If Sirius explodes into a supernova, will it destroy the Earth's ecology? Science tells you the answer

Sirius is one of the closest stars to Earth that can be seen with the naked eye, about 8.6 light-years away from us. If this star explodes in a supernova, how much energy will it have? Will it destroy the Earth's ecology, or is there any hope for humanity?

Now, let’s analyze it based on existing scientific common sense.

First, let’s talk about what kind of star Sirius is.

In fact, the closest star to us is Proxima Centauri, which is about 4.22 light years away from us. However, it is a very small red dwarf star with a mass of about 12% of the sun, so it is invisible to the naked eye. However, Proxima Centauri is a triple star system, and the other two are called Alpha Centauri A and Alpha Centauri B, which have a mass similar to the sun and are the third brightest star visible to the human eye.

Another star that is closer to us is Barnard's Star, which is also a red dwarf with a mass of about 15% of the Sun and cannot be seen with the naked eye. Further away is Sirius, which is about 8.6 light years away from us and is the brightest star besides the Sun. Its apparent magnitude reaches -1.47 at its brightest.

Sirius is a binary star system. The brightest star we see is Sirius A, a blue dwarf with a mass about twice that of the Sun, a diameter about 1.7 times that of the Sun, a surface temperature of about 10,000K, an age of about 242 million years, and a lifespan of about 1.76 billion years.

The sun is a yellow dwarf with a mass of about 2*10^30 kg. Stars with a greater mass and brightness than the sun are called blue dwarfs. Regardless of whether it is a yellow dwarf or a blue dwarf, a star with a mass of about 0.5 to 8 times that of the sun will become a red giant at the end of its evolution, after which the outer gas matter will gradually expand and dissipate in space, leaving a white dwarf in the core.

Modern astrophysics believes that only stars with a large enough mass can explode as supernovae in the late stages of their evolution. This mass requirement is at least 8 times that of the sun. In the late stages of the evolution of such stars, when the core hydrogen fuel is burned out, the huge gravitational pressure will cause a nuclear fusion chain to occur until the iron is reached, and eventually collapse to cause thermonuclear runaway, blowing up the outer shell or even the entire star.

According to this law of evolution, Sirius A has no chance of becoming a supernova. But the problem is that Sirius is a binary star system, which means two stars are bound together and entangled with each other under the action of gravity. Sirius B is a companion star with a smaller mass than Sirius A, but in fact, it is a dead star - a white dwarf.

The mass of this white dwarf is about the same as that of the sun, which means that before its death, it was a star with a greater mass than Sirius A. Astronomers have estimated through modeling that Sirius B was likely a blue dwarf with a mass of about five times that of the sun before its death.

A white dwarf is a special, highly dense celestial body. Due to its extremely small size, its mass is as great as that of the sun, but its volume is only as large as that of the earth. Therefore, its atoms are flattened by extreme gravity, and the planetary matter becomes a dense special substance supported by electron degeneracy pressure, with a density of 1 to 10 tons per cubic centimeter.

Although white dwarfs are the remains of stars, they are not dead yet. Due to their great gravitational force, they will attract interstellar matter close to them, which is also called accretion. Studies have found that the maximum limit of electron degeneracy pressure can only support 1.44 times the mass of the sun. This law was discovered by an Indian-American physicist named Subramanian Chandrasekhar, and people call this limit the Chandrasekhar limit.

When a white dwarf accretes and increases its mass to the Chandrasekhar limit, gravity will cause the star to collapse further, and the pressure will suddenly change from electron degeneracy pressure to neutron star degeneracy pressure. This sudden collapse will stimulate the carbon nuclear fusion of the entire white dwarf body. The energy cannot be released instantly, and thermal runaway causes a huge energy burst. This explosion is called a Type Ia supernova.

Will Sirius B accrete beyond the Chandrasekhar limit?

My answer is very likely. This is because the Sirius binary star system is not far away. The average distance between the two stars is about 20AU, which is 20 astronomical units. The average distance from the earth to the sun is about 150 million kilometers, and 20AU is about 3 billion kilometers.

