Pulsation Properties of Blazhko and Non-Blazhko RRab Stars

Abstract In this study, we conduct a comparative analysis of the properties of Blazhko and non-Blazhko RRab stars. We identified 1054 non-Blazhko and 785 Blazhko RRab stars in the photometric data observed by the K2 mission, which, combined with those 37 stars observed in the original Kepler field, constituted our study sample. Using the Fourier decomposition method, we calculated the pulsation parameters, including phase differences and amplitude ratios, for these RRab stars, revealing significant discrepancies in the pulsation parameters between Blazhko and non-Blazhko RRab stars. However, distinguishing between Blazhko and non-Blazhko RRab stars based on Fourier parameters remains challenging due to the significant overlap in their distributions. By crossmatching our sample with the low-resolution spectra of LAMOST Data Release (DR) 12, we identified 147 Blazhko and 111 non-Blazhko RRab stars, which exhibit similar metallicity distributions. Furthermore, crossmatching with Gaia DR3 data yielded 766 Blazhko and 950 non-Blazhko RRab stars, showing differences in color indices but not in absolute magnitudes. Our findings suggest that the Blazhko effect is linked to pulsation parameters and colors rather than metallicities or absolute magnitude.