Correlation of Successive Maxima in Mira, Chi Cygni, R Leonis, and R Hydrae

An anaylsis was done of the maxima of Mira, Chi Cygni, R Leonis, and R Hydrae, four Mira-type variable stars chosen from among those studied by Argelander in 1839. A negative correlation between the luminosity of consecuitve maxima was found, except for R Hya, M(i+1) - M(i) vs. M(i) yields a correlation index of r² = 0.6 for Mira and Chi Cyg, r² = 0.44 for R Leo, and r² = 0.25 for R Hya. Data analyzed range from the discovery of Mira (1596) to the present time; they include AAVSO data, and there are from 90( RHya) to 179 (Mira Ceti) pairs of consecutive maxima.