K2-18b Super-Earth Exoplanet

A K2-18b Super-Earth Exoplanet is a super-earth exoplanet that orbits in the habitable zone of a red dwarf star system (enabling potential habitability assessment for astrobiology research).

• AKA: EPIC 201912552 b, K2-18 b.
• Context:
  • It can typically maintain Hydrogen-Rich Atmosphere with methane and carbon dioxide molecules (detected via spectroscopic analysis).
  • It can typically orbit at Habitable Zone Distance from its k2-18b red dwarf star (receiving earth-comparable stellar radiation).
  • It can typically contain K2-18b Water Vapor in its k2-18b atmosphere (making it the first non-hot-jupiter with confirmed atmospheric water).
  • It can typically possess K2-18b Mass Characteristics of approximately 8.6 earth masses (placing it in the sub-neptune exoplanet category).
  • It can typically exhibit K2-18b Orbital Period of approximately 33 earth days (at 0.1429 astronomical units from its host star).
  • It can typically present K2-18b Size Characteristics of about 2.6 earth radii (suggesting a substantial gaseous envelope).
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  • It can often support K2-18b Hycean Classification characteristics with potential liquid water ocean beneath its hydrogen-rich atmosphere.
  • It can often contain K2-18b Biosignature Candidate Molecules such as dimethyl sulfide and dimethyl disulfide (requiring additional verification).
  • It can often experience K2-18b High-Energy Radiation Exposure from its red dwarf host star (potentially affecting its atmospheric chemistry).
  • ...
  • It can range from being a Water Ocean K2-18b Super-Earth Exoplanet to being a Gas-Rich Mini-Neptune K2-18b Exoplanet, depending on its interior composition.
  • It can range from being a Potentially Habitable K2-18b Super-Earth Exoplanet to being an Uninhabitable K2-18b Super-Earth Exoplanet, depending on its surface conditions.
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  • It can have K2-18b Atmospheric Study Significance for exoplanet habitability research and extraterrestrial life detection methodologies.
  • It can serve as K2-18b JWST Observation Target since 2023 (providing unprecedented spectroscopic data).
  • It can function as K2-18b Hycean World Prototype for exoplanet classification system.
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• Examples:
  • K2-18b Observational Study Periods, such as:
    • K2-18b Discovery Period (2015), characterized by initial detection using NASA Kepler Space Telescope.
    • K2-18b Water Vapor Detection Period (2019), demonstrating the first confirmed atmospheric water vapor in a non-hot-jupiter exoplanet.
    • K2-18b Carbon Molecule Detection Period (2023), revealing methane and carbon dioxide in its k2-18b atmosphere.
    • K2-18b Potential Biosignature Detection Period (2025), suggesting dimethyl sulfide presence at three-sigma significance level.
  • K2-18b Atmospheric Composition Theories, such as:
    • K2-18b Hydrogen-Rich Atmospheric Model supporting hycean world classification.
    • K2-18b Methane-Carbon Dioxide Profile indicating potential chemical disequilibrium.
    • K2-18b Dimethyl Sulfide Hypothesis suggesting possible biological origin.
  • K2-18b Interior Structure Hypothesises, such as:
    • K2-18b Liquid Water Ocean Model proposing subsurface habitability potential.
    • K2-18b Molten Rock Ocean Alternative explaining ammonia absorption patterns.
    • K2-18b Gas-Rich Mini-Neptune Structure without solid surface presence.
  • ...
• Counter-Examples:
  • Hot Jupiter Exoplanets, which orbit extremely close to their host stars and lack k2-18b habitable zone positioning.
  • Earth-Like Rocky Exoplanets, which have substantially lower mass-to-radius ratios than k2-18b super-earth exoplanet.
  • Solar System Sub-Neptune Planets, which do not exist within our solar system unlike the k2-18b exoplanet type.
• See: Exoplanet, Habitable Zone, Super-Earth, Sub-Neptune, Hycean World, Biosignature, James Webb Space Telescope, Red Dwarf Star.
• References:
  • Madhusudhan, N. et al. (2023). "Carbon-bearing Molecules in a Possible Hycean Atmosphere." The Astrophysical Journal Letters.
  • Madhusudhan, N. et al. (2025). "Potential Biosignatures in the Atmosphere of K2-18b." The Astrophysical Journal Letters.

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