What are proxima 6 trends. Astronomers have found the closest Earth-like planet. Does this exoplanet really exist?

With the help of telescopes of the European Southern Observatory (ESO), astronomers have managed to make another amazing discovery. This time they have found clear evidence of the existence of an exoplanet orbiting the closest star to Earth - Proxima Centauri. The world, called Proxima Centauri b (Proxima Centauri b), has long been sought by scientists all over the Earth. Now, thanks to his discovery, it has been established that the period of his revolution around his native star (year) is 11 earth days, and the surface temperature of this exoplanet is suitable for the possibility of finding water in liquid form. By itself, this stone world is slightly larger than the Earth and, like the star, has become the closest to us of all such space objects. In addition, it is not just the closest exoplanet to Earth, it is also the closest world suitable for the existence of life.

Proxima Centauri is a red dwarf, and it is located at a distance of 4.25 light years from us. The star got its name for a reason - this is another confirmation of its proximity to the Earth, since proxima is translated from Latin as “nearest”. This star is located in the constellation Centaurus, and its luminosity is so faint that it is completely impossible to see with the naked eye, and besides, it is quite close to the much brighter pair of stars α Centauri AB.

During the first half of 2016, Proxima Centauri was regularly observed using the HARPS spectrograph installed on the 3.6-meter telescope in Chile, as well as simultaneously by other telescopes from around the world. The star was studied as part of the Pale Red Dot campaign (a pale red dot or red speck), during which scientists from the University of London studied the oscillations of a star caused by the presence of an unidentified exoplanet in its orbit. The name of this program is a direct reference to the famous image of the Earth from the far reaches of the solar system. Then Carl Sagan called this picture (blue speck). Since Proxima Centauri is a red dwarf, the name of the program has been adjusted.

Since this topic of exoplanet search has caused a wide public interest, the progress of scientists in this work from mid-January to April 2016 was constantly publicly published on the program's own website and through social media. These reports were accompanied by numerous articles written by experts from all over the world.

“We received the first hints of the possibility of the existence of an exoplanet here, but our data then turned out to be inconclusive. Since then we have been working hard to improve our observations with the help of the European Observatory and other organizations. For example, the planning of this campaign took approximately two years,” Guillem Anglada-Escude, head of the research team.

Data from the Pale Red Dot campaign, combined with earlier observations from ESO's observatories and others, showed a clear signal of the exoplanet's presence. It has been very accurately established that from time to time Proxima Centauri approaches the Earth at a speed of 5 kilometers per hour, which is equal to the usual human speed, and then moves away at the same speed. This regular cycle of changing radial velocities repeats with a period of 11.2 days. Careful analysis of the resulting Doppler shifts indicated the presence of a planet here with a mass of at least 1.3 times more mass Earth is at a distance of 7 million kilometers from Proxima Centauri, which is only 5 percent of the distance from Earth to the Sun. In general, such a detection has become technically possible only in the last 10 years. But, in fact, even signals with smaller amplitudes have been detected earlier. However, the stars are not smooth gas balls, while Proxima Centauri is a very active star. Therefore, the exact detection of Proxima Centauri b became possible only after obtaining detailed description how a star changes on time scales from minutes to decades, and monitoring its luminosity with light-measuring telescopes.

“We continued to check the data so that the received signal did not contradict what we found. This was done every day for another 60 days. After the first ten days, we had confidence, after 20 days we realized that our signal was in line with expectations, and after 30 days all the data categorically stated the discovery of the exoplanet Proxima Centauri b, so we began to prepare articles on this event.

Red dwarfs, such as Proxima Centauri, are active stars and have many tricks in their arsenal to be able to mimic the presence of an exoplanet in their orbits. To eliminate this error, the researchers monitored the change in the brightness of the star using the ASH2 telescope at the San Pedro de Atacami Observatory in Chile and the Las Cumbres Observatory telescope network. Information about radial velocities as the star's luminosity increased was excluded from the final analysis.

Despite the fact that Proxima Centauri b rotates much closer to its star than Mercury orbits the Sun, Proxima Centauri itself is much weaker than our star. As a result, the discovered exoplanet is located exactly in the region around the star, suitable for the existence of life as we know it, and the estimated temperature of its surface allows the presence of water in liquid form. Despite such a moderate orbit, the conditions of existence on its surface can be very strongly influenced by ultraviolet radiation and X-ray flares from the star, which are much more intense than the effects that the Sun has on Earth.

