A subdivision of the RR-Lyrae type of variable stars, described by the American astronomer Solon Irving Bailey (1854–1931), based upon the shape and amplitude of the light-curve. In order of decreasing amplitude, the original types were designated a, b, and c, with mean periods of 0.48, 0.58, and 0.32 days, respectively. There is a continuous transition between types a and b, both of which have asymmetric light-curves, and so they are now regarded as one type, RRAB. Light-curves of type RRC are distinct, and frequently appear almost sinusoidal. Since Bailey's time, another subclass has emerged known as the double-mode RR Lyraes, abbreviated as RR(B) or RRd; these stars pulsate simultaneously in the fundamental and first overtone radial modes.
Subjects: Astronomy and Astrophysics.