Variable Stars: A Net of Complementary Methods for Time Series Analysis. Application to RY UMa

Abstract

cyclic change of semi-amplitude of pulsations between 0.01 to 0.37mag, which is interpreted as a bias between the waves with close periods and a beat period of 4000d (11yr). The dominating period has changed from 307.35(8)d before 1993 to 285.26(6)d after 1993. The initial epoch of the maximum brightness for the recent interval is 2454008.8(5). It is suggested that the apparent period switch is due to variability of amplitudes of these two waves and an occasional swap of the dominating wave.

MAVKA: Program of statistically optimal determination of phenomenological parameters of extrema. Parabolic spline algorithm and analysis of variability of the semi-regular star Z UMa

“…Хоча метод був запропонований для визначення екстремумiв, його можна використовувати й для визначення середнього моменту та характерного часу переходу з однiєї асимптоти на iншу, навiть, при вiдсутностi екстремуму. Наприклад, по дiаграмi "O − C" для моментiв екстремумiв (чи вiдповiдних фаз) при порiвняно рiзкiй змiнi перiоду [25].…”