The actual possibility of this kind of planet supporting liquid water and having life like Earth is a matter of intense but mostly theoretical debate. The main arguments that speak against the presence of life are related to the proximity of Proxima Centauri. For example, on Proxima Centauri b, such conditions can be created under which it always faces the star on one side, which is why there is eternal night on one half and eternal day on the other. The planet's atmosphere could also slowly evaporate or have more complex chemistry than Earth's due to strong ultraviolet and X-ray radiation, especially during the star's first billion years of life. However, so far, no argument has been definitively proven, and it is unlikely that they will be eliminated without direct observational evidence and obtaining exact specifications the atmosphere of the planet.

Two separate papers were devoted to the habitability of Proxima Centauri b and its climate. It has been established that today the existence of liquid water on the planet cannot be ruled out, and in this case it can be present on the surface of the planet only in the sunniest regions, either in the region of the hemisphere of the planet, always facing the star (synchronous rotation), or in tropical zone(3:2 resonant rotation). The rapid movement of Proxima Centauri b around the star, the strong radiation of Proxima Centauri and the history of the formation of the planet made the climate on it completely different from that on Earth, and it is unlikely that Proxima Centauri b has seasons at all.

One way or another, this discovery will be the beginning of large-scale further observations, both with current instruments and with the next generation of giant telescopes, such as the European Extremely Large Telescope (E-ELT). In the coming years, Proxima Centauri b will become a prime target for the search for life elsewhere in the universe. This is quite symbolic, since the Alpha Centauri system is also chosen as the target of humanity's first attempt to move to another star system. The Breakthrough Starshot project is a research and engineering project within the Breakthrough Initiatives program to develop a concept for a fleet of light sail spacecraft called the StarChip. This type of spacecraft would be able to travel to the Alpha Centauri star system, 4.37 light-years from Earth, at between 20 and 15 percent of the speed of light, which would take 20 to 30 years, respectively, and about 4 more years to notify the Earth of a successful arrival.

In conclusion, I would like to note that many accurate methods for searching for exoplanets are based on the analysis of its passage through the disk of a star and starlight through its atmosphere. There is currently no evidence that Proxima Centauri b passes through the disk of its parent star, and the chances of seeing this event are currently negligible. However, scientists hope that in the future the efficiency of observational instruments will increase.

Perhaps we have found a second Earth?

A planet possibly suitable for life has been discovered near the star closest to the Sun; imagination already draws on it dense atmosphere and oceans.

Found planet, named Proxima b, has an almost circular orbit, it is separated from the star by about 7.6 million kilometers (0.05 astronomical units, that is, the average distance of the Earth from the Sun). A year in this world lasts only 11 days, the mass of the planet is 1.3 times that of the earth, and average temperature surface is close to zero degrees Celsius - it is only ten degrees lower than that of the Earth, and several tens of degrees higher than that of Mars.

By space standards, Proxima Centauri is very close - only 4.24 light years.

The parent star Proxima Centauri itself, which is characterized by strong ultraviolet and X-ray flares, can prevent the appearance of this paradise. This is described in a study published in the journal Nature.

Computer modeling has long suggested to astronomers that our neighbor has at least one planet, and in general, exoplanets are found around red dwarfs.

Opening Proxima b was accomplished by observing the Doppler shift in the spectrum of a star due to the gravitational influence of the planet. The work was carried out on two scientific instruments of the European Southern Observatory - HARPS (High Accuracy Radial velocity Planet Searcher) and UVES (Ultraviolet and Visual Echelle Spectrograph).

Despite the seemingly catastrophic proximity to the luminary, this world can be very good in terms of life support, because the stars are cold.

The surface temperature of Proxima Centauri is more than twice (almost three thousand kelvins), the mass is ten times, and the luminosity is four orders of magnitude less than that of the Sun.

And in order for the water on the surface of the planet not to freeze, it must be closer to its star much more than the Earth is to the Sun.

In the solar system, Venus, Earth and Mars are located in a similar zone, and the distance interval for the Proxima Centauri system is from 0.04 to 0.08 astronomical units. It would seem that everything speaks in favor of the emergence of life, but there is one unpleasant moment that can cross out all the advantages.

A distinctive feature of red dwarfs is their high activity. Flares in the X-ray range, periodically occurring on Proxima Centauri, are stronger than the most intense flare on the Sun by about 400 times. How such radiation will affect the emergence and maintenance of life is unknown. Maybe such a superflare could spawn a chain chemical reactions with the formation of molecules of organic substances, but, on the other hand, it is able to “rip off” the atmosphere from the planet. Possess planet Proxima b, like the Earth, by its own magnetic field, the destructive effect of radiation would be reduced, but its presence could not be detected remotely.

