Preliminary analysis of light curves of seven carbon stars

Abstract

We present a preliminary analysis of the light curves of the following carbon stars: WZ Cas, VY UMa, Y CVn, RY Dra, T Lyr, HK Lyr and TT Cyg, constructed on the basis of our own BV photoelectric observations obtained at the Brno Observatory in 1979-94 and Hipparcos observations. The analysis suggests that "semiregular" light curves of all studied stars can faithfully be expressed by a superposition of long-term changes and a set of medium-term harmonic variations (possibly pulsations) with periods from 50 to 500 days.