THE LIGHT AND PERIOD VARIATION OF CV-CYGNI

The U, B and V observations confirmed, once more, after Vetesnik and P erek (1965) that CV Cygni is an eclipsing binary of W UMa type. Due to the variable depth (up to 0.1 magnitude) of one of the minima, the sy stem shifts from A to W-type (or vice versa). The (O-C) diagram of all available times of minima confirms the continous period decrease with a rate dP/dt approximate to 4.44 10(-7) day/yr. The relatively large orbital period (P approximate to 0.98 day), the shape of the light and color curves, and the position of the system in the color-period diag ram indicate that CV Cyg is an interesting highly evolved contact or n ear-contact binary which is rapidly evolving into deeper contact throu gh the angular momentum loss from the system.