A Guide to Realistic Uncertainties on Fundamental Properties of Solar-Type Exoplanet Host Stars

TL;DR

This paper discusses the limitations in accurately determining fundamental properties of solar-type exoplanet host stars due to measurement and model uncertainties, and offers tools and strategies to improve precision.

Contribution

It quantifies current uncertainties in stellar properties and provides open-source software and strategies to reduce these uncertainties in future analyses.

Findings

Systematic uncertainty floor of ~2% in temperature and luminosity.

Uncertainties of ~5% in stellar mass and ~20% in age.

Open-source software for uncertainty estimation.

Abstract

Our understanding of the properties and demographics of exoplanets critically relies on our ability to determine fundamental properties of their host stars. The advent of Gaia and large spectroscopic surveys has now made it in principle possible to infer properties of individual stars, including most exoplanet hosts, to very high precision. However, we show that in practice, such analyses are limited both by uncertainties in the fundamental scale, and by uncertainties in our models of stellar evolution, even for stars similar to the Sun. For example, we show that current uncertainties on measured interferometric angular diameters and bolometric fluxes set a systematic uncertainty floor of $\sim$2% in temperature, $\sim$2% in luminosity, and $\sim$4% in radius. Comparisons between widely available model grids suggest uncertainties of order $\sim$5% in mass and $\sim$20% in age for main sequence and subgiant stars. While the radius uncertainties are roughly constant over this range of stars, the model dependent uncertainties are a complex function of luminosity, temperature, and metallicity. We provide open-source software for approximating these uncertainties for individual targets, and discuss strategies for reducing these uncertainties in the future.