Researchers have discovered a planet outside the solar system, on which, in general, various forms of life are possible. They reported this in the Astrophysical Journal.
Scientists at the Hawaiian Observatory have observed the red dwarf star for 11 years. The star was named Gliese 581. Astronomers studied the oscillations of the star due to the influence of the planets revolving around it.
During the observation, they discovered 6 more planets orbiting the star.
Conditions are favorable
Conditions on one of these planets are theoretically favorable for the existence of living organisms. Planet Gliese 581g - as scientists called the find - has a gravitational field slightly stronger than the field of the Earth. Its distance from the star is 0.146 astronomical units and at the same time it makes one revolution around its sun in 36.6 days.
The planet under study is all the time turned to the star by the same part. On the illuminated side, the temperature is constant at about 160 degrees Celsius. At the same time, the temperature on the darkened part of the planet is approximately - 25 degrees Celsius.
Scientists believe that on the territory of the planet, located between the illuminated and darkened parts, climatic conditions may well be suitable for the existence of liquid water. This is a prerequisite for the existence of life, like the one that exists on Earth.
Now scientists believe that in addition to Gliese 581g, other planets may be located in the Gliese 581 system. On such planets, in principle, the existence of living organisms is likely.
Scientists continue to conduct their research and consider ways in which they can confirm or deny the theory of the existence of life in this system.
Star Gliese 710 is now 64 light-years from Earth, but in a million years it will pass extremely close to the Sun directly through the Oort cloud, which contains many large comets and ice-rich asteroids. Their orbits will be severely disturbed and a significant part should eventually collide with the Earth. Corresponding published in the journal Astronomy & Astrophysics.
Gliese 710 is an orange dwarf of spectral type K7. In terms of mass, it is twice as light as the Sun, and in terms of luminosity it is 30 times inferior to it. When observing this object, astronomers have long noticed that it has a very small proper motion - the position of a star in the sky changes very little, while there are signs that it is approaching the Earth.
Russian astronomers in 1996 found that as a result of such a convergence, the Sun and Gliese 710 will become the closest stars to each other - they will converge to 260,000 astronomical units or four light years. This is approximately equal to the distance to the planetary system closest to us - Proxima Centauri. The same group of scientists suggested that the orbits of part of the comets of the Oort cloud (up to 1.5-2.0 light years from Earth) may be disturbed by this approach, as a result of which comets may even fall on our planet.
However, over the past 20 years, great changes have taken place in astronomical technology outside our country - powerful space-based telescopes have appeared (in Russia, these are used exclusively for military purposes - for observing the Earth). Using the data of the newest among them European "Gaia", Polish astronomers analyzed the parameters of the motion of Gliese 710 in the direction of the solar system and significantly improved them. As it turned out, in 1.35 million years it will pass 6,250 astronomical units from our star (with a 90 percent probability). This is less than 0.1 light years and significantly less than all previous estimates gave. For comparison, it can be indicated that the average distance of the ninth planet from the Sun is only 10 times less than that of Gliese 710. Therefore, in the earth's sky it will be brighter than any other star, and only slightly inferior to Venus.
More importantly, from this figure it follows that the star will definitely "hit" with its gravity on the stability of the Oort cloud and much stronger than previously thought. In general, encounters with other stars are common in the solar system, and occur every 100,000 years. However, it all depends on the distance. A star at 4.00 and 0.1 light years away from the object acts on it with a force 1,600 times different. Accordingly, this passage will affect the bodies of the solar system incomparably stronger than the vast majority of other approaches.
For a million years after the "approach" of Gliese 710, comets from the cloud can strike the Earth. It is believed that 55 million years ago there was one cometary hit of this kind. The Oort cloud should also contain large ice-rich asteroids. Therefore, blows can bring more serious consequences -.
Scientists have recorded a signal from the planet Gliese 581d and have already managed to declare that the conditions on it are suitable for the origin and maintenance of life. At the moment it is known that the celestial body is 2 times larger than the Earth. The signals were recorded for a very long time, but only in 2014 was it possible to notice that they are repeated, they are cyclical. Not a single phenomenon in the Universe is capable of this, unless, of course, it is created artificially.
