A New Desalination Pump Help Define the pH of Ocean Worlds

Abstract

We study ocean exoplanets, for which the global surface ocean is separated from the rocky interior by a high-pressure ice mantle. We describe a mechanism that can pump salts out of the ocean, resulting in oceans of very low salinity. Here we focus on the H2O-NaCl system, though we discuss the application of this pump to other salts as well. We find our ocean worlds to be acidic, with a pH in the range of 2-4. We discuss and compare between the conditions found within our studied oceans and the conditions in which polyextremophiles were discovered. This work focuses on exoplanets in the super-Earth mass range (2 M_Earth), with water composing at least a few percent of their mass. Although, the principal of the desalination pump may extend beyond this mass range.

arXiv comment61 pages, 18 figures, accepted for publication in ApJ

References in corpus (12)

• Seven temperate terrestrial planets around the nearby ultracool dwarf star TRAPPIST-1
• The Mass Dependence Between Protoplanetary Disks and their Stellar Hosts
• A New Family of Planets ? "Ocean Planets"
• Volatile-Rich Earth-Mass Planets in the Habitable Zone
• Habitable Evaporated Cores: Transforming Mini-Neptunes into Super-Earths in the Habitable Zones of M Dwarfs
• Age consistency between exoplanet hosts and field stars
• The mass of the Mars-sized exoplanet Kepler-138 b from transit timing
• Formation and composition of planets around very low mass stars
• Scaling of plate-tectonic convection with pseudoplastic rheology
• The Abundance of Atmospheric CO2 in Ocean Exoplanets: A Novel CO2 Deposition Mechanism
• Structure and Dynamics of Cold Water Super-Earths: The Case of Occluded CH4 and its Outgassing
• Volatile Transport inside Super-Earths by Entrapment in the Water Ice Matrix

Cited by in corpus (5)

• Habitability of Exoplanet Waterworlds
• New Perspectives on the Exoplanet Radius Gap from a Mathematica Tool and Visualized Water Equation of State
• Super-Earths and Earth-like Exoplanets
• Dependence of Biological Activity on the Surface Water Fraction of Planets
• Internal Structure and CO${}_2$ Reservoirs of Habitable Water-Worlds