Main and Early Shocks in RR Lyrae Photometric Light Curves
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Date
2021
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Abstract
We explore the effect of the main and early shocks (giving rise to the so-called hump and bump features in the light curves, respectively) on the pulsation properties of non-modulated fundamental mode RR Lyrae stars. We utilized I-band photometry from the fourth release of the Optical Gravitational Lensing Experiment (OGLE). We determined the centers and strengths of humps and bumps in the phased light curves of the studied stars. The positions of both shock events in the phased light curves are highly correlated with the amplitudes, pulsation periods, and Fourier coefficients. RR Lyrae stars with prominent humps are located at the low-amplitude regime of the Bailey diagram, while variables with pronounced bumps have average and above average amplitudes. RR Lyrae stars close to the red edge of the instability strip have pronounced humps, while variables with a strong bump are located at the center and close to the blue edge of the instability strip. In general, the effect of the main and early shocks provides a new view on the period-amplitude distribution of fundamental mode RR Lyrae stars....