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Presence of water on exomoons orbiting free-floating planets: a case study

Published online by Cambridge University Press:  08 June 2021

Patricio Javier Ávila Open the ORCID record for Patricio Javier Ávila [Opens in a new window] ,
Tommaso Grassi ,
Stefano Bovino ,
Andrea Chiavassa ,
Barbara Ercolano ,
Sebastian Oscar Danielache  and
Eugenio Simoncini
Patricio Javier Ávila*
Affiliation:
Departamento de Astronomía, Facultad Ciencias Físicas y Matemáticas, Universidad de Concepción, Av. Esteban Iturra s/n Barrio Universitario, Casilla 160, Concepción, Chile
Tommaso Grassi
Affiliation:
Ludwig Maximilian University of Munich, Scheinerstr. 1, D-81673 Munich, Germany
Stefano Bovino
Affiliation:
Departamento de Astronomía, Facultad Ciencias Físicas y Matemáticas, Universidad de Concepción, Av. Esteban Iturra s/n Barrio Universitario, Casilla 160, Concepción, Chile
Andrea Chiavassa
Affiliation:
Universitè Côte d'Azur, Observatoire de la Côte d'Azur, CNRS, Laboratoire Lagrange, Bd de l'Observatoire, CS 34229, F-06304 Nice Cedex 4, France European Southern Observatory, Karl-Schwarzschild-Str. 2, D-85748 Garching bei München, Germany
Barbara Ercolano
Affiliation:
Ludwig Maximilian University of Munich, Scheinerstr. 1, D-81673 Munich, Germany
Sebastian Oscar Danielache
Affiliation:
Department of Material and Life Sciences, Faculty of Science and Technology, Sophia University, 8 Chiyoda, Tokyo 102-8554, Japan Earth and Life Science Institute, Tokyo Institute of Technology, Meguro, Tokyo 152-8551, Japan
Eugenio Simoncini
Affiliation:
Earth and Life Science Institute, Tokyo Institute of Technology, Meguro, Tokyo 152-8551, Japan
*
Author for correspondence: Patricio Javier Ávila, E-mail: [email protected]
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Abstract

A free-floating planet (FFP) is a planetary-mass object that orbits around a non-stellar massive object (e.g. a brown dwarf) or around the Galactic Centre. The presence of exomoons orbiting FFPs has been theoretically predicted by several models. Under specific conditions, these moons are able to retain an atmosphere capable of ensuring the long-term thermal stability of liquid water on their surface. We model this environment with a one-dimensional radiative-convective code coupled to a gas-phase chemical network including cosmic rays and ion-neutral reactions. We find that, under specific conditions and assuming stable orbital parameters over time, liquid water can be formed on the surface of the exomoon. The final amount of water for an Earth-mass exomoon is smaller than the amount of water in Earth oceans, but enough to host the potential development of primordial life. The chemical equilibrium time-scale is controlled by cosmic rays, the main ionization driver in our model of the exomoon atmosphere.

Keywords

Astrochemistryatmospheresplanets and satellites
Type
Research Article
Information
International Journal of Astrobiology , Volume 20 , Issue 4 , August 2021 , pp. 300 - 311
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Copyright © The Author(s), 2021. Published by Cambridge University Press

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