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Astronomers have revealed new details about how young stars shape their galactic surroundings in a new study. Researchers analyzed about 18,000 star-forming regions in nearby spiral galaxies using data from powerful instruments like the James Webb Space Telescope, Hubble Space Telescope and the Atacama Large Millimeter/submillimeter Array, whose observations were made as part of the PHANGS survey—a collaboration aimed at better understanding galactic evolution.
They found that in normal galaxies, pressure from ionized gas drives the expansion of young star-forming regions. However, whether these zones continue to grow or remain stagnant depends strongly on their surrounding environment, said Debosmita Pathak, lead author of the study and a graduate student in astronomy at The Ohio State University.
“When young massive stars are born, they’re very energetic and pump out a ton of photons into their surroundings,” said Pathak. “In that process, they disrupt their local environments and start to drive interstellar material out of the area.”
This mechanism, called stellar feedback, can influence galactic activity across many scales. Altering the evolution of dusty, cold gas in areas that are ripe for stellar birth can either trigger star formation or lead to the destruction of these star-forming regions.
Such changes can also drive the chemical evolution of a galaxy, as chemical properties play a crucial role in both planet formation and recording galactic history, said Pathak.
“The Milky Way, for example, forms roughly one star per year, while more luminous infrared galaxies can produce stars at 100 times that rate,” said Pathak. “But galaxies that have an abnormally high number of stars typically undergo a more violent process to form, such as a major merger, where two galaxies collide.”
The research was presented at a press conference at the 248th meeting of the American Astronomical Society (AAS) in Pasadena, California. The AAS selected the findings to be featured in the press conference.
To learn more about how young stars behave in these extremely dusty and turbulent environments, researchers compared the young stellar feedback pressures they found in normal star-forming galaxies with those of the bright starburst system NGC 3256, a pair of massive galaxies located about 100 million light-years from Earth.
Their results showed that the stellar feedback pressures there are about 100 times stronger than in other Milky Way-like spiral galaxies, meaning that while young, massive star clusters in the densest regions of the galaxy are confined by this intense pressure, most are likely powerful enough to continue expanding.
Additionally, the high levels of turbulence researchers found in NGC 3256 indicate that the gas within it is not settled in a simple flat disk, suggesting that the interplay between star formation and the usual conditions that precede it may be more unpredictable than in its normal, relatively stable galactic counterparts.
“These are pressure measurements that we haven’t been able to make before, and they are quite different from what we’ve seen in galaxies similar to the Milky Way,” said Pathak. “This will allow us to benchmark the physical processes driving galactic evolution.”
The study’s results have direct implications for understanding how star-forming regions evolve across many different cosmic settings, as well as how young stars help regulate and shape galactic evolution, even before high-powered blasts like supernovae can occur.
“It’s important to study environments in normal parts of the universe, but also how things deviate in the extremes,” said Pathak. “Without this type of research, we wouldn’t know if the physics that we’re working with and the models that we’re building actually hold true in such extreme places.”
This summer, alongside the GOALS collaboration, Pathak plans to continue her work measuring star formation in dusty environments as a visiting graduate student at IPAC at Caltech in Pasadena.
In advancing this work, Pathak expects the findings to inspire further insights in the scientific community.
“Events like AAS are great places to get interdisciplinary collaboration work started,” said Pathak. “It’s also nice to see folks who are still interested in learning more about natural sciences and get the word out that discovery is a very cool and fun thing to do.” https://news.osu.edu/across-the-universe-young-stellar-activity-drives-galactic-evolution/
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