The signals indicate the presence of an extraterrestrial civilization on the planet, trying to transmit a message to neighboring systems and galaxies. But it has not yet been possible to decipher the "letter".
About the planet
Gliese 581d is an exoplanet in the system of the same name (Gliese 581). At the moment, its existence is not precisely determined, but everything indicates that it does exist. The planet is located in the constellation Libra, and quite close to our solar system. It is only 20 light years away.
If you believe the information received in September 2010, the considered planet in its system is in fifth place from the star (Earth - in third, after Venus and Mercury). Many scientists call it "Super-Earth" because it is 2 times larger. And its mass is 6-8 times more.
The first message that a potentially habitable exoplanet was discovered was received from Switzerland on April 24, 2007. Together with Gliese 581d, Gliese 581c was recorded. The discovery belongs to several astrologers, whose actions were supervised by Stephen Udry.
Scientists are still arguing about the reality of the planet, but skeptics have always met in matters of space exploration.
Discovery process
According to British experts, their team of astronomers caught a message from the planet Gliese 581d. When the information is confirmed, disputes and discussions about the existence of a celestial body will be finally stopped. Now there are many opinions on this matter, starting with the reality of the planet and ending with physical anomalies, which are captured by earthly technologies.
At first, there was only one way to detect celestial bodies. They are viewed through powerful telescopes when they pass in front of their star. This technology was used by American scientists in 2014.
But their British colleagues expressed doubts about the relevance of the method. Only gas giants like our Jupiter can be found with it. They themselves used more modern technologies that confirmed the location and reality of the planet.
It is currently known that Gliese 581d is supposedly a potentially habitable planet located in the system of the eponymous red dwarf. It is 20 light years away.
Signal characteristic
When scientists first recorded a signal from the planet Gliese 581d, they did not attach much importance to it. Then the existence of her herself was under a big question, about this there were numerous discussions. Some astronomers still consider the signals to be a simple manifestation of stellar activity, but increased, because otherwise they would not have been able to reach the solar system.
In 2014, American scientists repeatedly tested the characteristics of the received signal. They did not find any evidence that it was being fed artificially. Astronomers speculate that it is a consequence of light and magnetic radiation propagated by the red dwarf. When they cross, they gather, creating a special cosmic noise that could not be detected before.
On March 7 this year, it became known that the signal from the potentially habitable planet Gliese 581d is not a consequence of cosmic noise. It repeats every few months and has a similar cycle.
Skeptical debate
After the report on the discovery of the planet was received, the data was rechecked using HARPS. But the Swiss scientists' discovery was not confirmed. Russian astronomers also made attempts to find a celestial body using their technologies until 2012. Then the scientist Roman Baluev expressed doubts about its reality.
In 2014, astronomers at the University of Pennsylvania attempted to confirm the existence of Gliese 581d. Calculations were carried out that refuted the information of Stefan Oudry. According to them, the recorded phenomena are only a consequence of stellar activity.
In early spring 2015, the denial of the data on Gliese 581d was questioned. British scientists have investigated the methods for detecting planets by American astronomers. They said that these methods are far from perfect and do not meet modern requirements.
Thus, if the planet Gliese 581d itself is directly questioned, the signal from it does not exist either. At least today there is no clear evidence of its reality.
As for the signal, skeptics point to light and magnetic emissions. When they are intertwined, they can make characteristic sounds that a person has mistaken for an extraterrestrial message. Its cyclical nature is actually absent. The signal changes, but very slowly, like everything that happens in the Universe (relative to people's lives).
Hypotheses and simulations
Despite disagreements with astronomers from many countries, British scientists believe in the existence of the planet Gliese 581d. Moreover, they insist that the signals supplied are some kind of algorithm of encrypted symbols. Those collectively are a message to neighboring systems and galaxies.
Astronomers from Britain are confident that if they use not only high-tech equipment, but also modern research methods, it will be possible to separate the signal from the interference. After that, you can try to decipher it. Perhaps a civilization from the Gliese system is also trying to find its brothers in reason.
