Rediscussion of eclipsing binaries. paper 14: the f-type system v-570 persei

V-570 Per is a binary star system containing two F-type stars in a 1 center dot 90-d period circular orbit. It shows shallow partial eclipses that were discovered from its Hipparcos light-curve. We present an analysis of this system based on two sectors of high-quality photometry from the NASA Transiting Exoplanet Survey Satellite (TESS) mission, and published spectroscopic light ratio and radial-velocity measurements. We.nd masses of 1 center dot 449 +/- 0 center dot 006 and 1 center dot 350 +/- 0 center dot 006 M-circle dot, and radii of 1 center dot 538 +/- 0 center dot 035 and 1 center dot 349 +/- 0 center dot 032 R-circle dot. The radius measurements are set by the spectroscopic light ratio and could be improved by obtaining a more precise light ratio. The eclipses in the TESS data arrived 660 +/- 30 s later than expected, suggesting the presence of a faint third body on a wider orbit around the eclipsing system. Small trends in the residuals of the.t to the TESS light-curve are attributed to weak starspots. The distance to the system is close to the Gaia DR3 value, but the Gaia spectroscopic orbit is in moderate disagreement with the results from the published ground-based data.