Habitable Zone Archives

Parameter space showing the effect of GR on eccentricity oscillations due to an exterior planetary companion for a variety of combinations of the mass ratio m2/m1 and semi-major axis ratio a2/a1. The interior planet was assumed to be a 1 M⊕ planet at 0.01 AU. When ξ < 1 (bottom-left, red), GR amplifies eccentricity oscillations; when ξ > 1 (top-right, black), GR suppresses them. The dashed line marks the transition as derived in F. C. Adams & G. Laughlin (2006). -- astro-ph.EP

Exoplanets, -moons, -comets, Habitable Zones, Status Report, Stellar Cartography

General Relativity Can Prevent a Runaway Greenhouse on Potentially Habitable Planets Orbiting White Dwarfs

by Keith CowingOctober 1, 2025October 1, 2025

Planets orbiting in the habitable zones of white dwarfs have recently been proposed as promising targets for biosignature searches.

Figure from Rebollido et al. (2024). The debris disk around Beta Pictoris seen with JWST/MIRI. -- astro-ph.IM

Astronomy & Telescopes, Beta Pictoris, Status Report

Debris Disks And Their Properties With The Habitable Worlds Observatory

by Keith CowingSeptember 30, 2025September 30, 2025

The study of the last stages of planet formation, also known as debris disks, is fundamental to place constrains on the formation of planetary sized bodies.

Exoplanets, -moons, -comets, Gaia - Planetary Perspectives, Habitable Zones, Status Report

Other Earths, Gaian bottlenecks and Darwinized Gaias

by Keith CowingSeptember 29, 2025September 29, 2025

In our galaxy, tens of billions of wet, rocky Earth-like planets orbit in the habitable zones of their host stars.

A directional flux beneath Navicula sp. via raphe grooves is revealed using fluorescent polystyrene beads (0.5 μ m), indicating that tracer particles latched to the ventral raphe move opposite to diatom motion. The thick curve shows the diatom’s trajectory; thin curves show tracer particles’ trajectories. Inset: Schematic illustrates tracer particles latched to mucilage threads that are moving along the ventral raphe. The tracer particle movement reflects internal acto-myosin kinetics. (Scale bar, 20 μm.) -- PNAS via PubMed

Analog Studies, Arctic / Antarctic / Alpine, Biosignatures & Paleobiology, Cryobiology, Extremeophiles and Extreme Environments, Genomics, Proteomics, Bioinformatics, Icy Worlds, Microbiology & Virology, Sample Return, Status Report

Ice Gliding Diatoms Establish Record-low Temperature Limits For Motility In A Eukaryotic Cell

by Keith CowingSeptember 29, 2025September 29, 2025

In the harsh Arctic environments, ice-dwelling diatoms remarkably survive and thrive, but their behavioral adaptations are poorly understood.

The modelled angular velocity evolution of stars of different masses, initial rotation periods and metallicities. The masses considered are 0.5𝑀 (left panel), 0.7𝑀 (middle panel) and 1𝑀 (right panel). The initial periods considered are 1 day (dashed lines) and 10 days (solid lines). The metallicities considered are -1 dex (dark blue lines), -0.5 dex (purple lines), 0 dex (orange lines) and +0.5 dex (yellow lines). The point at which the star transitions from the saturated to unsaturated regime (at Rocrit = 0.2) is indicated by a triangle along each track. -- astro-ph.EP

Astrochemistry, Atmospheres, Climate, Weather, Exoplanets, -moons, -comets, Habitable Zones, Space Weather & Heliophysics, Status Report

Modelling The Effect Of Stellar Metallicity On The XUV Evolution Of Low-mass Stars and its Impact on Exoplanet Atmospheres/habitability

by Keith CowingSeptember 29, 2025September 28, 2025

Understanding how exoplanet atmospheres evolve is a key question in the context of habitability. One key process governing this evolution is atmospheric evaporation by stellar X-ray and EUV emission (collectively, […]

Periodic table of elements and their nucleosynthesis. Biological utilisation of the elements and biometals (in orange and yellow) and their nucleosynthesis processes in the Universe are indicated. CHNOPS elements and elements used as electron donors/acceptors by biology are also reported. Iron and Manganese are the only biometals that not only serve as cofactors, but might also be used as metabolic substrates for redox reactions. -- astro-ph.EP

Astrobiology (general), Astrochemistry, Biochemistry & Organic Chemistry, Biogeochemical Cycles & Geobiology, Biophysics, Biosignatures & Paleobiology, Imaging & Spectroscopy, Interstellar, Status Report

Transition Metal Abundance As A Key Parameter For The Search Of Life In The Universe

by Keith CowingSeptember 28, 2025September 28, 2025

The search for Life in the Universe generally assumes three basic life’s needs: I) building block elements (i.e., CHNOPS), II) a solvent to life’s reactions (generally, liquid water) and III) […]

Signal amplitudes in the vicinity of the putative exomoon around β Pic b suggested by Poon et al. (2024) as a function of moon mass and semi-major axis for RV studies on the left and astrometric searches on the right. The grey shaded region is the parameter space where a P24- moon is likely to reside if it is indeed real. The dashed lines indicate contours delineating the provided signal strengths. -- astro-ph.EP

