Star legacy: strange star structures are the remains of the brutal collision of the Milky Way

Milky Way galaxy merged with dwarf galaxy

Five years ago in the outer space, the astronomers noticed a strange grouping of stars in the constellation of the Virgo. First of all, it attracted the attention of the scientists for its incredible density. It resembled a star cluster, but at the same time, later, separate studies found that some stars move towards the Earth, and some, on the contrary, in the opposite direction. The discovery turned out to be incredible and unexpected. But it made it clear that the discovered cluster of stars was not just a cluster of the stars, there was something else.

Last year, the next study revealed some unexpected facts. The group of stars was not a cluster of the stars, it was the shell of a dwarf spheroidal Galaxy that merged with the Milky Way. It was called the Maiden Star Stream.

A researcher Thomas Donlon from the Rensselaer University noted that in his next work, the astronomers claim that this shell is indeed the result of a radial merger of galaxies. There are several types of fusion, one of them is VOD, which is a radial fusion that occurs forcibly. It occurs when a group of stars interacts with different speeds. The scientists could not understand the principle of the formation of the Virgo Stellar Stream. But now, studying its movement in general, they figured out why the speeds are different and why the stars move that way.

When a dwarf Galaxy collides with the center of the Galaxy, it is repelled and then pulled back towards the center. And every time, reaching the farthest point, it leaves several stars along the way, each time forming a kind of shell.

By creating a computer model and using the information obtained as a result of astronomical observations, the astronomers calculated how many times a dwarf Galaxy appeared on the formed swing, reaching the edge, and then returning to the center when it merged with the Milky Way. It turned out that the merger began 2.7 billion years ago. Then the dwarf Galaxy first passed through the center of the Milky Way.

The merging of the galaxies of all shapes and sizes is an extremely rare phenomenon seen in space. They all leave their mark. Most of the stars that merged with the Milky Way, the scientists called space immigrants, they came from other galaxies. Over time, the tidal forces of the Galaxy transform these immigrants into long streams of stars.

These streams move in concert with each other through the halo. The astronomers name the phenomenon tidal mergers. But the merger of the dwarf Galaxy with the Milky Way was of a different nature. The multiple movements of the dwarf Galaxy back and forth formed shell shapes. And it is a completely new type of fusion that the scientists have to investigate.