several questions about the education and life of stars
What could be more beautiful than the night sky, shimmering with myriads of stars. American astrophysicist Lawrence Maxwell Krauss once said that every atom in the human body originates in an exploded star. Perhaps the atoms of the left hand originated in one star, and the right – in another. We are all stardust. This is the most poetic thing in physics.
Scientists have long been studying the structure of stars in the Universe, trying to understand the secrets of their formation and development. But existing hypotheses are not recognized by all representatives of the scientific community and contain questions that have yet to be answered.
Star Formation: A Popular Hypothesis
According to astronomers, on a cloudless night, about 6,000 stars can be observed in the sky with the naked eye. But no more than 3,000 of them will be visible directly above the horizon. However, this is a drop in the bucket. Using space telescopes, astrophysicists discovered only 10 in the visible part of the Universe24 stars that make up 10 trillion galaxies. At the same time, in our Milky Way galaxy, there are, according to various estimates, from 200 to 400 billion stars. Stars are assumed to be massive celestial bodies made of gas and plasma that emit light and heat. In their depths, thermonuclear fusion reactions occur.
All stars are divided into several classes: supergiants, bright giants, giants, subgiants, main sequence stars, subdwarfs and white dwarfs. The temperature of stars ranges from 2,000-3,000 K to 50,000 K. Their chemical composition also varies, but stars mainly consist of hydrogen (72-75% of mass) and helium (24-25%). Each star has its own magnetic field.
The evolution of stars, as modern science suggests, is divided into several stages. It is believed that stars are born from cold, tenuous clouds of interstellar gas. They are then compressed due to gravitational instability. At the same time, the temperature rises so much that thermonuclear reactions begin to synthesize helium from hydrogen. At this time, the protostar transforms into a main sequence star and remains in this state for most of its existence. This is exactly the state our Sun is in today. The further life of a star depends on its initial mass and chemical composition. As hydrogen burns out, stars change their characteristics. But the final evolution of stars is the same in most cases: shedding the outer shell, turning into a white dwarf or a supernova. After its explosion, a neutron star or black hole remains.
The exception is systems of closely located double stars, where in the later stages of evolution there is a flow of matter and a change in their parameters. This is the main hypothesis. But if you delve into the details of the processes described, many questions arise that you would like to get answers to.
Attraction and rotation: inconsistencies between theory and reality
If you look in detail at the description of the mechanics of the processes that arise during the formation of stars, then contradictions arise that require clarification. Gravitational instability, which, according to the main hypothesis, is the main cause of star formation, is an increase in spatial changes in the speed and density of matter under the influence of gravitational forces in clouds of cosmic gas of a certain mass.
But the process of star formation due to the gravitational forces of gas atoms looks artificial and unconvincing, as do the attempts by physicist D. Jeans, the author of the theory of gravitational instability, to explain the effect of rotation of stars forming in practically non-rotating gas clouds.
But the obvious cannot be denied: when a new star is born, a gigantic mass of hydrogen and helium atoms is concentrated into a protostar, which then begins to rotate around its axis at high speed. In our galaxy, the average rotation speed of stars is about 200 km/sec. In this case, interesting phenomena are observed.
In particular, the core of the Sun, according to data obtained from the European-American SOHO probe, makes a full revolution around its axis in about a week. At the same time, astrophysicists claim that the core of the Sun rotates four times faster than its outer layers. But why is still unknown. It is not surprising that any researcher inevitably has a question:
How does star formation actually occur?
What force makes stars rotate around their axis?
There are no clear answers to these questions yet.
Hypotheses for the origin of the process of rotation of stars, based on the originally existing relict “photon vortices” or as a result of the action of certain “tidal forces” arising at the moment of recombination in the cooling Universe, also do not look convincing. The fact is that their authors were never able to identify the sources and describe the nature of the occurrence of these phenomena.
I believe that the mechanisms of star formation, as well as the reasons for their rotation, need to be looked for in completely different areas. Other mechanisms that are logically explicable and consistent with the laws of physics must be involved here.
In this regard, I would like to receive answers to a number of questions:
– What is the nature of the force that initiated the rotation of a cluster of interstellar gas atoms for their further transformation into a star?
– What forces and how do they maintain the rotation of stars for billions of years?
– Why is the rotation speed of the star’s core much faster than the rotation speed of its outer layers?
– Is gravity capable of not only bringing gas atoms closer to each other, but also compressing them into the core of a star, overcoming the repulsive forces of protons that make up the core of the simplest hydrogen atoms?
