Periodicities of the light curve of the semiregular variable star Y Lyncis.

The paper discusses a 16.8-yr-long visual light curve of the long-period SRc-type red variable Y Lyn (from 1973 to 1990). Fourier analysis of the entire data set results in four significant periods: P₀ of 1190 d, P₁ of 595 d, P₁ of 214 d, and P₂ of 133 d. The presence of P₁ is probably due to the nonsinusoidal shape of the light variation. The wavelet transform of the light curve shows that the two shorter periods are unstable as observed in several other SR-type variable stars. The effect of the observational uncertainties and errors on the resultant periods are investigated. It demonstrates from the standpoint of period accuracy that the length of the observational time interval is much more important than the errors of the individual observations. Adopting P₀ as the fundamental radial pulsational period and using some theoretical and empirical relations made it possible to estimate some of the physical properties of the variable, namely, 580 solar radii, 25,000 solar luminosities, 3000 K, and 1.5-2 solar masses.