Variable Star Atlas - Fundamental RR Lyrae
RR Lyrae variables are stars that radially pulsate via the kappa (opacity) mechanism and are known for their short periods of pulsation. These stars are typically found in the spherical component of the Galaxy and some globular clusters where they appear as pulsating horizontal-branch stars. RR Lyrae types are typically divided into the following three subclasses: RRAB, RRC, and RRD. RRAB variables pulsate in the fundamental mode at short periods which range from ~ 0.3 - 1 day. The majority of RR Lyrae stars are of the RRAB type. The light curves of RR Lyrae stars are often asymmetric and have a steep ascending branch, followed by a shallower descending branch.