In August this year, scientists, barely holding back tears of joy, announced the discovery of the Earth-like planet Proxima b, located in the closest star system to us. Having studied all the information collected about it, scientists have come to the conclusion that the planet may have an atmosphere suitable for breathing and even, possibly, has areas covered with water.
The results of the latest exploration of this world offer us both good and bad news. The bad news is that the planet is most likely experiencing frequent outbreaks of "mass extinction" triggered by the activity of its home star. The good news is that, despite this, computer simulations show that the planet can still support life.
In the framework of computer simulations, scientists have found that if Proxima b actually has an atmosphere or magnetic field similar to that of the earth, then life on its surface will indeed be possible. However, if the planet does not have these protective barriers, all living things, if they were there, of course, were most likely extinct long ago.
Let's take a step back and figure out what the planet Proxima b is. First, it is very interesting because it is the closest candidate to the Earth for the title of an Earth-like planet. It is located just 4.25 light years, or 40 trillion kilometers, from us.
Of course, at first glance, the figure, on the contrary, may seem just very large, but earlier the title of the closest Earth-like planet to us belonged to an object located 14 light years away. Of course, at the moment, the planet is beyond the capabilities of our current space travel technologies, but in the future, this planet will certainly become the first on the list of planets outside the solar system that scientists will want to visit. In fact, Russian billionaire Yuri Milner was about to visit the planet in 2060. Not by himself, of course, but with the help of a tiny laser-powered unmanned spacecraft.
Secondly, Proxima b is located in the so-called Goldilocks zone. This means that the planet is close enough to its star to keep water in liquid form, and at the same time far enough for this water to be preserved on it at all. Against the background of this aspect, the researchers initially suggested that the planet could be habitable.
Thirdly, the radius of the planet is about only 1.3 times the Earth, and it itself is in orbit near the red dwarf Proxima Centauri, which is part of the Alpha Centauri star system. The orbital period of Proxima b is 11.2 Earth days. Due to the low luminosity of the native star, the planet receives just such an amount of heat so that water on its surface can exist in the form of a liquid and not freeze into eternal ice. Preliminary calculations indicate that the temperature on its surface is -40 degrees Celsius.
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It would seem like an almost perfect winter resort. However, there is one big problem. According to a new study, this world may face regular events that on the same Earth could lead to mass extinction. The reason for this is the native star, spitting from time to time in flashes that destroy all living things. In other words, the planet is often exposed to solar storms similar to those experienced by the Earth. However, the Earth has a magnetosphere and a dense atmosphere that protect it from the harmful radiation of the Sun. As for Proxima b, scientists do not yet have convincing evidence that the planet has the same "protective screens".
Since the discovery of Proxima b, astrobiologist Dimitra Atri of the Blue Marble Institute for Space Sciences in Seattle has conducted several computer simulations to find out how often the home star flares and in which case life on this planet (if it were there) could survive. within these outbreaks.
The results of his work show that Proxima b could indeed be habitable, but everything would primarily depend on its atmosphere.
“I would say that it is too premature to call Proxima b habitable. There are many factors, only taking into account which it would be possible to answer the question of whether this planet is capable of supporting the biosphere. New observations and analysis will help clarify this situation,”says Atri.
In order to find out in what cases life on this planet could survive, Atri took into account the type and size of all known stellar flares in the Universe; selected different parameters of the density of the planet's atmosphere, as well as different indicators of the strength of its magnetic field - a key component of shielding and protecting the planet from the solar wind. His calculations showed that all that Proxima b needs to be considered habitable is the presence of an atmosphere and magnetic field similar to those on Earth.
On the other hand, calculations also showed that in the presence of a thin, rarefied atmosphere and the complete absence of a magnetic field, the planet should not be considered as a promising place for life.
Until we get the opportunity to study the planet in more detail - whether in person or with the help of more advanced telescopes - we will not be able to accurately answer the questions about what characteristics it actually has. However, Atri clarifies that not all simulation models have been tested. If there were microbes resistant to harsh conditions on the planet, then it would be a completely different story. And the next thing Atri is going to check out is exactly that. At least in terms of computer simulations.
“One of the most important aspects of this study was the assumption that the planet already has a powerful magnetic field and a dense atmospheric screen. If the planet actually has these features, even the most powerful stellar flares will not seriously harm even the most primitive biosphere,”Atri notes.
NIKOLAY KHIZHNYAK