Although our galaxy is a “mega-city” of at least 200 billion stars, the details of how they formed remain largely hidden in the mystery.
Scientists know that stars form from the collapse of huge hydrogen clouds that compress under gravity to the point where nuclear fusion ignites, but only about 30% of the initial mass of the cloud ends up as a newborn star, which raises questions about where the rest of the hydrogen goes during this process? .
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It is assumed that a new star is releasing a lot of hot gas through strong flowing plasma bundles and hurricane-like winds being blasted from the surrounding disk by strong magnetic fields.
But a new and comprehensive survey shows that this more common explanation does not appear to be working, leaving astronomers in the dark.
The researchers used data previously collected from NASA’s Hubble and Spitzer Space Telescopes and the European Space Agency’s Herschel Space Telescope to analyze 304 growing stars (called primary stars) in the Orion Complex, the closest major star-forming region to Earth. (It is indicated that the Spitzer and Herschel telescopes are no longer functional.)
In this largest-ever survey of fledgling stars so far, the researchers found that gas purification by the outflow of a star may not be as important in determining its final mass as traditional theories suggest. The researchers’ goal was to determine whether stellar outflows from stars halted the collision of gas into a star and prevented it from growing.
Instead, they found that cavities in the surrounding gas cloud formed by the outflow of a forming star do not grow uniformly as they mature, theories suggest.
Lead researcher, Nolan Hubble, from the University of Toledo, Ohio, explained: “In one model of star formation, if you start with a small cavity, as the protostar rapidly becomes more sophisticated, the outflow from it creates a continuously larger cavity until the surrounding gas is finally detonated. Leaving a lonely star. “
“Our observations indicate that there is no gradual growth that we can find, so the cavities do not grow until they push all of the mass in the cloud outward. Therefore, there must be another process underway to get rid of the gas that does not end up in the star,” he added. .
NASA, ESA, STScI, N. Habel and ST Megeath / University of Toledo
During the relatively short birth stage of a star, which lasted only about 500,000 years, the star swells very quickly. And what causes chaos is that, as the star grows, it releases winds, as well as a pair of beams spinning in opposite directions. These outflows begin to erode into the surrounding cloud, which creates cavities in the gas.
NASA, ESA, STScI, N. Habel and ST Megeath / University of Toledo
Popular theories predict that as the young star evolves and the outflows continue, the sockets widen until the entire gas cloud around the star is completely pushed away. And when its gas tank is empty, the star stops gaining mass, in other words, it stops growing.
To search for cavity growth, the researchers first sorted the primary stars by age by analyzing Herschel, Spitzer and Hubble data for each light output for each star.
NASA, ESA, STScI, N. Habel and ST Megeath / University of Toledo
Astronomers then observed the cavities in near-infrared light using Hubble’s near-infrared camera, a multi-body spectrophotometer, and a wide field camera 3.
The notes were taken between 2008 and 2017. Although the stars themselves are covered with dust, they emit powerful rays that strike the walls of the cavity and scatter grains of dust, which illuminates the gaps in the gas envelopes in infrared light.
NASA, ESA, STScI, N. Habel and ST Megeath / University of Toledo
Hubble images reveal details of the cavities produced by the elementary stars at various stages of evolution. The team used the images to measure the shapes of the structures and estimate the volumes of gas discarded to form the cavities. From this analysis, they can estimate how much mass was removed by the star’s explosions.
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Future telescopes such as NASA’s James Webb Space Telescope will delve deeper into the process of primitive star formation. The telescope’s spectral observations will monitor the interior of disks surrounding elementary stars in infrared light, looking for plasma beams in the smallest sources. James Webb will also help astronomers measure the rate of material accumulation from the disk to the star, and study how the inner disk interacts with the outer flux.
Astronomer Tom Megeth of the University of Toledo said: “We found that at the end of the initial star phase, where most of the gas from the surrounding cloud falls onto the star, a number of young stars still have rather narrow cavities. “What determines the star’s mass and what stops the gas blockage is that this increased outflow cavity sweeps away all the gas. This was very fundamental to our idea of how stars are formed.”
The researchers said that although wind and flowing beams could still play some role in star formation, this role did not seem as important as we thought. Slower and denser outflows may be responsible, but they take longer to clear the cavity, but without more detailed observations it is impossible to know.
Therefore, this would be one of the next steps for scientists to try to identify other mechanisms that could trigger growth stopping with a much lower contribution from stellar reactions.
Source: Live Science
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