K2-18b, an exoplanet about 124 light years away in the constellation Leo, has drawn close attention because it orbits within the habitable zone of a red dwarf star. Observations from the James Webb Space Telescope have shown an atmosphere rich in carbon dioxide and methane, making it a leading candidate for a so-called Hycean world with a thick hydrogen-rich atmosphere and a possible global ocean, according to ScienceDaily.
Because of those conditions, researchers recently used two major radio telescopes to look for signs of artificial transmissions from the system. The campaign combined data from the Karl G. Jansky Very Large Array in New Mexico and MeerKAT in South Africa in an unusually coordinated search.
The team analyzed the data with automated software designed to separate Earth-based interference from possible signals of interest. They applied several filters, including checks for radio-frequency contamination, Doppler shifts, signal-to-noise limits, and whether a signal appeared in only the beam aimed at K2-18b.
Although the observations produced millions of candidate detections, none survived all of the screening steps. The researchers reported no convincing technosignatures in the narrowband radio frequencies they examined, while also noting the search helped place limits on how strong any transmitter in the K2-18b system could be.
