Characterisation of seven longer period eclipsing binary systems

Abstract We report a joint analysis of TESS photometry and minerva-Australis spectroscopic observations for seven long-period eclipsing binary systems with F- and early-G-type dwarf primaries: TIC 37606218, TIC 73723286, TIC 172462064, TIC 220567625, TIC 270805930, TIC 308050066, and TIC 308991822. The companions are late-K to late-M dwarfs with orbital periods of ~7–24 d, with all but one system exhibiting significant eccentricity. The combination of low-mass companions and relatively long orbital periods place these binaries in a regime where tidal interactions are comparatively weak, making them valuable benchmarks for testing low-mass stellar models with minimal tidal contamination. For the systems analysed here, together with those from our previous studies, we find that the radii and effective temperatures of the low-mass companions are broadly consistent with MIST isochrone predictions, with only a modest mean radius anomaly of ~1% and no statistically significant temperature anomaly. We furthermore find no compelling evidence for correlations between either anomaly and orbital period or metallicity, suggesting that the processes commonly invoked to explain the radius–temperature anomaly are either not the dominant drivers, or operate much less efficiently in the longer-period regime.