Four-colour photometry of eclipsing binaries. VII. SZ Cen, light curves, photometric elements, absolute dimensions and determination of helium content.

Summary. Photometric elements are derived for the eclipsing binary SZ Cen using the Russell-Merrill method and the model simulation method by Wood. The two methods give very nearly equal elements. The elements are very well determined since the primary minimum is a totality. The absolute dimensions are derived combining with spectroscopic elements. SZ Cen is in a hydrogen shell burning phase just beyond the main- sequence. There seems to be some remarkable deviations from standard evolutionary sequences. The helium content is normal, Y =0.30. Key words: eclipsing binary uvby photometry light curves photometric elements absolute dimensions helium content