New O-Cs for the Classical Cepheids RY Cas and V Lac over a Century (1873-2022)

Abstract

We give here new O-C diagrams of the two classical Cepheids RY Cas and V Lac, established on a large basis of times of maximum of light, which covers more than a century. These two Cepheids present a variation of their period for which it is possible to calculate an annual rate. This rate equals +1.86 s/yr for RY Cas and -0.81 s/yr for V Lac. Based on these two new O-C diagrams neither of them seems to show any association to a binary system.