5 Conclusions

The adopted spot model for YY CMi fits extremely well the observed light curves. The absolute elements based on its spectral classification and the present photometric solution are also given in Table 4. We can use these elements to estimate the evolutionary status by means of the mass-radius (MR), mass-luminosity (ML) and HR diagrams of Hilditch et al. (1988). In these diagrams, both components of YY CMi lie beyond the TAMS, in a region occupied mostly by the primaries of A-type W UMa systems.

On the other hand, the degree of contact is almost zero (indicating marginal contact) and the thermal contact is poor $(T_1~-~T_2)\approx 650$ K. These results together with the high photometric mass-ratio $q\approx 0.88$ indicate that YY CMi is very probably a system at the beginning or the end of the contact phase (Lucy & Wilson 1979). However, more definite conclusions about the evolutionary status of YY CMi can only be drawn by means of new photometric and spectroscopic observations of the system.

Acknowledgements

We thank the referee Dr. R.E. Wilson for his valuable comments on an earlier version of the manuscript. Figures 6 and 7 were produced by Binary Maker 2.0.