Do the legendary Sirians really exist?

The Sirius we often refer to actually refers to Sirius A. The luminosity of this star itself is 25 times higher than that of the sun, but because it is 8.6 light-years away from the earth, it is far less bright than ours on the earth. The sun is so spectacular.

But it is indeed the brightest star in the sky at night, twice as bright as the second brightest star Canopus (Carina? Star). Although Sirius can emit light by itself, its brightness is still not as bright as Some planets in our solar system light up by reflecting sunlight.

For example, its brightness will be weaker than the moon, Venus, and Jupiter, and sometimes the brightness of Mercury and Mars will exceed the brightness of Sirius A. This shows that in addition to the brightness of the celestial body itself, the distance is how a celestial body looks. The key factor is whether it is bright or not, because the luminosity of a celestial body is inversely proportional to the square of the distance.

In fact, not only do some people suspect that there are habitable planets in Sirius, there are also rumors and speculations that there are intelligent life in the Sirius system. Humans call them Sirians, and they have also visited the earth? So where did this rumor come from?

Because there is an ancient Dogon tribe in Africa. The people of this tribe have astronomical knowledge that is inconsistent with their scientific level and knowledge. For example, they knew a long time ago that there are still stars near Sirius A. There is a star that is invisible to the naked eye. How do they know the existence of Sirius B without advanced telescopes?

Not only that, the Dogon people also recorded that there is a third star in the Sirius system. However, we have not yet discovered where this star is, so some people speculate that the reason why the Dogon people know so much is because the Sirians once visited the earth and taught them some astronomical knowledge.

So based on our current understanding of the Sirius system, let’s analyze whether there is a possibility of habitable planets in the Sirius system, or do the legendary Sirians really exist? Sirius System

Based on our current understanding of the Sirius system, we know that there is a pair of binary stars in this system. The one visible to the naked eye is Sirius A, and the one invisible to the naked eye is Sirius B.

Among them, Sirius A is a metal-rich star with a mass of 2.063 times that of the sun. Its volume is slightly larger than that of the sun. Its surface temperature is about twice that of the sun, reaching 9940K, and it emits blue-white light. The light is an A-class blue dwarf star. Its habitable zone ranges from approximately 2 to 5 astronomical units.

The current Sirius A is in the main sequence star stage. Most of the energy is consumed by hydrogen elements to produce helium-4 through the C-N-O cycle, and the process of producing helium-4 through the fusion of proton-proton chains is only Provides a small amount of energy.

For example, for a star with the mass of our sun, its only energy comes from the fusion of proton-proton chains. The energy generated by the C-N-O cycle only accounts for 1.7% of the solar energy.

The current lifespan of Sirius A is 300 million years. According to predictions of its mass, in 1 billion years, the core of Sirius A will run out of hydrogen fuel, expand into a red giant, and finally die in its core. Leaving behind a white dwarf star.

Sirius B is the companion star of Sirius A. It is a white dwarf star with 1.018 times the mass of the sun and the same size as the earth. It has a surface temperature of 25000K. It is the remnant of a star after its death. This shows that Sirius B is the predecessor of Sirius B. It is a very massive star, estimated to be 5 times the mass of the sun, which explains why Sirius B died so early.

Sirius A and B orbit each other, the distance between them is 20 astronomical units, the orbital period is about 50 years, the eccentricity is about 0.5, and the center of mass is 8.6 light years away from the earth. Will there be intelligent life in the Sirius system?

For intelligent life to exist, there must be a planet. Life cannot live on a star! A distance of 8.6 light years is actually not very far, at least in terms of the scope of the universe.

Since the planet itself does not emit light, it is very difficult to detect. It cannot be directly observed and can only be discovered through indirect means.

Currently we humans generally use the planet transit method, radial velocity method, and microgravitational lensing to search for extraterrestrial planets. These methods are all indirect ways of observing the impact of possible planets on the movement of the main star and the light of the star.

These methods have great limitations. For example, if the planet has a very small mass and is far away from the host star, its impact on the star's light and star motion will not be observable, and even more so The important point is that if we want to see the impact of extraterrestrial planets on their host stars, we must keep the host stars, planets and the Earth in a straight line. This results in many planets that we cannot discover.

Therefore, the planets we have discovered so far are either very massive or very close to their parent stars. Planets like the Earth or planets with a mass smaller than the Earth are generally difficult to find.

Therefore, we have not found any planets in the Sirius system now, which does not necessarily mean that others do not have them. Let's assume that there are habitable planets in the Sirius system and see if there is intelligent life there?

First of all, the biggest factor hindering the emergence of intelligent life is that the Sirius system is very young, only 300 million years old.

Compared with the age of the solar system, it is far different, and based on the time scale for the emergence of intelligent life on our earth, it is impossible for civilization to evolve on Sirius. If there is life, at most it will be like the primitive life on the earth at the beginning. .

And the main star Sirius will emit strong ultraviolet light due to its more violent nuclear fusion. It is impossible for life to exist on land directly under ultraviolet rays. The only home for life is the deep sea area. Where can life exist? It can avoid ultraviolet rays and hydrothermal vents on the seabed can sustain the energy necessary for life.

But we don’t know whether such beings can evolve wisdom in the future, but what we do know is that even if they can evolve wisdom, they will not live too long, because Sirius’s lifespan is only In just one billion years, whatever life exists will be extinct following the death of the star.

In addition to Sirius A, there is also Sirius B. This star expanded into a red giant a long time ago, and finally evolved into a planetary nebula and died. In the process, the star will eject a large amount of energy outwards. High-energy particles, if there was life in the Sirius system at that time, then the death of Sirius B would also cause a mass extinction of life.

So we currently believe that it is difficult to evolve intelligent life in the Sirius system. If Sirians really exist, the radio waves emitted by their daily activities should have been received by us humans long ago. After all, 8.6 light Years are not very far away.

As for Sirius C recorded by the Dogon people, we have not found it yet. Perhaps this star is a brown dwarf very far away from the Sirius binary star system, orbiting the Sirius system in a very long period orbit. This is also possible.

After all, it is difficult to observe failed stars that do not emit light like brown dwarfs. It is possible that there is also a brown dwarf near our solar system. However, there is basically no possibility for the Sirians to exist.