SETI Targets K2-18b for Technosignatures
SETI researchers are conducting targeted radio observations of Hycean world K2-18b following JWST detections of CO2 and methane as potential biosignatures. The exoplanet orbits a red dwarf star, and scientists are searching for alien technosignatures despite the challenges posed by its stellar environment.
- The JWST's atmospheric data for K2-18b included a potential detection of dimethyl sulfide (DMS). On Earth, this chemical is almost exclusively produced by living organisms, particularly marine phytoplankton. - This potential biosignature is highly contested; the detection has a low statistical significance and some scientists argue the signal could be noise or another chemical compound. If confirmed, the concentration of DMS would be thousands of times stronger than on Earth. - The term "Hycean" is a portmanteau of "hydrogen" and "ocean," describing a class of exoplanets with deep global oceans underneath hydrogen-rich atmospheres. This type of world could support life under conditions very different from Earth's. - K2-18b is located 124 light-years from Earth and was first discovered in 2015 by the Kepler space telescope. It has a mass about 8.6 times that of Earth and a radius 2.6 times larger, completing an orbit of its star in just 33 days. - The planet's M-dwarf star, K2-18, is smaller and cooler than the Sun. Planets orbiting this close to a red dwarf are likely to be tidally locked, with one side in permanent daylight and the other in permanent darkness. - Intense and frequent stellar flares from red dwarf stars pose a significant challenge, as the resulting radiation could potentially strip away a planet's atmosphere and render its surface inhospitable. - A technosignature is any evidence of technology that could be detected from a distance. While the current search focuses on radio signals, other examples include laser light pulses, industrial pollutants in the atmosphere, or the waste heat from massive artificial structures.
