When were stars born, and how were stars born?

The universe is generally thought to have been formed 15 billion years ago. According to most astronomers, the peak of star formation was between 7 billion and 8 billion years ago. The latest observations by astronomers suggest that a large number of stars in the universe may have been born earlier than previously thought.

A team of scientists from the University of Edinburgh, Imperial College London and Cavendish Laboratories in the United Kingdom, published in the British journal Nature in '99, said that they had observed signs of rapid formation of young stars in a distant dusty galaxy. The formation of these stars is estimated to be about 12 billion years ago, about 5 billion years earlier than is generally believed. Astronomers made the discovery using a British-built Scuba camera.

Stellar formation is the process by which high-density regions of molecular clouds collapse into spherical plasma to form stars. As a branch of astrophysics, the study of star formation ranges from interstellar matter and macromolecular clouds as a precursor to star formation, with early star and planet formation being direct results. The theory of star formation, not only the formation of a single star, but also the statistics of the combined star and the initial mass function.

According to current theories of star formation, the core of a molecular cloud (especially the high-density region) will begin to collapse due to gravitational instability, from fragments (commonly known as natural star formation, see Kings instability), or by impulse shocks from supernovae, or by other energetic astronomical processes in the vicinity that trigger star formation in a molecular cloud (commonly known as triggered star formation). Some of the gravitational energy is lost in the form of infrared light during the collapse, and the rest is used to increase the temperature of the celestial core. When the temperature and density are high enough, the nuclear fusion of deuterium will be initiated, and the outward pressure will be generated, as a result of which the collapse will slow down (but not stop), and the matter composed of clouds and gas will continue to rain down on the original star.

At this stage, perhaps caused by the angular momentum falling into the matter, a bipolar jet will be generated. Eventually, the hydrogen in the core begins to merge into a star, at which point the surrounding material will begin to be driven away. The development of the protostar will follow the forest trajectory on the Hérae diagram, and the protostar will continue to contract until it reaches the forest boundary, and then the contraction will continue at a stable temperature until the Kelvin-Hermholtz time scale.

Stars with masses lower than the mass of the Sun will enter the main sequence zone, and the heavier protostars will still slowly collapse at the end of the forest trajectory, following the Heyer trace to approach hydrostatic equilibrium. This form of activity would make the mass of the star around about one solar mass. The process of high-quality star formation has a similar evolutionary (developmental) timeline, but the time is much shorter and it is not clearly defined.

The development of later stellar stages falls under the category of stellar evolution research. The process of star formation is thought to be different with different masses. The theory of low-mass star formation, supported by a large number of observations, suggests that low-mass stars are formed by the gravitational collapse of a rotating molecular cloud due to the gradual increase in density.

From the above description, gas and dust form a rotating molecular cloud, which collapses leading to the formation of an accretion disk, through which the mass of the channel forms a protostar. However, the history of star formation with masses greater than 8 times the mass of the Sun is still unclear. Massive stars emit a large amount of radiation, pushing the material that falls towards the center.

In the past, radiation pressure was thought to be sufficient to prevent mass from accumulating into giant protostars, and to prevent the formation of stars with masses of up to dozens of suns. Recent theoretical work has shown that the resulting jets and effluents clear the voids, so that the radiation pressure of many massive protostars escapes without hindering the passage of material through the accretion disk to the central protostar. As a result, the new theory suggests that massive stars also form through a similar process to low-mass stars.

According to astronomical observations, nebulae and stars are intertransformative. Stars are born from nebulae, and when stars evolve to a certain extent, they will eject a large amount of matter into interstellar space, which becomes part of the raw materials of nebulae.

At a certain point in the development of the universe, the universe is filled with homogeneous clouds of neutral atomic gases, that is, nebulae. Nebulae collapse due to their gravitational instability. In this way, the star enters the formation phase.

At the beginning of the collapse, the pressure inside the gas cloud is very small, and the matter accelerates to the center under the influence of gravity.

On the one hand, the density of the gas increases dramatically, and on the other hand, the temperature of the gas increases greatly due to the conversion of the lost gravitational potential energy into heat energy, and the pressure of the gas is equal to the product of its density and temperature, so that in the process of collapse, the pressure increases faster. In this way, a pressure field is quickly formed inside the gas that is sufficient to compete with the gravitational force, and this pressure field finally stops the gravitational collapse and establishes a new mechanical equilibrium position, called the star billet.

