Small sun immigrants

This topic seems a little scary, but please rest assured that this article only popularizes some basic astronomical knowledge through whether Sirius will explode. As for whether and when Sirius will erupt, we will naturally understand.

Sirius was taken out because Sirius was really special. It is the brightest star in the night sky and a star system close to us.

Sirius is the brightest object in the night sky, which means a star. In fact, Sirius is not the brightest star we can see in the night sky, because several planets are brighter. A star is a celestial body that can emit heat and light by itself. It is ten thousand times larger than a planet. For example, the sun is the only star in the solar system, with a mass 330,000 times greater than that of the Earth.

Therefore, planets are all subsidiary celestial bodies of stars. They don't emit light themselves, but reflect sunlight, but they look brighter because they are close to each other. For example, at night, we can't see the lights that can glow by themselves in the distance, but we can see the houses and other non-luminous objects nearby. That's the reason.

We can see the planets brighter than Sirius with the naked eye, and only four are Venus, Jupiter, Mars and Mercury. The moon is not a planet, but the nearest planetary satellite is the brightest celestial body in the night sky.

Generally speaking, stars are far away, and the distance from us is calculated in light years.

1 light-year is the distance that light travels for one year, which is about 9.46 trillion kilometers. The nearest star is Alpha Centauri, which is 4.3 light years away. This is a ternary system. Sirius ranks fifth in the nearest 10 star system to the sun (the binary star Trinary star system is only one level in terms of star system).

Most of the nearest 10 star systems are red dwarfs, that is, stars with much less mass than the sun. Only two Alpha Centauri galaxies are equivalent to the sun, and Sirius has the largest mass among 10 galaxies, so it will be the brightest.

There are generally four endings in the evolution of stars: 1, a red dwarf whose life span is much shorter than that of the sun, will slowly burn out the fuel and become a black dwarf; 2. At the end of evolution, the red giant will expand, and the peripheral gas will gradually spread into space, leaving a white dwarf in the center. 3. A star whose mass is more than 8 times that of the sun will have a supernova explosion at the end of its evolution, and a dense neutron star will be left in the core after the smoke clears; 4. A star whose mass is more than 30 times that of the sun will leave the black hole directly after the supernova explosion.

In the system of 10 stars around the sun, there is no star 8 times larger than the sun, and Sirius is no exception. But why did Sirius explode? This is because the supernova explosion is determined by the quality of the star itself, and there are several other situations, the most common being the la supernova explosion.

This kind of explosion is due to the fact that the mass of the white dwarf exceeds the upper limit, which will cause a big collapse, leading to the uncontrolled explosion of the thermonuclear. Although Sirius is not massive, its star B is a white dwarf, which is the source of danger.

The white dwarf, originally a remnant of a star, has died and its core nuclear fusion has stopped. Without an energy source, it will only slowly cool down, and after a long cooling time, it will eventually go out into a black dwarf.

However, some white dwarfs don't want to die silently, and they will erupt again at the first time, making some noise and brushing the sense of existence. This sense of existence is the la supernova explosion, which I call "corpse forgery".

This is because the white dwarf is not a stable corpse, and its existence follows the Pauli exclusion principle, relying on the degeneracy pressure of electrons to barely support its own gravity. Pauli exclusion principle is a physical law, that is, all fermion particles (including electrons, neutrons, protons, etc. ) has mutually exclusive properties. As long as these particles are close to a certain extent, the law of repulsion will occur.

White dwarfs are large in mass and small in size. A white dwarf star like Sirius B has a mass more than 1 times that of the sun and a volume only the size of the earth, so the density of matter is extremely high, reaching several tons per cubic centimeter. This kind of thing is not what we usually know.

The huge gravitational centripetal pressure of the white dwarf squeezes all the atoms, and the extranuclear electrons of the atoms leave their original orbits and become free electrons, which are squeezed to an energy level closer to the nucleus. Electrons tend to be squeezed together, so they rely on the strong repulsive force (pressure) between electrons, also called electron degeneracy pressure, to resist the huge gravitational pressure, so that the nucleus remains intact and floats in the ocean of free electrons, thus maintaining the shape of a white dwarf.

But there is a limit to the degeneracy of electrons, which is called the Chandraseka limit. When the mass of the white dwarf reaches 1.44 times that of the sun, the electron degeneracy pressure can no longer support the gravitational pressure, and the whole planet shape will collapse, and the huge centripetal pressure will lead to a sharp rise in the core temperature, thus stimulating carbon nuclear fusion.

Nuclear fusion broke out in a few seconds, which led to a thermal runaway reaction inside the white dwarf, and huge energy was released instantly, which blew the white dwarf into pieces and became a la supernova. Because all la supernova explosions have the same energy, they become the standard candlelight in astronomical observation, which provides an important basis for celestial observation and distance calculation.

Mainly Sirius B. As mentioned earlier, as long as the white dwarf reaches 1.44 times the mass of the sun, la supernovae will occur. At present, the mass of Sirius B is only about 1. 1 times that of the sun. If it stays like this, it won't explode and die slowly. The problem is that it is only 3 billion kilometers away from its partner Sirius A.

The supergravity of a white dwarf will devour all the interstellar matter around it. Of course, Sirius A is still so far away that it will not be accreted by Sirius B in theory, but the problem is that after Sirius dies, it will become a red giant and lose most of its mass.

