A highly luminous, yellow supergiant pulsating variable; abbr. RV. Spectra are F–K at maximum, K–M at minimum. The light-curves have overall amplitudes of 3–4 mag.; all have double maxima (normally with slightly different amplitudes) and an intervening secondary minimum. The amplitudes of the maxima and secondary minimum vary, and the secondary minimum may become as deep as (and replace) the primary minimum. The formal period is the double interval from one deep minimum to the next, and generally lies in the range 30–150 days. In the RVA subtype the mean magnitude remains constant with time. The RVB subtype exhibits a superimposed secondary wave, with amplitudes up to 2 magnitudes and periods of 600–1500 days. RV Tauri itself, of RVB subtype, varies between mags. 8.9 and 11.1 every 78.7 days, changing in spectral type from G2 to M2.