Two stars approach the sun at once and threaten life on earth. What it is

Gliese 581 g- This is the so-called exoplanet, which is located in the system of the star Gliese 581 in the constellation Libra, at a distance of about 20 light-years from Earth. This planet was discovered by Stephen Vogt from the University of California and Paul Butler from the Carnegie Institute in Washington on September 29, 2010 and boldly called by scientists a "potentially habitable planet" or "super-earths".

The exoplanet was discovered by scientists in the Keck 1 telescope (Hawaii, USA) and the telescope at the La Silla Observatory (Chile). Stephen Vogt, who led the team of astronomers who discovered the planet, informally named the space body "Zarmina" (after his wife). According to Vogt, this object was very difficult to detect - more than 200 measurements were made for this.

However, an employee of the Geneva Observatory Francesco Pepe said that Michel Mayor's group (who discovered the first exoplanet - 51 Pegasi b) could not find confirmation of the very existence of the planet Gliese 581 g and Gliese 581 f, despite processing the data accumulated over six and a half years, but not ruled out the possibility of the existence of the planet in the habitable zone. In response, Stephen Vogt said he was confident in the accuracy of his data, complaining about the inability to get acquainted with the observations of the Swiss team.

According to scientists, the planet, located in the red dwarf system, has a radius equal to 1.5 Earth's, and its mass exceeds the Earth's by 3-4 times. The landscape of the planet is represented mainly by stones and rocks, but there is indirect evidence that water may well appear on the surface in liquid state... The discovered gravity gives scientists the opportunity to assume the presence of an atmosphere.

The orbital period of the planet around the star is 36.6 Earth days, while its orbit only slightly differs from the circular one. The acceleration of free fall is 1.1-1.7 times greater than that of the Earth. According to experts, due to its proximity to the star, the planet is always facing it with only one side (the second always remains in the shadows; similar situation observed on the moon). As a result of the analysis of the data obtained, scientists determine the temperature range on the planet from -34 degrees Celsius on the unlit side to 71 degrees Celsius on the illuminated side.

The constant turn of the planet to the star with only one side of it can lead to a constant displacement of air masses towards the unlit side. However, if there is dense atmosphere it is possible that the heat that the planet receives from the red dwarf will be distributed more evenly.

The chemical composition of the planet is not yet known. Detection on Gliese 581 g of oxygen and carbon dioxide would be another positive factor in the existence of life on the planet in one form or another.

Shortly after the discovery of the exoplanet, Australian scientist Ragbir Bhatal made a sensational statement that the flares that were seen in the area were very similar to the action of a laser, which allowed the scientist to assume that this planet was indeed inhabited. These observations were recorded in the framework of the international project SETI (Search for Extraterrestrial Intelligence), whose task is to search for extraterrestrial intelligence. However, most scientists were very skeptical about this bold statement.

In any case, the discovery of an exoplanet is a very important milestone in space exploration. Since red dwarf systems are the most common type of system in our Galaxy, scientists have concluded that 10-20 percent of these systems may have potentially viable planets.

Galetic Julia, Update date - 01/15/2013
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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 that 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 Last year XVI century Giordano Bruno (Giordano Bruno, 1548-1600) argued that there is life for everyone celestial 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 a well-known theoretical physicist, one of the founders of quantum electrodynamics and a very effective technique visualization of computations in theory elementary particles, called "Feynman diagram", Freeman Dyson (Freeman Dyson). Several years ago, speaking at the Institute of Theoretical and Experimental Physics, where he was awarded international award Pomeranchuk, Dyson expounded 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

Making assumptions about the 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 an astrobiologist at the Institute space exploration the name Goddard (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 for assimilation sunlight plants can use more than chlorophyll; depending on evolution, to ensure the process of photosynthesis, another compound can be taken, which will take the maximum available energy from the light of the star. 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 greatest number photons, and blue has the highest energy for each photon. Plants mostly reflect green light.

A group of scientists led by Victoria Meadows from the Virtual Planetary Laboratory (VPL) of California Institute of Technology(California Institute of Technology) has developed computer models that simulate planets close in parameters to Earth, and their light spectra - as they can be seen in space telescopes. Plants on planets about more bright stars(for example, spectral class F) will reflect the red-yellow-orange part of the spectrum, that is, have an "autumn look" - 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 from 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.

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 refined 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). It's less than 0.1 light year 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 1600 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 -.

The astronomer claims that two years ago he detected a strange pulse of light in the constellation Libra - where a planet suitable for human life had just been discovered.

Who's there? And who is there?

"A planet has been discovered in the constellation Libra, which possibly has life" - this was the title of the material published on October 1, 2010. We will remind, astronomers from the University of California reported that they discovered new planet the star Gliese 581, which is located in the constellation Libra, about 20 light years from Earth.

The sensation is that the planet, dubbed Gliese 581 g, is located right in the middle of the so-called habitat zone. Like our Earth. In 2007, astronomers have already found planets near Gliese - "c" and "d", which were located at the edges of the habitat. Like our Venus and Mars. And they did not strongly deny that life on them could exist in one form or another. Since the planets can contain water in liquid form. But on the newly discovered planet "g", conditions are the best. And if brothers in mind exist, then on this very "g" they have the very place.

True, we complained: they say, it is strange that there is no news from the Glizeans. After all, if they are at least equal to us in terms of development, then they should have hinted about their existence long ago. After all, our radio and television signals, which have been spreading throughout the Universe for more than 60 years, have long reached the Gliese system. Only 20 years were needed. This is there. Another 20 years - back. In total, we could have gotten something from them 20 years ago. But didn’t seem to get anything?

There is a contact!

And literally the next day, British newspapers published a report by Dr Ragbir Bhathal, an astronomer from the University of Western Sydney, who works on the SETI program - a program for the search for extraterrestrial civilizations.

According to the doctor, back in December 2008, he received a strange light signal from the Gliese 581 region. That is, it happened even before a planet suitable for life was discovered there - 581 g. And it was only known about "c" and "d" - conditionally suitable.

The signal was sharp, says Batal, like a laser flash. And communication by means of a powerful laser is quite possible. We are looking for such signals.

Unfortunately, the second signal did not follow the first signal. But the SETI specialists are still going to take a closer look at what they have already received. They assure that they have a special method of analysis.

The planet Gliese 581 g is about 3 times heavier than Earth. It is 1.2-1.4 times larger in diameter. The average temperature at the equator is about 20 degrees Celsius. It is frosty at the poles, just like on Earth.

As the brave discoverer of Gliese 581 g, professor of astronomy and astrophysics Dr Steven Vogt, said today, "I am 100 percent sure there is life there."

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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 about - 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. In principle, living organisms are likely to exist on such planets.

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.