We have found « fingerprints » from extraterrestrial life, allow scientists
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In a potentially remarkable discovery, scientists using the James Web Space Telescope have received what they call the strongest signs of a possible life outside our solar system, finding in the atmosphere of a foreign planet chemical fingerprints of gases that are produced only by biological processes on Earth.
The two gas – dimethylsulfide (DMS) and dimethyldisulfide (DMDS), included in observations with the « web » on the planet K2-18 B, are generated on Earth by living organisms, mainly microbial life such as marine phytoplankton and algae.
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This suggests that the planet can be full of microbial life, the researchers said. However, they stressed that they did not declare the discovery of actual living organisms, but rather a possible biosignor – an indicator of a biological process – and that the discoveries should be considered cautiously, with more observations being needed.
However, they are excited about the result. These are the first signs of an extraterrestrial world to be inhabited, said astrophysicist Niku Madhusudhan of the University of Cambridge Astronomy Institute, a lead author of the study published in the Astrophysical Journal Letters.
« This is a turning point in the demand for life outside the solar system, in which we demonstrated that it is possible to find biosagnaries of potentially habitable planets with the current equipment. We have entered the era of observation astrobiology, » Madhusudhan said.
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Madhusudhan noted that different efforts are being made to seek signs of life in our solar system, including various statements about an environment that can be favorable for life in places such as Mars, Venus and various ice moons.
- K2-18 B is 8.6 times more massive than Earth and has a diameter about 2.6 times larger than our planet.
- It circles in the « habitable area » – a distance where liquid water, a key ingredient for life, can exist on the surface of the planet.
- The planet is a star red dwarf, smaller and less glowing than our sun, located about 124 light-years from Earth in the constellation Lion. (One light year is the distance that light passes in one year – 9.5 trillion km).
- Another planet has been identified in orbit around this star.
Hicer
About 5800 planets outside our solar system, called exoplanets, have been discovered since the 1990s. Scientists allow the existence of exoplanets called hicer worlds – covered by a liquid water ocean, inhabited by microorganisms and with a hydrogen -rich atmosphere.
Earlier observations of the Web, which started in 2021 and began functioning in 2022, identified methane and carbon dioxide in the atmosphere of the K2-18 B, the first time carbon molecules were registered in the atmosphere of exoplanet in the habitable area of the star.
| « The only scenario that currently explains all the data received so far from JWST (James Web Space Telescope), including past and current observations, is the one where the K2-18 B is a chichene world that is full of life, » Madhusudhan said. « However, we must continue to explore other scenarios. » |
Madhusudhan said that in the hiccial worlds, if they exist, « we are talking about a microbial life, probably like what we see in the oceans on Earth. » It is assumed that their oceans are warmer than earthly. Asked about possible multicellular organisms or even an intelligent life, Madhusudhan said, « We will not be able to answer this question at this stage. The main assumption is for elementary microbial life. »
- DMS and DMDS, both of the same chemical family, are predicted as important biosigantums of exoplanets.
- Web found that one or the other, or probably both, are present in the planet’s atmosphere with a security level of 99.7%.
- This means that there is still a 0.3% chance of observation being a statistical coincidence.
The gases have been found at atmospheric concentrations over 10 parts per million in volume.
| « For reference, this is thousands of times higher than their concentrations in the earth’s atmosphere and cannot be explained without biological activity based on existing knowledge, » Madhusudhan said. |
Scientists who do not participate in the study advise on caution to his conclusions.
« The rich data from the K2-18 B makes it a tempting world, » said Christopher Glane, a major scientist in the Southwestern Southwestern Research Institute in Texas. « These recent data are a valuable contribution to our understanding. And yet we have to be very careful to test the data as deep as possible. I look forward to seeing an additional, independent work analysis work, which will start next week. »
What method is used
The K2-18 B is part of the planet « under Neptune »-with a diameter larger than that of Earth, but smaller than that of Neptune, the smallest gas planet in our solar system.
- To determine the chemical composition of the exoplanet atmosphere, astronomers analyze the light of its star as the planet passes before it from the point of view of Earth. This is called a transit method.
- As the planet passes, WebB can detect a decrease in star brightness and a small part of the star light passes through the planetary atmosphere before being caught by the telescope.
- This allows scientists to determine the components of the planet’s atmosphere.
- Web’s previous observations on this planet have brought a conditional hint of DMS. His new observations used a different tool and a different range of wavelength of light.
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The « Holy Grail » of Exoplanets Science, said Madhusudhan, is to find evidence of life on a planet like a similar planet outside our solar system. Madhusudhan said that our species has been wondering « We are » in the universe for thousands of years, and now we can only be a few years since the discovery of a possible extraterrestrial life in the Hichene world.
- « First, we need to repeat the observations two to three times to make sure that the signal we see is stable and to increase the importance of detection to the level, whereby the chances of statistical coincidence are below one million, » said Madhusudhang.
- « Second, we need more theoretical and experimental studies to make sure that there is or not another abiotic mechanism (not including biological processes) to create DMS or DMDS in a planetary atmosphere such as that of K2-18 B. Although previous studies should be said (such as) stable biosigenhers Madhusudhan.
So the findings are « big » whether « whether observations are due to life and is not in » no interest in claiming prematurely that we have found life, « Madhusudhan said.
