What do the neighbors around the solar system look like? How are their family backgrounds? Is there anyone at home?

The solar system is a large family, with hundreds of planets of all sizes, as well as countless asteroids, comets, etc. In this large family, the sun is of course the largest, accounting for 99.84% of the mass of the entire solar system, and the rest are the eight planets, which account for almost all of the remaining 0.14%. The earth, a planet that seems huge to humans, only accounts for 0.0003% of the mass of the solar system, and all other asteroids and their fragments together only account for a few of the earth's mass.

Because all planets in star systems are condensed from the residue left over during the formation of stars, most star systems should have planets, but stars have absolute "hegemony". So what are the neighbors around the solar system, and what do they look like?

Now let us learn about the 10 star systems around the sun, from near to far. They are Alpha Centauri, Barnard's Star, Wolf 359, Lalande 21185, Sirius, UV Ceti, Ross 154, Ross 248, Epsilon Eridani, and Lacaille 9352.

1. Alpha Centauri, 4.3 light years away

Alpha Centauri, also known as Alpha Centauri, is a triple star system, which is composed of three stars. The biggest feature of this neighbor is that it is the closest to us. The smallest of them is only 4.2 light years away from us, so it is called Proxima Centauri. This is a very small red dwarf star, with a mass of only 12% of the sun, and it is invisible to the human eye; while its two older brothers, the eldest and the second, have a mass similar to that of the sun, so they are visible and very bright, ranking sixth and twentieth among the bright stars in the sky.

The first and second largest stars do not have planets, but the third largest star, Proxima Centauri, has two planets. One of them is in the habitable zone, a rocky planet with a mass about 1.3 times that of the Earth. Some scientists believe that there may be life on it. A special article about the details of Proxima Centauri was published two days ago. If you are interested, you can read it. I will not elaborate on it here.

2. Barnard's Star, 6 light years away

This is our second closest stellar neighbor, also a red dwarf, located near Beta Ophiuchi. Its mass is about 15% of the Sun, its surface temperature is about 3000K, its absolute magnitude is 13.22, its brightness is only 1/2500 of the Sun, and its visual magnitude is 9.54, which is invisible to the naked eye.

There has always been controversy about the planets of Barnard's Star. In the 1960s, astronomers discovered that Barnard's Star may have a planet with a mass of about 1.6 times that of Jupiter. New analysis shows that Barnard's Star has two planets, one of which is 0.8 times the mass of Jupiter, with an orbital period of 11.7 years (Earth years, the same below), and an orbital semi-major axis of about 2.7AU (astronomical units, each astronomical unit is about 150 million kilometers); the other is about 0.4 times the mass of Jupiter, with an orbital period of 20 years and an orbital semi-major axis of 3.8AU.

Since both planets are outside the habitable zone of Barnard's Star, they are extremely cold, with surface temperatures below -100°C and no liquid water, making it unlikely that life could exist.

3. Wolf 359, 7.7 light years away

This is our third closest stellar neighbor, and is another red dwarf, located in the constellation Leo. Its mass is only 9% of the Sun, its surface temperature is about 2800K, its absolute magnitude is about 16.64, its brightness is only 1/53000 of the Sun, and its apparent magnitude is 13.54, which is invisible to the naked eye.

Astronomers have discovered that Wolf 359 is accompanied by two planets. Wolf 359b has a mass about 3.8 times that of the Earth, a semi-major axis of about 0.018 AU, and is too close to the main star, so it revolves very fast, with an orbital period of only 2.7 days (Earth day, the same below); Wolf 359c has a mass about 44 times that of the Earth, a semi-major axis of about 1.8 AU, and an orbital period of about 2938 days.

One of the two planets is too close and should have been tidally locked, with the sides facing the star and the sides facing away from the star being a world of ice and fire; while the other is too far away and is a cold planet. Therefore, neither planet is suitable for the growth and survival of life.

4. Lalande 21185, 8.26 light years away

This is our fourth closest stellar neighbor, and it is also a red dwarf located in the Ursa Major. Its mass is about 0.46 of the Sun, so it is a relatively large red dwarf, with a surface temperature of 3828K, an absolute magnitude of 10.46, and a brightness of about 1/179 of the Sun. It is the brightest red dwarf in the northern celestial sphere, but its apparent magnitude is only 7.52, so it is still invisible to the naked eye.

