A survey of multiperiodicity in RR Lyrae field stars

Our survey consists of photometric observations of 107 RR Lyrae stars of type RR$\sb{\rm ab}$ and has the goal of systematically studying multiperiodicity. Characteristics of our survey sample are compared with characteristics of RR$\sb{\rm ab}$ stars from the General Catalogue of Variable Stars to show that our sample was representative of RR Lyrae stars of type RR$\sb{\rm ab}$ in general. Observations were made though Cousins V and R filters with a CCD attached to the 30-inch reflecting telescope of Behlen Observatory. Observations were focused around the phase of maximum light where multiperiodicity could be easily identified. Six stars were investigated in depth. The light curves of FM Per, BT Leo, GV And, ES Peg, and TU Per exhibit variations in the magnitude of light curve maxima (the anomalous Blazhko effect). FM Per shows substantial scatter around minimum light as well as maximum. The following list details for each star the number of points, the Blazhko period and lower limits for the Blazhko amplitudes: FM Per (389 points, $\rm P\sb{B}=120\ days,\ \Delta V\sb{B}=0.42,\ \Delta R\sb{B}=0$ 34), BT Leo (229 points, $\rm P\sb{B}=76\ days,\ \Delta VB=0.27,\ \Delta R\sb{B}=0.24),$ GV And (194 points, $\rm P\sb{B}=35\ days,\ \Delta V\sb{B}=0.56,\ \Delta R\sb{B}=0.44),$ ES Peg (229 points $\rm P\sb{B}=57\ days,\ \Delta VB=0.17\ \Delta R\sb{B}=0.14),$ and TU Per (66 points, $\rm P\sb{B}=58\ days,\ \Delta V\sb{B}=0.20,\ \Delta R\sb{B}=0.13).$ DR And exhibits the classical Blazhko effect. The analysis of 99 observations yielded a possible period of about 60 days. The observations were sufficient for analysis for 73 of our program stars. These stars were classified into four periodicity categories based on their light curve scatter. 51% were classified monoperiodic, 34% multiperiodic, 5% showed excess scatter due to changing periods, and 10% inconclusive. No star with a primary period larger than 0.625 days was observed to be multiperiodic. No correlation was found between the nature of an RR$\sb{\rm ab}$ star\u27s periodicity and its distance from the galactic plane Z. No correlation was found between primary period and Blazhko period for the multiperiodic stars. A new nomenclature for discussing RR Lyrae stars is proposed