white dwarf Archives - Page 2 of 4 - Astrobiology

LEFT: Predicted 22Ne mass fraction as a function of metallicity for the WD remnants of stars in the Hypatia Catalog (Hinkel et al. 2014). The colors represent [N/H] for the same stars. MIDDLE and RIGHT: C and N abundances of the same stars from the Hypatia Catalog. The color bars represent the predicted neon mass fraction, X(22Ne), in their remnants. Two chemically peculiar low-metallicity objects, BD+80 245 and HD 19445, are labeled and marked as stars. -- astro-ph.SR

Astronomy & Telescopes, Habitable Zones, Imaging & Spectroscopy, Status Report, Stellar Cartography

The Fraction Of Distilled White Dwarfs With Long-Lived Habitable Zones

by Keith CowingAugust 19, 2025

After carbon and oxygen, 22Ne is the most abundant element in white dwarf interiors. As C/O white dwarfs (WDs) crystallize, they are predicted to go through a distillation process in […]

False-color image of the WD 1856+534 system constructed using three JWST/MIRI imaging bands: F770W (7.7 µm, blue), F1500W (15 µm, green), and F1800W (18 µm, red). The FOV measures 74′′× 113′′, corresponding to 1835 AU × 2802 AU at the system’s distance of 24.8 pc. The (blended) white dwarf and planet are the bluish-white star at the center of the image. The two bright stars near the right-hand side of the field of view (FOV) are mid-M dwarf companion stars to the white dwarf, at a projected separation of 1030 AU. Numerous colorful background stars and galaxies are visible throughout the image -- astro-ph.EP

Astronomy & Telescopes, Atmospheres, Climate, Weather, Exoplanets, -moons, -comets, Gas Giants, Icy Worlds, Imaging & Spectroscopy, Status Report

Thermal Emission and Confirmation of the Frigid White Dwarf Exoplanet WD 1856+534b

by Keith CowingApril 25, 2025April 25, 2025

We report the detection of thermal emission from and confirm the planetary nature of WD 1856+534b, the first transiting planet known to orbit a white dwarf star.

Astrochemistry, Astronomy & Telescopes, Atmospheres, Climate, Weather, Biochemistry & Organic Chemistry, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Icy Worlds, Imaging & Spectroscopy, Status Report

MIRI-LRS Spectrum Of A Cold Exoplanet Around A White Dwarf: Water, Ammonia, And Methane Measurements

by Keith CowingMarch 14, 2025March 14, 2025

The study of the atmosphere of exoplanets orbiting white dwarfs is a largely unexplored field. With WD 0806-661 b, we present the first deep dive into the atmospheric physics and […]

A planet orbiting a white dwarf star -- Grok via Astrobiology.com

Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Habitable Zones, Press Release

Gauging The Livability Of Exoplanets Orbiting White Dwarf Stars

by Keith CowingFebruary 25, 2025September 18, 2025

Among the roughly 10 billion white dwarf stars in the Milky Way galaxy, a greater number than previously expected could provide a stellar environment hospitable to life-supporting exoplanets, according to […]

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.

A parameter space plot showing ocean survival plotted by planet final semi-major axis and the time since white dwarf formation at which the scattering event occurred. This plot was constructed for an Earth-like planet with an initial semi-major axis of 5 AU, varying initial eccentricity, and an initial ocean mass of 1 TO. The location of the habitable zone, defined by where water could be liquid on the surface of an Earth-like planet, is overlaid. -- astro-ph.EP

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

The Fate of Oceans on First-Generation Planets Orbiting White Dwarfs

by Keith CowingDecember 18, 2024December 19, 2024

Several groups have recently suggested that small planets orbiting very closely around white dwarf stars could be promising locations for life to arise, even after stellar death. There are still […]

Climate comparison of a non-synchronous, fast-rotating K62 planet with both synchronous planets. The non-synchronous K62 planet is warmer overall, with a surface temperature pattern that is longitudinally homogeneous. All longitudes of the planet receive sunlight over some portion of the planet’s 10-hr day, giving rise to a lower cloud fraction and a larger amount of ice contributing to the surface and TOA albedos than the synchronous planets’ (dayside) ice. This higher fraction of dayside ice on the non-synchronous planet contributes to a larger equator-to-pole temperature difference compared to either of the synchronous planets, as shown in Figure 8A. Relevant values for surface temperature, TOA albedo, and ice fraction are given in Table 2. -- astro-ph.EP

Astronomy & Telescopes, Atmospheres, Climate, Weather, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Gas Giants, Habitable Zones, Icy Worlds, Status Report, Water/Hycean Worlds & Oceanography

Increased Surface Temperatures of Habitable White Dwarf Worlds Relative to Main-Sequence Exoplanets

by Keith CowingDecember 6, 2024December 6, 2024

Discoveries of giant planet candidates orbiting white dwarf stars and the demonstrated capabilities of the James Webb Space Telescope bring the possibility of detecting rocky planets in the habitable zones […]

Habitable zone for a white dwarf (blue region) at ages of 2, 6, and 10 Gyr compared to the habitable zone of the red dwarf TRAPPIST-1 (orange region). The inset shows the size comparison of a typical 0.6M⊙ white dwarf (cyan region) to that of TRAPPIST-1 (pink region). The optimistic habitable zone for TRAPPIST-1 is calculated from the recent Venus and early Mars limits from Kopparapu et al. (2013) using the luminosity and effective temperature from Van Grootel et al. (2018). The magenta region specifies where overlap of the two habitable zones occurs. The dashed black line shows the orbital radius at which an Earth-like planet around a 0.6M⊙ white dwarf stays in the habitable zone for the maximum amount of time (i.e., maximum habitable lifetime), and the dashed red line shows the Roche limit (i.e., tidal disruption limit) for such a system. -- astro-ph.EP

Atmospheres, Climate, Weather, Biochemistry & Organic Chemistry, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Habitable Zones, Imaging & Spectroscopy, Origin & Evolution of Life, Status Report

Potential For Life To Exist And Be Detected On Earth-like Planets Orbiting White Dwarfs

by Keith CowingDecember 2, 2024December 2, 2024

With recent observations confirming exoplanets orbiting white dwarfs, there is growing interest in exploring and quantifying the habitability of temperate rocky planets around white dwarfs.

Overview of our models for gas disk and particles evolution in different disk regions. The blue and yellow particles represent silicates with and without refractory carbon. The light blue particles represent icy pebbles. The pink particles show the oxygen atoms which are formed by the destruction of oxygen molecules because of the FUV radiation which is described as red arrows. The light blue dashed line is the snow line. Icy pebbles enclosing many small silicates drift to the snow line (blue dashed line) from the outer region. Orange upper and lower layers are FUV-exposed regions, where oxygen atoms exist. -- astro-ph.EP

Astrochemistry, Astrogeology, Biochemistry & Organic Chemistry, Biosignatures & Paleobiology, Habitable Zones, Imaging & Spectroscopy, Interstellar, Status Report

Effect of Different Stickiness Between Icy and Silicate Particles on Carbon Depletion in Protoplanetary Disks

by Keith CowingOctober 12, 2024October 12, 2024

Earth and other rocky bodies in the inner Solar System are significantly depleted in carbon compared to the Sun and interstellar medium (ISM) dust.

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

This Rocky Planet Orbiting A White Dwarf Resembles Earth — 8 Billion Years From Now

by Keith CowingSeptember 27, 2024September 27, 2024

The discovery of an Earth-like planet 4,000 light years away in the Milky Way galaxy provides a preview of one possible fate for our planet billions of years in the […]