In the second-most distant star system from the Sun, located 6 light-years away, a rocky exoplanet has been discovered that is at least 3.2 times more massive than Earth and orbits a red dwarf star near the snow line. The paper, which describes the research and findings based on more than 20 years of observations of Barnard's Star using ten different instruments around the world, is presented in the journal Nature .

“Barnard's Star is one of the most notorious objects for astronomers because planets have been discovered in its orbit in the past, but reanalysis of the data indicated errors in the calculations. However, we can now say with 99 percent certainty that at least one planet is there!” – says Guillem Anglada Escudé, one of the study participants from Queen Mary University in London (UK).

An artist's impression of the Super-Earth at Barnard's Star. Credit: ESO/M. Kornmesser

The exoplanet was discovered as part of the Red Dots and CARMENES projects and is the result of close collaboration between an international team of more than 60 scientists.

The fastest star in the sky

Barnard's Star lives in the equatorial constellation Ophiuchus, visible throughout Russia with the exception of the northern regions. It is the fourth farthest star from the Sun and the closest single luminary. It was discovered in 1916 by the American astronomer Edward Emerson Barnard, and was named after him. In the late 1960s, American astronomer Peter van de Kamp announced the existence of three gas giants in its system, but today his calculations are considered erroneous.

Distance from the Sun of Barnard's star. Credit: IEEC/Science-Wave/Guillem Ramisa

Barnard's Star is a cool, old, low-mass red dwarf star estimated to be between 7 and 10 billion years old. Both in mass and in radius it is approximately six times smaller than our Sun. Barnard's Star is often called a "flying" or "runaway" star because it has the fastest angular movement across the celestial sphere of all known. Over 174 Earth years, this red dwarf shifts in the sky by half a degree, which corresponds to the full disk of the Moon, and the total speed of the star relative to the Sun is approximately 500,000 kilometers per hour.

Twenty-year monitoring of the star Barnadra

The search for exoplanets orbiting Barnard's Star has been going on for several decades, but until now, astronomers have been left empty-handed. The breakthrough was achieved only by combining measurements from several high-precision instruments mounted on telescopes in different parts of the world.

“We combined archival data obtained by other researchers with new, overlapping measurements of Barnard's Star made with different equipment. It was this combination that became the key factor in the discovery of the extrasolar world,” explained Guillem Anglada Escudé.

To search for an exoplanet, astronomers used the Doppler effect, the essence of which is as follows. A massive object orbiting a star causes it to move slightly due to gravity. When a star moves away from Earth, its spectrum is red-shifted, meaning the wavelengths in the spectrum increase slightly, and when a star moves toward Earth, the wavelengths of its radiation shift to the shorter, bluer side.

Researchers are using this effect to measure changes in a star's speed caused by the presence of an exoplanet, which requires extraordinary precision. The European Southern Observatory's HARPS receiver, which played an important role in the discovery, is capable of detecting changes in the speed of the star at 3.5 kilometers per hour. This method of “catching” distant worlds is called the radial velocity method, and it was first used to detect a super-Earth in an orbit so far from its parent star.

“We used observations made with a variety of instruments over twenty years, creating one of the longest and largest data sets ever used for precise radial velocity measurements. As a result, we obtained a huge amount of information - an array of 771 measurements,” added Ignacius Ribas, lead author of the study from the Institute of Space Research of Catalonia.

Frozen super-Earth and life on it

The new planet, designated Barnard's star b (GJ 699 b), is the second-farthest known from Earth, after . Observational data suggests that it belongs to the class of “super-Earths.” Its mass is at least 3.2 Earth masses, and one year on the exoplanet lasts 233 Earth days.

Given that its parent star is quite faint, Barnard's star b receives from its star only 2 percent of the energy received by the Earth from the Sun.

Despite its relative proximity to its host star, about 0.4 astronomical units, the exoplanet lies near the snow line, the boundary beyond which volatile components such as water vapor can condense into ice. In this frozen and dark world, the temperature is probably close to -170 degrees Celsius. These conditions cannot be called favorable for life in the form we know.

