The search for life beyond Earth has long since ceased to be a wacky pseudoscientific quip to become a fascinating scientific adventure. But that adventure moves very slowly. First, extrasolar planets began to be detected, of which more than five thousand have already been located. And then it was necessary to detail which of them had the possibility of harboring life. And here appeared one of the biggest stumbling blocks. “The problem,” he says Ester Lázaro, researcher at the Center for Astrobiology—, is that we have put little imagination into it and what has been considered up to now have only been planets similar to Earth”.
But A study recently published in the magazine The Astrophysical Journalproposes new candidates, planets very different from our Earth but that “we must study, to increase our chances of identifying habitable planets”, according to anna wolf, from the University of California at Irvine (United States) and first signatory of the article. The planets that Lobo has investigated are very peculiar and orbit around the so-called M dwarfs or red dwarfs. “These stars are the most common and account for 70% of all stars in the galaxy,” explains the lead researcher.
Compared to our sun, M dwarfs are “low-mass stars, with a mass between one-tenth and 60% of the mass of the Sun. They are small and cooler, but they are very abundant, both in our neighborhood and in the rest of the galaxy,” says Cristina Rodriguez Lopez, researcher at the Institute of Astrophysics of Andalusia. The abundance and characteristics of these stars, which make it easier to locate planets around them, have made them the most investigated suns for the search for extrasolar planets capable of hosting life. However, it is not very common to find Earth-like planets around these stars.
As they are dimmer (that is, with temperatures much lower than our sun), their so-called habitable zone (in which planets whose temperatures allow the existence of liquid water are supposed to be) is much closer to the star than in our solar system. For this reason, in a large part of that habitable zone, the proximity of the star causes the synchronous rotation of the planets with their star, something similar to what happens between the Earth and the Moon. And as it happens with our satellite, the result is that these planets always have a light side and a dark side.
“When you think of planets with a burning face, over a thousand degrees, and another icy one, with less than one hundred below zero, they are immediately ruled out as possible to harbor life”, says Esther Lázaro. And the astrobiologist delves into it: “The interesting thing about this new research is that it proposes a possibility that could make the existence of life possible in them. It doesn’t prove it to be so, but it opens up a lot of possibilities for the future.”
The key in the research of Lobo’s team are the so-called zones terminator (or terminator, in Spanish), as the work details: “Just as the equator is a strip between the northern and southern hemispheres of the Earth, terminator It is the strip that separates the permanent day side and the also permanent night side on these planets”. The new research has analyzed what that strip is like on planets that have a limited amount of water, that is, they are not planets totally covered in oceans that were considered until now. “If those planets have limited amounts of water, the zone terminator it can remain at moderate temperatures favorable for habitability”, affirms Lobo.
Research opens up new possibilities; tells the ‘Webb’ space telescope: hey, other worlds can be interesting too. A wake-up call about what was being discarded
Cristina Rodríguez López, researcher at the Institute of Astrophysics of Andalusia
This work introduces a variable that can be decisive when programming future research for the search for extraterrestrial life, as Lobo herself explains: “Very often we affirm the habitability of a certain exoplanet as a simple yes or no answer. But Earth has a wide range of climates, and extrasolar planets may have even greater diversity. It is possible that habitable worlds are not necessarily habitable over their entire surface, but could have regions that are and others that are not.”
The scientist Cristina Rodríguez López, who has not participated in the research, explains the importance of this work as follows: “What it does is open up new possibilities and, furthermore, it does so at a very important moment because, from now on, to begin to characterize the exoplanets discovered, and that work will be done by the James Webb Space Telescope. That is why groups around the world are proposing favorable planets for the telescope to observe. What does the work published in The Astrophysical Journal that is to say: hey, these other worlds can also be interesting. It is a wake-up call about what was being discarded ”.
Of course, nobody thinks of little green men or women with antennas, Lázaro qualifies: “If there is life in those areas terminator it is most likely that it is microscopic life because it seems very difficult that in a limited space, as those regions should be, more complex life can develop. But even if we were talking about microscopic life, it would still be life.”
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