2026A&A...706A.257P

Context. In low-mass stars, the connection between magnetic activity, rotation period, and age provides key insights into the functioning of dynamos. Fully understanding the activity-rotation-age relationship requires access to stars with precise fundamental parameters, measured rotation periods, and reliable magnetic activity indicators (e.g. X-ray luminosity). Thanks to space-based photometry, asteroseismology is now the leading method for determining stellar parameters with unprecedented precision and accuracy. The best-characterised solar-like stars compose the Kepler LEGACY sample, with the highest quality asteroseismic data for 66 stars, most of which have measured rotation periods. In the X-ray band, these stars were observed by the ROentgen Survey with an Imaging Telescope Array (eROSITA) telescope on the Russian Spektrum-Roentgen-Gamma (SRG) satellite in the course of its all-sky survey.
Aims. We reviewed different components of the stellar activity-rotation-age relationship using the largest sample of solar-like stars with highly accurate fundamental parameters from asteroseismology, along with their measured rotation periods and X-ray luminosities.
Methods. We cross-correlated the Kepler LEGACY sample with the SRG/eROSITA source catalogue, finding X-ray detections for 13 of them. We derived their fundamental parameters using the Forward and Inversion COmbination (FICO) procedure and revisited widely studied activity-age and activity-rotation relationships by consistently incorporating our subsample of 13 stars with literature samples.
Results. By implementing revised activity-rotation-age relationships in a star-planet interaction (SPI) code to compute the X-ray luminosity tracks and by comparing the results with observations, we found an improved agreement for seven stars of our subsample. We explored the effect of the revised relationships on the mass loss of planets in the radius valley, finding a modest impact on planet size distributions.
Conclusions. A larger and more varied sample of stars with asteroseismically characterised parameters, rotation period, and activity indicators is needed to accurately determine the multiple components of the activity-rotation-age relationship.