Further Study

“We will continue to observe this fast-flying star to rule out possible – although extremely unlikely – natural variations in its brightness that could be erroneously interpreted as the presence of a planet,” says Ignacius Ribas.

Further observations aimed at increasing confidence in the result obtained are already underway at various observatories. In addition, Barnard's star system is an excellent candidate for study by the next generation of telescopes specifically designed to directly image exoplanets, in particular NASA's Wide Field Infrared Survey Telescope (WFIRST), which is scheduled to launch in 2024.

If Barnard's star b is imaged directly, it will provide important information about its properties, as well as expand understanding of the types of planets that form around red dwarfs.

When asked what the closest star to Earth is called, many will not be able to answer correctly. The correct answer is actually very simple. The closest star to us is called the Sun.

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The Sun is the closest star to Earth

The bright ball that rises above the horizon every day is the star closest to us. It was formed approximately 4.5 billion years ago. The Sun belongs to the group of young stars. Scientists believe that we owe the appearance of the star to a supernova explosion. This is confirmed by data on the anomalous amount of gold in the matter of the solar system. The luminary consists of hot gases and impurities of relatively small amounts of other elements.

Its chemical composition:

• hydrogen (70%);
• helium (28%);
• iron;
• nickel;
• oxygen;
• nitrogen;
• silicon;
• magnesium.

The sun produces enormous amounts of energy through nuclear fusion. Now these are reactions associated with the conversion of hydrogen into helium. The surface temperature is 5780 kelvin (approximately 5500 ̊C). According to the accepted classification, this is not the largest star in the universe, located in one of the arms of the Milky Way galaxy. Thanks to the gigantic force of gravity, the Sun has become the center around which the planets of the solar system, as well as asteroids, meteorites, cosmic dust, and other cosmic bodies revolve.

Interesting Facts:

• the star makes up 99.8% of the mass of our planetary system;
• here, every second, 4 billion tons of matter are converted into energy;
• 1300 planets like ours could fit inside;
• its diameter is equal to 109 diameters of the Earth;
• its mass is comparable to 332940 masses of the blue planet;
• The Sun moves around the center of the galaxy at a speed of approximately 217 km/s;
• it is brighter than 85% of the stars in the Milky Way galaxy;
• The light of the Sun is actually almost white: it acquires a yellow tint as it passes through the Earth's atmosphere;
• photons of light from the surface of the star reach planet Earth in 8 minutes;
• the Sun's magnetic field is very strong and can change its direction every 11 years;
• solar wind, sunspots, flares and giant prominences arise under the influence of a magnetic field;
• it was noted that solar activity cycles last 11 years;
• geomagnetic storms simply would not exist on the planet without the magnetic field of the closest star, because they arise as a result of the interaction of force flows.

The closest star supports life on the blue planet. It is the source of light necessary for the process of photosynthesis. This ensures the creation of organic matter from inorganic substances, as well as the synthesis of oxygen. Without it, life could not have arisen. Thanks to photosynthesis, ancient plants obtained energy, which is contained in coal, oil, and other carbon-containing minerals. High doses of ultraviolet radiation from the Sun are dangerous for all living things; it is contained by the ozone layer of the atmosphere. But at the same time, ultraviolet light has antiseptic properties and is necessary for the production of vitamin D by the human body. Solar flares and strong fluctuations in its magnetic field can cause interruptions in the operation of electrical appliances and affect people's well-being.

The sun is the center of our planetary system, so the future of humanity is directly related to the future of the star that is closest to our planet. Now the star is approximately halfway through its life cycle. Scientists have found that such stars have existed on the main sequence for 10-12 million years. What future awaits our luminary?

Scientists have calculated:

• in 1.1 billion years the Sun will increase its brightness by 11%, which threatens the end of life on the surface of the Earth;
• after 3.5 billion years, the Sun will become 40% brighter; this will make the Earth like Venus in our time;
• in 6.4 billion years, the hydrogen in the core will run out, it will begin to shrink and become denser;
• Another 7.7 billion years will pass and the Sun will inevitably become a red giant, the radius of which will be 206 times larger than today; if it does not absorb the Earth, water and atmosphere will definitely disappear from it;
• the mass of the Sun will not allow it to turn into a supernova, so then the phase of a planetary nebula and a white dwarf will follow; then the Sun will be similar in size to the Earth;
• In about 20 million years, the white dwarf will fade away.

