water world Archives - Page 8 of 14 - Astrobiology

Mass of surface water in the collapsed state as a function of the stellar flux S∗ and the background surface pressure pdry (A), and a function of S∗ and the CO2 concentration fCO2 (B). In panel(A), fCO2 = 376 ppmv; in panel(B), pdry = 1 bar. Gray dashed curves in both panels mark the boundaries of runaway greenhouse state where no surface water can exist, and red stars correspond to the example shown in Figure 2. -- astro-ph.EP

Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Habitable Zones, Status Report, Venus, Water/Hycean Worlds & Oceanography

Retention Of Surface Water On Tidally Locked Rocky Planets In The Venus Zone Around M Dwarfs

by Keith CowingMay 20, 2025May 20, 2025

Terrestrial planets within the Venus zone surrounding M dwarf stars can retain surface ice caps on the perpetual dark side if atmospheric heat transport is inefficient, (as suggested by previous […]

Exoplanets with masses error and radii error less than 25%. Symbol size is proportional to mass. Colors correspond to equilibrium temperatures calculated with bond albedos of 0.3 and redistribution factors of 4. Colors are loosely binned according to physical processes: planets with icy surfaces should they have any water (0-273 K), planets that allow for liquid water (273-373 K), planets that are in runaway greenhouse below the critical point of water (373-670K), hot planets that cannot have water clouds (670-1200K) and magnetic effects on their atmospheres are negligible, hot planets where magnetic effects like ohmic dissipation are important, very hot planets where magnetic effects are less important (due to full ionization and freezing to magnetic field). Solar system planets are labeled and shown as black symbols for reference. -- astro-ph.EP

Astrochemistry, Astrogeology, Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Exoplanets, -moons, -comets, Gaia - Planetary Perspectives, Gas Giants, Ice Giant, Icy Worlds, Status Report, Water/Hycean Worlds & Oceanography

Diversity Of Exoplanets

by Keith CowingMay 16, 2025

This review article delves into the study of low-mass exoplanets: super-Earths, mini-Neptunes and the new categories within and between that we are starting to discover.

Phase folded and offset-subtracted ESPRESSO RVs with the modeled best-fit allesfitter RV curve for HD 35843 b (left) and HD 35843 c (right), with residuals plotted on the bottom. Stellar jitter has been added in quadrature with measurement uncertainties. -- astro-ph.EP

Astronomy & Telescopes, Exoplanets, -moons, -comets, Habitable Zones, Imaging & Spectroscopy, Status Report, Water/Hycean Worlds & Oceanography

HD 35843: A Sun-like Star Hosting A Long Period Sub-Neptune And Inner Super-Earth

by Keith CowingMay 5, 2025May 5, 2025

We report the discovery and confirmation of two planets orbiting the metal-poor Sun-like star, HD 35843 (TOI 4189). HD 35843 c is a temperate sub-Neptune transiting planet with an orbital […]

Cartoon explaining the mechanism behind the formation of self-sustaining vortices at the temperature plateau at water snow region. The temperature substructure gives rise to marginal mismatch in the gas accretion rates, seeding the initial perturbation in gas surface density. The dust is attracted towards the resulting pressure maximum, which in turn lowers the local dust-dependent viscosity. This in turn causes a bottleneck to angular momentum transport, amplifying the perturbation in gas and thus, leading to positive feedback loop. In a one-dimensional disk, such a feedback leads to viscous ring instability (VRI), forming multiple concentric rings. In two-dimensional simulations, the gradient of gas surface density eventually becomes sharp enough to trigger Rossby wave instability and vortices are formed. The positive feedback responsible for VRI contributes towards stability of formed vortices. -- astro-ph.EP

Astrochemistry, Astrogeology, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Icy Worlds, Imaging & Spectroscopy, Status Report, Water/Hycean Worlds & Oceanography

Dust-driven Vortex Cascades Originating At Water Snow Region: A Pathway To Planetesimal Formation

by Keith CowingApril 29, 2025April 29, 2025

The origin of observed planetary systems, including our solar system, as well as their diversity is still an open question.

Global distribution of serpentinization-influenced environments that have been investigated microbiologically and those that hosted 70 publicly available shotgun metagenomes used in the meta-analysis of this review. Geologic systems are indicated by points and abbreviations on the map, with those in green hosting metagenomes that were used in the meta-analysis of this review. Bottom left insert shows the pH distribution of water samples from which the metagenomes were derived, as reported by the original publication. Additional information for metagenomes is shown in Supplementary Table 1. Abbreviations are defined as follows (and further identified in Supplementary Table 1). NEY: Ney Springs; CED: The Cedars; CROMO: Coast Range Ophiolite Microbial Observatory; SEO: Santa Elena Ophiolite; TBL: Tablelands Ophiolite; RHF: Rainbow Hydrothermal Field; LCHF: Lost City Hydrothermal Field; LVF: Logatchev Vent Field; AVF: Ashadze Vent Field; AUR: Aurora Seamount; LEKA: Leka Ophiolite; CDV: Cabeço de Vide; VOL: Voltri Massif; YAN: Yanartaş; ALL: Allas Springs; SAM: Samail Ophiolite; KMR: Khalilovsky Massif; KHF: Karei Hydrothermal Field; OCHF: Old City Hydrothermal Field; HHS: Hakuba Happo Hot Springs; MAN: Manleluag Spring; LCR: La Crouen Spring; PBHF: Prony Bay Hydrothermal Field. -- ISME via PubMed