Thanks to numerous computer simulations, it was possible to establish that there are water oceans on the planet in question. The presence of the atmosphere and clouds with precipitation in the corresponding zone is also noted. And as previously reported, for life to arise, water is needed. Consequently, Gliese is suitable in all respects for living. It is located in a favorable zone relative to its luminary, has water, and clouds with precipitation indicate its circulation.
Signal data
No one can say for sure when the signal was first sent from the planet Gliese 581d. Initially, he was not taken seriously, since then the celestial body itself was not discovered. Later, after the first conversations about it, more attention was paid to the reality of the planet, rather than the message.
Until the spring of 2015, the signal was assumed to be ordinary cosmic noise. Such sound waves have already been captured by terrestrial equipment, and more than once.
Astronomers now claim that the signal repeats at small intervals. It is full of noise, but attempts are underway to clear the message. Ultimately, scientists plan to decode signals from a potentially habitable planet.
Communication with alien civilizations
If it happens that Gliese 581d really turns out to be a real planet with its own population, then humanity needs to be more careful in trying to start a dialogue with it. The scientist has repeatedly urged people to beware of communicating with alien civilizations.
He reasons his statement by the fact that the resources of any celestial body that has something similar to the globe are limited. They can stop. And then the inhabitants will have no choice but to look for a similar planet in order to use it as a source of resources.
Conclusion
Despite the abundance of debate and skepticism around the planet Gliese 581d, many scientists, as well as all people on Earth, would very much like it to be habitable. Then humanity will have the opportunity to exchange experience and knowledge, breakthroughs in technology, medicine, programming.
After all, all people would like to go on a journey beyond the solar system. And the planet Gliese 581d is great for the destination. It remains only to arrange a visit with her population. Perhaps this can be done if scientists still decipher the received signal.
In 1.35 million years, a star will fly near the Sun, sending many comets to the Earth and other planets. These conclusions were reached by Polish scientists, using updated data on the trajectory of this star.
A star half the size of the Sun rushes towards the Solar System at a speed of 51 thousand km / h. When it gets closer to the Sun, cometary rain will fall on the planets, which will last for millions of years. However, it is too early to build shelters - it is expected to appear in about 1.35 million years.
As scientists from the Polish Adam Mickiewicz University in Poznan write in the journal Astronomy & Astrophysics, the star Gliese 710 is now 64 light years from the solar system. One light year is 9,461,000,000,000 km.
According to their forecasts, the star will pass the Earth in only 77 light days (for comparison, the closest star to the Earth apart from the Sun, Proxima Centauri, is at a distance of 4.22 light years). According to earlier estimates, it should have traveled nearly one light-year, that is, five times further.
Gliese 710 will not collide with the Earth, but will pass through the Oort cloud - a region around the solar system consisting of trillions of comet nuclei larger than 1.3 km and which is the source of long-period (with a period of more than 200 years around the Sun) comets. Its outer boundaries are located at a distance of one light-year from the Sun. It is assumed that the gravitational field of Gliese 710 may cause disturbances in the cloud.
This will lead to the fact that objects in it in large numbers will fall into the solar system and with a high probability will crash into the Earth. "The star Gliese 710 will provoke a cometary rain of about 10 comets annually for 3-4 million years," the study authors note.
Polish astronomers used data from the European Space Agency's Gaia space telescope. It was launched into orbit in 2013 to help scientists compile a detailed map of the distribution of stars in our galaxy, the Milky Way. It is assumed that with its help a three-dimensional map will be compiled, indicating the coordinates, direction of movement and spectral type of about a billion stars, and about 10 thousand exoplanets will be discovered. According to experts, the new data is 10 times more accurate than the previous ones.
Gliese 710 was considered the most likely candidate for rendezvous with the solar system for decades, but until the data collected by Gaia, astronomers could not determine exactly how far it would travel. Some scientists suggest that it was the passage of the star through the Oort belt 65 million years ago that caused the asteroid to fall to Earth, which caused the death of the dinosaurs.
However, the emergence of the Gliese 710 could cause more significant damage.
As the Gliese 710 comes close to Earth, it will become the brightest and fastest-moving observable object in the sky. As the authors of the study note, this will be "the strongest destructive collision in the future and in the entire history of the solar system."