Astronomy & Telescopes, Exoplanets, -moons, -comets, Habitable Zones, Status Report

Astrometric Exomoon Detection By Means Of Optical Interferometry

by Keith CowingSeptember 27, 2025September 27, 2025

Context: With no conclusive detection to date, the search for exomoons, satellites of planets orbiting other stars, remains a formidable challenge. Detecting these objects, compiling a population-level sample and constraining […]

Stars selected by the AYO (Stark et al. 2024) 8m LUVOIR B yield calculation (left) and the 6m ”scenario F” yield calculation (right) in distance vs. luminosity space. Points are color coded based on the fraction of simulations in which each star was selected. Gray points in the background are the stars in the HPIC (Tuchow et al. 2024). -- astro-ph.IM

Astronomy & Telescopes, Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Habitable Zones, Status Report

HWO Target Stars And Systems: A Prioritized Community List of Potential Stellar Targets For The Habitable Worlds Observatory’s ExoEarth Survey

by Keith CowingSeptember 26, 2025September 26, 2025

The HWO Target Stars and Systems 2025 (TSS25) list is a community-developed catalog of potential stellar targets for the Habitable Worlds Observatory (HWO) in its survey to directly image Earth-sized […]

A panoramic picture of one of five hot springs during winter, showing the source water and CO2 bubbles. Credit Fatima Li-Hau, ELSI

Atmospheres, Climate, Weather, Away Teams & Field Reports, Biogeochemical Cycles & Geobiology, Biophysics, Biosignatures & Paleobiology, Extremeophiles and Extreme Environments, Habitable Zones, Microbiology & Virology, Origin & Evolution of Life, Press Release

Hot Springs In Japan Give Insight Into Ancient Microbial Life On Earth

by Keith CowingSeptember 26, 2025September 26, 2025

Earth was not always the blue-green world we know today: the early Earth’s oxygen levels were about a million times lower than we now experience. There were no forests and […]

A classification scheme for volatile-rich sub-Neptunes. The schematic compares different types of sub-Neptunes with H2 and H2O dominated atmospheres as a function of the equilibrium temperature and H2 content. Ice worlds: Cold subNeptunes where any water is frozen in a layer of ice atop high-pressure ice, with a thin H2-dominated atmosphere (65). Hycean worlds: Warmer than ice worlds, hycean worlds have a thin H2-rich atmosphere overlying an ocean of liquid water, which itself is above a layer of high-pressure ices. These planets have the potential to support habitable conditions (9). Mini-Neptunes: Sub-Neptunes with a deep H2-rich atmosphere followed by a mixed H2O-H2 supercritical layer below before reaching a layer of high-pressure ice and then a core (17, 65). Steam worlds: Water worlds with H2O dominated atmospheres. At equilibrium temperatures above Tcrit, a high proportion of H2O exists in the atmosphere, with a supercritical mixed-envelope at higher pressures. Supercritical mini-Neptunes: These planets are hotter than Tcrit, and contain interiors where H2 gas is highly soluble in supercritical H2O (46, 65). This mixed-envelope would lie over a layer of high-pressure ice above the core. Legend: The legend at the top shows the different compositions corresponding to the colors in the schematic, including the core, different phases of H2O and envelope composition; high-P ice refers to high-pressure ice. Note that the core has further distinct layers but we do not label them here. Sharp phase transitions are shown for ice-atmosphere and ocean-atmosphere transitions. Other phase transitions are marked by a gradient, as they may not be sharp phase transitions (83). -- astro-ph.EP

Astronomy & Telescopes, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Status Report

Exploring The Sub-Neptune Frontier With JWST

by Keith CowingSeptember 25, 2025September 25, 2025

Sub-Neptune planets, with sizes and masses between those of Earth and Neptune, dominate the exoplanet population.

Habitable Zone

General Relativity Can Prevent a Runaway Greenhouse on Potentially Habitable Planets Orbiting White Dwarfs

Debris Disks And Their Properties With The Habitable Worlds Observatory

Other Earths, Gaian bottlenecks and Darwinized Gaias

Ice Gliding Diatoms Establish Record-low Temperature Limits For Motility In A Eukaryotic Cell

Modelling The Effect Of Stellar Metallicity On The XUV Evolution Of Low-mass Stars and its Impact on Exoplanet Atmospheres/habitability

Transition Metal Abundance As A Key Parameter For The Search Of Life In The Universe

Astrometric Exomoon Detection By Means Of Optical Interferometry

HWO Target Stars And Systems: A Prioritized Community List of Potential Stellar Targets For The Habitable Worlds Observatory’s ExoEarth Survey

Hot Springs In Japan Give Insight Into Ancient Microbial Life On Earth

Exploring The Sub-Neptune Frontier With JWST

Astrobiologist Dale Andersen’s Antarctic Field Report: 9 November 2026: Lake Untersee Basecamp Update

Astrochemistry: Hubble and JWST Observe Star Formation in The Carina Nebula

Mapping the Historical Roots of Astrobiology: A Reference Publication Year Spectroscopy (RPYS) Analysis

The Agentic Observer Hackathon: Autonomous Decision-making in Simulated Astronomical Surveys

Tracking The Evolution of sub-Neptunes. I. Gyrochronology of Planet Hosting Stars