Colloquium
Pushing the boundaries on the accuracy of fundamental stellar parameters

Abstract

Most of what we know about the masses and radii of stars comes from the studies of eclipsing binary stars (EBs). As the physical principles that govern the motion are well understood, modelling EB data represents a tractable geometrical problem. The attained accuracy of fundamental parameters is ~2-3% in the best possible cases (Torres et al. 2010), which plays a paramount role in stellar astrophysics: these results are used to calibrate the mass-radius relationship, critically test stellar evolution models, provide fundamental parameters (temperature, luminosity, mass and radius) for stellar and substellar objects across the main sequence, and anchor the distance scale. Given that so much in stellar astrophysics hinges critically on the values derived from EBs, we naturally wonder whether there are any circumstances that would allow us to beat down the uncertainties by another order of magnitude, say to a ~0.2-0.3% level, and thus achieve a 10-fold increase in calibration and gauge reliability. This could be done if the correlations between parameters were somehow reduced, and solution degeneracy somehow broken. If, for example, we had a third star in the system that happens to eclipse the binary, then the shapes of extraneous eclipses in a light curve would constrain the orbital inclination and stellar radii much more than the binary eclipses alone.
In this talk, I will discuss these and similar considerations and show what Kepler, K2 and TESS missions brought to the table.