The Hubble telescope detected the protective shield of the Milky Way’s moon galaxies

A protective shield called the galactic corona protects the Large and Small Magellanic Clouds as the Milky Way's moon galaxies. The Hubble telescope detected the protective shield of the Milky Way’s moon galaxies

A protective shield called the galactic corona protects the Large and Small Magellanic Clouds as the Milky Way's moon galaxies.

But the surprising thing is that Despite the outflow of gas and the intense formation of new stars, these galaxies remain intact. Dhanesh Krishnarao, an assistant professor at Colorado College in this field, said: "Many people have been trying to explain how these streams of material can exist and if this gas is ejected from these galaxies, how stars form in them. Now, with the help of data from NASA's Hubble Space Telescope and a retired satellite called the Far Ultraviolet Spectroscopy Probe (FUSE), a team of astronomers led by Krishnarao has the answer: the Magellanic system, by A "corona" or protective shield surrounds the hot supercharged gas. This huge cocoon prevents the gas of the galaxies from escaping towards the Milky Way, and thus these dwarf galaxies can continue to form new stars. is, in fact, deals with a new aspect of galactic evolution. "Andrew Fox" (Andrew Fox), one of the researchers of the Space Telescope Science Institute, noted about this: "Galaxies cover themselves in a kind of gas cocoons that act as a defensive shield against other galaxies."

Astronomers They predicted the existence of the galactic corona several years ago. Elena D'Onghia, a researcher at the University of Wisconsin, said about this issue: "We found that if we include a corona in the simulations of the Magellanic Cloud falling into the Milky Way, we can explain the mass of the outflowing gas for the first time. to give "We knew that the Large Magellanic Cloud must be massive enough to have a corona." It is virtually invisible, and mapping it required examining 30 years of archived data to get the right measurements.

Researchers think that a galaxy's corona is the remnants of a primordial cloud of gas that collapsed into itself billions of years ago to form the galaxy. Is. Although coronas have been seen around more distant dwarf galaxies, astronomers had never before been able to study one in this detail. What the corona should look like and how it interacts over billions of years exists, but observationally, we can't test most of them because dwarf galaxies are usually very difficult to detect. But because the Magellanic Clouds are so close to us, they provide an ideal opportunity to study how dwarf galaxies interact and evolve."

In search of this direct evidence from the Magellanic Crown, scientists from the Hubble Data Archive and "Fuse" ( FUSE) for ultraviolet observations of quasars billions of light-years behind. Quasars, or quasars, are the extremely bright cores of galaxies that contain active supermassive black holes.

The team reasoned that although the corona is dark on its own and cannot be seen, it must be a kind of fog that has bright light patterns. Distant quasars absorb the background, making them visible. Such a method was previously used by Hubble to map the corona around the Andromeda galaxy.

  • Map of the Andromeda galaxy halo

Being able to detect the galactic corona required very precise ultraviolet spectra. Krishnarao pointed out in this regard: "The separation power of Hubble and Fuse was very important for this study. The gas in the corona is so diffuse that it is difficult to even detect its presence. In addition, it mixes with other gas, including outflows from the Magellanic Clouds and material originating from the Milky Way.

Mapping these results, the scientists also found that the amount of gas increased with distance. It decreases from the center of the Large Magellanic Cloud. According to them, "This strongly suggests that this corona really exists, enveloping the galaxy It protects it.

But how can such a thin layer of gas protect the galaxy from destruction? Krishnarao said: "Anything that wants to enter the galaxy has to pass through this material first, so it can absorb some of this incoming shock." He added: "Furthermore, The corona is the first material that can be ejected from the galaxy. With a little release from the corona, it is protected from the gas inside the galaxy itself, which is capable of forming new stars."

Cover photo: Graphic design of the corona of the Magellanic Cloud and the Milky Way
Credit: NASA

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