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  • Writer's pictureayush devak

NASA Hubble Spots Protective Shield Defending 2 Small Galaxies

Ground-based image of the Large Magellanic Cloud.Hubble's view of the Large Magellanic Cloud.

Just a space train stop from the Milky Way, two little galaxies have a fortified barricadeprotecting them from falling to pieces, astronomers said Wednesday in the journal Nature.

These starry realms are staunchly locked in orbit around each other, yet during their journey across the universe, they seem to be unraveling like balls of yarn. They perpetually leave stringy remnants of gas behind - material integral to their galactic job: star-making.

What’s interesting is that despite losing pieces of themselves for millennia, both these galaxies -- the Large and Small Magellanic Clouds -- are yet to be dismantled. And,they're still making stars.

"If this gas was removed from these galaxies, how are they still forming stars?"

By tapping into data collected by NASA's Hubble Space Telescope and the now-retired Far Ultraviolet Spectroscopic Explorer(FUSE), Prof.DhaneshKrishnaraoand fellow scientists realized the Magellanic cloud system is surrounded by a sort of thin hot bubble of supercharged gas-agalactic shield.

This cocoon, or corona as the scientists call it, prevents these galaxies from spitting out too much of their gas supply even though the Milky Way's immense gravitational pull tugs on the galaxies and space-borne phenomena try to invade them.

In turn, this sort of defense system is the reason our universe continues to be blessed with these galaxies' starry twinkles.

"Anything that tries to pass into the galaxy has to pass through this material first, so it can absorb some of that impact," Krishnarao said. "In addition, the corona is the first material that can be extracted. While giving up a little bit of the corona, you're protecting the gas that's inside of the galaxy itself and able to form new stars."

Already, experts had predicted the existence of the defensive Magellanic corona. The big thing about this discovery, though, is the fact that we now have eyes on the shield.

"The resolution of Hubble and FUSE were crucial for this study," Krishnarao said. "The corona gas is so diffuse, it's barely even there."

Because this corona stretches more than 100,000 light-years from the galaxies it protects, it's rather difficult to spot. But Hubble and FUSE were able to get around the corona's invisibility hurdle because both powerful instruments have an extensive archive of data regarding some of our universe's most extreme, brilliant marvels: quasars.

Quasars are pretty much giant jets of lightprotruding from the centres of active black holes.Quasars act kind of like cosmic flashlights, serendipitously placed across the universe to elucidate even the darkest of interstellar secrets with dazzling illumination.

In this case, they were perfect tools to help us finally detect this kind of hypothesized, cagey corona around the Magellanic galaxies.

For their new study, the team analyzed patterns of ultraviolet light from 28 quasars, then characterized what kind of material may lie around the Large Maganellic cloud first.

Plus, the Large and Small Magellanic Clouds are, respectively, only 160,000light-years and 200,000 light-years away from us, so they're much easier to study, and therefore, their corona will be, too.

They're also dwarf galaxies, which are thought to hold boons of novel information for astronomers, like insight into how galaxies arose and evolved in the first place long, long ago. According to NASA, coronas have been seen around more distant dwarf galaxies before, but they haven't been probed with much detail.

Shown in purple, the corona stretches more than 100,000 light-years from the main mass of stars, gas and dust that make up the Magellanic Clouds, intermingling with the hotter and more extensive corona that surrounds the Milky Way.


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