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How are the stars born – and was it always like this? Observations of the small cloud of Magalhães: a view of the formation of stars in environments similar to those of the first universes.
The stars form in regions of space known as starwhere high concentrations of gas and dust merge to form a baby star.
Also called molecular cloudsthese regions of space can be massive, extending to hundreds of light years and forming thousands of stars.
And while we know a lot about a star’s life cycle thanks to advances in technology and observation tools, accurate details remain obscure.
For example, did the stars form this way at the beginning of the universe?
In a new one, published this month in The Astrophysical Journalresearchers at the University of Kyushu, in collaboration with the Osaka Metropolitan University, found that at the beginning of the universe some stars may have been formed in molecular clouds “cute“.
The results were obtained from observations from the small cloud of Magalhães and can provide a new perspective on the formation of stars throughout the history of the universe.
In our Galaxy Via Milky, the molecular clouds that facilitate the formation of stars have a stretched “filament” structure about 0.3 light years wide.
Astronomers believe that the solar system formed the same way, when a large filament molecular cloud separated to form an egg stellaralso called molecular cloud core.
Over hundreds of thousands of years, gravity would attract gases and nucleus matter to create a star.
“Even nowadays, our knowledge of star formation is still under development, and understanding how stars have formed in the primitive universe is even more difficult,” explains Kazuki Tokuda, a postdoctorate at Kyushu University and first Author of the study in one of the university.
“The primitive universe was quite different from the currentbeing mostly populated by hydrogen and helium. The heaviest elements were later formed in high mass stars, ”says Tokuda.
“We can’t go back in time To study the formation of stars in the primitive universe, but we can observe parts of the universe with environments similar to those of the primitive universe, ”adds the astronomer.
The team focused on the small cloud of Magalhães (SMC), a dwarf galaxy near the Milky Way about 20,000 light years from Earth.
SMC contains Only about one fifth of the heavy elements From the Milky Way, which makes it very close to the cosmic environment of the beginning of the universe, about 10 billion years ago.
However, spatial resolution to observe molecular clouds in SMC was often insufficient, and it was unclear whether the same filament structure could be seen.
Fortunately, the Alma radiotelescope in Chile was powerful enough to capture high resolution images of SMC and Determine the presence or absence of philamentary molecular clouds.
“In total, we collected and analyzed Data from 17 molecular clouds. Each of these molecular clouds had growth stars growing with 20 times the mass of our sun, ”says Tokuda.
“We found that About 60% of molecular clouds we observed had a filament structure with a width of about 0.3 light yearsbut the remaining 40% had a cute way“, He explains
“In addition, temperature inside the philamentary molecular clouds era higher than the cute molecular clouds“Adds Tokuda.
Example of a filamentous (left) and cute (right) molecular cloud in the small cloud of Magalhães captured by the soul telescope. Radio waves emitted by carbon monoxide molecules are shown in color. The brighter the color, the stronger the radio emission. The crosses in the middle indicate the presence of giant babies stars. The left figure shows a molecular cloud with a filament structure, and the right figure shows an example of a molecular cloud with a cute shape. Scale bar: a light year.
This temperature difference between the filamentous clouds and the cute clouds is probably due to the fact that The cloud has been formed for a long time. Initially, all clouds were filamentous with high temperatures due to the fact that the clouds crashed into each other.
When the temperature is high, the turbulence in the molecular cloud is weak. But when the cloud temperature descends, the kinetic energy of the gas that enters causes more turbulence and softens the filament structure, resulting in the cute cloud.
If the molecular cloud maintains its filament shape, it is more likely to leave along its long “rope” and Form many stars like our suna low mass star with planetary systems. On the other hand, if the filament structure does not maintain itself, such stars may be difficult.
“This study indicates that the environment, such as a proper supply of heavy elements, It is crucial to maintain a filament structure And it can play an important role in the formation of planetary systems, ”concludes Tokuda.
“In the future, it will be important to compare our results with molecular cloud observations in environments rich in heavy elements, including Milky Via galaxy. These studies should provide new knowledge about the formation and temporal evolution of molecular clouds and the universe, ”he concludes.