Now the question is which star is closest to the blue planet and will not take you by surprise. What is the name of the closest star other than the Sun? This is a more complex question.

Distance from Earth to the nearest star

Scientists have long calculated how many kilometers separate the Earth from the Sun. The distance from Earth to the nearest star is approximately 150 million kilometers. Since the Earth's orbit is elliptical, the exact value may vary. Astronomers call the minimum distance to the Sun perihelion (148 million km), and the maximum - aphelion (152 million km). Aphelion occurs in July and perihelion in January.

The closest star to Earth other than the Sun: not so simple

After the Sun, the closest star to the blue planet is a very unusual star called Alpha Centauri. The distance to it is 4.37 light years. Alpha Centauri is not a single object.

It consists of three objects:

• Alpha Centauri A;
• Alpha Centauri B;
• Proxima Centauri.

They make revolutions around one common center of gravity. But most of all we are interested in Proxima Centauri, which makes a complete revolution around the Alpha Centauri system in 500 thousand years. It is the one closest to Earth. The distance from it to Earth is 4.23 light years. This is 270 thousand times the distance between the Earth and the Sun. Astronomers claim that it has occupied this position for about 32 thousand years. And after 55 thousand years, according to scientists, this distance will decrease to 3.11 light years. The diameter of Proxima Centauri is 7 times smaller than the diameter of the Sun. The mass is also approximately the same number of times less than the mass of our star.

Alpha Centauri is located in the constellation Centaurus, which is only visible from the Southern Hemisphere. It is impossible to see it with the naked eye. This is probably why astronomers saw Proxima Centauri only in 1915, and research on this interesting object continues to this day. Scientists have been actively searching for planets around this star, but so far without success. Also, without a powerful telescope, it will not be possible to view the star closest to Earth in the Northern Hemisphere. It is called Bernard's Star, located 5,978 light years away in the constellation Ophiuchus and belongs to the group of red dwarfs.

Of the stars that can be seen with the naked eye in the night sky, Sirius is the closest to Earth (8.6 light years). It is twice the size of the Sun in radius and mass. The second name for Sirius is Alpha Canis Majoris. There are no brighter stars in the night sky. It ranks sixth in brightness in the sky.

Only the following celestial bodies shine brighter than Sirius:

1. Sun;

3. Jupiter;

4. Venus;

Due to its brightness, Sirius has been an object of study and worship since ancient times among various peoples of the world from different continents. It is visible from almost anywhere on the planet, although it belongs to the southern hemisphere of the starry sky. This is a double star. Sirius B is not as bright as Sirius A (the part of the system visible from Earth), but at the same time these space objects rotate around a common center of mass. The frequency of such rotation is 50 years. Sirius B is a white dwarf, which means it used to be much larger than Sirius A. Scientists estimate the age of Sirius to be approximately 230 million years.

It now emits a bluish-white light, although researchers from earlier eras describe it as a bright red star. There is no scientific explanation for this fact yet. It is known that the bright appearance of Sirius from Earth is due to the fact that the star is close, and not to its own brightness. Astronomers have calculated that in our time Sirius is approaching our planet at a speed of 7.6 km/s, so its apparent brightness will increase over time. Sirius is the eighth closest star to Earth.

List of stars by proximity to Earth:

• Sun;
• Alpha Centauri (Proxima Centauri);
• Bernard's Star;
• Luhmann 16;
• WISE 0855-0714;
• Wolf 395;
• Lalande 21185;
• Sirius.

Perhaps, soon astronomers will make new discoveries, and this list will be replenished with new names of such distant, but at the same time close stars.

The statement that Alpha Centauri is the closest star to the sun can often be found in various media. But this statement is not correct, since Alpha Centauri is not a star, but a system of stars consisting of Alpha Centauri A and Alpha Centauri B. Why most people consider Alpha Centauri the star that is closest to is still not clear. The system is 4.36 light years away from the Sun and is 0.21 light years further than the star Proxima, which will be discussed later.