Processes on the Sun: mysteries of the yellow dwarf
Before looking for answers to the above questions, it would be interesting to understand the nature of the processes occurring on the Sun, on which life on planet Earth completely depends. As you know, the Sun is one of the stars in our galaxy and the only one in the solar system. According to the spectral classification, the Sun is a yellow dwarf and belongs to the G2V type.
The current age of the Sun, estimated using computer models of stellar evolution, is about 4.5 billion years. Scientists believe that in about 5 billion years the Sun will exhaust its reserves of hydrogen and helium and turn into a red giant. During this process, it will engulf Mercury, Venus and possibly Earth.
The average density of the Sun is 1.4 g/cm3, and the effective temperature of its surface is 5780 K. Therefore, the star shines with an almost white, even light. However, near the surface of our planet, its light acquires a yellow tint due to stronger scattering and absorption of the short-wavelength part of the spectrum by the Earth's atmosphere.
The sun consists of hydrogen (≈73% of mass and ≈92% of volume), helium (≈25% of mass and ≈7% of volume) and other elements: iron, nickel, oxygen, nitrogen, silicon, sulfur, magnesium, carbon, neon, calcium and chromium. The mass of the Sun is 99.866% of the total mass of the entire Solar System.
The central part of the Sun with a radius of 150–175 thousand km (20-25% of the radius of the star), where thermonuclear reactions occur, is called the solar core. The density of the substance in the core is 150 times higher than the density of water and 6.6 times higher than the density of osmium, the densest metal on Earth. The temperature in the center of the core, according to astrophysicists, is more than 14 million TO.
The distance from the Earth to the Sun is approximately 150 million km. Sunlight only takes about 8 minutes to reach our planet. The Sun is approximately 1.3 million times larger than the Earth in volume, and 332,940 times larger in mass.
Despite the abundance of information about our star, the Sun has its own secrets and mysteries.
One of the main ones is the significant difference in the temperature of the Sun's chromosphere (the lower layer of its atmosphere, in which continuous light of the visible spectrum is formed), and its outer shell – the corona, which is located much further from the solar core than the chromosphere. With an effective temperature of the Sun's chromosphere of about 6000 K, the temperature of its corona reaches 1,000,000 K, and sometimes 2,000,000 K.
The question arises: why does the corona of the Sun, located 70,000 km from its surface, have a temperature many times higher than the chromosphere, which is much closer to the core of the star?
An equally interesting mystery is the Schwabe-Wolf cycle. He describes a sharp increase in the number of sunspots lasting about 4 years, and then a decrease over 7 years. This cycle in our time takes about 11 years, but in the 18th–19th centuries its duration varied from 7 to 17 years, and only starting from the 20th century it began to be about 11 years. Scientists have been monitoring this periodicity for several centuries in a row, but have not yet been able to explain its nature. There is also no generally accepted hypothesis for the reasons for the appearance of sunspots. At the same time, researchers have derived an interesting pattern of the influence of solar activity on social processes on the planet.
According to the data of the English economist and statistician of the 19th century W.I. Jevons, economic crises in society occur with a frequency corresponding to maximum solar activity. Following him, at the beginning of the twentieth century, Russian biophysicist A.L. Chizhevsky stated that epidemics of plague, smallpox, cholera, etc. are also directly dependent on the eleven-year cycle of solar activity. According to the scientist, the largest wars and revolutions of the 19th and early 20th centuries occurred during the greatest activity of the Sun.
In this regard, it is important for humanity to know:
Why do spots appear on the Sun and what is responsible for the stable periodicity of their occurrence?
An important phenomenon for astrophysicists are solar flares that occur near the sites where sunspots form. Their duration does not exceed several minutes. Most often, but not in all cases, they are accompanied by coronal mass ejections and are classified as: A, B, C, M and X. Solar flares initiate streams of charged particles consisting of electrons, protons and helium nuclei directed towards the Earth. This leads to a short-term increase in background radiation at the planet’s poles, disturbance of the Earth’s magnetic field and powerful magnetic storms. The most severe solar flares negatively affect the operation of electronic devices and human health.
Thus, another important question arises that also needs to be answered:
Why do solar flares occur on the Sun?
At the same time, it should be noted that there are scientific hypotheses for all the proposed questions, but none of them is indisputable and satisfactory to the scientific community. Astrophysicists have not yet provided clear and generally accepted answers explaining the nature, physical essence and mechanisms of these cosmic phenomena. At the same time, the Sun and the processes occurring on it continue to remain one of the most interesting, important and amazing mysteries of the Universe.
