The above video simulates an interaction between the Small Magellanic Cloud and the Large Magellanic Cloud, which began 1 billion years ago. It shows a collision about 100 million years ago. And indeed, astronomers believe that this has happened.
Astronomer Gurtina Besla of the University of Arizona used a computer a few years ago to model what would have happened if the Large and Small Magellanic Cloud had collided in the past. The above simulation comes from their work. She and her team predicted at that time that a direct collision would cause the southeastern region of the Small Magellanic Cloud ̵
… the first unequivocal evidence that the Small and Large Magellanic Clouds have recently collided.
The Magellanic Clouds, visible from the southern hemisphere of the Earth, are small satellite galaxies of our Milky Way galaxy. They are not far apart on the dome of the sky. Star moves in the smaller cloud provide evidence of the collision, but we did not have data on these movements before Gaia, whose second data release was last April. Astronomers have broken down the Gaia data to gain all sorts of interesting insights into our galaxy and its environment, and here's another one. Astronomer Sally Oey of the University of Michigan, lead author of the study, said:
This is truly one of our exciting results. You can actually see that the wing is its own separate region, away from the rest of the Small Magellanic Cloud.
Oey and colleagues published their findings in The Astrophysical Journal Letters .
A statement from the University of Michigan described some of the processes that these astronomers used to make their discovery:
Together with an international team, Oey and undergraduate researcher Johnny Dorigo Jones investigated the SMC [Small Magellanic Cloud] for "Runaway "Stars or stars that have been ejected from clusters within the SMC. To observe this galaxy, they used a recent data release from Gaia …
Gaia was designed to re-stage stars over several years to draw their movement in real time. In this way, scientists can measure how stars move across the sky.
We have seen very massive, hot young stars – the hottest, brightest stars that are quite rare. The beauty of the Small Magellanic Cloud and the Large Magellanic Cloud is that they are their own galaxies, so we look at all the massive stars in a single galaxy.
The study of stars in a single galaxy helps astronomers in two halves ways, these researchers said. First, it provides a statistically complete sample of stars in a parent galaxy. Second, astronomers have a uniform distance to all stars, which helps them to measure their individual speeds. Dorigo Jones said:
It's really interesting that Gaia got the right moves from these stars. These movements contain everything we see. For example, if we observe someone in flight in the cabin of an airplane, the movement we are seeing contains the movement of the plane and the much slower movement of the person walking.
So we removed the mass movement of the entire Small Magellanic Cloud to learn more about the velocities of individual stars. We are interested in the speed of single stars because we try to understand the physical processes within the cloud.
Oey and Dorigo Jones investigate runaway stars to determine how they were ejected from these clusters. In one mechanism, the so-called binary supernova scenario, a star in a gravitational binary pair explodes as a supernova and throws the other star like a slingshot. This mechanism produces x-ray emitting binaries.
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Another mechanism is that a gravitationally unstable star cluster eventually emits one or two stars from the group. This is called a dynamic ejection scenario that creates normal binary stars. The researchers found a significant number of out-of-control stars in both x-ray binaries and normal binaries, indicating that both mechanisms are important in ejecting stars from clusters.
Viewing this data, the team also observed all stars within the wing – the southeastern part of the SMC – moving in a similar direction and speed. This shows that the SMC and LMC probably had a collision several hundred million years ago.
Dorigo Jones commented:
We want to gather as much information about these stars as possible about these ejection mechanisms
Everyone likes it To admire images of galaxies and nebulas that are incredibly far away. The Small Magellanic Cloud is so close to us that we can see its beauty in the night sky with the naked eye. This fact, together with Gaia's data, allows us to analyze the complex movements of stars within the Small Magellanic Cloud and even determine factors of their evolution.
Bottom line: The movements of stars in the Small Magellanic Cloud, as shown by the Gaia Space Observatory, show that this small satellite galaxy of our Milky Way galaxy has in the past collided with its larger neighbor, the Large Magellanic Cloud.
Via University of Michigan
Read more … Gaia's 2nd Data Release: 1.7 Billion Stars!