WAVELET ANALYSIS OF 173 SEMI-REGULAR VARIABLES

Анотація

We made the wavelet analysis of 173 semi-regular pulsating variable stars of different sub-types. For the analysis, we have used 1,000,000 individual brightness estimates from the published international databases of the VSOLJ (Japan) and AFOEV (France). They were visually checked using the program OL (I.L.Andronov, 2001OAP....14..255A), and bad points were removed from the data files. The wavelet analysis was performed using the program WWZ (I.L.Andronov, 1998KFNT...14..490A) which improves the discrete Morlet-type wavelet transform to the case of irregularly spaced data. Mean weighted wavelet periodograms are presented, as well as wavelet maps. Dependences of the wavelet-based periods and amplitudes on time are presented for the investigated stars. Some stars exhibit switchings between preferred periods, which are interpreted as switchings of the pulsation mode. Additional criteria for classiffication of the pulsating variables based on the stability of periods and amplitudes are discussed. Results are shown for the semi-regular star RU And, for which the semi-amplitude varies drastically from 0.027 (\nearly constant star") to 1.204 mag (\Mira"- type pulsating variable. The phase of pulsations also varies drastically by 0.7P, and the wavelet estimates of the period - from 210 to 270 days.