As a result of the most powerful flares on the Sun, up to a trillion megatons of TNT is released into the surrounding space in a few minutes. This is about a fifth of the energy radiated by the Sun in one second, and all the energy that a person will develop in a million years (assuming it is produced at modern rates). Superflares usually occur over big stars ax spectral classes F8-G8 - massive analogues of the Sun (belonging to class G2). These luminaries usually do not rotate rapidly around their axis and may be part of a close binary system. The power of superflares exceeds typical solar flares by tens of thousands of times, however, scientists do not exclude the possibility of such a cataclysm on the Sun.

Besides, planet Proxima b due to its proximity to the star, it is always turned to one side to it, that is, it is in a state of tidal capture, like the Moon in relation to the Earth. This means that one half of the planet is constantly hot, while the other is always cold. Simulations have shown that this will not be an insurmountable obstacle to the existence of life, provided there is a dense atmosphere. Constant convective flows will ensure heat exchange between the halves of the planet and a comfortable temperature can be established in the "border zone".

Most likely, such big planet was formed in remote areas of the system and, over time, moved to its current position. Looking at solar system it can be argued that this celestial body contains a large number of water.

Proxima Centauri is probably part of a triple star system, which also includes the double star Alpha Centauri, the stars in it are separated by only 23 astronomical units. The period of revolution of a red dwarf around two sun-like stars is more than 500 thousand years.

Flight to Alpha Centauri

Astrophysicist Philip Lubin University of California in Santa Barbara) it was proposed to send a group of small automatic stations with . A system of lasers in Earth's orbit will accelerate them to near-light speed. A similar idea was proposed by Russian businessman Yuri Milner and British theoretical physicist Stephen Hawking.

The plans of both missions include only a flight through the system, because it will be impossible to slow down.

Difficulties in the implementation of the project are related to its technical component and price. To implement the Lyubin project, it will be necessary to deploy a constellation in Earth orbit that is a hundred times larger in mass than the ISS. It will take the miniature probe 15 years to reach Alpha Centauri and send back some photos, but the price of the issue is tens of trillions of dollars.

Modern space ship it could be done much cheaper, but it would take 70,000 years.

Lubin's idea was supported by Congressman John Culberson, who urged NASA to begin work on an automatic mission to Alpha Centauri as early as 2017. The station, according to the plans of the Republican, should start in 2069 - the centenary of the landing of astronauts on the moon. The Milner-Hawking team also did not stand aside. At the Proxima b launch event, it was announced that Russian businessman planned to send probes to the mother star and the planet as early as 2030. The devices should reach the goal in 20 years. The first images of the nearest exoplanetary system on Earth will be seen in 2055.

The ideas of scientists and politicians were perceived with skepticism by most of their colleagues, and the remote study of Proxima b remains in the foreground. Problems when observing from Earth and from near space may arise due to the low luminosity and modest size of Proxima Centauri.

The closeness of the open world to the Sun makes it a prime target for future research. In addition, it is likely that there is a super-Earth in the orbit of Proxima Centauri, located outside the zone suitable for life. The period of its revolution around the star is from 100 to 400 days.

An Earth-like planet orbiting our closest star, Proxima Centauri. The planet is called Proxima b (the name of exoplanets is made up of the name of their star and a unique letter number), its size is approximately the size of the Earth, and the orbit suggests that the planet has liquid water. Many scientists have been excited about the prospect of a potentially habitable planet not too far from our own, and even hatched plans to send a research probe there. However, a closer look showed that astronomers' forecasts may be overly optimistic, and Proxima b is not suitable for colonization.

The habitable zone of any star can be briefly described as a region in which temperature and other climatic conditions allow water to exist in a liquid state. If the planet is too close to the star, like Venus, then it overheats. If it is too far, it will freeze, as happened with Mars. Proxima b is located right in the middle of the habitable zone of its star, and therefore has become a prime candidate for potential life or conditions suitable for humans.

But liquid water, of course, is far from the only ingredient necessary for life, and therefore the “habitability” of the zone may be in question. A team of NASA scientists closely examined similar planets orbiting small red dwarf stars and found that intense stellar flares and coronal mass ejections can reduce, if not eliminate, the habitable zone.

For a long time, astronomers believed that such solar activity was the exclusive prerogative of large stars, but Proxima Centauri made it clear a few months ago that hot plasma ejections were not uncommon. Since the star itself is much smaller than the Sun, the habitable zone on it is even closer, and therefore plasma emissions are a direct threat to any life on the planet. If Proxima b does not have a strong magnetic field, then intense solar flares and plasma storms will destroy much of the atmosphere. This means that hydrogen, oxygen and nitrogen will simply escape into space, which will make the conservation of water and the presence of protein life on it almost impossible.

