This still from a computer animation shows a simulation of a giant space cloud falling into Sagittarius A*, the supermassive black hole at the center of our own Milky Way galaxy, in mid-2013.
Image: European Research Media Center
The giant black hole at the center of the Milky Way is preparing to gobble up a tasty gas cloud in a cosmic meal astronomers are eager to witness.
Most galaxies are thought to host humongous black holes at their cores, and the Milky Way's, which is called Sagittarius A* (pronounced "Sagittarius A-star") contains about 4 million times the mass of our sun.
It's about to add a tiny bit more mass to its girth, when it swallows a cloud on a collision course with it. Scientists think it will take the black hole about a year to completely devour the cloud, with the peak of its feast occurring around September of this year.
"This is the first chance we've had to witness such an event in nearly 40 years of monitoring the galactic center, so this is a rare privilege," said P. Chris Fragile, an astrophysicist at the College of Charleston who works on computer simulations of the cloud's fall. The phenomenon, he said, "will be one of the most carefully observed astronomical events ever."
In contrast to the enormous size of the black hole, the cloud is just about three times the mass of Earth — "just a tiny little snack," said Stefan Gillessen, an astronomer at the Max Planck Institute for Extraterrestrial Physics in Garching, Germany. [Milky Way Black Hole Eats Gas Cloud (Video)]
Gillessen and his colleague Reinhard Genzel have been observing the cloud and plan to ramp up their observations soon to catch its descent toward the black hole. Observing the event will require some of the most sensitive observatories on Earth, such as the Very Large Telescope in Chile, where Gillessen and Genzel will be making their observations.
"It's at the limit of what telescopes can do," Gillessen told SPACE.com. "It's very faint, and we have to look for quite some time to see it."
Already, scientists have seen the cloud speed up and stretch out as it gets pulled closer and closer to its doom. Gravitational tidal forces from the black hole have caused it to morph from a roughly circular shape, in 2004, into a thin, oblong object in 2012. And while eight years ago the cloud was moving about 620 miles per second (1,000 kilometers per second), it is now zooming at a brisk 1,500 miles a second (2,500 km/s).
The upcoming cosmic spectacle should offer scientists a chance to test some of their theories about how black holes pull in, or accrete, mass.
"It might be a very unique opportunity to see how it is accreting," Gillessen said. "The most exciting thing would be if Sagittarius A* changes its accretion state. If the accretion rate increases, you might expect that Sagittarius A* itself will turn significantly brighter, and it might also change its structure. There's a slight chance that radio telescopes can actually catch that."
Scientists also hope to learn more about the cloud and where it came from. For example, some theories suggest there could be a hidden star buried beneath the gas that is currently invisible, but which is feeding the cloud with gas from within.
"We can obviously learn more about the nature of the cloud itself, we can learn about the conditions of the background gas, and ultimately we can learn more about how the black hole at the center of our galaxy is really fed," Fragile said.
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6 Comments
Add CommentI think planet Earth is going to do a little accreting this year too. It seems stuck in an asteroid swarm in this region of the galaxy they are currently passing through so there will be lots of meteors for Russians to go around and pick up.
Reply | Report Abuse | Link to thisIf there is a star in the middle, things will get interesting. I wonder if the "peak of the feast" would be changed if that was true...
Reply | Report Abuse | Link to thisThe strange thing (well, another strange thing) is that this is ancient history - Sag A* swallowed the cloud 26,000 years ago, and the light is just reaching us now. Our improving instruments are making the rest of the universe feel closer and closer, but we're actually seeing further and further back in time.
Reply | Report Abuse | Link to thisGood point but, in the proximity of a SMBH at least, we can observe cosmological processes and events actually unfolding in 'real time'. Observing the actual rotation of the galaxy, for example, would require observational durations exceeding the technological history of humanity. We can simulate the dynamics of galaxy mergers all we want, but can never observationally validate our models...
Reply | Report Abuse | Link to thisThis makes me wonder just how ineffective the machines looking for alien species are.
Reply | Report Abuse | Link to thisJust think, If we discovered an alien species 20 light years away we would observe a civilization as it existed 20 years ago. If we sent them a communication, we might receive a reply in 40 years.
Reply | Report Abuse | Link to thisI can hardly wait.