Hycean world Archives - Page 3 of 3 - Astrobiology

(a) Top-of-atmosphere Galactic cosmic ray spectrum at 1au at 200Myr. Spectra for a slow (black dotted line), medium (red dashed line) and fast (blue dot-dashed line) solar rotation rate. The LIS is shown by the solid grey line. The enhanced LIS shown by the dot-dashed grey line is discussed in Section 4. The spectrum for the fast rotation rate has been multiplied by 102 to allow all of the spectra to be shown within a reasonable range on the same axes. (b) Top-of-atmosphere solar cosmic ray spectrum at 1au at 200Myr for a slow, medium and fast solar rotation rate. The linestyles represent the same scenarios as in the Galactic cosmic ray spectra. The green line represents the fit of the observed spectrum Reeves et al. (1992) of the solar energetic particle event measured at Earth in October 1989. -- astro-ph.EP

Atmospheres, Climate, Weather, Biophysics, Extinction events, Habitable Zones, Impact events, Magnetic Fields, Electromagnetism, bioelectricity,, Meteorites & Asteroids, Origin & Evolution of Life, Space Weather & Heliophysics, Status Report, Terraforming & Geoengineering, Water/Hycean Worlds & Oceanography

Ray Ionisation Of A Post-impact Early Earth Atmosphere: Solar Cosmic Ray Ionisation Must Be Considered In Origin-of-life Scenarios

by Keith CowingApril 4, 2025

Cosmic rays (CR), both solar and Galactic, have an ionising effect on the Earth’s atmosphere and are thought to be important for prebiotic molecule production. In particular, the H2-dominated atmosphere […]

Artist’s impression shows the planet K2-18b, its host star and an accompanying planet in this system. ESA/Hubble, M. Kornmesser

Astrogeology, Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Habitable Zones, Icy Worlds, Origin & Evolution of Life, Press Release, Water/Hycean Worlds & Oceanography

Atmospheres Of New Planets Might Have Unexpected Mixtures Of Hydrogen And Water

by Keith CowingMarch 28, 2025March 28, 2025

Recent studies show that the most common type of planets in our galaxy, those between the sizes of Earth and Neptune, typically form with a hydrogen atmosphere, resulting in conditions […]

Artist's illustration of a potential Hycean world, where methyl halide gases would be detectable in the atmosphere. Credit NASA, ESA, CSA, Joseph Olmsted/STScI

Astrochemistry, Astrogeology, Atmospheres, Climate, Weather, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Habitable Zones, Imaging & Spectroscopy, Press Release, Water/Hycean Worlds & Oceanography

Signs Of Alien Life May Be Hiding In These Gases

by Keith CowingMarch 13, 2025March 13, 2025

Scientists have identified a promising new way to detect life on faraway planets, hinging on worlds that look nothing like Earth and gases rarely considered in the search for extraterrestrials.

A hycean world -- Grok via Astrobiology.com

Atmospheres, Climate, Weather, Biochemistry & Organic Chemistry, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Habitable Zones, Icy Worlds, Imaging & Spectroscopy, Status Report, Water/Hycean Worlds & Oceanography

Examining the Potential for Methyl Halide Accumulation and Detectability in Possible Hycean-Type Atmospheres

by Keith CowingFebruary 24, 2025February 24, 2025

Some sub-Neptune planets may host habitable conditions; for example “Hycean” worlds with H2 envelopes over liquid water oceans can maintain potentially hospitable pressures and temperatures at their surface.

K2-18 b vertical velocity 𝜔 at the 0.01 bar level. Negative (positive) 𝜔 indicates upwards (downwards) motion. The global overturning circulation is clearly visible. Irradiation concentrated on the dayside heats and expands these atmospheric regions, driving upwards motion. There is corresponding subsidence on the nightside. -- astro-ph.EP

Atmospheres, Climate, Weather, Exoplanets, -moons, -comets, Habitable Zones, Status Report, TRAPPIST-1, Water/Hycean Worlds & Oceanography

A New Convection Scheme For GCMs Of Temperate Sub-Neptunes

by Keith CowingFebruary 19, 2025February 19, 2025

Atmospheric characterisation of temperate sub-Neptunes is the new frontier of exoplanetary science with recent JWST observations of possible Hycean world K2-18b.

Hycean world K2-18 b -- Grok via Astrobiology.com

Atmospheres, Climate, Weather, Biochemistry & Organic Chemistry, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Habitable Zones, Origin & Evolution of Life, Status Report, Water/Hycean Worlds & Oceanography

Prospects For Biological Evolution On Hycean Worlds

by Keith CowingFebruary 13, 2025February 13, 2025

Recent detections of carbon-bearing molecules in the atmosphere of a candidate Hycean world, K2-18 b, with JWST are opening the prospects for characterising potential biospheres on temperate exoplanets.