Lyman-α Archives

Sky map of the Lyα brightness seen from Europa for visit 12 (Jan 26, 2015) from interplanetary medium H scattering model (Pryor et al. 2024). The direction to the Sun is shown by the small white circle, the anti-Sun direction is shown by the white asterisk. -- astro-ph.EP

Astrochemistry, Astronomy & Telescopes, Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Europa, Icy Worlds, Imaging & Spectroscopy, Space Weather & Heliophysics, Status Report

Europa’s Lyman-α Emissions From HST/STIS Observations

by Keith CowingApril 23, 2026April 23, 2026

Context. An image of Lyman-α (Lyα) emission from Europa obtained with the Hubble Space Telescope’s Space Telescope Imaging Spectrograph (HST/STIS) provided the first evidence for localized water vapor (H2O) aurora, […]

Temperature-column mass structures for the models of each star. We shade the approximate temperature ranges over which the core and wings of Lyα forms in purple (≈8000–25,000 K for the core, and ≈4000–7500 K for the wings), the actual range of temperatures varies by star and is determined by where the optical depth, τ (λ), equals to one. -- astro-ph.SR

Astronomy & Telescopes, Atmospheres, Climate, Weather, Exoplanets, -moons, -comets, Habitable Zones, Imaging & Spectroscopy, Interstellar, Press Release

Lyman-Alpha Emission From K And M Dwarfs: Intrinsic Profiles, Variability, And Flux In The Habitable Zone

by Keith CowingSeptember 12, 2025September 12, 2025

Lyman-α (Lyα) is the most prominent ultraviolet emission line in low-mass stars, playing a crucial role in exoplanet atmospheric photochemistry, heating, and escape.