Astronomers discovered a new filament of gas-dense material at the edge of our galaxy. The feature, nicknamed "Cattail", is still not fully mapped and could represent a previously undiscovered arm of the Milky Way galaxy.
The Milky way is a huge spiral galaxy with a central bulge and coiling arms that contain stars, gas, and dust. NASA reports that our galaxy contains four spiral arms, two major arms called Scutum-Centaurus, Perseus and two minor arms called Norma, Sagittarius and Perseus. Earth is located on the Orion Spur branch of the Sagittarius arms.
Researchers at the Five-hundred-meter Aperture Spherical Radio Telescope, (FAST), in Guizhou province, China have been studying a region of the sky known as Cygnus-X for the past few years. Keping Qiu is an astronomer at Nanjing University.
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FAST is able to see the universe through the radio spectrum. It's particularly useful in observing cold gas clouds containing hydrogen. Qiu also said that FAST can be used to view the entire electromagnetic spectrum. Qiu and his associates noticed hydrogen gas clouds that appeared to be far away from Cygnus-X. This is an immense star-forming region, approximately 4,500 light-years distant.
The researchers combined FAST observations with data from two telescopes in Australia and Germany to map the feature. It is approximately 3,600 light years across and lies at 68,000 light years from Earth. This makes it the longest and farthest giant gas filament that has ever been observed.
The team calculated that Cattail could have a mass of 65,000 suns. However, its true size might be as large as 16,000 light years across. The team presented their findings in an Aug. 4 paper to the arXiv preprint database. It has been accepted for publication by the Astrophysical Journal letters.
Cattail lies at the outer edge the Milky Way and is three times further from the galactic center that we are. The center is where most of our galaxy's bulk is located, which makes the huge feature somewhat of a puzzle.
Qiu stated that we don't know how such a massive filamentary gas structure could be formed in such extreme locations.
He and his colleagues have not yet been able to determine whether Cattail is a separate gas filament or wraps around and connects to the main portion. Qiu suggested that it could be an unknown branch or an arm previously undiscovered.
There are many questions about this feature. Qiu said that although our galaxy is believed to be warped at the edges, Cattail does not seem to follow the same warped pattern. His team plans to continue investigating the filament using FAST to better understand it.
Felix J. Lockman (an astronomer at Green Bank Observatory in West Virginia) said that the experience reminded him of the fact that we don't know a lot about the Milky Way. "Every time we look deeper, there's more information there."
Cattail may be an area of the galaxy that has not been seen before because FAST offers a higher resolution than other radio telescopes. Lockman stated that it is odd that the feature does not appear to follow the galactic Warp in the region. However, the exact details of the warps are still up for debate.
Original publication on Live Science
