Scientists have made an exciting discovery on the exoplanet K2-18 b using the James Webb Space Telescope. They have detected the presence of carbon-containing molecules, including methane and carbon dioxide, in the planet’s atmosphere. This finding provides valuable information about the nature of K2-18 b, which is suspected to be a Hycean exoplanet with a hydrogen-rich atmosphere and a water-covered surface.
K2-18 b orbits within the habitable zone of its host star, making it a potential candidate for the existence of liquid water. Data from NASA’s Hubble Space Telescope initially suggested the unique properties of the exoplanet’s atmosphere and led to further investigation.
K2-18 b is located about 120 light-years from Earth and is about 8.6 times the size of our planet. These types of exoplanets, known as sub-Neptunes, are not common in our solar system and have not been studied as extensively as gas giants like Jupiter and Saturn.
The detailed spectrum captured by the James Webb Space Telescope showed an abundance of methane and carbon dioxide in the atmosphere of K2-18 b, supporting the hypothesis that the planet may have a hydrogen-rich atmosphere with an ocean of water beneath it. The telescopic observations also suggested the possible presence of dimethyl sulfide (DMS), a molecule produced primarily by living things on Earth, particularly phytoplankton in marine environments. Further observations are required to confirm the existence of DMS in K2-18 b.
Despite the potential for life on K2-18 b, the planet’s size and the extreme heat of its ocean surface may pose a challenge to sustaining life. Its immense size suggests the presence of a highly pressurized ice mantle inside, similar to Neptune. In addition, the brightness of the planet’s parent star posed a challenge to collecting accurate spectral data.
To overcome these challenges, the Webb Telescope observed K2-18 b’s transit in front of its star, recording changes in brightness and collecting data about the planet’s atmosphere as it was illuminated by the star. This method of observing transits has been fundamental to the study and discovery of exoplanets.
Data collected from just two transits of K2-18 b have demonstrated the power and sensitivity of the Webb telescope. Future observations are planned that will provide researchers with more data and possibly the discovery of additional molecules. The Webb Mid-Infrared Instrument spectrograph will be used for these next observations.
This discovery highlights the importance of considering different habitable environments when searching for life on exoplanets. While the focus was primarily on smaller rocky planets, larger Hycean worlds such as K2-18 b offer more favorable conditions for atmospheric observations.