Size comparison of 4 stars, from left to right: Sun, Alpha Centauri A, Alpha Centauri B, Proxima

In classical astronomy there is a theory that the star Proxima is the third element of the Alpha Centauri system, which is located at a great distance from the main ones and makes a full revolution around them in half a million Earth years. Now this hypothesis is subject to some doubt, since scientists are putting forward more and more new theories, one of which says that Proxima is an independent star, independent of the Alpha Centauri system.

Close-up view of Proxima. The image was simulated using the Space Engine program

There is no exact answer to the question of whether Proxima belongs to the Alpha Centauri system, but today, it is the closest star to Earth (after the Sun) and the closest star to the Sun. It is 4.14 light years away from us, and this distance is almost 270,000 times greater than the distance between the Sun and our planet.
Red dwarfs are the most numerous type of stars in the Galaxy, to which Proxima belongs. They are small red stars with dim light that release small amounts of energy. At a great distance, these stars are almost impossible to see. It is worth noting that Proxima is 7 times smaller than the Sun and 150 times larger than Jupiter.

Computer model of the star Proxima, made in the Celestia program

Space has long attracted people with its mystery. Even in ancient times, astronomers tried to at least slightly lift the curtain hiding the secrets of the universe, to find out where the star closest to us is located. Inventing various devices, they looked at the lights flickering in the night sky. Today, scientific advances make it possible to study celestial bodies located at a great distance from our planet. Thanks to this, it was possible to establish which stars are closest to our planet.

The Sun is the closest star to us

The closest star, almost 15 million km away from the Earth, is the Sun. It, like all stars, does not have a solid surface. This is a ball containing helium and hydrogen gases. They are held together by their own gravity. The Sun is a yellow dwarf and emits almost white light.

The most interesting facts are the following:

• the star is the only luminary in the solar system;
• the age of the Sun is approximately 4.6 billion years;
• temperature on the surface of the star – 5.5 million °C;
• temperature in the center of the core – 15 million °C;
• To recreate the amount of energy a star produces, about 100 billion tons of dynamite would need to be detonated every second.

Having studied the amount of nuclear energy in the Sun, scientists have determined that the star can still exist for about 5 billion years. After depleting its hydrogen reserves, the Sun will become a Red Giant. Subsequently, the core will collapse, the star will become a White Dwarf, and the final phase of its existence will begin.

The closest star to Earth after the Sun is Proxima Centauri. Its distance from our planet is about 4.22 light years. It is almost seven times smaller than the Sun. This star was discovered in 1915. It is impossible to see it without a telescope, since it is a red dwarf and emits a small amount of energy.

Proxima Centauri is part of the Alpha Centauri system. Scientists believe that planets may revolve around this star. It is quite difficult to observe them. In 2018, a powerful space telescope will be launched, with the help of which astronomers plan to study the star and its planets in more detail.

Alpha Centauri

The third place in the ranking in terms of distance from our planet is occupied by the stars Alpha Centauri A and Alpha Centauri B. The distance to these luminaries of the Centaurus constellation is about 4.36 light years. It is impossible to see these two stars in the sky at once with the naked eye. Due to the close distance, they practically merge into one bright point. But armed with even a small telescope, you can see both luminaries.

Alpha Centauri A is one and a half billion years older than the Sun. The star is also a yellow dwarf, but is slightly larger than the star of our system. Alpha Centauri B is an orange dwarf.

Bernard's star is in fourth place in terms of proximity to our planet. The red dwarf was discovered by American astronomer Edward Barnard in 1916. It is located 5.96 light years from Earth. You can only see the star using a telescope, since it emits little energy. Scientists have not yet been able to establish whether the only star in the constellation Ophiuchus has planets.

Luhmann 16

At a distance of about 5.98 light years from Earth in the constellation Vela, the stars Luhmann 16 A and Luhmann 16 B were discovered, which occupy fifth place in the ranking of proximity to our planet. These brown dwarfs were discovered in 2013 by the famous American astronomer Kevin Luhmann, after whom they were named. The distance between the stars is 3 astronomical units. It has not yet been possible to discover whether stars have planets.

