A NEW APPROACH TO THE CEPHEID PERIOD LUMINOSITY LAW - DELTA SCUTI STARS AS SMALL CEPHEIDS

Arguments are presented for believing that delta-Sct stars and classical Cepheids belong to the same family and obey the same period-luminosity (P-L), period-luminosity-color (P-L-C), and period-radius (P-R) relations. Existing data for delta-Sct stars and for classical Cepheids are used to establish P-L and P-R relations that have internal precisions three-five times better than previous versions. The P-L relation so established is [GRAPHICS] Adopting a color coefficient of 2.1 leads to a P-L-C relation that is(~)[GRAPHICS](~)The P-R relation is found to be(~)[GRAPHICS]