Astronomers know many details about the universe. However, that part of it that can be considered our home "city" - the Milky Way - keeps a disproportionate amount of mysteries. It is difficult to study Moscow while standing on Red Square: the structure of the metropolis is more noticeable from a bird's eye view. Therefore, the discovery of the first rupture in the spiral arm of the Galaxy can be called a real scientific sensation. The nature of this formation is completely incomprehensible, therefore its observation is doubly interesting.
The curious find was reported by an international team of scientists in the Astronomy & Astrophysics magazine. An abnormal formation looks like a chip jumped out of cracked wood or a feather sticking out from the wing. The so-called rift is located in the Sagittarius arm, at a distance of about three and a half thousand light years from our solar system (located in the neighboring small arm of Orion). It is formed by a chain of young stars, their clusters and gas and dust clouds (nebulae) stretching over 3000 light years.
The discovery was made thanks to observations by NASA's Spitzer space telescope, carried out shortly before its decommissioning in January last year. The device took pictures in the infrared range, which allowed it to "see" in detail the stars, the light of which in the visible part of the spectrum is blocked by astronomical objects closer to us. Additional information was provided by the European space telescope Gaia, which specified the distances to nearly two billion stars in the Milky Way.
By combining these two datasets, the scientists found that the fragment of the Sagittarius arm of interest has a different twist angle than the whole. This is one of the key characteristics that describe the structure of spiral galaxies. The Sagittarius arm itself is twisted by about 12 degrees, and the gap - by all 60. The movement of objects in it is coordinated and somewhat different in characteristics from the arm. Such formations are known in other spiral galaxies, but their existence in the Milky Way was questionable until recently.
It is not enough to say that astrophysicists are intrigued by the new discovery: they will now with redoubled zeal look for similar "feathers" or "chips" in other regions of the Galaxy. And the fact that the nature of such formations is still completely incomprehensible only spurs the interest of scientists. This gap is essentially a huge breakthrough in understanding the detailed structure of the Milky Way. A detailed study of it will allow humanity to better understand the structure of spiral galaxies.
Interestingly, the mechanism of sleeve formation itself has not yet received a single all-encompassing model. So a recently discovered structure in the immediate vicinity (by the standards of the Universe) from us may become an important piece of evidence that will finally help solve this fundamental mystery.
And one more curious fact: the rupture of the Sagittarius arm discovered by scientists includes the well-known nebulae - Eagle, Omega, Triple and Lagoon - observation of which in the middle of the 20th century made it possible for the first time to discover the spiral nature of our Galaxy.