of this compositional range are less likely to produce planets able to tectonically regulate their climate and may be inhospitable to life as we know it.'
author:
- 'Cayman T. Unterborn'
- 'Scott D. Hull'
- Lars Stixrude
- 'Johanna K. Teske'
- 'Jennifer A. Johnson'
- 'Wendy R. Panero'
bibliography:
- 'main.bib'
date: June 2017
title: Stellar Chemical Clues as to The Rarity of Exoplanetary Tectonics
---

Introduction
============

The Earth is unique in our Solar System. It is the only planet with plate tectonics and liquid water on the surface. It is not known, however, the extent to which the Earth is unique among all terrestrial planets beyond our Solar System. The *Kepler* mission’s discoveries establish that Earth-sized planets are common in the Galaxy, with as many as 11% of Sun-like stars hosting planets 1-2 times the radius of the Earth and receiving comparable solar flux [@Marc14; @Fult17]. Together with other discovery campaigns, we know now of many exoplanets with masses and radii consistent with being terrestrial, rock/metal-dominated planets, rather than gas-dominated. The degree to which these planets can maintain surface oceans, plate tectonics or even be considered “Earth-like” is not known and is a complex function of 