How much do we know about how stars form?And what were the very first luminaries, formed shortly after the birth of the universe? Researchers hope that the new James Web Space Telescope will provide answers to many questions, but the world will not see the first pictures until July. And yet, some things we know for sure, such as how the life of supernovae ends. Their explosions accelerate the cosmic cycle of the birth and decay of matter. And they serve as a factory of chemical elements that make up the world around us. To understand the complex stellar evolution, scientists create computer models that take into account many different factors at the same time. Recently, astronomers at the Carnegie Observatory in California came to an interesting conclusion - the formation of some stars may take longer than previously thought. But why and what conclusion follows from this? Let's try to figure it out.
clouds of stardust
It is believed that for the birth of stars you need gas, dustand gravity. With the naked eye, we see only the glow of the Milky Way - the combined light of billions of stars on the disk of our Galaxy. Thanks to optical and radio observations, we know that there is a lot of gas in the universe, and star dust is ubiquitous. This dust is made up of microscopic mineral elements such as silicon, magnesium, iron and other metals, as well as carbon in its various forms.
And although interstellar dust can be scattered by a thinlayer, it forms dense clouds that trap heat from nearby stars. Thanks to radio observation, we know that these clouds are filled with molecules, including those unknown to us, since they simply do not exist on Earth. But there is plenty of room in space.
When the star comes to the end of its path and explodes, gas and dust clouds collide, turning them into turbulent accumulationswithin which new stars are formed.So, the real exhibits are gaseous, dusty and diffuse nebulae. They occur where interstellar clouds are in close proximity to hot stars with temperatures over 26,000 Kelvin or so.
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The ultraviolet radiation emittedluminaries, can destroy molecules, which causes the interstellar gas to glow. Deep within the supernova remnant of the Crab Nebula (M1) lies its beating heart: a pulsar left over from its massive progenitor star finally halting nuclear fusion and dying.
These accumulations are slowly evaporating, and theirconstituents dissipate over time. Researchers believe that our Sun may have been born in one of these clusters. In addition, most of this action takes place within large dark clouds and is invisible until stellar radiation and winds disperse the parent dust clouds.
When a new protostar shrinks under the actiongravity, its core heats up. Eventually the temperature gets high enough to initiate nuclear reactions in which four hydrogen atoms are converted into the next heavier atom, helium, with a slight loss of mass (m). Therefore, energy (E) is created in accordance with Einstein's famous relation E= mc2 (c is the speed of light).
Surprisingly, many stars often formaround the same time, and their mutual gravity binds them into an open cluster with a large range of masses, such as the Pleiades (M45) or the Hive (M44). Over time, these more than 600 million year old clusters will begin to slowly move away from each other.
Stars and computer models
Although the main process of star formation is goodstudied, there are still many questions. In an attempt to get more information, scientists are turning to giant molecular cloud computer models (GMCS) for help. And the findings hint that we may need to rethink our understanding of star formation.
Clouds - they are also called star nurseries contain mostly hydrogen molecules. Their mass is at least 10,000 times that of our Sun, and their diameter ranges from 15 to 650 light years.
Inside such clouds, hydrogen molecules begin tocome together. And when the clusters reach a certain density, the process of star formation starts. The authors of the study, published in the journal Nature, have run one of the most advanced simulations of giant molecular clouds.
Their computer model traces 9 million years of evolution in the stellar nursery - a giant molecular cloud in which stars are born.
The developed simulation takes into account the mainphysical feedback mechanisms such as stellar winds, magnetic fields and gravity. The reference point is a cloud, the initial mass of which is 20,000 times the mass of our Sun, and the diameter is 65 light years. As the simulation progresses, brighter, more massive stars form, with more than 10 times the mass of our Sun.
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Life and death in the vastness of the universe
The simulation went on for about 9 million years and came to an end shortly after one of the first stars formed by the cloud went supernova. During this time, approximately 1000 new stars were formed.. The authors of the work came to the conclusion that for the full formation of stars, it may take from 1 to 3 million years, that is, much longer than previously thought.
Star formation is complex.It includes many different processes working together. Our challenge is to put all the different ingredients together and get a result that really looks like reality,” the researchers write.
In the future, the developed model can bebe used for a detailed study of stellar evolution. For example, to track a star through time to see where its mass originally came from. By changing the constraints, researchers can build a more accurate picture of which physical mechanisms are most important in star formation.
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Looking closely at the simulation, we will seea huge cloud of cosmic gas - about 20 parsecs or 65 light-years across - which collapses to form new stars. The white patches indicate denser regions of gas, including young stars.
Turbulence within the cloud creates densecenters that are destroyed, forming new luminaries. These stars then emit radiation and stellar winds, exploding in supernovae. In the end, these phenomena blow away the last remnants of the cloud and leave behind a whole garden of young stars.
The process itself takes millions of years - or months of computational time when it comes to computer models.
The birth of stars is connected with their death - theyexploded so that today you read this article. The most that neither is the poetry of science, agree? We will wait for the answer here and in the comments to this article. The stars died for us and these are not just words.