Presentation #132.01 in the session Extrasolar Planets: Populations I.
Signatures of life beyond Earth continues with ongoing ground and space-based transmission spectroscopy campaigns to search for the biosphere of a temperate, Earth-like exoplanet. Jupiter’s moon Europa however, offers a distant vantage point beyond the canonical habitable zone where life may exist today, born in a tidally-heated saltwater ocean. Given the potential for ocean worlds to multiply the number of nearby habitable systems in the galaxy, we study the cryomagma ascent and outgassing of possible Europa-like exomoons, hereafter “exo-Europas”. We present the boundary conditions over which these hidden ocean worlds can overwhelm exoplanet atmosphere signatures via evaporative transmission spectroscopy at the resonance lines of sodium and potassium (Na/K), as well as molecular oxygen (O2) and water-product bands. Our model treats the eruption and escape of magmatic liquid water (along with trace constituents of salts and O2) from two reservoirs: (I) temperate and (II) tidally-heated, corresponding to two distinct orbital scenarios of a surface and sub-surface saltwater ocean at ~1 AU and beyond. Our predictions therefore serve as spectral guides for future searches for transiting exomoons and, in principle, life.