UX Men: Detached Eclipsing Binary as a Benchmark Candidate

We present ultra-precise fundamental parameters for the detached eclipsing binary UX Men based on 31 TESS sectors (about 882 d) and radial velocities from HARPS, FEROS, CORALIE, and UCLES. The light curves were detrended for spot-induced variability and modelled independently with JKTEBOP and ALLESFITTER, while radial velocities were extracted via TODCOR and fitted with a Keplerian orbit. Spectral disentangling yielded individual component spectra analysed with iSpec to determine T eff and[M/H]. Multi-band photometry was used to determine the fluxes, flux ratios and ultimately to measure photometric T eff. We obtain the masses M A = 1.2300 plus or minus 0.0012 M, M B = 1.1946 plus or minus 0.0012 M and radii R A = 1.3605 plus or minus 0.0031 R, R B = 1.2801 plus or minus 0.0069 R with sub-percent precision. Uncertainties were found to be dominated by systematic effects coming from (weak) stellar activity. T eff,A = 6302 plus or minus 77, T eff,B = 6292 plus or minus65 & Metallicity estimates are [M/H] A = 0.02 plus or minus 0.13 dex and [M/H] B= 0.07 plus or minus 0.10 dex. Isochrone fitting yields a consistent age of τ = 2.75 plus or minus 0.13 Gyr. The system exhibits a about 673-day periodicity in eclipse-timing variations, likely due to stellar activity, with no evidence for a third body. Results are independent of the modelling code used, but without proper treatment of activity-induced systematics the uncertainties would be underestimated. UX Men is a high-precision benchmark binary providing stringent tests of stellar models and a robust calibration source for PLATO. Expanding the sample of well-characterised detached eclipsing binaries will strengthen the empirical foundations for stellar physics and the calibration of future photometric missions