When Sirius a becomes a red giant, its radius will expand to 200~300 times. Sirius A's radius is now about 1.7 times that of the sun. The radius of the sun is about 696,000 kilometers, and the radius of Sirius is 1 19000 kilometers. After becoming a red giant, its radius is about1400,000 km to 200 million km.

It seems that the distance between the two stars is still very large, and Sirius B seems to be smaller than Sirius A, but we should not forget that the red giant will expand more and more, and the peripheral materials will float into space. In the end, Sirius A will only leave a white dwarf skeleton in the core, which is only about 0.6 solar mass, and the remaining 1.4 solar mass will flow into space.

At this time, Sirius B's chance came, and the substance floating near it was inevitably pulled to the body by strong gravity, increasing its mass. At present, Sirius B is about 1. 1 times the mass of the sun. If the mass of the sun increases by 0.3 points, it will reach the Chandraseka limit. Will Sirius B absorb so much mass?

Maybe, maybe not. This is why Sirius may erupt in the future. Of course, the life span of Sirius is still 65.438+0.5 billion years, so this explosion will not happen until 65.438+0.5 billion years later.

What is the energy of la supernova explosion? It is generally believed that at the moment when the white dwarf exceeds the Chandraseka limit, most of the carbon and oxygen converge into heavy elements in a few seconds, the internal temperature rises to several billion degrees instantly, and the energy of thermonuclear reaction is greater than 10 44J (Joule).

The energy of solar nuclear fusion is 3.78 * 10 26j, which means that the energy of la supernova will reach 2.65 billion times that of the sun, which means that there are 2.65 billion suns shining on us. This huge energy will instantly blow the white dwarf into pieces, and each particle will be thrown out in the form of shock wave, with a speed of 5000~20000 kilometers per second, and the highest speed is close to 7% of the speed of light!

The absolute magnitude of the explosion can reach-19.3, which is 4.5 billion times the brightness of the sun.

If this explosion happened in the position of the sun, the earth would be evaporated without a trace. But it happened 8.6 light years away. It took 8.6 years after the explosion for light waves to reach the earth. If there were humans on the earth at that time, people could see a dazzling star.

But if the shock wave keeps the explosion speed, it will take 122~505 years to reach the solar system.

The conversion formula between apparent magnitude and absolute magnitude is: m=M-5log(d0/d), where m stands for apparent magnitude, m stands for absolute magnitude, d0 is 10 parsec (about 32.6 light years), and d is the actual distance of celestial bodies (in light years).

So according to the formula, Sirius, the supernova on the earth, has an apparent magnitude of -22.2 and so on. The apparent magnitude of the sun is -26.7 and that of the full moon is-12.7. Apparent magnitude means that the smaller the data, the brighter it is, and the more negative it is, the brighter it is. The brightness difference of each level is 2.5 12 times. So the Sirius la supernova seen by people on earth is a bright star 1288 times brighter than the moon and 63 times brighter than the sun.

It is like a small sun, hanging in the sky all day and night (at the right angle), and it is quite cloudy during the day at night, so reading no longer needs lighting. But this little sun, which looks a little dazzling, will not harm the earth's ecology. The real destruction is that after 122~500 years, high-energy particles from supernova explosions came to the solar system.

The high-energy particles of the sun invade the earth in the form of solar wind every day, but most of them flow to the distance along the magnetic field lines due to the resistance of the earth's magnetic field. Only in the weak magnetic field of the poles, a little bit enters, so we can see the brilliant light from the game between the atmosphere and the solar wind, which is the aurora.

The energy of the solar wind is not too great, and the maximum speed is only 800 kilometers per second. These charged solar particles will form a solar sheath around the solar system to resist the invasion of interstellar rays. However, the energy wind of supernova explosion, that is, the speed of particle shock wave reaches the highest speed of 20000 kilometers per second, and the solar sheath is obviously unable to resist.

This will inevitably affect the earth's magnetic field. Under this impact, the earth's magnetic field is very weak and hard to resist, so these energy particles will inevitably invade the earth's surface. At that time, if there are human beings, they will see the brilliance of the sky, which is a life-and-death game between the atmosphere and charged particles.

In the end, these particles are likely to destroy the atmospheric ozone layer, and the high-energy particles that are not blocked by the atmosphere will attack the earth's creatures intensively, breaking through the DNA molecular bond of the creatures, and the earth's ecology will not be spared.

Fortunately, Sirius's la supernova explosion, even if it really happens, will be 65.438+0.5 billion years later. At that time, it was hard to say whether human beings still existed. If human beings can really persist for so long, after more than 654.38 billion years of evolution and development, they would have emigrated to the outside of the solar system and become a multi-planet species. Avoiding and dealing with this natural disaster would have been a piece of cake.

Therefore, we don't have to worry about how future generations will deal with the Sirius catastrophe.

In fact, the supernova explosions that humans may see are several red giants that have been observed now, such as Haishan II and Betelgeuse. The explosions of these red giant stars are likely to happen in a short time, and may even have erupted, but the light has not yet reached us.

These red giants are much more energetic than Sirius la supernovae, but these stars are hundreds or even thousands of light years away from us. As long as there is no gamma-ray storm sweeping the earth, it will not have a great impact on the earth's ecology.

That's all, welcome to discuss, thank you for reading.

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