It is important to note that the strength of solar storms depends on the age of the star. Stars are especially aggressive when young, but with age they settle down and throw out plasma much less often. If the planet formed late in the life of a star, then it is likely to be relatively safe. However, if it arose when the star was still young, then the atmosphere, if it was, probably had long since dissipated.

For humanity, this is not the most joyful news. As you know, Proxima Centauri is still young, which means that the planets closest to it are constantly bombarded by solar matter and radiation. NASA scientists have come to the conclusion that if Proxima b has an atmosphere left, it will disappear rather quickly, and therefore it is unlikely that the planet will be able to support proteinaceous life.

The new planet orbits the star Proxima Centauri, which is four light years away. “This is not only the closest terrestrial planet to us, it is probably the closest planet to us outside the solar system, since there are simply no stars closer to Proxima Centauri,” the magazine said at a press conference. Nature one of the study participants Ansgar Reiners from the University of Göttingen in Germany.

Astronomers found hints of the planet's existence in data from the European Southern Observatory as early as 2000, but it took them more than 15 years to confirm their discovery. The planet was discovered by the Doppler method: turning around the star, the planet pulls it towards itself, because of this, the star all the time moves a little towards the Earth, then moves away from it. As a result, the emission spectrum of the star, which is caught by telescopes on Earth, changes.

temperature on the planet

The star Proxima Centauri is a red dwarf, it is smaller than the Sun - its mass is only 12% of the Sun's - and much dimmer - only 0.15% of the Sun's brightness. The mass of the planet Proxima b is 1.3 Earth. Researchers believe that this is a terrestrial planet. It is much closer to its star than the Earth is to the Sun. The distance between them is 7.5 million kilometers, which is 20 times less than from the Earth to the Sun. Proxima b makes a revolution around the star in 11.2 days.

Alpha Centauri AB and Proxima Centauri. Photo: Digitized Sky Survey 2 Acknowledgment: Davide De Martin/Mahdi Zamani

“From this information, we can calculate the surface temperature of the planet, if you do not take into account the atmosphere - minus 40 degrees Celsius. Without the atmosphere, the temperature of the Earth would be similar - minus 20 degrees," Reiners explained.

Water, life, atmosphere

There may be liquid water on Proxima b, however, whether it actually exists there is not exactly known and depends on the history of the formation of the planet and the activity of its star. The age of both is comparable with the age of the Sun and the Earth, respectively. However, discussions about their history are still an area of ​​​​pure speculation.

Perhaps there was water and an atmosphere at first, and then they were gone, because the atmosphere was blown away by the stellar wind of Proxima Centauri. However, we do not know how active the star was in the past. Perhaps the planet was protected from the stellar wind by a magnetic field, just as the Earth's magnetic field protects our planet from the solar wind, but we do not know if Proxima b has it. Maybe the planet first lost water and atmosphere, and then, like the Earth, it survived "" by comets, which again brought water to it. In general, there are many scenarios, and what actually happened and is happening on the planet will become clear in the process of further research.

However, if the atmosphere and water are found, this does not mean that the conditions on the planet are so comfortable. “Proxima b receives more X-ray and ultraviolet radiation than the Earth. If we on Earth received such a dose, it would affect life, although I am not sure that living organisms would have died out completely, ”said Reiners.

Planet exploration

Earth-like planets outside the solar system have been found more than once. However, "this planetary system is much closer to us than any other, and this makes it much easier to study it in detail," said Reiners.

It is possible to determine whether a planet has an atmosphere if it is at some point in its orbit between its star and the Earth. Then the atmosphere can be seen thanks to the backlight. But whether there is such a position in the orbit of Proxima b, we do not yet know, and the chances of this are not very high. Another possibility is to catch

Since the beginning of the space age, people have been using chemical rockets to get into space. Although this method is certainly effective, it is very expensive and requires a lot of resources. Scientists became interested in the question - can hypothetical aliens leave their planets using similar technologies?

Two studies

Harvard professor Abraham Loeb and astronomer Michael Gippke, an independent researcher associated with the Sonneberg Observatory, attempted to analyze this question in two recently published papers. Professor Loeb looked at the problems extraterrestrial beings might face when launching rockets from Proxima b. Gippke's research is devoted to a similar question - can aliens living on a super-Earth get into.
In his study, Loeb argues that we humans are lucky to live on a planet that is well suited for space launches. In order for the rocket to leave the surface of the Earth and begin to orbit the Sun as its satellite, it needs to reach a speed of 11.186 km / s. The speed required to leave Earth's orbit and leave the solar system is about 42 km/s relative to the Sun.

