PHOTOMETRIC LIGHT CURVE SOLUTION OF FOUR SHORT PERIOD K-SPECTRAL TYPE ECLIPSING BINARY SYSTEMS

The filtered B, V, R and I light curves of four short period (P < 0.25d) eclipsing binary systems are presented and analysed; two having P ≈ 0.22d, close to the short period limit for contact binaries (CBs). New ephemerides are provided. No third light was found necessary in any case, and one or more spots were introduced to account for asymmetries in the light curves. Two systems belong to the W sub-type of the W-UMa CBs and a third one to the A sub-type of the W-UMa type CBs. The last one is a semi-detached binary with a large temperature difference between the components and a low mass ratio q = 0.191. All components of the binaries are of the K spectral type, and the secondary of the semi-detached binary is of the M spectral type. Absolute parameters of the components were calculated using different evolutionary diagrams. Interestingly, two target have estimated total masses that are smaller than the lower mass limit known for Cbs.