The Milky Way is a spiral galaxy. The branches develop in a spiral from the center towards the edge. But if you look closer, the branches don’t start exactly from the center of the galaxy. Right in the center there is an elongated bar-shaped structure, and it is only from the ends of this bar that the spiral branches begin.
Now, a group of scientists claims that the formation of this elongated bar was strongly favored by a historically known intergalactic collision.
Similar bars are found at the centers of most spiral galaxies.
Scientists have hypothesized that the central bars of galaxies may form simply as a result of the long-term effect of density waves of galactic matter, but recently it has been thought that the bars may also form as a result of the collision of a galaxy with another galaxy. .
Our galaxy, the Milky Way, has collided with several smaller galaxies over time.
We learned about these collisions in retrospect through precise analysis of the movement of stars in the Milky Way, made possible by unprecedentedly precise measurements made by the European Space Agency’s Gaia space telescope.
One of the largest of these collisions, with the Gaia-Enceladus dwarf galaxy, occurred between 8 and 11 billion years ago.
Interestingly, the models show that the central bar of the Milky Way also formed in the same time period.
Alex Merrow of John Moores University in Liverpool, England, and his colleagues wanted to know whether there might be a causal relationship between the two events.
To do this, they computer modeled the possible courses of events in the history of the Milky Way.
The findings now allow them to write, in a non-peer-reviewed paper published in the arXiv online repository, that the collision between the Milky Way and Gaia-Enceladus likely helped accelerate the formation of the bar.
The bar would probably have formed in the center of the Milky Way even without the help of Gaia-Enceladus, but probably about two billion years later.
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2023-12-12 06:48:00
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