The most resonant pulsation frequency of δ Scuti stars

Abstract

Pulsation of the Sun with a period of PO 160 min discovered about two decades ago, is still waiting explanation. In view of the hypothesis about its cosmological origin, and attempting to find signature of this PO periodicity among other (short-period variable) stars, the pulsation frequencies of 6 Sct stars are subjected to specific analysis. With a confidence level z 3 . 8~ it is found that the frequency vo = PO-' z 104 ~€ 1 2 , within the error limits, appears indeed to be the most "resonant" one for the total sample of 318 pulsating st,ars of 6 Sct type (the most commensurable, or "synchronizing", period for all these stars occurs to be 16? f 4 min). We conjecture that a) the Po oscillation might be connected with periodic fluctuations of gravity field (metrics), and b) the primary excitation mechanism of pulsations of 6 Sct stars, reflected by this "ubiquitous" PO resonance, must be attributed perhaps to superfast rotation of their inner cores (their rates tend to be in near-resonance with tlie "universal" vo frequency). T h e argun1ent.s are given favouring a cosmological nature of the PO oscillation.Key words: variable stars: 6 Scuti stars -pulsation -rotation A A A subject classification: 122 I n t r o d u c t i o nA particular interest to global oscillations of the Sun is connected with the periodicity PO M 160.010 min discovered in the 70-th by Doppler shift measurements of the Fraunliofer spectral lines (Brookes et al. 1976; Severny et al. 1976). This oscillation has been seemingly confirmed by Grec et al. (1980), Scherrer and Wilcox (1983), but was not supported by the observations of Elsworth et al. (1989). Scherrer et al. (1993) recently suggested that an actual cause of the observed variation of the solar 160-min pulsation rriight be rooted well beneath the solar convection zone or even in the (rapidly rotating) inner core of the Sun. The true nature of this solar oscillation which amplitude is dificult to explain on any basis, is yet a mystery. The precise period (in minutes) was determined to be Po = 160.0101 f 0.0001, (1) with the corresponding frequency vo M 104.160 pHz (Kotov 1995). In the present study, being stimulated by previous results (Kotov 1985 and attempting t o get reasonable explanation of the 160min "solar" periodicity, we extend investigation to detailed analysis of oscillation frequencies of the most popular sample of short-period variables -6 Sct stars.

Astrophysics in 1997

“…"The luminescence process for proto objects moving with a peculiar velocity at high redshift" (Dubrovich 1997), and 4. Our absolute favorite, the metric of Kotov & Kotov (1997), which oscillates at a period of about 160 minutes and so accounts both for that period in the Sun and for the peak mode of d Scuti at 162 minutes.…”

Harmony of the solar system

“…The F ( ν ) maximum corresponds to the best commensurate frequency for a total set of observed frequencies, or motions, , where P i is the period with the ordinal number i = 1, 2, … N , and N is the total amount of periods, or motions. The corresponding algorithm (Kotov & Kotov ) finds, by the least‐square technique, the minimum of deviations of ratios from the nearest integers Z i , with q = 1 or −1.…”