Death by Black Hole: Gory Details of Dust Cloud's Demise Revealed

First spotted in 2011, a gas cloud several times the mass of the Earth has entered its death spiral around the black hole located at the center of the Milky Way.

Astronomers using the European Southern Observatory's Very Large Telescope (VLT) reveal in a new study that, as a result, it is being "grossly stretched" as it moves through the black hole's extreme gravitational field.

"The gas at the head of the cloud is now stretched over more than 160 billion kilometers around the closest point of the orbit to the black hole," Stefan Gillessen of the Max Planck Institute for Extraterrestrial Physics in Garching, Germany, said in a press release. "And the closest approach is only a bit more than 25 billion kilometers from the black hole itself - barely escaping falling right in."

As a reference point, Pluto's average distance from the Sun is 5.9 billion kilometers (3.67 billion miles) - or just one-thirtieth of the total space covered by the dust cloud

For this reason, Gillessen explains that the approach of the cloud "is not a single event but rather a process that extends over a period of at least one year."

In other words, it's going to be a slow, painful death for the doomed dust cloud.

Furthermore, as the gas cloud is stretched its light gets harder to see. Only by staring at the region close to the black hole for more than 20 hours with the SINFONI instrument on the VLT - the deepest exposure of this region ever with an integral field spectrometer - were the researchers able to measure the cloud's various velocities.

"The most exciting thing we now see in the new observations is the head of the cloud coming back towards us at more than 10 million km/h along the orbit - about 1% of the speed of light," said Reinhard Genzel, leader of the research group that has studied this particular region of the galaxy for nearly 20 years. "This means that the front end of the cloud has already made its closest approach to the black hole."

The origin of the gas cloud remains unknown, though Gillessen explains that the predominant theory currently is that it probably came from the stars orbiting the black hole.

However, one thing that is becoming more apparent, he says, is the cloud's likely lack of a star.

"Like an unfortunate astronaut in a science fiction film, we see that the cloud is now being stretched so much that it resembles spaghetti," he said. "This means that it probably doesn't have a star in it."

However, Avi Loeb, a theoretical astrophysicist at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., is the champion of the star theory and, according to Nature, is not ready to give up on it just yet. In defense of his thesis, Loeb points to the fact that the cloud has so far remained intact and is following an elliptical orbit, which would be expected in the case of a star.

Either way, the slow finale of this unique event is expected to continue to unfold well into the next year. As it does so, astronomers around the world are involved in an intense observing campaign from which they believe a wealth of data will arise not only about the gas cloud but about the regions close to the black hole and the effects of such intense gravity.