We report the discovery of 16 detached M-dwarf eclipsing binaries with J < 16 mag and provide a detailed characterisation of three of them , using high-precision infrared light curves from the WFCAM Transit Survey ( WTS ) .
Such systems provide the most accurate and model-independent method for measuring the fundamental parameters of these poorly understood yet numerous stars , which currently lack sufficient observations to precisely calibrate stellar evolution models .
We fully solve for the masses and radii of three of the systems , finding orbital periods in the range 1.5 < P < 4.9 days , with masses spanning 0.35 - 0.50 { M } _ { \odot } and radii between 0.38 - 0.50 { R } _ { \odot } , with uncertainties of \sim 3.5 - 6.4 \% in mass and \sim 2.7 - 5.5 \% in radius .
Close-companions in short-period binaries are expected to be tidally-locked into fast rotational velocities , resulting in high levels of magnetic activity .
This is predicted to inflate their radii by inhibiting convective flow and increasing star spot coverage .
The radii of the WTS systems are inflated above model predictions by \sim 3 - 12 \% , in agreement with the observed trend , despite an expected lower systematic contribution from star spots signals at infrared wavelengths .
We searched for correlation between the orbital period and radius inflation by combining our results with all existing M-dwarf radius measurements of comparable precision , but we found no statistically significant evidence for a decrease in radius inflation for longer period , less active systems .
Radius inflation continues to exists in non-synchronised systems indicating that the problem remains even for very low activity M-dwarfs .
Resolving this issue is vital not only for understanding the most populous stars in the Universe , but also for characterising their planetary companions , which hold the best prospects for finding Earth-like planets in the traditional habitable zone .