Discrepancies between isochrone fitting and gyrochronology for exoplanet host stars?

TL;DR

This study compares isochrone fitting and gyrochronology for 68 exoplanet host stars to assess potential biases in age estimates caused by tidal interactions, finding inconclusive evidence for systematic discrepancies.

Contribution

It provides a comparative analysis of two stellar age estimation methods and explores the influence of tidal interactions and orbital alignment on their accuracy.

Findings

Isochrone fitting tends to give older ages than gyrochronology.

No clear correlation between tidal timescales and age discrepancies.

Sample size limitations prevent definitive conclusions.

Abstract

Using a sample of 68 planet-hosting stars I carry out a comparison of isochrone fitting and gyrochronology to investigate whether tidal interactions between the stars and their planets are leading to underestimated ages using the latter method. I find a slight tendency for isochrones to produce older age estimates but find no correlation with tidal time-scale, although for some individual systems the effect of tides might be leading to more rapid rotation than expected from the stars' isochronal age, and therefore an underestimated gyrochronology age. By comparing to planetary systems in stellar clusters, I also find that in some cases isochrone fitting can overestimate the age of the star. The evidence for any bias on a sample-wide level is inconclusive. I also consider the subset of my sample for which the sky-projected alignment angle between the stellar rotation axis and the planet's orbital axis has been measured, finding similar patterns to those identified in the full sample. However, small sample sizes for both the misaligned and aligned systems prevent strong conclusions from being drawn.