Hello and welcome to my new video.NASA’s James Webb Space Telescope has made a significant discovery about K2-18 b, an exoplanet 8.6 times the mass of Earth. The telescope found carbon-bearing molecules, including methane and carbon dioxide, on the planet. This finding suggests that K2-18 b might be a Hycean exoplanet, with the potential for a hydrogen-rich atmosphere and a surface covered by a water ocean.
The initial insight into K2-18 b’s atmosphere came from NASA’s Hubble Space Telescope, leading to further studies that changed our understanding of this exoplanet. K2-18 b orbits a cool dwarf star called K2-18 in the habitable zone and is located 120 light-years away in the Leo constellation. These “sub-Neptunes,” planets with sizes between Earth and Neptune, are unique and poorly understood because there are no similar planets in our solar system.
The suggestion that K2-18 b could be a Hycean exoplanet is intriguing to astronomers, as these worlds are considered promising environments in the search for extraterrestrial life. The presence of methane, carbon dioxide, and a lack of ammonia supports the hypothesis of a water ocean beneath a hydrogen-rich atmosphere on the planet.
Additionally, Webb’s observations hinted at the possible presence of a molecule called dimethyl sulfide (DMS), which on Earth is produced by life, particularly phytoplankton in marine environments. However, further validation is required to confirm this.
Despite lying in the habitable zone and harboring carbon-bearing molecules, K2-18 b’s large size, with a radius 2.6 times that of Earth, suggests it may have a high-pressure ice mantle, a thin hydrogen-rich atmosphere, and a possibly too-hot ocean surface. Characterizing the atmospheres of such exoplanets is challenging due to the brightness of their parent stars.
The team overcame this challenge by analyzing starlight passing through K2-18 b’s atmosphere during its transits, allowing them to determine the gases present in the atmosphere. This was made possible by the Webb telescope’s extended wavelength range and sensitivity, providing robust data with just two transits, compared to years of observations with Hubble.
The team’s findings, published in The Astrophysical Journal Letters, are just the beginning of Webb’s potential in studying habitable-zone exoplanets. They plan to conduct further research using the telescope’s Mid-Infrared Instrument (MIRI) spectrograph to validate their findings and gain more insights into K2-18 b’s environmental conditions. Ultimately, the goal is to identify signs of life on a habitable exoplanet, which could transform our understanding of the universe. Thank you for watching.
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