In this star system, it is now discovered that there may be a planet with a mass of about 2.99 times that of the Earth, an orbital semi-major axis of about 0.079AU, and an orbital period of about 13 days. In such a star system with a surface temperature of about 4000K, this distance is too close, so this is a hot planet, and the star's flares and tidal activities are also full of threats and damage to the planet, and the possibility of life is not high.

5. Sirius, 8.6 light years away

This is the fifth closest star system to us, a binary star system, and the most massive star system among the 10 neighbors around the sun. Its main star, Sirius A, is a blue dwarf with a mass of about 2.1 times that of the sun; its companion star, Sirius B, is a white dwarf with a mass of about 1.1 times that of the sun. Sirius is the brightest star in the night sky, with an apparent magnitude of -1.46. Since ancient times, there have been many legends about Sirius.

There are no planets around the two stars of Sirius (one of which is a corpse), and the white dwarf is a time bomb that is likely to explode in 1.5 billion years. I published an article a few days ago to learn more about the situation of Sirius. If you are interested, you can go and read it. I will not elaborate on it here.

6. UV Cetus, 8.73 light years away

This is the sixth closest star system to us, also called Luyten 726-8, a binary star system consisting of two red dwarf stars, Luyten 726-8A and Luyten 726-8B. The latter is UV Aurora, the closest star to Earth in the constellation Aurora. Both stars are flare stars, but UV Aurora is more famous and is the flare star with the most dramatic luminosity variation found so far.

Flare stars are stars that change light irregularly, and they can suddenly brighten many times. In fact, Proxima Centauri, Barnard's Star, and Wolf 359 all have this property, but this UV Aquarius star is more significant, with brightness changes that can increase sharply by several magnitudes, or dozens of times, within a few minutes.

Flare stars generally only occur on red dwarfs, and mainly occur in the unstable infancy of red dwarfs. They are caused by large-scale flare explosions in the chromosphere on the surface of red dwarfs. They are also called flares or brightenings, which are similar to solar flares, but much more violent than solar flares.

UV Auriculariae has a mass of only 10% of the Sun, a surface temperature of about 2670K, an absolute magnitude of about 15.37, and an apparent magnitude of about 12.99, which is completely invisible to the human eye. Its companion star Luyten 726-8A, also known as BL Auriculariae, is also a red dwarf with a similar apparent magnitude. It is also a flare star, but its flare is smaller than that of UV Auriculariae.

The two stars orbit each other around a void particle with an orbital period of 26.5 years. So far, no planets have been reported to be associated with this star system.

7. Ross 154, 9.7 light years away

This is the 7th closest star system to us, also called V1216 Sagittarius, and is the closest star to Earth in Sagittarius. It is also a red dwarf and a flare star, with a frequent flare cycle, with an average interval of about 2 days between two major flares, and its brightness can increase by 3 to 4 magnitudes when flaring.

The star has a mass of about 17% of the Sun, a surface temperature of about 3105K, a brightness of only 0.38% of the Sun, an absolute magnitude of 13.07, and an apparent magnitude of 10.95, which is invisible to the naked eye. So far, no planets have been found to accompany it.

8. Ross 248, 10.32 light years away

This is the 8th closest star system to us, located in Andromeda. It is also a red dwarf and a flare star, but it is a long-period variable star with a variation period of up to 4.2 years. The luminosity does not change much, and the apparent magnitude is between 12.23 and 12.34, so it is invisible to the naked eye.

The star has a mass of about 12% of the Sun, a surface temperature of about 2799K, an absolute magnitude of 14.79, and a brightness of only 0.18% of the Sun. Voyager 2, launched by NASA in the last century, is flying towards the star at a speed of 16.6km/s and will pass by it at a distance of 1.76 light years in 40,176 years.

Long-term observations by the Sproul Observatory in the United States suggest that there may be invisible companion stars that disturb its orbit, and indicate that these companion stars may be 100 to 400 AU away from the primary star. However, so far, these possibilities have neither been confirmed nor denied.

But even if these companion stars really exist, they are too far away, far greater than the approximately 40 AU distance from Pluto to the Sun, and Ross 248 is just a very dim red dwarf. The temperature of a planet at such a long distance is basically close to absolute zero, making it impossible for life to be nurtured and exist.