Biochemistry & Organic Chemistry, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Extremeophiles and Extreme Environments, Fossils & Paleontology, Gaia - Planetary Perspectives, Habitable Zones, Icy Worlds, Origin & Evolution of Life, Status Report, Water/Hycean Worlds & Oceanography

Microbial Ecology Of Serpentinite-hosted Ecosystems

by Keith CowingApril 8, 2025April 8, 2025

Serpentinization, the collective set of geochemical reactions initiated by the hydration of ultramafic rock, has occurred throughout Earth history and is inferred to occur on several planets and moons in […]

Mosaic of the Valles Marineris hemisphere of Mars projected into point perspective, a view similar to that which one would see from a spacecraft. The distance is 2500 kilometers from the surface of the planet, with the scale being .6km/pixel. The mosaic is composed of 102 Viking Orbiter images of Mars. The center of the scene (lat -8, long 78) shows the entire Valles Marineris canyon system, over 2000 kilometers long and up to 8 kilometers deep, extending form Noctis Labyrinthus, the arcuate system of graben to the west, to the chaotic terrain to the east. Many huge ancient river channels begin from the chaotic terrain from north-central canyons and run north. The three Tharsis volcanoes (dark red spots), each about 25 kilometers high, are visible to the west. South of Valles Marineris is very ancient terrain covered by many impact craters. Credit: NASA

Astrogeology, Biogeochemical Cycles & Geobiology, Habitable Zones, Mapping, Geodesy, Cartography, Bathymetry, Mars, Press Release, Water/Hycean Worlds & Oceanography

New Study on Why Mars Is Red Supports Potentially Habitable Past

by Keith CowingApril 6, 2025April 6, 2025

A new international study partially funded by NASA on how Mars got its iconic red color adds to evidence that Mars had a cool but wet and potentially habitable climate […]

Observable signatures and freezing characteristics for the 1 km thick reservoir located 1 km deep below Europa’s surface. -- Nature

Astrogeology, Biochemistry & Organic Chemistry, Biogeochemical Cycles & Geobiology, Cryobiology, Europa, Habitable Zones, Icy Worlds, Imaging & Spectroscopy, Missions & Hardware, Status Report, Water/Hycean Worlds & Oceanography

Identifying Signatures Of Past And Present Cryovolcanism On Europa

by Keith CowingApril 4, 2025April 4, 2025

Europa, the most visibly active icy moon of Jupiter, is a prime target for the search for life in the outer solar system.

The “HCN machine”: Geological, atmospheric, meteoritic, and chemical processes synthesizing the building blocks of life on the Hadean Earth (artist’s impression, own creation, © Klaus Paschek).

Astrochemistry, Astrogeology, Atmospheres, Climate, Weather, Biochemistry & Organic Chemistry, Biogeochemical Cycles & Geobiology, Biophysics, Biosignatures & Paleobiology, Habitable Zones, Impact events, Lava / magma ocean / Volcanic Worlds, Origin & Evolution of Life, Panspermia, Status Report, Water/Hycean Worlds & Oceanography

Deep Mantle-Atmosphere Coupling And Carbonaceous Bombardment: Options For Biomolecule Formation On Aan Oxidized Early Earth

by Keith CowingMarch 21, 2025March 21, 2025

Understanding what environmental conditions prevailed on early Earth during the Hadean eon, and how this set the stage for the origins of life, remains a challenge.

Top row: Final semi-major axes and planet masses for the planet population after disc dissipation. The color denotes the final atmosphere mass fraction. The dashed lines show the pebble isolation mass at the start and end of the disc lifetime; the variation is due to the temporal change of the stellar luminosity. Bottom row: Atmosphere mass fraction as a function of core masses. The colors of the points show the injection location in the disc. In the left column we show the the population when gas accretion at the inner edge is halted. In the middle column we show the population when gas accretion continues at the inner edge while in the right column we show the planet population when we vary the inner edge. In general, atmosphere mass fractions for massive cores are similar in all three models. If gas accretion is halted at the inner edge, atmosphere mass fractions are low (up to ∼0.1-5%) due to the efficient migration happening in the disc. When gas accretion continues at the inner edge, the atmosphere mass fractions of the smallest cores can reach up to 1%. Finally, when varying the inner edge, planets that are accreting gas further away from the star are able to accrete more gas due to more efficient contraction, reaching atmosphere mass fractions of almost ∼10%. -- astro-ph.EP

Exoplanets, -moons, -comets, Habitable Zones, Imaging & Spectroscopy, Status Report, Stellar Cartography, Water/Hycean Worlds & Oceanography

A Primordial Radius Valley As A Consequence Of Planet Formation

by Keith CowingFebruary 18, 2025

The radius distribution of close-in planets has been observed to have a bimodal distribution with a dearth of planets around ~1.5-2.0 R⊕ commonly referred to as the ”radius valley”.

Ocean on Ancient Earth -- Grok via Astrobiology.com

Atmospheres, Climate, Weather, Biochemistry & Organic Chemistry, Biogeochemical Cycles & Geobiology, Biophysics, Biosignatures & Paleobiology, Habitable Zones, Origin & Evolution of Life, Press Release, Water/Hycean Worlds & Oceanography

When Did Earth’s Ocean Acidity Allow Life To Commence?

by Keith CowingFebruary 18, 2025February 18, 2025

Scientists at Yale and in Singapore have devised what may be the ultimate acid test — a comprehensive model for estimating the origins of Earth’s habitability, based in part on […]