![Left: Orbital separations of inspiralling planets over time. Right: Mass accreted onto planets over time. For each initial planet mass, we show results for 𝜀 ∈ [0.01, 0.1, 0.3, 0.5, 1.0], with an increasing efficiency denoted by an increasing opacity. We also allow the accretion to increase up to 10× the Eddington limit, denoted by the dotted lines. Accretion stops when 𝑅𝐵 < 𝑅Jup (see §2.3). -- [astro-ph.EP]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/08/Atmospheric-Signatures.png?resize=1200%2C722&ssl=1)
[astro-ph.EP] The majority of confirmed exoplanets orbit within 1 au of a main-sequence (MS) star. When their stellar hosts evolve off the MS, many of these planets will be engulfed […]
WD 1856 b
![Best-fitting spectrum and atmospheric properties of WD 1856 b. a. Spectral decomposition illustrating the model components required to explain WD 1856 b’s JWST transmission spectrum (FIREFLy reduction; orange circles with 1 σ error bars). The best-fitting model (black curve) contains absorption from multiple CH4 features (purple shading), H2 + He continuum absorption (dark grey shading), and tentative evidence of C2H6 near 3.4 µm (brown shading) and PH3 near 4.3 µm (orange shading). Aerosol continuum opacity (silver shading) blocks thermal emission from the deep atmosphere in windows between CH4 bands, obscuring the ‘negative spikes’ that would otherwise be observed near 0.7 µm, 2.9 µm, and longwards of 4.0 µm for a clear atmosphere. The best-fitting model without nightside thermal emission (blue dashed curve) cannot explain the significantly lower transit depths longwards of 3.5 µm. b. Retrieved atmospheric properties, planetary mass, and aerosol properties from WD 1856 b’s JWST transmission spectrum for the FIREFLy (orange histograms) and Juniper (green histograms) data reductions. The median (solid line) and 1 σ credible intervals for each parameter (dashed lines) are overlaid. c. Residuals between the data and best-fitting model. -- [astro-ph.EP]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/07/Aerosols.png?resize=1200%2C719&ssl=1)
Posted inAtmospheres, Climate, Weather
Aerosols And Hydrocarbons In The Atmosphere Of A White Dwarf Planet
[astro-ph.EP] Most stars, including our Sun, will one day evolve into red giants and, subsequently, white dwarfs. Several planet candidates have recently been identified orbiting white dwarfs, demonstrating that planets […]
Posted inAstronomy & Telescopes, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Press Release
The Giant Nature Of WD 1856 b Implies That Transiting Rocky Planets Are Rare Around White Dwarfs
White dwarfs (WDs) have roughly Earth-sized radii – a fact long recognized to facilitate the potential discovery of sub-Earth sized planets via transits, as well atmospheric characterization including biosignatures.