9. Epsilon Eridani, 10.5 light years away

This is the 9th closest star system to us, also called Eridanus, which is about 0.85 times the mass of the sun. It is the closest star to us in the constellation Eridanus and is about 1 billion years old.

Although this star is smaller than the Sun, its stellar wind is 30 times stronger than the Sun, probably because it is younger than the Sun, indicating that its energy activity is quite intense. The surface temperature of this star is 5073K, its brightness is about 28% of the Sun, its absolute magnitude is 6.19, and its apparent magnitude is 3.73, so it is visible to the naked eye. It is the third closest star to us in the sky that humans can see with the naked eye (the first and second are Alpha Centauri A and B).

Observation results suggest that there is at least one planet in the star system, namely, HD 22049b. This planet has a mass about 1.5 times that of Jupiter, an average distance of about 3.4 AU from the host star, an orbital period of 2502 days, and a high orbital eccentricity of 0.702.

There are two asteroid belts around the star, one at 3AU and the other at 20AU. Some studies have suggested that this may be material perturbed by another planet that has not yet been confirmed, but the existence of this second planet has not yet been confirmed.

It is difficult for life to exist on such a huge gas planet, which is located far away from the host star.

10. Lacaille 9352, 10.74 light years away

This is the 10th closest star system to us, also called GJ887 (Gliese 887), the closest star to us in Piscis Austrinus, and also a red dwarf, the largest and brightest red dwarf near the Earth. Its mass is about 0.5 times that of the Sun, its apparent temperature is 3626K, its absolute magnitude is about 8.7, its apparent magnitude is about 7.34, and its brightness is about 3.3% of the Sun, invisible to the naked eye.

This red dwarf is relatively gentle and quiet, and may have passed its infant stage with intense flare activity. Astronomers have discovered at least two planets around it, one with a mass of about 4.2 times that of the Earth and an orbital period of 9.3 days, and the other with a mass of about 7.6 times that of the Earth and an orbital period of 21.8 days.

These two planets may be rocky planets close to the inner habitable zone of the host star. Because they are relatively close to the host star, the surface temperatures reach 195℃ and 75℃ respectively, making it difficult to maintain the existence of liquid water. The slightly farther planet may be surrounded by an atmosphere.

Based on gravitational perturbations, there is likely a third planet a little further away, within the habitable zone, with an orbital period of about 51 days.

Well, that’s all for the introduction to the solar system’s 10 closest neighbors. As for whether there is life or aliens in these neighboring star systems, current human detection methods are unable to draw a conclusion.

Extend and supplement some basic common sense

The scientific community believes that red dwarfs account for about 80% of the total number of stars in the universe. The lifespan of a star is determined by its mass. The greater the mass, the shorter the lifespan, and vice versa. Generally, red dwarfs have an extremely long lifespan, ranging from hundreds of billions to trillions of years.

Our universe is only 13.8 billion years old, so all red dwarfs are still in their infancy or adolescence. The younger the red dwarf, the more active it is, and it will gradually calm down as it ages. Scientists believe that red stars are the cradle of life, but this cradle will be more suitable for the birth of life only when the red dwarf becomes quiet.

At present, humans can only see a bright spot when observing stars with a telescope. Extraterrestrial planets cannot be "seen" at all, and can only be "guessed". The main methods are the transit method and the gravitational perturbation method. The transit method is to use various rays and optical telescopes to observe the shading phenomenon and light change period when the planet moves between the star and our line of sight (see the figure below); the gravitational perturbation method is that the movement of the planet will affect the orbit of the star. According to the observed state of the change of the star's movement, the law of universal gravitation can be used to calculate whether there are planets and the number, size and operation period of the planets.

Therefore, the planets that have been observed now are not necessarily very accurate; and the planets that have not been observed are not necessarily non-existent.

In addition, the smaller the magnitude, the brighter it is. There are also negative numbers, and the more negative, the brighter it is. The brightness difference between each magnitude is 2.512 times, so the brightness difference of different magnitudes is calculated with 2.512 as the base and the magnitude difference as the power. The human eye can only see stars with an apparent magnitude of 6.

That’s all for now, thank you for reading and welcome to discuss.

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