A bar in our galaxy could be formed as a result of a collision

Scientists used new data from the Gaia telescope to simulate the development of the Milky Way in the past. They were sure that the bar at the center of our galaxy was formed as a result of a merger with another system several billion years ago.

A bar in the Milky Way. Source: www.ucl.ac.uk

Bars in spiral galaxies

The Milky Way is a spiral galaxy with a bar. Recently, scientists suggested that it could have been formed as a result of a collision and merger with another star system several billion years ago. 

Bars are bright, elongated formations that seem to permeate the core of some spiral galaxies, including our own. They consist of bright stars and are clearly visible in the images, and for a long time, it was believed that their appearance was caused solely by the density of luminaries in the star system.

However, no one knows for sure, especially regarding our galaxy. We observe it from the inside, so we understand the general structure quite roughly. In particular, it is only relatively recently that scientists have begun to find evidence that the Milky Way has experienced several large-scale collisions in the past.

Result of collisions

The Gaia Space Telescope played a central role in our understanding of how the Milky Way was formed in the past. In particular, thanks to these studies, the remains of another galaxy were discovered inside our system, which, due to the shape that these stars form, were called the “Gaia Sausage”. 

The collision occurred 8–11 billion years ago, and as a result, the Milky Way received up to 50 billion solar masses of matter in various forms, as well as several globular clusters. The stars that became part of the Galaxy then can still be recognized by their high metallicity and unusual orbits.

Scientists said that the collision occurred at about the same time when the Milky Way collided with an unknown galaxy, which was just in the process of forming spiral arms. Therefore, the scientists decided to conduct a simulation and check how these two processes could affect each other.

It turned out that the conditions in our galaxy at that time strongly prevented the formation of a bar. And the collision accelerated this process. Without it, the formation of the bar would begin 2 billion years later. Astronomers hope that further research will reveal more about the Milky Way’s past.

According to phys.org

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