According to Gaia, the Gliese 710 flyby will be the closest flyby of a star past the solar system in the next few billion years.
Flor van Leeuwen, an astronomer from Cambridge, called the work "a high-profile study refining the results obtained during the HIPPARCOS (High Precision Parallax Collecting Satellite) space telescope mission." HIPPARCOS was launched back in 1989 with the aim of measuring coordinates, distances and proper motions of luminaries. For 37 months of work, he collected data on more than a million stars.
Leuven notes that the combination of data from HIPPARCOS and Gaia allows astronomers to determine the motions of many nearby stars with very high accuracy.
As Gazeta.Ru previously wrote, the Russian astronomer Vadim Bobylev came to the conclusion that Gliese 710 was approaching in 2010. He used data from the HIPPARCOS telescope and found nine stars that will approach the Sun in the next couple of million years. The Gliese 710 will come up especially close. According to Bobylev's calculations, it should have passed two light years from the Sun and had an impact on the objects of the Kuiper belt - the belt of small bodies of the solar system located outside the orbit of Neptune. The gravitational impact of Gliese 710 could cause changes in the orbits of objects and increase the number of comets that will travel towards the Sun and giant planets.
Falling on them in large numbers, comets would spawn a swarm of meteor showers and create new meteoroid bodies.
In addition, according to NASA astronomer Paul Weissman, the star is capable of changing the orbit of Neptune. Weissman had previously studied the possibility of the Gliese 710 and the Sun approaching each other and concluded that it could be quite close. “It's nice to see that this assumption has been confirmed using the best models and the best data,” he said of Bobylev's study.
Gliese 710 is not the only star to be wary of, the aforementioned Leuven said. There are also many red dwarfs, the exact paths of which are still unknown. Over time, Gaia will investigate them and make measurements as accurate as the Gliese 710, or even better. "It is likely that among these stellar dwarfs there are those that threaten the solar system with a collision," says Leeuwen. "We just haven't found them and measured them yet."
It is hoped that life exists on the third exoplanet in the star system Gliese 581 (Gleise 581). Of course, it is easy to foresee the objection: there is hope for a closer life - for example, on Mars. But this hope and this one have completely different grounds. About Mars - a separate conversation. There is exactly one reason that there is life on Gliese 581 s: water, if it is there, can be in liquid form. As it turned out this spring, the planet Gliese 581c makes one revolution in orbit in 13 days, and the distance from it to the parent star is about 14 times less than the distance from the Earth to the Sun. But since Gliese 581 is a red dwarf, that is, a relatively cool star, the average temperature on the planet's surface should be low - from 0 ° to 40 ° C, or, as they say in astronomy, the planet is in the Habitable zone of the star ...
Distant life
With all the abundance of our knowledge about life, in some ways they are radically limited. For example, we do not know what other forms of life are possible, with the exception of the only one known to us - earthly life. But terrestrial life is possible only under terrestrial conditions and is very sensitive to fluctuations in temperature, pressure, and the level of solar radiation. In the solar system, another planet with such or even similar conditions is impossible even theoretically. We need planets somewhere “in other worlds”.
“Red dwarfs like Gliese are ideal for finding such planets: they emit less light, and their zone of life is closer to them than to the Sun,” says young French astrophysicist Xavier Bonfils. currently working at the Center for Astronomical and Astrophysical Research of the University of Lisbon (Centro de Astronomia e Astrofisica
da Universidade de Lisboa). Planets in this zone can be easily detected using the radial-velocity method, the most successful method for detecting exoplanets to date.
The discovery of Gliese 581c was made with the help of the 3, 6-meter telescope of the La Silla Observatory (La Silla) of the European Organization for Astronomical Research in the Southern Hemisphere (ESO) and installed on it the world's most accurate spectrograph HARPS. HARPS is capable of capturing speed changes with an accuracy of one meter per second (or 3.6 km / h) and is by far the most successful tool for detecting exoplanets, especially those with low mass.
There is one more indirect indication of the possibility of the existence of life on Gliese 581c. It was discovered by members of the MOST project launched four years ago. Due to the unusual nature of this project, it is worth talking about it separately before talking about its results.
