Double-Mode Stellar Pulsation

Double Mode Pulsation as a Resonance Phenomenon

8 - Stellar Pulsation and Oscillation

That some stars vary in brightness has been known from time immemorial. That this variation is the result of intrinsic changes in the star itself has been known for less than 100 years and the causes of those variations have been understood for less than 30 years. It is not a simple matter to distinguish the light variations resulting from eclipses by a companion from those caused by physical c...

Letter to the Editor A nonlinear model for RR Lyrae double mode pulsation

The Vienna nonlinear code for modelling pulsating stars is applied to the problem of RR Lyrae double mode pulsation. For stellar parameters of M = 0.65 M , log(L/L ) = 1.72 and XYZ=(0.760, 0.239, 0.001) we find a stable double mode solution in a small effective temperature range around 6820 K. The fundamental period is given by P0 = 0.5279 days and period and amplitude ratios corresponding to P...

Physical properties of double-mode RR Lyrae stars based on pulsation and evolution models

We determine the fundamental stellar parameters of altogether 20 double-mode RR Lyrae (RRd) stars from the Galactic Field and the Large Magellanic Cloud, following our approach employed on the field RRd star BS Comae [1]. The stars were selected to cover wide ranges of periods and period ratios, implying diverse stellar parameters. From the possible observed quantities we use only the periods a...

Is the Blazhko Effect the Beating of a Near-resonant Double-mode Pulsation?

In this paper it is shown that the Blazhko Effect may result from a near-resonant type of double-mode pulsation, where two periodic oscillations with slightly different frequencies gradually slip in phase by one pulsation cycle every Blazhko cycle, producing a beat frequency type of modulation. One of the oscillations is strongly non-sinusoidal while the other is not. This paper extends previou...