And what is this protective shield?NASA Hubble Spots Protective Shield Defending 2 Small Galaxies
Just a space train stop from the Milky Way, two little galaxies have a fortified barricade protecting 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 -- you know, material integral to their galactic job: star making.
But there's something weird going on.
Despite losing pieces of themselves for millenia, both these galaxies -- the Large and Small Magellanic Clouds -- are yet to be dismantled. And, yup, they're still making stars.
"A lot of people were struggling to explain how these streams of material could be there," Dhanesh Krishnarao, assistant professor at Colorado College, said in a statement. "If this gas was removed from these galaxies, how are they still forming stars?"
The answer? A galactic shield, of course.
Supercharged gas? LOL! In other words ... PLASMA.By tapping into data collected by NASA's Hubble Space Telescope and the now-retired Far Ultraviolet Spectroscopic Explorer, Krishnarao and fellow scientists realized the Magellanic cloud system is surrounded by a sort of thin hot bubble of supercharged gas. A shield, if you will.
In turn, this sort of defense system is the reason our universe continues to be blessed with these galaxies' starry twinkles.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.
"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."[/quote]
As the article says ...
Wait … the corona extends 100,000 light years from the Magellanic Cloud? But earlier the article called the shield a “thin hot bubble”. Considering that the Large Megellanic Cloud is only 160,000 light years from Earth and only 14,000 light years in diameter, I wouldn’t call that “thin”. So I assume the author just meant supercharged gas is rarified. And these bubbles appears to surround all the galaxies they’ve examined and in the case of the Milky Way and Megellanic Clouds, they even seem to overlap.Awesome. Now what?
Already, experts had predicted the existence of the defensive Magellanic corona. It isn't exactly a completely new find. What's big 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, so until now, this corona was only a hunch. 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.
… snip …
In this case, they were perfect tools to help us finally detect this kind of hypothesized, cagey corona around the Magellanic galaxies -- and in fact, quasars also lit the way in 2020 for Hubble, when the beloved telescope found a similar protective corona surrounding the Andromeda galaxy. (In 2000, the Milky Way's corona was confirmed with quasars, too!)
Now let’s look at the paper this article is reporting on …
https://www.nature.com/articles/s41586-022-05090-5
Doing that confirms that the “supercharged gas” is indeed hot plasma. And the density of the gas in the protective corona is over 1 particle per cm cubed. In fact, they calculate a mass of over 10^^11 solar masses for this corona. The mass of the LMC is about 1/10th that of the Milky Way (which has a mass of 9 - 15 × 10^^11 solar masses). So the mass of the protective corona is between 0.9 and 1.5 times the mass of the LMC, proper.Observations of a Magellanic Corona
Now that’s interesting since astrophysicists believe that the mass of the bulge in the LMC is about the same as the mass of the DM around the LMG (See table 1 of this: https://academic.oup.com/mnras/article/ ... ogin=false). You don’t suppose the dark matter that mainstream astrophysicists have been adding to their models to make their galaxy rotation curves match observations is the hot plasma in these protective shields?