Too little light on exoplanets around red dwarfs to produce complex life.

in Popular STEM5 days ago

Too little light on exoplanets around red dwarfs to produce complex life.




Red dwarfs have given us many exoplanets because discovering exoplanets around a red dwarf is relatively easy for the technology we currently have, the smaller the star and the larger the planet, the easier it will be to discover the planet or capture it in some way, which is why there are so many exoplanets orbiting red dwarfs.


Most of the discoveries of exoplanets are because the planet passes in front of the star and the red dwarfs are small, and their habitable area and their system are usually also very small, they are planets that perhaps have their year last a few days, 20 or 30 days, so, in a year of observations, to a red dwarf, you have a lot of passes of that planet and therefore you have a lot of data to confirm that there is a world, that is why there are so many planets discovered around red dwarfs, but it is not the best place in the universe for life to emerge and, above all, for evolved life to emerge, as this research demonstrates.




And the latest research in this regard was published on January 5, with the title "The scarcity of active photosynthetic radiation suggests that there is no complex life on our planets of late M stars", and for this they have analyzed the worlds of the Trappist system, it is amazing, by the way, Trappist-1, is a cold red dwarf star about 40 light years away, it has seven rocky exoplanets the size of the Earth, three of which are in the habitable zone of the star, one of them is Trappist E1E.


In the video that NASA prepared at the time when the system was discovered, we see the planets of this Trappist system based on the one that is closest, which is a volcanic world, to the one that is furthest away, which would already be an icy world, and those in the middle, since they are in the habitable zone and are supposed to have liquid water on the surface.


This system and these planets are very interesting, since their size is quite similar to that of those on Earth, there are some that are a little larger, H is the smallest, it is a bit the size of Venus, but they are more or less in that range, the problem is that red dwarfs are smaller stars, also much colder than the Sun and therefore the habitable zone, that is, where a planet receives an amount of energy from its star, so that if it has an atmosphere it can maintain liquid water on the surface, is a very large band. smaller and much narrower.


In the case of stars like the Sun, the habitable area would reach, so that you have a reference, almost to the asteroid belt, that is, a little beyond Mars, it would start more or less where Venus and end more or less where Mars, a little beyond Mars, although that can be flexible because if a little further there existed a planet a little larger than the Earth, with a slightly denser atmosphere and with more greenhouse gases, then it could retain more heat and even if it were further from the sun, it could also have liquid water on the surface, so it is a habitable area that has some margin.



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All the planets in this Trappist-1 system, pay attention to this fact because it has always amazed me a lot, they are all planets of curious size, the size of the Earth or somewhat larger, they all orbit in a narrow strip, the furthest one is 9.3 million kilometers from the star, that is almost six times closer than Mercury is to the Sun, all of them are included in a package of 9.3 million kilometers. How can there be so many planets and of a size as respectable as Earth or somewhat larger orbiting so close to their star?


Literally, if you were on the surface of one of the middle ones, the one that was most habitable, so that you could be calm and comfortable, you could see how one or more of the neighboring planets arrived, you would see them appear in the sky and grow to a size of almost the size of our moon or even larger, because there are some that are larger than the Earth, you would see them enormous, pass over you and then move away.


This is thanks to the miracle of orbital resonance that has allowed this very compact system to be stable for about 7,000 million years, 1,500 million years longer than the solar system, and can remain so for 10 billion more years, about 1,000 times longer than the sun can live, since red dwarfs live a very long time.


This also shows us that the solar system is quite poor in planets, there may be stars like the sun that have habitability in the distance of their area, that is, up to what I am telling you about more or less almost the asteroid belt, instead of having Venus, Earth and Mars, three potential planets, although there is only life on one, instead of three they can easily have 20 planets the size of the Earth, as long as they are in resonance, of course.



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The important thing about this research is that it tells us that there is a habitability problem in these worlds and not because it is very close to the star and that the red dwarfs are unstable, that not all of them are unstable, it is not a problem that they receive flares due to explosions from the star or radiation from the star, or that they are anchored by tidal forces, well no, the problem, what they have analyzed and as they say in the title, is the radiation that the stars receive so that photosynthetic life can occur.


And they came to a conclusion by analyzing what had happened here on Earth, the great oxidation event that occurred about 2.3 billion years ago, although it is possible that it was a slow process that began a few hundred million years before, it is a process that changed the Earth's atmosphere completely. Initially, the Earth's atmosphere when life and bacteria emerged, etc., and for quite a long time, was an atmosphere loaded with CO2 and without oxygen.


When new organisms appeared that used a more efficient photosynthesis that produced oxygen as a by-product, what they did was load the atmosphere with oxygen, achieving a curious effect and that is that oxygen is a much more powerful chemical fuel than CO2 and this allowed complex life to develop, but for this to happen light is needed, a lot of light, a light that a red dwarf is not capable of giving, which is why researchers have come to the conclusion that although it is not impossible for complex life to arise on these planets, there may be life. bacterial perfectly.




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