If Sirius B wants to accrete to increase its mass to 1.44 times the mass of the sun, a little dust in the empty space is far from enough. It must absorb a large amount of matter from Sirius A to increase its mass to the Chandrasekhar limit.

Our solar system has only one star, and the sun's gravity locks the eight planets and several dwarf planets, as well as hundreds of planetary satellites and countless asteroids and dust. The gravitational influence range reaches more than 1 light year. The farthest planet from the sun, Neptune, is 30AU away, and Pluto is 40AU away.

The Sirius binary is only 20AU apart, so it is not impossible for Sirius B to get some food from Sirius A.

But at such a long distance, it seems difficult for B to get 0.44 solar masses from A, and it will be difficult to achieve it even if the world ends. The opportunity may come when Sirius A dies, that is, 1.5 billion years later. When the hydrogen in the core of Sirius is burned out, nuclear fusion will evolve in the order of helium, lithium, beryllium, boron, carbon, and finally end with carbon.

At the same time, its outer matter expands due to the star's gravity and internal radiation changes, and the star's radius will expand by 200 to 300 times. In this way, Sirius A, which has a radius of about 1.19 million kilometers, will become a red giant with a radius of about 238 to 357 million kilometers. Even so, the distance between the two stars is still very far. The chance of Star B is that the expansion of Star A will continue, and eventually more than 70% of the outer matter of this planet will spread into the surrounding space.

In this way, a lot of displaced interstellar matter will be captured by the huge gravity of Sirius B. Will the 1.4 times the mass of the sun's matter lost to space by Sirius A eventually be captured by Sirius B to reach a shocking mass? It's hard to say.

However, since the two stars are entangled with each other in a cycle of about 9.1 years, in such a cycle, Sirius B is likely to eat up all the matter from star A that has spread to the vicinity of the orbit, just like the snake eating beans in the computer game, which is enough to gather enough energy for a shocking explosion.

How powerful is Sirius's explosion into a supernova, and what impact will it have on Earth?

The supernova that explodes from a white dwarf is called a la supernova, and its explosion conditions follow the Chandrasekhar limit, which is 1.44 solar masses. Therefore, all la supernovae are extremely standard energy explosions, with similar explosion energies, and basically the same brightness and light curves.

In this way, as long as this type of Ia supernova explosion is discovered, no matter how far away the explosion occurs, its absolute magnitude should be the same. However, at different distances, the apparent magnitude of the star is different, that is, the brightness seen is different. These two brightnesses can be converted, and by converting, we can get the distance at which the explosion occurred. Therefore, this type of Ia supernova is called the standard candle in the universe.

The energy emitted by celestial bodies is proportional to their brightness, so as long as the brightness of the celestial body is known, its energy can be calculated. The benchmark for measuring the brightness of celestial bodies is the magnitude. The absolute magnitude refers to the brightness of a self-luminous celestial body at a distance of 32.6 light years, while the apparent magnitude refers to the brightness that can be seen by the human eye.

The smaller the magnitude, the brighter it is, and the more negative it is, the brighter it is. The brightness of each magnitude differs by 2.512 times. The absolute magnitude of the sun is 4.83, and the absolute magnitude of a supernova explosion can reach -19.5, which is about 4 billion times the brightness of the sun.

The energy radiated during a supernova explosion can reach 10^46 joules/second, while the radiation energy of the sun is 3.78*10^26 joules/second. The total radiation of the sun in its 10 billion years of life is about 1.2*10^44 joules. In other words, the energy radiated by a supernova explosion is equivalent to the energy radiated by 100 trillion suns, which is equivalent to the total radiation of 83 suns in their lifetime.

So, if a supernova explosion occurs at the position of Sirius, what impact will its energy have on the Earth? Some people say that a supernova explosion can destroy all life within a 50-light-year radius. How do we understand this power?

