Abstract:
Detailed period study of the eclipsing binary ST Per is presented. A new period (P=2.ͩ 648339) is given. Period changes in different portions of the O-C diagram with a new period have been estimated. The total changes in period (ΔP) ranges from 2.17x10⁻⁵d to 2.64x10⁻⁴d which is appreciably large. Sufficient number of minima in the time interval 1934 to 1985 for this system are available. Distinct increasing and decreasing trends are evident, the change in the tendency appears to have occurred around 1947. Sinusoidal variation is seen between cycles 7000-10000, which indicates that ST Per is a three-body system, the period of the third body being about 22 years. However, the sinusoidal variation is not perfectly symmetric in shape, therefore, it is suspected that ST Per is a four-(or multi-) body system.
