The Small Magellanic Cloud appears to be unraveling by the gravitational hands of its sister galaxy, the Large Magellanic Cloud, which has been found to be unwrapping its little sister’s stars.
He Little and Big The Magellanic Clouds (SMC and LMC for short) are two irregular dwarfs galaxies passing near the Milky Way. The LMC is about 163,000 light years away from us, while the SMC is about 200,000 light years away. light years of us. Both are subject to the disturbance of the Milky Way’s gravity, which triggers explosions of star formation within it and rips a stream of gas from both, called Magellanic Current.
However, new results from the Visible and Infrared Astronomical Survey Telescope (VISTA) at the European Southern Observatory’s Paranal mountaintop site in Chile have shown that the Milky Way is not the only galaxy affecting the SMC. It turns out that the tiny galaxy’s big brother, the LMC, is also a disruptive influence.
As part of VISTA’s Magellanic Cloud Survey (VMC), the four-meter aperture telescope has spent the past 11 years carefully mapping the movements of millions of individual stars in the Magellanic Clouds. VISTA’s near-infrared vision sees through some of the dust in the Magellanic Clouds, giving you a clearer view of the stars.
“When I first saw the results, I was surprised by the quality of the measured stellar motions,” said Florian Niederhofer of Germany’s Leibniz Institute for Astrophysics Potsdam (AIP) in a statement. “By combining observations taken over a timeline of more than a decade, we were able to map the internal kinematics of the Small Magellanic Cloud with a level of detail outstanding for ground-based observations.”
Niederhofer’s team published the results from the LMC in 2022, which reveals how stars move through the dwarf galaxy’s off-center bar, which is similar to a galactic bar often found at the center of large spiral galaxies, including the Milky Way. There were no big surprises, but the results of the SMC measurements surprised everyone.
Previous measurements implied that the motion of stars in the SMC was indicative of the dwarf galaxy’s rotation, but according to these new results, this was a misinterpretation. Instead, stars move en masse outward from the core of the SMC, in directions generally aligned along an axis pointing from (as seen from Land) from southeast to northwest. Extend that line and it will point all the way to the LMC. This is exactly what we would expect if the gravitational tidal forces of the LMC pulled on the part of the SMC closest to it, stretching the SMC.
The average speed of these stars is 17 kilometers (10.6 miles) per second, and over the course of a few hundred million years, these stars could travel several thousand light years. This gives an indication of the extent to which the SMC has been distorted over billions of years. In the past its structure must have been more compact and defined, unlike its current amorphous form.
“The results reveal large-scale tidal expansion across the SMC and challenge long-standing assumptions that the Small Magellanic Cloud behaves like a rotating disk,” said AIP’s Sreepriya Vijayasree, lead author of the research paper describing the findings. “The study shows that the internal motions of stars in the Small Magellanic Cloud are not dominated by ordered rotation, but by gravitational perturbations caused by repeated encounters with the LMC over billions of years.”
The movements of stars are like a time machine, a legacy of past events that have been imprinted on the way stars travel through space. Another example is that VISTA has also detected that older people save giant stars in the SMC everyone seems to have their own mass movement north. These red giants are stars that were born about two billion years ago and their movement is the result of some other gravitational interaction that dates back to that time. Since astronomers believe the Magellanic Clouds are passing near our galaxy for the first time, this mysterious interaction two billion years ago may not even have taken place near the Milky Way.
As for the future, the Magellanic Clouds are slowing down as they interact with the Milky Way halo, and recent simulations have shown that the Magellanic Clouds are destined to merge with the Milky Way within billions of years. Until then, the two brothers of the dwarf galaxy will remain together, even if the older brother continues to bother the younger one.
The findings were published in Astronomy and Astrophysics.
