Since its launch in late 2021, NASA's James Webb Space Telescope has opened up new possibilities for detecting signs of life on exoplanets beyond our solar system. Research shows that the James Webb Space Telescope can help confirm whether there are life-supporting atmospheres on exoplanets located in the "Blonde Zone", thereby increasing the possibility of discovering extraterrestrial life.
In this search, the most promising candidates are rocky planets orbiting low-mass stars called M-dwarfs, rather than gaseous planets. These stars are the most common types in the universe. TRAPPIST-1, a nearby M-dwarf star about 40 light-years away, has a planetary system that is being closely studied for its potential to support life.
Previous research has cast doubt on the habitability of TRAPPIST-1. The researchers found that intense ultraviolet radiation from the star could burn away the water on the planet's surface, leaving it dry and potentially full of reactive oxygen species that would hinder the formation of life.
However, a new study led by the University of Washington and published in Nature Communications shows that a series of processes in the evolution of some rocky planets orbiting M dwarf stars may lead to the development of stable atmospheres over time.
One of the most fascinating questions in exoplanet astronomy right now is: "Can rocky planets orbiting M-dwarfs form stable atmospheres? Can rocky planets orbiting M-dwarfs maintain atmospheres that support life?" said first author Joshua Krissansen-Totton, assistant professor of Earth and Space Sciences at the University of Washington. "Our findings give us reason to hope that some of these planets do have atmospheres, which greatly increases the chances that these ordinary planetary systems can support life."
The James Webb Space Telescope is sensitive enough to observe a handful of these planetary systems. The data returned so far indicate that the hottest rocky planets closest to TRAPPIST-1's star do indeed lack significant atmospheres. But the telescope has not yet been able to clearly characterize planets located in the "blond zone," which are slightly farther from their stars and at the most favorable distances to support liquid water and life.
The new study simulates the process of a rocky planet forming from melt to cooling into a solid terrestrial planet over hundreds of millions of years. The results suggest that hydrogen or other light gases did initially escape into outer space. But for planets farther from their stars and with more moderate temperatures, hydrogen can also react with the oxygen and iron in the planet's interior. This created water and other heavier gases, creating an atmosphere that the study shows is stable over the long term.
The results also show that for these "blond zone" planets, water pours out of the atmosphere very quickly, making it less likely for water to escape.
"It is easier for the Webb telescope to observe hot planets closest to their stars because they emit more thermal radiation and are not affected by stellar interference. For these planets, we have a fairly clear answer: they do not have thick atmospheres," Krissanson-Totten said. "To me, this result is interesting because it suggests that temperate planets may have atmospheres and should be carefully observed with telescopes, especially given their habitability potential."
The Webb telescope has not yet been able to detect whether planets slightly farther from the TRAPPIST-1 star have atmospheres. But if they did, that would mean they likely had surface liquid water and a mild climate conducive to life.
"With the telescopes we have now, the James Webb Telescope and the upcoming Very Large Ground-based Telescope, we can really only observe the atmospheres of a very small number of rocky habitable zone planets - namely TRAPPIST-1 and a few others," said Krissanson-Totten. "Given the huge interest in finding life elsewhere, our results show that it is worth investing telescope time to continue studying the habitability of these systems using the technology we have now, rather than waiting for the next generation of more powerful telescopes."
Compiled from /ScitechDaily
DOI:10.1038/s41467-024-52642-6