THE LONG-PERIOD FIELD RR LYRAE STARS

VR light curve3 have been obtained for 16 faint variable stars with periods shorter than 1 day. Although, as expected, most of the light curves are typical of Bailey-type ab RR Lyrae stars, some have slower rises to maximum and flatter tops. Fourier decomposition was performed to further explore these trends. Combining these data with previously published Fourier decompositions of RR Lyrae light curves, we find that the Fourier coefficients are essentially constant for periods shorter than three-quarters of a day for Bailey-type ab RR Lyrae stars but that the amplitude ratios, R (12), R (13), and R (14), decrease and the phase differences, φ(21) and φ(31), increase at longer periods. This photometry lends support to the previous suggestion that the star XZ Cet is a good candidate for a Galactic anomalous Cepheid, and we add BW Com as another possibility. When the Fourier parameters for known anomalous Cepheids are compared with those of the RR Lyrae stars, it is found that the scatter precludes an unambiguous segregation of the anomalous Cepheids from the RR Lyrae stars. The longest period star in our sample, V742 Cyg (period = 0.94 days) is possibly a type II Cepheid but an unambiguous conclusion does not seem possible from Fourier decomposition