We report extensive photometric and spectroscopic observations of the 6.1-day period , G+M-type detached double-lined eclipsing binary V530 Ori , an important new benchmark system for testing stellar evolution models for low-mass stars .
We determine accurate masses and radii for the components with errors of 0.7 % and 1.3 % , as follows : M _ { A } = 1.0038 \pm 0.0066 M _ { \sun } , M _ { B } = 0.5955 \pm 0.0022 M _ { \sun } , R _ { A } = 0.980 \pm 0.013 R _ { \sun } , and R _ { B } = 0.5873 \pm 0.0067 R _ { \sun } .
The effective temperatures are 5890 \pm 100 K ( G1 v ) and 3880 \pm 120 K ( M1 v ) , respectively .
A detailed chemical analysis probing more than 20 elements in the primary spectrum shows the system to have a slightly subsolar abundance , with { [ Fe / H ] } = -0.12 \pm 0.08 .
A comparison with theory reveals that standard models underpredict the radius and overpredict the temperature of the secondary , as has been found previously for other M dwarfs .
On the other hand , models from the Dartmouth series incorporating magnetic fields are able to match the observations of the secondary star at the same age as the primary ( \sim 3 Gyr ) with a surface field strength of 2.1 \pm 0.4 kG when using a rotational dynamo prescription , or 1.3 \pm 0.4 kG with a turbulent dynamo approach , not far from our empirical estimate for this star of 0.83 \pm 0.65 kG .
The observations are most consistent with magnetic fields playing only a small role in changing the global properties of the primary .
The V530 Ori system thus provides an important demonstration that recent advances in modeling appear to be on the right track to explain the long-standing problem of radius inflation and temperature suppression in low-mass stars .