The mechanical equilibrium of the billet is caused by the internal pressure gradient against the gravitational force, while the existence of the pressure gradient depends on the inhomogeneity of the internal temperature, that is, the temperature of the center of the billet is higher than the temperature of the periphery, so thermally, this is an unbalanced system, and the heat will gradually flow outward from the center. This natural tendency towards thermal equilibrium plays a weakening role in mechanics. The billet must then contract slowly, increasing its temperature by decreasing its gravitational potential energy, thus restoring mechanical equilibrium; At the same time, it also uses the reduction of gravitational potential energy to provide the energy required for the radiation of the star billet.

This is the main physical mechanism of the evolution of star blanks, and it is also the process by which stars gradually form and shine outward.

With the passage of time, the evolution of the star billet gradually stabilized, and the protostar was born. Fixed star.

13.8 billion years ago. Because the first star was created after the cosmic singularity**, the first star was born in the universe about 13.8 billion years ago.

I think it was the beginning of the universe, when it first came out, and the center was the first star.

Scientists use NASA's Hubble Space Telescope, NASA's Spitzer Space Telescope and the European Southern Observatory's Very Large Telescope in Chile to search for "Population III" stars in a variety of distant galaxies. The third group of stars is the first stars formed in our universe 13.8 billion years ago, and their unique composition becomes the basis for our identification, the first stars generally only have hydrogen, helium and lithium, because they are the only elements around the big **, and the heavier elements are forged in the core of these stars and their successors. The first group of stars, such as Earth's Sun, are rich in heavy elements, while the second type of stars are much less numerous and so on.

The third category is the least.

How are stars born?

From an astronomical point of view, it goes like this: it starts with a lot of hydrogen. As long as there is enough hydrogen, some other gases and dust particles will not mix together much of a difference.

You didn't ask where hydrogen came from, which is another amazing story, so we're going to continue to make it the main ingredient. The second component is gravity, which is of course inherent to the hydrogen atom, and its atomic weight is 1. If you want to see the birth of a star the size of the sun, we need about x 10 57 hydrogen atoms.

This number starts at 119 and goes all the way up to 55 zeros. Like I said, a lot. I think it goes without saying that the other necessary factor is space.

Once these hydrogen atoms come together in their respective regions of space, their masses make them attract each other due to their own gravitational pull. The entire hydrogen cloud gradually shrinks, and like any falling object, this process accelerates as the hydrogen cloud shrinks more and more. As the pressure of hydrogen increases, so does its temperature.

The temperature rises because the gravitational potential energy is converted into kinetic energy when the clouds collapse.

Hydrogen eventually becomes dense and hot and is no longer a true gas state. By this time, the electrons have been separated from the single proton that is the core of the hydrogen atom. These protons are all positively charged, so they repel each other.

Even though they repel each other, the gravitational pull increases, making them more tightly packed together. When two protons are within a certain radius, they suddenly overcome the repulsion that separates them, and the strong nuclear gravity takes over. This is known as the Coulomb barrier.

When two protons pass through the Coulomb barrier, they fuse together and release a large amount of energy, which is converted into one helium atom. This energy makes everything hotter. And then the pressure really went up....

When the gas cloud collapses, it also starts to rotate, so when the star finally forms, some of the remaining gas revolves around the star. Depending on the composition of the cloud, different types of planets can be formed. In a very young universe, when the first stars were formed, the material that formed them was pure hydrogen, so there were no terrestrial planets containing carbon, iron, oxygen, nitrogen, or any other element in the periodic table.

How these elements came into being during the formation of stars in the following generations is another amazing story.

In the universe soon after, particles began to form, the universe is a large ocean of particles, 380,000 years ago, the universe became transparent, hydrogen was formed, light began to pass through the universe, nebula formed, nebula is the first generation of stars.

The matter of the universe has nine kinds of primordial electrons, with a negative electron, and the total amount of positive and negative electrons accounts for half of each, but the positrons are divided into nine kinds, and these nine positrons are the differences that have evolved various elements, and there is no classification of nine electrons. From the evolution of the earth's matter, we can know that the stars of the universe are formed in the form of photons, and each photon carries a negative electron, so from ancient times to the present, the combination of yin and yang is the main factor in the formation of stars.

The birthplace of stars is nebulae, and nebulae are mainly composed of hydrogen, because of gravitational pull, these hydrogens accumulate more and more, and the pressure and temperature inside also continue to rise, and when they reach a certain level, they trigger nuclear fusion and begin to shine and heat, and stars are born. There is a famous nebula called the "Pillar of Creation", which is pregnant with a large number of stars, which can be clearly observed, and many "Pillars of Creation" Hubble** can be seen from above, which is very spectacular. Planets were also born from nebulae, and the collision at the time of formation led to the current rotation.