Professor Loeb says:

“Acceleration of a rocket to space speeds requires a huge mass of fuel, which grows exponentially. By a happy coincidence, the rate of escape from the Earth's orbit around the Sun is at the speed limit achievable by chemical rockets. However, the habitable zone around fainter stars is closer to them, making it harder for chemical rockets to escape gravitational pincers. his star."

As Loeb points out in his essay, the escape velocity is calculated as Square root stellar mass divided by the distance from the star. This means that the rate of escape from the habitable zone is directly proportional to the stellar mass and inversely proportional to the distance from the star.

This infographic compares the planet's orbit around Proxima Centauri (Proxima b) with the same region of the solar system.

Proximity to a star is not good for planets that orbit M-type stars (red dwarfs). These stars are the most common type of stars in the Universe, accounting for about 75% of such objects in the Galaxy. Milky Way. In addition, recent studies have found many rocky planets orbiting red dwarf stars, and some scientists believe that such planets are the most promising places to look for potentially habitable worlds.

Is it possible to fly from Proxima b?

Using the closest star to our own world (Proxima Centauri) as an example, Loeb explains that it would be much more difficult for a chemical-fueled rocket to reach takeoff speed from a planet located in its habitable zone.
"The closest star to the Sun, Proxima Centauri, is an example of a faint star with only 12% of the mass of the Sun," he said. “A couple of years ago, this star was discovered to have a planet the size of , named Proxima b. It lies in the habitable zone, which is 20 times closer to the star than the Earth is from the Sun. At this point, the departure velocity is 50% greater than in the Earth's orbit around the Sun. Civilizations on Proxima b will have a hard time leaving their world with chemical rockets."

What did Hippke research?

Gippke's research begins by arguing that the Earth may not actually be the most common type of planet in our universe. For example, planets that are more massive than the Earth will have a higher surface gravity, which means they will be able to hold on to a denser atmosphere that will protect it from harmful cosmic rays and solar radiation.

Also, a planet with higher gravity would have a flatter topography, resulting in archipelagos instead of continents and shallower oceans - an ideal situation if we are talking on the development of biodiversity. However, when it comes to launching rockets, the increased surface gravity will mean the need to gain higher airspeed. As Gippke pointed out in his study:

“Rocket motion obeys the Tsiolkovsky equation (1903): if the rocket carries fuel, the ratio total weight rocket to terminal velocity is an exponential function, making high speeds(or heavy loads) more expensive.”

For his calculations, Gippke uses Kepler-20 b, the "Super-Earth" located 950 light-years away. This planet has a size 1.6 times the size of the Earth and it is 9.7 times the mass of our planet. While a body's exit velocity around the Earth is approximately 11 km/s, a rocket attempting to leave super-Earth like Kepler-20 b would have to achieve a departure velocity of ~27.1 km/s. As a result, a single-stage rocket on Kepler-20 b would have to burn 104 times more fuel than a rocket on Earth in order to reach orbit.

To put all this more clearly, Gippke looks at specific payloads launched from Earth. “In order to bring out a payload of 6.2 tons, as is required in the case of the space telescope. James Webb from the planet Kepler-20 b, the fuel mass will increase to 55,000 tons, which is equal to the mass of the largest ocean battleships, ”he writes. "For a classic Apollo to the Moon (45 tons), the rocket would have to be significantly larger, ~400,000 tons."

Gippke's analysis allows us to conclude that chemical rockets will still provide the speeds necessary for departure from the planet on super-Earths with up to 10 Earth masses. However, the amount of fuel required for this fuel makes this method impractical. As Gippke noted, this can seriously affect the development of an alien civilization.

"I'm amazed at how lucky we humans are to be on a planet that's comfortable enough for spaceflight," he said. “Other civilizations, if they exist, may not be so lucky. On more massive planets, space flight will be more expensive, and its possibility will decrease exponentially depending on the mass of the planet. Such civilizations will not have satellite television, a mission to the Moon, or space telescope Hubble.

Both of these articles provide some clear conclusions that relate to the search for extraterrestrial intelligence (). First, this means that civilizations on planets that orbit red dwarfs or super-Earths are less likely to master space which makes them difficult to detect. The results of the study also indicate that humanity may be one of the few civilizations that has been given the opportunity to explore space through.