Potential Habitability as a Stellar Property: Effects of Model Uncertainties and Measurement Precision

Abstract

Knowledge of a star’s evolutionary history combined with estimates of planet occurrence rates allows one to infer whether a star would be a good target in a search for biosignatures, and to quantify this intuition using long-term habitability metrics. In this study, we analyze the sensitivity of the biosignature yield metrics formulated by Tuchow & Wright to uncertainties in observable stellar properties and to model uncertainties. We characterize the uncertainties present in fitting models to stellar observations by generating a stellar model with known properties and adding synthetic uncertainties in the observable properties. We scale the uncertainty in individual observables and observe the effects on the precision of properties such as stellar mass, age, and our metrics. To determine model uncertainties, we compare four well-accepted stellar models using different model physics and see how they vary in terms of the values of our metrics. We determine the ability of future missions to rank target stars according to these metrics, given the current precision to which host star properties can be measured. We show that obtaining independent age constraints decreases both the model and systematic uncertainties in determining these metrics and is the most powerful way to improve assessments of the long-term habitability of planets around low-mass stars.