The Benchmark Eclipsing Binary V530 Ori: A Critical Test of Magnetic Evolution Models for Low-Mass Stars

We report accurate measurements of the physical properties (mass, radius, temperature) of components of the G+M eclipsing binary V530 Ori. The M-type secondary shows a larger radius and a cooler temperature than predicted by standard stellar evolution models, as has been found for many other low-mass stars and ascribed to the effects of magnetic activity and/or spots. We show that models from the Dartmouth series that incorporate magnetic fields are able to match the observations with plausible field strengths of 1-2 kG, consistent with a rough estimate we derive for that star.