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Astronomers have discovered that galaxies pollute their surroundings, and the team used a new imaging system to confirm that what goes into the galaxy is much cleaner than what comes out.
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Co-lead author Dean Fisher, professor at the Center for Astrophysics and Supercomputing at Swinburne University in Australia, said: “Massive clouds of gas are drawn into galaxies and used in the process of formation. stars, and on their way are made up of hydrogen and helium. Using new equipment called Keck Cosmic Web Imager, we were able to confirm that stars made of this fresh gas end up pushing a huge amount of material out of the system, mostly through supernovas. ‘is purer, it contains many other elements, including oxygen, carbon and iron.
The process of the flow of atoms in galaxies, known as “accumulation”, and their eventual expulsion, known as “exits”, is an important mechanism that controls the growth, mass and size of the atoms. galaxies.
So far, however, the makeup of internal and external flows can only be guessed. This research is the first time that the full cycle has been confirmed in a galaxy other than the Milky Way.
To reach their conclusions, astronomers focused on a galaxy called Mrk 1486, which is located about 500 million light years from the sun and is experiencing a period of very rapid star formation.
Dr Alex Cameron, who recently moved from the University of Melbourne in Australia to the University of Oxford, said: “We have found that there is a very clear structure of how gases enter and exit. “
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He continued, “Imagine the galaxy is a spinning compact disc. The relatively unpolluted gas from the outer universe enters, around the ocean, and then condenses to form new stars. When those stars later explode, they expel another gas, which contains other elements. “
Each different chemical element has a specific set of colors of light, or wavelengths, that it emits, called emission lines.
“If we measure the relative brightness of different emission lines of different elements such as oxygen and hydrogen, this allows us to determine the chemical composition of the gas,” Cameron explains.
KCWI can do this in different regions of the galaxy at the same time, allowing scientists to measure the chemical composition of the flowing gas.
They focused on Mrk 1486 as undergoing high rates of star formation.
The gas enters the relatively unpolluted galaxy around the ocean and condenses to form new stars. After these stars have lived their lives and exploded, they push another gas, now containing heavier elements, in the supernova explosion, through the top and bottom of the galaxy, scientists say.
The new study is helping astronomers understand how galaxies, including the Milky Way, form and evolve over time.
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“In the early universe, before the formation of the first galaxies, hydrogen and helium were essentially the only elements present,” says Cameron. “The elements that make up the rest of the periodic table of elements were made up of stars, which formed inside galaxies.”
When the stars create these new elements, some of them can be recycled by their host galaxies and transformed into new stars.
However, scientists weren’t sure how much of these elements were retained by the galaxy and how much expelled from the galaxy?
Cameron explained, “We know that in the current Milky Way a number of these elements are heavier than in the very first universe. Measuring the elements in the inflow and outflow of galaxies helps us understand what may have happened in the history of the galaxy as it has developed over time, to the galaxy as it is. is today.
Source: phys.org
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