Which leads to a galaxy
On August 30, 2021, astronomers described a process by which clouds of pure hydrogen and helium gas are dragged into galaxies, to be used in creating new stars. Stars turn these very simple elements (hydrogen and helium) into more complex elements, including oxygen, carbon, and iron. And then galaxies pump this “escape,” as astronomers called it, back into intergalactic space. Supernova explosions cause most of the outer flow. The video above illustrates this process, showing the concept of an artist in the galaxy Mrk 1486, going through a period of very rapid star formation. It shows material released from the stars through supernovae, charged with elements such as oxygen and iron, which leave the galaxy. In other words, these astronomers said:
… What flows into a galaxy is much cleaner than what comes out.
Astronomers Alex Cameron and Deanne Fisher of ASTRO 3D in Australia, a consortium of nine Australian universities, as well as international partners, led this research. The team used new equipment called the Keck Cosmic Web Imager at the WM Keck Observatory in Hawaii. The peer review Letters from astrophysical journals published the new work on 30 August.
So it’s the same story we’ve known for decades. These are elements that are forged inside stars and then released by supernovae. We’re star stuff, right? But this story focuses on the process as it occurs across the galaxy.
Astronomers describe the process of atoms flooding into galaxies accretion. They use the word way out for the eventual expulsion of atoms from galaxies. Until now, these astronomers said, they could only guess the composition of this inner and outer flow of material. However, accretion and release are vital processes in galaxies. They govern the growth, mass, and size of galaxies. And so astronomers want to understand them. In this new research, for the first time, astronomers were able to confirm the complete cycle in a different galaxy from our home galaxy, the Milky Way.
Mrk 1486: Perfect for study
The researchers studied the star-forming galaxy called Mrk 1486. Alex Cameron said:
We have found that there is a very clear structure of how gases enter and leave. Imagine that the galaxy is a spinning frisbee. The gas enters relatively uncontaminated from the outer cosmos, around the perimeter, and then condenses to form new stars. When these stars later explode, they expel another gas, which now contains these other elements, through the top and bottom.
These astronomers said that Mrk 1486 was the perfect candidate for observation as it is located on the edge of the Earth. And that means astronomers could see the gas coming out more easily than, say, if they looked at a galaxy face to face. Deanne Fisher added:
This work is important for astronomers, as for the first time we have been able to put limits on the forces that strongly influence how galaxies form stars. It takes us one step closer to understanding how and why galaxies look like they do and how long they will last.
Conclusion: For the first time, astronomers were able to measure the entry of hydrogen and helium atoms and the exit of more complex atoms in a galaxy other than our Milky Way.
Summary: Hydrogen and helium gases flow into a galaxy. It is used to make new stars. These stars make new elements, which are then released back into intergalactic space.
Source: The DUVET Survey: Tea-based direct metallicity mapping of metal-enriched outlets and metal-poor inputs in Mrk 1486
Via Science in Public