An unprecedented new study shows that the stellar nursery is more diverse than astronomers initially imagined. The astronomers of the PHANGS (Physics at High Angular Resolution in Nearby Galaxies) project have systematically mapped 100,000 star nurseries in 90 galaxies, and found that each is more unique than originally thought.
It takes tens of millions of years to form a star, starting from a molecular cloud with a mass of millions of times the sun, to collapsing under its own gravity to form a mildly luminous protostar, and then begin to rotate and attract the surrounding matter to form a disk, obtaining enough After the mass, the core begins to ignite nuclear fusion and become a sphere like the sun. But this process consumes a stellar nursery room to store gas and dust quickly, and how many stars can be formed depends on the position of the star nursery in the galaxy.
We thought that all star nurseries in each galaxy looked the same, but the results of this study show that this is not the case. This five-year study uses the Chilean Atacama Large Millimeter and Submillimeter Wave Array (ALMA). The reason for using radio wave telescopes to assist observations is that it can focus more on the emissions from dark and dense molecular clouds. The faint light of, instead of the visible light from young stars bred by these molecular clouds, allows astronomers to study how the star’s parent cloud is shaped and formed.
▲ Part of the stellar nursery drawn by ALMA.
“To understand how a star is formed, you need to connect the birth of a star to its location in the universe. If a galaxy represents a city, the community is the spiral arm, the house is the unit of star formation, and the nearby galaxy is the neighboring city.” PHANGS Lead researcher Eva Schinnerer said these observations tell us that “neighbors” have a small but significant impact on the location and number of stars.
They found that the way stars are forged is different, depending on whether the resulting molecular cloud is located in the galactic disk, rod-like structure, spiral arms, or the center of the galaxy. Compared with quiet areas, molecular clouds in dense regions of galaxies are generally larger, denser, and more turbulent. The speed at which molecular clouds form stars and the process by which their high-density regions collapse into stars seem to depend on the location of the molecular cloud.
Next, the team will try to figure out what this change might mean for the formation of stars and planets, and our position in the universe. Researchers pointed out that this is the first time we have a clear understanding of the number of nurseries in nearby stars. In a sense, this is a big step in understanding where we are from. It is now known that stellar nurseries vary from place to place, but hope to understand the differences and how they affect the formation of stars and planets in the near future.
(This article is reprinted with permission from the Taipei Planetarium; Image source: ALMA)
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