The Identification of Pulsation Modes of High‐Amplitude δ Scuti Stars in ω Centauri and the Carina Galaxy

Abstract

ABSTRACTWe analyze photometric observations of high‐amplitude δ Scuti stars (HADS) in the globular cluster ω Cen and the Carina galaxy. The pulsation modes of the HADS are inferred primarily from their positions in V, log P diagrams. For ω Cen we identify nine fundamental pulsators (F), 22 first‐overtone (1, O), one second‐overtone (2, O), and probably two third‐overtone (3, O) stars. The majority of the F pulsators have light amplitudes ΔV≥0.15 mag, but two have ΔV<0.15 mag. Four of the 1, O pulsators have ΔV>0.15 mag, but the majority have smaller amplitudes. We find that the F pulsators tend to have more asymmetric light curves. The Carina variables are all large‐amplitude variables. Fourteen are F pulsators and six are 1, O pulsators. At least one and possibly two 1, O stars appear to have asymmetric light curves unlike those found in ω Cen. The data are very uncertain, so the asymmetry may be an artifact of observational uncertainty.The HADS data along with their P‐L relation are utilized to find the distances to ω Cen and the Carina galaxy and absolute magnitudes of their horizontal branches (HB) or RR Lyrae stars. We find the distances to be d = 6370 pc to ω Cen and d = 124,000 pc to the Carina galaxy. The Mv(RR)‐values for the ω Cen RR Lyrae stars are Mv(RR) = 0.14 (Oost II variables) and Mv(RR) = 0.28 (Oost I stars); Mv(HB) = 0.29 for the Carina galaxy.