The MOST satellite (short for Microvariability & Oscillations of STars - which means "microvariability and oscillation of stars") was launched into orbit from the Russian Plisetsk cosmodrome in 2005 and became the only Canadian space observatory. The satellite itself was created jointly by the Canadian Space Agency, aerospace equipment manufacturer Dynacon Enterprises Limited, and two universities - Toronto and British Columbia in Vancouver. However, not only scientists have access to the telescope installed on the satellite, but also the most ordinary Canadians - student astronomers or simply amateur astronomers.
During one and a half months of their continuous observations of the star, its parameters practically did not change. Thus, this red dwarf is a stable source of light and heat for the planet's surface, whose climate, therefore, is little subject to strong changes that would be detrimental to the formation and development of life.
"Among other things, this means that the star is old and 'calm", - quotes the words of professor of physics and astronomy at the University of British Columbia Jamie Matthews (Jaymie Matthews) university press release. - The planets around it are several billion years old. We know that life on Earth developed over 3.5 billion years before man appeared, so we can hope for the possibility of complex life on any of the planets around Gliese 581, if it is even that old. "
We can assume that the discovery of the planet Gliese 581 s again transfers the question of the existence of life outside the Earth from speculation to the plane of concrete scientific practice. One of the world's leading experts on exoplanets, the Swiss astrophysicist Michel Mayor - by the way, more recently the scientific mentor of the now famous Xavier Bonfis - sets himself a more ambitious goal: to find not indirect signs, but direct evidence of extraterrestrial life. He believes that advanced researchers are less than two decades from detecting signs of life on other planets - provided that there is such a thing, of course.
Revived hopes
The question of whether there are life forms on other planets similar to earthly ones has long worried the minds of people, regardless of their faith. Inspired by humanistic freethinking, thinkers of the Renaissance, and then of the European Enlightenment, were convinced that the heavens are full of life. Galileo Galilei's first book, The Star Messenger, was instantly sold out precisely because his contemporaries hoped: with the help of a telescope, Galileo saw the inhabitants of the moon. Burned in the last year of the 16th century, Giordano Bruno (1548-1600) argued that life is on all heavenly bodies. Almost our contemporary, the Russian cosmist philosopher Vladimir Ivanovich Vernadsky (1863-1945) believed that life is a fundamental property of matter, and until his very old age he tried to find its signs in the deepest geological layers. However, alas. The end of the twentieth century brought deep disappointment. Life was increasingly presented to scientists as a unique phenomenon and, apparently, very limited in time. When science fiction writers portrayed a distant and inhuman intelligent life in their works, everyone understood: this is their way to turn to earthly and human problems. We are alone in the Universe, our presence here is fleeting and accidental.
However, ideas don't die. No matter how bizarre some beliefs may seem, there are always eccentrics who, despite all evidence and all reasonable arguments, continue to share them. For more than a decade, an international effort to search for extraterrestrial intelligence, the SETI project, has continued. They continue, although they remain still sterile. The hopes of finding traces of life - even the past - on Mars are systematically dying and reviving.
Among the enthusiasts is the famous theoretical physicist, one of the founders of quantum electrodynamics and a very effective technique for visualizing computations in the theory of elementary particles, called "Feynman diagrams", Freeman Dyson. Several years ago, speaking at the Institute for Theoretical and Experimental Physics, where he was awarded the International Pomeranchuk Prize, Dyson presented his theory of extraterrestrial life. If his theory is correct, then it is necessary to look for life on distant planets or even asteroids of the solar system. Their distance from the Sun may not be so important: collecting the scattered rays of a distant star, peculiar plants with spreading petals will be able to keep the required amount of water in a liquid state.
But one of the main principles of the search for extraterrestrial life was and remains the principle of "follow the water" approach. They searched for water and continue to search within the solar system: the data obtained in 1997 by the NASA space probe on the presence of water on Jupiter's satellite Europa became a sensation. Last year, news of signs of liquid water under the southern, volcanic pole of Saturn's moon Enceladus was received with no less enthusiasm.
