Using data from the ESA Gaia space telescope, astronomers have identified a region in the southeast of the Small Magellanic Cloud, consisting of bright stars that are moving away from the main part of the galaxy, indicating a recent astronomical collision of two of the closest satellites of the Milky Way.
This is a very exciting result. The data really shows that the wing of the Small Magellanic Cloud is a separate region that departs from the rest of it.
-Sally Oay, lead author of a study from the University of Michigan (USA)
If you find yourself in the southern hemisphere on a clear night, you can see two luminous clouds of stars that are satellites of the Milky Way and are called the Small Magellanic Cloud (SMC) and the Large Magellanic Cloud (LMC). As part of studying the processes in these dwarf galaxies, astronomers from the University of Michigan analyzed the data of Gaia in search of runaway stars.
It is very important that Gaia received its own movement of these luminaries. Thanks to this, we calculated their speeds and directions without taking into account the movement of the SMC itself, which help to understand the physical processes occurring inside the galaxy.
-Dorigo Jones, co-author of the study from the University of Michigan
Astronomers were interested in two processes that lead to the appearance of runaway stars. The first is to break a binary pair, when one of them explodes a supernova and throws the companion away from the system. Such a mechanism is identified by X-rays. The second is based on the gravitational instability of a cluster of stars, which leads to the ejection of one or two members from the group, while no X-ray emission is observed.
After reviewing the data from Gaia and finding a large number of such systems, the team was able to confirm the important role of both mechanisms in removing stars from clusters. However, the most exciting was another – scientists noticed that all the stars in the wing of the SMC are moving in the same direction with a similar speed. This, according to researchers, as well as the results of a simulation of such an event by astronomers from the University of Arizona prove the recent (several hundred million years ago) direct collision of SMC and LMC.
Collision of two galaxies near the Milky Way
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