A team of astronomers using the Atacama Large Millimeter / Submillimeter Array (ALMA) has completed the first census of molecular clouds in the nearby universe, revealing that contrary to previous scientific belief, these star schools do not all look and act the same. In fact, they are as diverse as the people, homes, neighborhoods, and regions that make up our own world.
Stars are formed by clouds of dust and gas called molecular clouds or star schools. Each star school in the universe can form thousands or even tens of thousands of new stars during its lifetime. Between 2013 and 2019, astronomers on the PHANGS project (Physics at High Angle Resolution in nearby GalaxieS) conducted the first systematic study of 100,000 star schools in 90 galaxies in the nearby universe to gain a better understanding of how they connect back to their parent galaxies.
“We used to think that all star schools in every galaxy should look more or less, but this study has revealed that this is not the case, and star schools go from place to place,” said Adam Leroy, associate professor of astronomy. at Ohio State University (OSU) and lead author of the paper that presented the PHANGS ALMA study. “This is the first time we’ve ever taken millimeter-wave images of many nearby galaxies that have the same sharpness and quality as optical images. And while optical images show us light from stars, these groundbreaking new images show us the molecular clouds that make up these stars. . ”
The researchers compared these changes with the way people, houses, neighborhoods and cities exhibit similar characteristics but change from region to region and country to country.
“To understand how stars are formed, we need to link the birth of a single star back to its place in the universe. It’s like connecting a person to their home, neighborhood, city and region. If a galaxy represents a city, then the neighborhood is the spiral arm, the house the star-forming unit, and nearby galaxies are neighboring cities in the region, “said Eva Schinnerer, astronomer at the Max Planck Institute for Astronomy (MPIA) and lead researcher for the PHANGS collaboration.” These observations have taught us, that the ‘neighborhood’ has small but significant effects on where and how many stars are born. ”
To better understand star formation in different types of galaxies, the team observed similarities and differences in molecular gas properties and star formation processes in galaxy disks, star bars, spiral arms, and galaxy centers. They confirmed that the location or neighborhood plays a critical role in star formation.
“By mapping different types of galaxies and the different environments found in galaxies, we track the full range of conditions in which star-forming clouds of gas live in the current universe. This allows us to measure the impact that many variables have along the way. , how star formation occurs, “said Guillermo Blanc, an astronomer at the Carnegie Institution of Science and co-author of the paper.
“How stars form and how their galaxy affects this process are fundamental aspects of astrophysics,” said Joseph Pesce, National Science Fund’s program officer for NRAO / ALMA. “The PHANGS project leverages the ALMA Observatory’s exquisite observational power and has provided remarkable insight into the history of star formation in a new and different way.”
Annie Hughes, an astronomer at the L’Institut de Recherche en Astrophysique et Planétologie (IRAP), added that this is the first time scientists have a snapshot of how star-forming clouds really are in such a wide range of different galaxies. “We found that the properties of star-forming clouds depend on where they are located: clouds in the dense central regions of galaxies tend to be more massive, denser and more turbulent than clouds located on the quiet edge of a galaxy. the life cycle of clouds also depends on their environment. How fast a cloud forms stars and the process that ultimately destroys the cloud both seem to depend on where the cloud lives. ”
This is not the first time that star schools have been observed in other galaxies using ALMA, but almost all previous studies focused on individual galaxies or part of one. Over a five-year period, PHANGS gathered a full overview of the nearby population of galaxies. “The PHANGS project is a new form of cosmic cartography that allows us to see the diversity of galaxies in a new light, literally. We finally see the diversity of star-forming gas across many galaxies and are capable to understand how they change over time. It was impossible to produce these detailed maps before ALMA, “said Erik Rosolowsky, associate professor of physics at the University of Alberta and co-author of the research. “This new atlas contains 90 of the best maps ever made, revealing where the next generation of stars is to be formed.”
For the team, the new atlas does not mean the end of the road. While the survey has answered questions about what and where, it has raised others. “This is the first time we’re getting a clear overview of the population of star schools throughout the nearby universe. In that sense, it’s a big step toward understanding where we’re coming from,” Leroy said. “While we now know that stargazing facilities vary from place to place, we still do not know why or how these variations affect the stars and planets formed. These are questions that we hope to answer in the near future.”
Ten papers describing the results of the PHANGS study will be presented this week at the 238th meeting of the American Astronomical Society.
Hubble sees vortices of forming stars
PHANGS-ALMA: Arcsecond CO (2-1) Imaging of nearby star-forming galaxies, Leroy et al. ApJS accepted, preview. arxiv.org/abs/2104.07739
Provided by the National Radio Astronomy Observatory
Citation: Cosmic Cartographers Map Near the Universe Revealing the Diversity of Star-Forming Galaxies (2021, June 8) Retrieved June 9, 2021 from https://phys.org/news/2021-06-cosmic-cartographers- nearby-universe-revealing.html
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