Scientific research shows that a supernova explosion will blast the entire star into extremely fine particles. These high-energy charged particles spread in all directions in the form of shock waves, with the fastest speed reaching more than 20,000 kilometers per second, close to 7% of the speed of light! These shock waves will reach the earth in 122 years at the fastest, and may cause species extinction.

The first to arrive is of course the light of the explosion, which arrives 8.6 years later at the speed of light. How bright is this? We use the absolute magnitude and apparent magnitude conversion formula: m=M-5log(d0/d). According to the absolute magnitude M of the la supernova, which is about -19.5, we can get the apparent magnitude m of the Sirius supernova as seen from Earth, which is about -22.39.

The sun is the closest star to us, with an apparent magnitude of -26.7; the moon is the closest extraterrestrial body to us, with an apparent magnitude of -12.7 when it is full, relying on the reflection of sunlight; and the apparent magnitude of Sirius's supernova is about -22.39. It seems that the supernova from Sirius is still not as bright as the sun, with a brightness difference of dozens of times; but the brightness of this supernova is already the brightest celestial body in the sky except the sun, which is 7520 times brighter than the moon.

In this way, during the period when Sirius explodes into a supernova, people can see a very bright star in the sky, which can be seen during the day as long as it does not coincide with the sun.

But this is only visible light. The X-rays and gamma rays produced in the explosion are high-energy rays that are harmful to life. If there are a lot of these rays and they come to the earth at the speed of light, they will destroy life on earth before the shock wave arrives.

Can humans survive the Sirius supernova explosion?

My answer is definitely yes. But this "yes" has two meanings. One is that humans have long been extinct and cannot experience all this, which can also be considered as escaping this disaster; the other is that if humans can survive until that day, dealing with this situation will be a piece of cake.

The premise is that if Sirius is to explode into a supernova, it will take more than ten billion years.

The history of human evolution is only millions of years old, the history of Homo sapiens evolution is only hundreds of thousands of years old, the history of human civilization is only thousands of years old, and the history of human technology is only hundreds of years old. However, human technology development has entered the fast lane, and almost one year in modern times can achieve thousands of years in ancient times.

If the heavens could give mankind another billion years to live, technological civilization would have developed to an unimaginable god-level stage, or humans would have left Earth and colonized other star systems or even galaxies outside the Milky Way. In this case, if Sirius exploded again, would it still matter to humans?

Therefore, what humans need to worry about is whether they can continue to survive, as they have reached the bottleneck of survival and development. Environmental and greenhouse effect issues, self-destruction issues such as nuclear war, asteroid impacts, solar catastrophic changes, etc., are like the sword of Damocles, always hanging on the single-plank bridge of human survival. Once it falls, there will be no recovery.

Therefore, developing science and technology, protecting and restoring the ecological environment, and achieving win-win cooperation are the only way out for mankind. If we are to worry about supernova explosions, we should probably worry more about Betelgeuse, which has long reached the end of its evolution, has expanded greatly and is very unstable. Recent observations show that Betelgeuse is sometimes bright and sometimes dim, and seems to be about to explode. Perhaps it has already exploded.

If it exploded today, we would not be able to see it until 700 years later because the star is about 700 light-years away from us.

Betelgeuse is a star about 12 times the mass of the sun. According to the laws of stellar evolution, it is bound to explode. However, due to its great distance, even if it explodes, it will not have a great impact on life on Earth. We will only see a star with a brightness similar to that of a full moon.

But there is one exception. If a gamma-ray burst occurs during the explosion and happens to be aimed at the Earth, we will be in trouble. Some studies believe that the Ordovician mass extinction occurred 445 million years ago as a result of a gamma-ray burst from a supernova. This supernova was caused by the collision of two neutron stars, 6,000 light-years away from us.

However, the probability of a gamma-ray burst from a star like Betelgeuse, which is not very massive, is very small, and even if it is emitted, it may not be directly facing the Earth. Therefore, please be at ease, eat and drink as you should, and go to bed after eating and drinking. What do you think? Welcome to discuss and comment.

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