Two Satellite Galaxies Conflicted ‘Recently’

Two galaxies colliding

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Two galaxies colliding

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People on Earth living near the Southern Hemisphere are able to see two luminous clouds not too far from the Milky Way. These two clouds are known as the Small Magellanic Cloud, SMC, and the Large Magellanic Cloud, LMC. As of November 8, 2018, new data shows that these two dwarf galaxies collided.

The Magellanic Clouds are a pair of irregular dwarf galaxies orbiting the Milky Way. However, these two dwarf galaxies aren’t part of the Milky Way but are a separate small galaxy. These two satellite galaxies are linked by gravitational forces and a “Magellanic Bridge” made of gas and stars that got pulled by the gravitational forces. The LMC is visible to humans living along the Earth’s Southern Hemisphere. The SMC is also visible but as a faint bit of the Milky Way which is 3.6B M☉(the term “☉” is equal to the mass of the Sun) smaller than the LMC mass of 10B M☉.

As of November 7, a team led by Sally Oey from the University of Michigan made a discovery that the LMC and the SMC once collided as a large chunk of the SMC has moved away from the rest of the SMC. This large piece of the SMC is moving toward the Magellanic Bridge and the LMC. The collision of two satellite galaxies actually occurred 100 to 200 million years ago due to the fact of the speed of light and the distance of the collision from Earth. This is a unique event as people can witness part of a galaxy dividing.

The discovery of the collision discovered by Sally Oey team was unintentional as they were actually looking for young, fast-moving, massive stars called “runaways” ejected from clusters in the SMC. To observe the SMC, this team used a current data release from Gaia, an orbiting telescope that has plotted over 1 billion stars paths closest to Earth to see how stars move across the sky which was launched by the European Space Agency launched. Oey’s team noticed stars located in the eastward “wing” of the SMC moved in concert. This could only be caused by the LMC’s gravity on the two satellite galaxies.

The collision was predicted a few years ago by astronomers from the University of Arizona predicting that the SMC’s wing region would travel closer toward the LMC.

Space is a vast area of science that humanity hasn’t quite covered yet and is still trying to make sense of. Hopefully, one day, humanity won’t be confined to the Milky Way and be able to explore and even set foot on planets outside the Milky Way, but there is still a long way to go in order to reach that goal.