide as the distance between Earth and the Sun. Itself invisible to direct observation, Sgr A* makes its presence known through its effect on nearby stars, sending them hurtling through space in complex orbits at speeds upwards of 600 miles a second. And it emits a dull but steady glow in x-ray radiation, the last cries of its most recent meals. Gas, dust, stars… solar systems… anything in Sgr A*’s vicinity will be drawn inexorably towards it, getting stretched, shredded and ultimately absorbed (for lack of a better term) by the dark behemoth, just adding to its mass and further strengthening its gravitational pull.
Now, for the first time, a team of researchers led by Reinhard Genzel from the Max-Planck Institute for Extraterrestrial Physics in Germany will have a chance to watch a supermassive black hole’s repast take place.
A cloud of cool ionized gas has been spotted rapidly approaching the accretion disk of Sgr A*, picked out within several years’ worth of observations made with the European Southern Observatory’s Very Large Telescope array located in the high, dry mountains of Chile’s Atacama Desert.
These images taken over the last decade using the NACO instrument on ESO’s Very Large Telescope show the motion of a cloud of gas that is falling towards the supermassive black hole at the center of the Milky Way. (ESO/MPE)
The cloud, estimated to be three times the mass of Earth, has already begun to break apart due to the powerful tidal forces created by Sgr A*’s gravity. These will only intensify as the cloud moves closer to the black hole, eventually ripping it apart entirely and creating shockwaves of energy and radiation flares.
Of course, this is exactly what researchers are hoping for.
This will be the first time that the feeding process of a supermassive black hole will be witnessed from start to finish. There is still much to be learned about the enigmatic curiosities that reside at the centers of many galaxies, and witnessing Sgr A*’s latest meal will help increase our working knowledge of SMBHs, and black holes in general.
“The idea of an astronaut close to a black hole being stretched out to resemble spaghetti is familiar from science fiction. But we can now see this happening for real to the newly discovered cloud. It is not going to survive the experience,” said Stefan Gillessen, the lead author of the paper.
“It’s very exciting,” he added.
It’s estimated that the entire process could take up to a decade to unfold, with the gas cloud encountering Sgr A*’s event horizon in 2013.
The video above takes us on an amazing flight into the heart of the Milky Way beginning at our planet’s location within an outlying arm and zooming all the way to where Sgr A* resides. Inside the galactic hub we can see massive stars orbiting an invisible yet undeniably massive point, and the hazy cloud of gas that’s destined for dinner is circled in white, showing its locations from 2002 until now.
It’s only a matter of time before it succumbs to the black hole’s embrace. And when it does, our telescopes will be watching.
The next two years will be very interesting and should provide us with extremely valuable information on the behaviour of matter around such remarkable massive objects.”
– Reinhard Genzel, team leader
The team’s paper was published today in this week’s issue of the journal Nature. Read more on the ESO press release here.
Video credit: ESO/MPE/Nick Risinger ( Emerson/Digitized Sky Survey 2 Music: xxx
Source: Universe Today

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