The discovery of new galaxies in space has been done several times by astronomers. But the newly discovered galaxy this time confuses them.
Because the newly discovered galaxy has no dark matter.
As has long been known, every galaxy always has dark matter. Dark matter is a mysterious material that is abundant but does not emit light or energy.
Until now, not much information about dark matter from the galaxy. But, it has been considered an important part of all galaxies.
Not only that, according to galactic evolution, dark matter is a requirement for the birth of a new galaxy.
This makes the galaxy called NGC1052-DF2 confusing the researchers. Actually, the galaxy is 65 million light-years away, it has almost the same physical size as the Milky Way.
Only, in the galaxy has fewer stars.
The discovery of this unique galaxy originated from the image using the Dragonfly Telescope Array, which was deliberately created for imaging of very dim objects.
"The discovery of galaxies without dark matter is unexpected because the unseen mysterious substance (dark matter) is the most dominant of any galaxy," says Pieter van Dokkum.
"For decades, we thought that the galaxy started its life as a blob of dark matter, after which gas came down into dark matter circles, turned into stars, and gradually formed and ended up into a galaxy like the Milky Way," added van Dokkum .
This discovery has had a major effect in the study of dark matter. Because despite having no dark matter, this galaxy has a star.
This proves that dark matter actually exists in other galaxies and is separate from baryonic matter (visible celestial bodies).
The absence of dark matter in the galaxy really makes it different from other galaxies.
"It's like you're taking (a material) of a galaxy and just have a halo of stars and spheres, and somehow forgets the other stuff," van Dokkum said.
"There is no theory that predicts this type of galaxy, this galaxy is a complete mystery, because everything is weird.How it can form completely unknown," he continued.
Despite the astronomers' confusion, there is one of the most plausible explanations of this galaxy.
According to a report published in the journal Nature, NGC1052-DF2 is in a cluster of galaxies dominated by a very large elliptical galaxy called NGC 1052. This could be one of the possible formations of the galaxy.
In the report, it was argued that smaller galaxies could form from the gas that runted toward the formation of NGC 1052 but split before it arrived there.
In addition, there is the possibility that the galaxy was created from gas released when there are two other galaxies joined.
Could also be, there was an extraordinary event that swept away all the gas and dark matter from it.
Unfortunately, all these speculations have not been proven to explain the strangeness of the galaxy. Therefore, van Dokkum and his team returned using the Dragonfly telescope to search for similar galaxies.
The hope, they can compose a statistical picture of the strange galaxy.
"Every galaxy we know before has dark matter, and they all fall into similar categories like spiral or elliptical galaxies," says van Dokkum.
"But what will you get if there is no dark matter at all? Maybe this will happen," he concluded.
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