Combined radio/optical image shows Milky Way, Magellanic Clouds, and the new radio image of the Magellanic Stream. Blue and white are the Milky Way and Magellanic Clouds. Red is the hydrogen gas in the Magellanic Stream, in the disks of the Magellanic Clouds, and in the stream’s Leading Arm. The Milky Way is horizontal in the middle of the image; the Magellanic Clouds are the light spots at the center-right portion of the image, from which the gas stream originates. Brown is dust clouds in the Milky Way
CREDIT: Nidever, et al., NRAO/AUI/NSF and Meilinger, Leiden-Argentine-Bonn Survey, Parkes Observatory, Westerbork Observatory, Arecibo Observatory.
A giant stream of gas flowing from neighbor galaxies around our own Milky Way is much longer and older than previously thought, astronomers have discovered. The new revelations provide a fresh insight on what started the gaseous intergalactic streamer.
The astronomers used the National Science Foundation’s Robert C. Byrd Green Bank Telescope (GBT) to fill important gaps in the picture of gas streaming outward from the Magellanic Clouds. The first evidence of such a flow, named the Magellanic Stream, was discovered more than 30 years ago, and subsequent observations added tantalizing suggestions that there was more. However, the earlier picture showed gaps that left unanswered whether this other gas was part of the same system.
“We now have answered that question. The stream is continuous,” said David Nidever, of the University of Virginia. “We now have a much more complete map of the Magellanic Stream,” he added. The astronomers presented their findings to the American Astronomical Society’s meeting in Washington, DC.
The Magellanic Clouds are the Milky Way’s two nearest neighbor galaxies, about 150,000 to 200,000 light-years distant from the Milky Way. Visible in the Southern Hemisphere, they are much smaller than our Galaxy and may have been distorted by its gravity.