Orbital dependence of hydrogen (H₂) outgassing and atmospheric escape for planets L 98-59b (blue) and L 98-59d (orange). Solid lines represent energy-limited escape rates, while dashed lines show estimated H₂ outgassing rates driven by tidal heating for Earth-like outgassing conditions (moles H₂ kg⁻¹ magma). Shaded regions highlight the “outgassing zones” (OZs)—orbital ranges where volcanic H₂ outgassing exceed atmospheric escape, enabling the potential buildup of a secondary H₂-dominated atmosphere. The gray vertical band marks the conservative habitable zone (HZ) based on the R. K. Kopparapu et al. (2013) criteria. Points indicate the present-day semimajor axes of L 98-59b (circle) and d (square), showing that both planets reside inside their respective outgassing zones. The inner limit of the outgassing zone is not shown in the figure, as it lies interior to 0.01 au.