Higher Water Loss on Earth-like Exoplanets in Eccentric Orbits

Abstract The climate of a terrestrial exoplanet is controlled by the type host star, orbital configuration and characteristics atmosphere surface. Many rocky exoplanets have higher eccentricities than those in Solar System, about 18% planets with masses <10 M⊕ e > 0.1. Underexplored are implications such high on atmosphere, climate, potential habitability planets. We use WACCM6, state-of-the-art fully-coupled Earth-system model, to simulate climates two Earth-like planets; one circular orbit (e = 0), an eccentric 0.4) same mean insolation. quantify effects eccentricity atmospheric water abundance loss given importance liquid for habitability. asymmetric temperature response results vapour mixing ratio stratosphere (>20 ppmv) that approximately five times greater (∼4 ppmv). This leads at most ∼3 increases both hydrogen rate ocean compared case. Using Planetary Spectrum Generator, we idealised transmission spectra cases. find absorption features stronger all wavelengths 0.4 spectrum Hence, highly-eccentric may be prime targets future spectroscopy observations confirm, or otherwise, presence vapour.