Water may not be as rare in space as it was thought forty years ago. The expansion of cosmic bodies, where one can count on her presence, can be considered encouraging in this sense. At the time of this writing, 236 exoplanets have already been discovered. True, most of them belong to the type of "hot Jupiters", but the point is not at all that there are more planets of this type, it is simply easier to notice them. Gliese 581c is still unique in its resemblance to the Earth.
Favorable closeness
When making assumptions about nascent, young life on exoplanets, scientists inevitably compare it with life on ancient Earth. As a rule, young planets are a difficult place to survive, so the molecules from which living organisms develop must be very resistant to harsh conditions.
With the help of the NASA space telescope Spitzer (Spitzer) managed to find out that organic molecules - polycyclic aromatic hydrocarbons, presumably being the "building blocks of life", can survive even a supernova explosion. For example, significant amounts of polycyclic aromatic hydrocarbons have been found near the surface of supernova remnants N132D, located 163,000 light-years away in the neighboring Large Magellanic Cloud galaxy. These molecules have been found inside comets, around star-forming regions and protoplanetary disks. Since all life on Earth is based on carbon, astronomers assume that carbon originally came to Earth as part of these molecules - probably from comets that fell on the then young planet.
Scientists claim that a large star exploded near the solar system nearly five billion years ago. If so, then the polycyclic aromatic hydrocarbons that survived this explosion could become the "seeds" of life on our planet. There are reasons to expect that and not only on ours. Just to recognize them, you need to know at least approximately what they might look like.
Other worlds, if viewed through a telescope, may not be at all like Earth. Plants on other planets, according to astrobiologist from the Goddard Institute for Space Research (GISS) Nancy Jiang (Nancy Kiang), can be any color, except, perhaps, blue. The color of vegetation depends on many parameters: a different spectrum of suns, differences in the atmosphere, the chemistry of which depends on the composition and parameters of the parent stars.
And the spectrum of radiation on the planet's surface will be very different for planets living near stars of different spectral types (from hot F2, through G2, K2 to very dim M5), and it will also depend on the concentration of oxygen, ozone, water vapor in the atmosphere, etc. carbon dioxide. It is equally important that plants can use not only chlorophyll to assimilate sunlight; depending on evolution, to ensure the process of photosynthesis, another compound can be taken, which will take the maximum available energy from the star's light. Plants tend to absorb the most energetically saturated part of the spectrum, and the color of their leaves depends on the frequency of light that the plant absorbs least. So, chlorophyll absorbs mainly blue and red, because red light carries the largest number of photons, and blue has the most energy for each photon. Plants mostly reflect green light.
A team of scientists led by Victoria Meadows from the California Institute of Technology's VPL has developed computer models that simulate Earth-like planets and their light spectra as they appear. they can be seen with space telescopes. Plants on planets near brighter stars (for example, spectral class F) will reflect the red-yellow-orange part of the spectrum, that is, they will have an "autumn appearance" - after all, blue and ultraviolet rays predominate in the light of these stars.
Plants on a planet orbiting a red dwarf (stars of spectral class M, the mass of which is 10-50% of the mass of the Sun) may look black! Such stars are dimmer than the Sun and emit mainly light in the infrared, invisible to the human eye, range, and local plants will have to try to assimilate the entire spectrum of radiation incident on them. The black color, as you know, almost does not reflect the rays falling on it.
The least likely, according to Victoria Meadows, is that vegetation on other planets will be blue. Blue is light of a higher frequency, therefore, it also carries more energy, so plants will "try" to use it as much as possible. In addition to these colors, terrestrial planets can be purple if microorganisms develop on them that synthesize purple or purple pigments (retinol), as happened on ancient Earth. Organisms of this color exist even now - these are the so-called halobacteria, in the membrane of which retinol absorbs green light and reflects red and violet, the combination of which seems to us violet.
Considering the models of scientists, one can assume which "spectral signatures" and colors, indicating the presence of life, can be looked for on the planets: purple, green, yellow or black. However, one should not forget that both computer models and theoretical calculations were made on the basis of knowledge about life on earth, and it remains to be seen how true they are for exoplanets.
Loading ...