Kevin Luhmann discovered the sixth closest star to Earth in 2014. It was possible to see it using the WISE telescope, whose name it now bears. A brown dwarf has weak radiation, making it invisible to the naked eye. The distance to it is 7.27 light years. Astronomers have determined that WISE 0855-0714 is the coolest star in outer space that has already been studied.

In 1918, using astrophotography, German astronomer Max Wolf managed to discover a star that was in seventh place in the ranking of proximity to our planet. The red dwarf was named after its discoverer. The radiation of this star is very weak, so it can only be observed with the help of astronomical equipment. Wolf 359 is approximately 7.78 light years from Earth.

The star Lalande 21185 was also included in the top ten closest stars to Earth. The discovery of this star, made in 1801, belongs to the French astronomer Joseph Lalande. It is a red dwarf star located about 8.29 light years from our planet. Thanks to ongoing research, it became known that Lalande 21185 is a flare star that is part of the constellation Ursa Major. Astronomers have not yet been able to detect planets orbiting this star.

In ninth place in terms of proximity to the Earth are two stars: Sirius A and Sirius B. Until 1844, it was believed that this was one star, until Friedrich Bessel suggested that there were two luminaries merging into one. This was proven by Alvan Clark, who discovered the star Sirius V in 1862.

Sirius A is a white dwarf, and Sirius B is a yellow dwarf. Both stars are approximately 8.58 light years away from Earth. The double star Sirius AB is clearly visible in the night sky. It can be observed from all corners of the planet, not counting the northernmost region.

The final place in the top ten stars closest to Earth is occupied by Leuthen 726-8. This is a double star approximately 8,728 light years distant from our planet. Both luminaries are located in the constellation Cetus. The Dutch-American astronomer Jacob Leijten was able to see them in 1948. It was found that both flare stars are red dwarfs.

Instructions

The Sun is one of the hundred million stars in the Milky Way galaxy, and is approximately the 4th largest among them. According to the spectral classification, the Sun is classified as a yellow dwarf, and its age, according to rough calculations, is about 4.5 billion years. The Sun is currently in the middle of its life cycle. The closest star to the Sun is called Proxima Centauri and is located at a distance of 4 light years from it. The distance from planet Earth to the Sun is 150 million km; light travels this distance in 8 minutes. The Sun is located at a distance of 26 thousand light years from the center of the galaxy, and its rotation speed relative to the center is 1 revolution per 200 million years.

When the Sun reaches an age of about 7 billion years, this star will turn into a red giant. Its outer shells will expand and reach the orbit of the Earth or even Saturn, pushing these planets to a greater distance. The star consists of 92% hydrogen and 7% helium, having a very complex structure.

At the center of the Sun is its core, the radius of which is approximately 150,000 - 175,000 km, which is about 25% of the total radius of the star. In the center of the core, the temperature reaches 14,000,000 K. The core rotates around its own axis at a high speed, which significantly exceeds the outer shells of the star. It is here that, as a result of the reaction, helium is formed from 4 protons, which releases a large amount of energy. This is what is emitted from the photosphere as kinetic energy and light.

Above the core of the Sun there is a zone of radiative transfer with temperatures in the region of 2-7 million K. This zone is followed by a convective zone with a depth of approximately 200 thousand km. In this zone there is no re-emission and energy transfer; plasma mixing occurs here. the surface of this layer reaches 5800 K. The photosphere, which makes up the visible surface of the star, is the main part of the solar atmosphere along with the chromosphere. The last outer shell of a star is considered to be the corona, from the outer part of which the solar wind emerges - a stream of ionized particles.

Life on planet Earth exists mainly only thanks to the Sun. The planet rotates around its axis, and every day a person can observe the dawn and, and at night, stars in the dark sky. The Sun has a huge impact on the life activity of all life on the planet: the star participates in photosynthesis and contributes to the formation of vitamin D in the human body. The penetration of solar wind into the Earth’s atmosphere is visible to the naked eye. These are the northern lights, which also cause storms. About every 11 years, solar activity decreases or increases.