Habitable Zone Archives

RV dataset of HD 20794 for the different datasets. The HARPS RVs have been extracted using YARARA (Cretignier et al. 2021a, 2023). For ESPRESSO, RVs have been extracted with sBART (Silva et al. 2022). -- Astronomy and Astrophysics

Astronomy & Telescopes, Exoplanets, -moons, -comets, Habitable Zones, Imaging & Spectroscopy, Press Release

A Super-Earth Laboratory For Searching Life Elsewhere In The Universe

by Keith CowingFebruary 2, 2025February 1, 2025

‘‘Are we alone in the Universe?’’ For thousands of years, this question was confined to philosophy, and it is only very recently that modern science has begun to provide solid […]

Statistical power of the habitable zone oxygen hypothesis test on the ELT for different values of η⊕ and different fractions of exo-Earth candidates (EECs, left) and fractions of exo-super Earth candidates (ESECs, right) with Earth-like levels of O2. Statistical power contours for 50% and 95% are shown in black. More planets with oxygen and/or higher values for η⊕ result in a greater ability to test this hypothesis, however, the inclusion of all super-Earths does not necessarily improve this ability. We note that these figures are super-sampled to highlight differences. -- astro-ph.EP

Astrochemistry, Astronomy & Telescopes, Atmospheres, Climate, Weather, Biochemistry & Organic Chemistry, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Habitable Zones, Imaging & Spectroscopy, Proxima Centauri, Status Report

Bioverse: GMT and ELT Direct Imaging and High-Resolution Spectroscopy Assessment – Surveying Exo-Earth O2 and Testing the Habitable Zone Oxygen Hypothesis

by Keith CowingFebruary 1, 2025February 1, 2025

Biosignature detection in the atmospheres of Earth-like exoplanets is one of the most significant and ambitious goals for astronomy, astrobiology, and humanity. Molecular oxygen is among the strongest indicators of […]

Cartoon depiction of the sulfur-cycle in different planetary regimes. In the Earthlike case (A), atmospheric SO2 is scrubbed from the atmosphere by wet deposition (19). In the Venus-like case with high-UV irradiation (B), for example irradiation by the Sun, SO2 can be abundant in the deep atmosphere, however in the upper atmosphere SO2 is efficiently catalysed into H2SO4 by UV photons and subsequent reaction with H2O (80). In the Venus-like case with low-UV irradiation (C), such as irradiation by a low-UV M-dwarf, SO2 can survive in the upper atmosphere (20), potentially enabling SO2 to be identified in spectroscopic observation and thereby revealing the lack of a surface water ocean. -- astro-ph.EP

Astronomy & Telescopes, Atmospheres, Climate, Weather, Exoplanets, -moons, -comets, Habitable Zones, Status Report, Stellar Cartography

Tracing the Inner Edge of the Habitable Zone with Sulfur Chemistry

by Keith CowingJanuary 31, 2025January 31, 2025

The circumstellar liquid-water habitable zone guides our search for potentially inhabited exoplanets, but remains observationally untested. We show that the inner edge of the habitable zone can now be mapped […]

Exoplanet HD 20794 d -- University of Oxford

Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Exoplanets, -moons, -comets, Habitable Zones, Press Release, Water/Hycean Worlds & Oceanography

Existence Of Exoplanet HD 20794 d In A Habitable Zone Confirmed

by Keith CowingJanuary 28, 2025January 28, 2025

An international team has confirmed the discovery of a super-Earth orbiting in the habitable zone of a nearby Sun-like star. The planet was originally detected two years ago by Oxford […]

All known exoplanets shown in terms of their host star’s temperature and the incident stellar flux they receive. Transiting rocky exoplanets are shown as circles, planets where only minimum mass is known as diamonds. Exoplanets in the HZ are shown in blue, with exoplanets ≤ 2 𝑅⊕ and ≤ 5 𝑀⊕ shown as smaller symbols in solid colors. Empirical HZ limits and the 3D inner HZ limit are shown as dashed lines. A light gray line indicates similar irradiation to modern Earth for different stellar temperatures. -- astro-ph.SR

Astropharmacy / Biotechnology, Biogeochemical Cycles & Geobiology, Biophysics, Exoplanets, -moons, -comets, Habitable Zones, Status Report, Water/Hycean Worlds & Oceanography

Probing The Limits of Habitability: A Catalog Of Rocky Exoplanets In The Habitable Zone

by Keith CowingJanuary 27, 2025January 27, 2025

Several ground- and space-based searches have increased the number of known exoplanets to nearly 6000. While most are highly unlike our planet, the first rocky worlds in the Habitable Zone […]

The mean iceline latitude as a function of orbit-averaged solar constant for planets in warm-start and coldstart scenario orbiting F-, G-, K-, and M-dwarf host stars are shown. The warm-start cases are represented by dotted lines, and the cold-start cases are shown by solid lines. The green, blue, and orange lines correspond to eccentricities of 0, 0.5, and 0.9, respectively. -- -- astro-ph.EP

Astrochemistry, Astrogeology, Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Habitable Zones, Icy Worlds, Status Report

