What can methyl halides, which are gases that consist of one carbon and three hydrogen atoms while being attached to a halogen atom, help scientists identify life beyond Earth? This is what a recent study published in The Astrophysical Journal Letters hopes to address as an international team of researchers investigated how methyl halides on exoplanets known as “Hycean” worlds could indicate the presence of life as we know it, or even as we don’t know it. Hycean exoplanets possess liquid water oceans with a hydrogen atmosphere above them, potentially enabling appropriate surface temperatures and pressures for life to exist.
For the study, the researchers discussed the potential for using NASA’s James Webb Space Telescope (JWST) to observe large exoplanets orbiting red dwarf stars, which are smaller and cooler than our Sun. The researchers noted that recent observations of K2-18 b and TOI-270 d, which are designated as Super-Earth and Neptune-like exoplanets, respectively, while each orbiting red dwarf stars. Additionally, such exoplanets could be ideal targets for JWST to identify methyl halides in their atmospheres. The reason Hycean exoplanets are considered ideal targets is due to the difficulty of observing Earth-sized exoplanets orbiting brighter stars.
Artist's illustration of a potential Hycean exoplanet, where methyl halide gases in the atmosphere could be identified. (Credit: NASA, ESA, CSA, Joseph Olmsted/STScI)
“Oxygen is currently difficult or impossible to detect on an Earth-like planet,” said Michaela Leung, who is a PhD student at the University of California, Riverside, and lead author of the study. “However, methyl halides on Hycean worlds offer a unique opportunity for detection with existing technology. One of the great benefits of looking for methyl halides is you could potentially find them in as few as 13 hours with James Webb. That is similar or lower, by a lot, to how much telescope time you’d need to find gases like oxygen or methane. Less time with the telescope means it’s less expensive.”
The primary reason researchers have become interested in methyl halides is that they are produced by life on Earth. However, the amount of methyl halides within Earth’s atmosphere is very small due to the atmospheric composition. In contrast, the atmospheres of Hycean exoplanets could enable the existence of large amounts of methyl halides, and potentially enough to be detected by telescopes from Earth.
How will methyl halides help researchers find life beyond Earth in the coming years and decades? Only time will tell, and this is why we science!
As always, keep doing science & keep looking up!
Sources: The Astrophysical Journal Letters, EurekAlert!, NASA, NASA (1), UC Riverside News
