Gas being drawn into the Milky Way’s black hole at 10 million km/hour

Ars Technica » Scientific Method 2013-07-18

The gas cloud has been stretched out as it approaches the Milky Way's central black hole.

A couple of years ago, astronomers identified a large cloud of gas near our galaxy's center. Based on their calculations, the gas was streaming in towards what might end up being its final destination: the supermassive black hole that resides at the center of the Milky Way. The expected arrival date? Some time in 2013. Those of you who've checked your calendars recently will realize it is now 2013 and, right on schedule, some astronomers at the Max Planck Institute for Extraterrestrial Physics have found that the gas cloud, now stretched out to a long filament, seems to have looped around the back of the black hole.

That finding comes courtesy of measurements of light emitted by the atoms of the cloud. Many parts of it appear to be moving away from us at about 3,000km a second (6.7 million miles an hour), based on the fact that the light is red shifted. But other parts of the cloud appear to be blue shifted by an equal amount, suggesting they're moving towards us at 3,000km/s. This strongly suggests that the cloud has arrived close to the central black hole and is now being drawn around by its gravitational pull. At the closest approach, the gas passed within 25 light-hours of the black hole.

These observations were made with the European Southern Observatory's Very Large Telescope, but a number of other instruments are keeping watch on our galactic center, so there may be more news about the biggest black hole in the neighborhood before the year is out.

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