Mysterious megastructure seen in the spiral arm of the Milky Way

Mysterious megastructure seen in the spiral arm of the Milky Way
Mysterious megastructure seen in the spiral arm of the Milky Way

Scientists at NASA's Jet Propulsion Laboratory have discovered a previously unknown giant structure in one of the spiral arms of our Milky Way galaxy. Its orientation is strikingly different from that of the arm itself, and its length is about 3,000 light years, which makes it one of the largest structures in near space.

The study was published in the journal Astronomy & Astrophysics, and the discovery is briefly described on the website of the American space agency NASA. It is reported that the discovered mysterious structure on the spiral arm of the Milky Way looks like a splinter sticking out of it. This is the first large structure, the orientation of which differs sharply from the orientation of the sleeve itself.

To get more detailed data about it, astronomers used the array of observations from the Spitzer space telescope. A year and a half ago, this apparatus was "retired", but it managed to provide scientists with useful information. By the way, Spitzer was designed specifically to search for newborn stars in gas and dust nebulae. He caught the infrared light that penetrated from the stars through these clouds. This characteristic made it possible to capture the light of the stars that make up the giant structure.

The researchers also created a three-dimensional image of the section of the spiral arm that interested them. To do this, they used the most recent data sheet from the ESA (European Space Agency) mission. His device Gaia allows you to accurately measure distances to stars. Combining all of the findings, the scientists found that the long, thin structure associated with the so-called Sagittarius arm in the Milky Way is composed of young stars. It was also found that these stars move at almost the same speed and in the same direction.

"A key property of spiral arms is how tightly they wrap around the galaxy," says lead author Michael Kuhn, an astrophysicist at California Institute of Technology. Milky Way models suggest that the Sagittarius arm forms a spiral tilted about 12 degrees, but the structure we examined stands out because it is at almost 60 degrees."

Similar structures have previously been found in the arms of other spiral galaxies. Sometimes they are called "spurs" and "feathers". This is the first time such a structure has been discovered in the Milky Way. The most difficult thing for researchers was measuring distances.

By the way, it turned out that the first attempts to measure the distance to stars from the giant structure were made by a group of astronomers back in the 1950s. But then scientists believed that they were studying ordinary nebulae. No one imagined that four nebulae of the Milky Way at once are in reality combined into one giant structure.

"Distance is one of the most difficult things to measure in astronomy," says co-author Alberto Crone-Martins. "Only recent direct distance measurements with Gaia have made the geometry of this new structure so obvious to us."

Combining data from Gaia and Spitzer resulted in a detailed 3D map. She helped calculate that the mysterious structure is about 3,000 light-years long. At the same time, quite a lot of smaller complex structures were revealed inside the structure, which scientists did not notice before. We add that astronomers still do not fully understand what mechanism creates spiral arms in galaxies.Perhaps further study of the Milky Way will solve this mystery.

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