Published: Fri, March 30, 2018
Sci-tech | By Eric Barnett

Galaxy void of dark matter baffles astronomers

Galaxy void of dark matter baffles astronomers

"This is the first galaxy astronomers have discovered to be so lacking in dark matter, which is thought to comprise 85% of our universe's mass", the Wednesday statement reads.

The slower the objects in a system move, the less mass there is in that system.The team's calculations show that all of the mass in the galaxy could be attributed to the mass of the stars, which means there is nearly no dark matter in NGC1052-DF2."If there is any dark matter at all, it's very little". "It's so rare, particularly these days after so many years of Hubble, that you get an image of something and you say, 'I've never seen that before'".

Van Dokkum said NGC1052-DF2 is so sparse that "it is literally a see-through galaxy".

Based on its its size and brightness, NGC 1052-DF2 is classified as an ultra diffuse galaxy that is larger than the Milky Way, but contains about 250 times fewer stars. The galaxy is missing most, if not all, of its dark matter. And it was also mostly transparent, with other galaxies visible behind it.

Scientists say that there is about five times the amount of dark matter in a galaxy than regular matter. "There is no theory that predicts these types of galaxies - how you actually go about forming one of these things is completely unknown", Merritt said.

A galaxy entirely bereft of dark matter raises vexing questions that, so far, have stumped astronomers.

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There have been several ideas that have floated around regarding the true nature of dark matter, and discoveries like this will only push astronomers to unlocking its secrets.

And what about NGC 1052-DF2? Dark matter seems to be needed to draw in sufficient material to form the galaxy and its stars, and halos of dark matter keep galaxies from spinning apart as they rotate.

"We thought all galaxies were made up of stars, gas and dark matter mixed together, but with dark matter always dominating", says Prof. One idea suggests it's a result of a galaxy merger, and that the gas concentrated after being ejected. When van Dokkum and his team found NGC 1052-DF2, they expected to see something similar. If there were no such thing as dark matter and the current laws of physics were just slightly wrong, you'd expect the laws to be just as wrong in NGC 1052-DF2 as they are everywhere else.

Ordinarily, not the greater part of a galaxy's mass is obvious.

The "ghost" galaxy, known as NGC1052-DF2, is some 65 million light-years away and about the size of the Milky Way. But how it formed is a complete mystery. Imaging them enabled the research study group to establish their activities orbiting the galaxy, which could, consequently, give an action of the quantity of mass that is associated with maintaining the things in position. When dark matter is present, that galaxy's gravity will be bulked up, causing its stars to move faster than if just normal matter were present. This is only expected if dark matter is bound to ordinary matter through nothing but gravity. For example, they can look at how fast stars cruise around a galaxy. This would allow the gas to form stars away from clumps of dark matter. "So finding the opposite, namely an absence of dark matter really came out of the blue for us", he added. Already have suspicions of three, whom they will notice better. Thus, this leaves no speculative room for the existence of dark matter. They gravitationally attract ordinary, or baryonic, matter which eventually settles within the extant cloud of dark matter. NASA's Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope.

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