A One-Dimensional Energy Balance Model Parameterization for the Formation of CO2 Ice on the Surfaces of Eccentric Extrasolar Planets

by Keith CowingJanuary 24, 2025January 24, 2025

Eccentric planets may spend a significant portion of their orbits at large distances from their host stars, where low temperatures can cause atmospheric CO2 to condense out onto the surface, […]

Borehole -- Sanford Underground Research Facility

Analog Studies, Biogeochemical Cycles & Geobiology, Biophysics, Biosignatures & Paleobiology, Caves, Craters, Mountains, Subsurface, Lava Tubes, Exploration Gear & Tech, Extremeophiles and Extreme Environments, Habitable Zones, Microbiology & Virology, Origin & Evolution of Life, Sample Return, Status Report, Water/Hycean Worlds & Oceanography

Calorimetric Measurement Of Energy And Nutrient Stimulation Of Microorganisms From The Continental Deep Subsurface

by Keith CowingJanuary 18, 2025January 18, 2025

Microbial activity in the deep continental subsurface is difficult to measure due to low cell densities, low energy fluxes, cryptic elemental cycles and enigmatic metabolisms. Nonetheless, direct access to rare […]

Beating planets mimic synchronous circulation patterns despite being asynchronous and show long-term variability. a. Height map of an Earth-like asynchronous planet when subjected to time-varying instellation of period same as that of rotation (= 1 day). Note that the fixing of the hotspot to the planet-frame-of-reference makes it similar to the tidally synchronous case in Fig. 2 (top). The colorbar used is the same as above. b1-b3. Motion of substellar point (green) and the corresponding hotspot (black) for ω = 2π/(1, 1.01, and 0.99) days−1 , respectively. When instellation is constant the hotspot simply lags the substellar point as in Fig. 2 (bottom). However, due to varying instellation, here we observe a fixed, an eastward, and a westward creeping hotspot, respectively, for the same remaining parameters. Note that the large oscillations between 0◦ and 360◦ in b2-b3 occur because 0◦ and 360◦ are effectively the same longitudes on a spherical planet. -- astro-ph.EP

Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Habitable Zones, Status Report, Stellar Cartography

Planetary Rhythms: Synchronous Circulation On Variably Irradiated Asynchronous Planets

by Keith CowingJanuary 18, 2025January 18, 2025

Tidal locking of planets to their host stars results in an atmospheric circulation with a hotspot fixed to the frame of reference of the planet. On the other hand, asynchronously […]

Ocean retention (in terrestrial oceans) for a planet with 1 T.O. of initial surface water orbiting a 0.8 M⊙ white dwarf as a function of its final orbital distance af and the planet’s time of arrival at its observed orbit (measured since the white dwarf’s formation). Red shading represents desiccation of the planetary surface, while blue shading represents substantial retention or surface water. The black lines denote the boundaries of the habitable zone. -- astro-ph.EP

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

Long-lived Habitable Zones Around White Dwarfs Undergoing Neon-22 Distillation

by Keith CowingJanuary 14, 2025September 18, 2025

White dwarf stars have attracted considerable attention in the past 15 years as hosts for potentially habitable planets, but their low luminosity and continuous cooling are major challenges for habitability.

Biophysics, Biosignatures & Paleobiology, Commercial & Private Sector, Extremeophiles and Extreme Environments, Habitable Zones, Microbiology & Virology, Nanotechnology & SynBio, Origin & Evolution of Life, Status Report

Extremophiles and Extremophilic Behaviour – New Insights and Perspectives

by Keith CowingJanuary 13, 2025January 12, 2025

Extremophiles, throughout evolutionary time, have evolved a plethora of unique strategies to overcome hardships associated with the environments they are found in.

Habitable Zone

A Super-Earth Laboratory For Searching Life Elsewhere In The Universe

Bioverse: GMT and ELT Direct Imaging and High-Resolution Spectroscopy Assessment – Surveying Exo-Earth O2 and Testing the Habitable Zone Oxygen Hypothesis

Tracing the Inner Edge of the Habitable Zone with Sulfur Chemistry

Existence Of Exoplanet HD 20794 d In A Habitable Zone Confirmed

Probing The Limits of Habitability: A Catalog Of Rocky Exoplanets In The Habitable Zone

A One-Dimensional Energy Balance Model Parameterization for the Formation of CO2 Ice on the Surfaces of Eccentric Extrasolar Planets

Calorimetric Measurement Of Energy And Nutrient Stimulation Of Microorganisms From The Continental Deep Subsurface

Planetary Rhythms: Synchronous Circulation On Variably Irradiated Asynchronous Planets

Long-lived Habitable Zones Around White Dwarfs Undergoing Neon-22 Distillation

Extremophiles and Extremophilic Behaviour – New Insights and Perspectives

COP31 Ice Planet Update: Earth’s Cryosphere Decline Is Beyond Safe Planetary Limits

Possible Lake Remnants Inside a Crater at the Edge of Isidis Planitia, Mars

Seven Genome Sequences Of Bacterial Environmental Isolates From The Western Coast Of The Greenland Ice Sheet

Cosmic-ray Particles Can Help Probe The Powerful Electric Fields Inside Earth’s Thunderstorms

When Communication Enables Catastrophe: Nuclear Risk and the Short Lifetimes of Technological Civilizations: A Bayesian Scenario Analysis of Civilizational Survival and the Fermi Paradox