Internal Structure and CO$_2$ Reservoirs of Habitable Water-Worlds

Nadejda Marounina; Leslie A. Rogers

doi:10.3847/1538-4357/ab68e4

paper

Internal Structure and CO $_{2}$ Reservoirs of Habitable Water-Worlds

arXiv:1904.10458 · doi:10.3847/1538-4357/ab68e4

Abstract

Water-worlds are water-rich (>1 wt% H $_{2}$ O) exoplanets. The classical models of water-worlds considered layered structures determined by the phase boundaries of pure water. However, water-worlds are likely to possess comet-like compositions, with between ~3 mol% to 30 mol% CO $_{2}$ relative to water. In this study, we build an interior structure model of habitable (i.e. surface-liquid-ocean-bearing) water-worlds using the latest results from experimental data on the CO $_{2}$ -H $_{2}$ O system, to explore the CO $_{2}$ budget and to localize the main CO $_{2}$ reservoirs inside of these planets. We show that CO $_{2}$ dissolved in the ocean and trapped inside of a clathrate layer cannot accommodate a cometary amount of CO $_{2}$ if the planet accretes more than 11 wt% of volatiles (CO $_{2}$ + H $_{2}$ O) during its formation. We propose a new, potentially dominant, CO $_{2}$ reservoir for water-worlds: CO $_{2}$ buried inside of the high-pressure water ice mantle as CO $_{2}$ ices or (H $_{2}$ CO $_{3}$ . H $_{2}$ O), monohydrate of carbonic acid. If insufficient amounts of CO $_{2}$ are sequestered either in this reservoir or the planet's iron core, habitable zone water-worlds could generically be stalled in their cooling before liquid oceans have a chance to condense.

arXiv commentSubmitted to ApJ October 1st, 2018

Internal Structure and CO $_{2}$ Reservoirs of Habitable Water-Worlds

Abstract

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Cited by in corpus (8)

Internal Structure and CO2​ Reservoirs of Habitable Water-Worlds

Abstract

References in corpus (32)

Cited by in corpus (8)

Internal Structure and CO $_{2}$ Reservoirs of Habitable Water-Worlds