<! – -> [embedded content] The above video simulates an interaction between the little Magellanic Cloud and the Large Magellanic…
The above video simulates an interaction between the little Magellanic Cloud and the Large Magellanic Cloud, which started 1 billion years ago. It shows a collision about 100 million years ago. And really astronomers now believe that this happened.
A few years ago, astronomer Gurtina Besla at the University of Arizona used a computer to model what would have happened if ever before the big and small magellan clouds collided. The simulation above comes from her work. She and her team predicted at that time that a direct collision would lead to the southern area of the little magellan cloud ̵
1; which astronomers call the wing – to move towards the Great Magellanic Cloud. On the other hand, if the two galaxies simply pass close to each other, the wing stars should move in the perpendicular direction. Last week (October 25, 2018) – thanks to ESA’s Gaia Space Observatory – Michigan astronomers could confirm that what Besla and the team predicted actually occur. The wing is which moves away from the bulk of Small Magellanic. They said that this observation gives:
… the first unambiguous evidence that small and large magellan clouds collided recently.
Magellanic Clouds, visible from the southern hemisphere of the earth, are known to be small satellite galaxies in our Milky Way. They are not far apart from the sky’s dome. Star motion in the smaller cloud gives evidence of the collision, but we did not have data about these movements before Gaia, whose second computer license was in April last year. Astronomers have mined Gaia data to learn all sorts of interesting insights about our galaxy and its space area, and now this is another. Astronomer Sally Oey from the University of Michigan, senior 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 that goes away from the rest of the little magellan 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 detect:
Together with an international team, Oey and research scientist Johnny Dorigo Jones investigated SMC [Small Magellanic Cloud] for “runaway” stars or stars who have sprayed from clusters within SMC. To observe this galaxy, they used to use a new Gaia data …
Gaia is designed for image stars over and over again for a period of several years to plot their motion in real time. This way researchers can measure how the stars move across the sky.
We have looked at very massive hot young stars – the hottest, most bright stars, which 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.
Reviewing stars in a single galaxy helps the astronons in two ways, these researchers said. First, it gives a statistically complete selection of stars in a parent galaxy. Secondly, this provides astronomers with equal distances to all stars, helping them to measure their individual speeds. Dorigo Jones said:
It’s very interesting that Gaia got the true moves in these stars. These movements contain everything we’re looking at. For example, if we observe someone in the cabin on an airplane in flight, we see the movement we see of the plane and the slower movement of the person walking.
So we removed the bulge movement of the entire Small Magellanic Cloud to learn more about the speeds of individual stars. We are interested in the speed of individual stars because we try to understand the physical processes that occur in the cloud.
Oey and Dorigo Jones study volatile stars to determine how they were expelled from these clusters. In a mechanism called binary supernova scenario, a star explodes in a gravitational binary couple like a supernova that exudes the second star as a snake threat. This mechanism produces x-ray binary stars.
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Another mechanism is that a gravitationally unstable cluster of stars eventually sprains one or two stars from the group. This is called the dynamic ejection scenario, which produces normal binary stars. The researchers found significant numbers of volatile stars among both x-rays and normal binaries, indicating that both mechanisms are important for ejecting stars from clusters.
Looking at these data, the team also observed that all the stars within Wing – the southeastern part of the SMC – move in the same direction and speed. This shows that SMC and LMC were likely to collision a few hundred million years ago.
Dorigo Jones commented:
We want as much information about these stars as possible to better limit these ejection mechanisms.
Everyone loves to marvel at pictures of galaxies and nebulae that are unbelievably far away. The little magellan cloud is so close to us that we can see its beauty in the night sky with just our naked eye. This fact, along with data from Gaia, allows us to analyze the complex movements of stars in the little magellan cloud and also determine factors in its development.
Bottom line: The movements of the stars in the small magellan cloud – as revealed by the Gaia Space Observatory – show that this little satellite galaxy of our Winter Street collided earlier with its larger neighbor, the Great Magellanic Cloud.
Via University of Michigan
Read more … Gaias second data version: 1.7 billion stars!