delta Scuti and related stars: Analysis of the R00 Catalogue

We present a comprehensive analysis of the properties of the pulsating delta Scuti and related variables based mainly on the content of the recently published catalogue by Rodríguez et al. (\cite{retal00a}, hereafter R00). In particular, the primary observational properties such as visual amplitude, period and visual magnitude and the contributions from the Hipparcos, OGLE and MACHO long-term monitoring projects are examined. The membership of these variables in open clusters and multiple systems is also analyzed, with special attention given to the delta Scuti pulsators situated in eclipsing binary systems. The location of the delta Scuti variables in the H-R diagram is discussed on the basis of HIPPARCOS parallaxes and uvbybeta photometry. New borders of the classical instability are presented. In particular, the properties of the delta Scuti pulsators with nonsolar surface abundances (SX Phe, lambda Boo, rho Pup, delta Del and classical Am stars subgroups) are examined. The Hipparcos parallaxes show that the available photometric uvbybeta absolute magnitude calibrations by Crawford can be applied correctly to delta Scuti variables rotating faster than v sin i ~ 100 km s{<SUP>-1</SUP>} with normal spectra. It is shown that systematic deviations exist for the photometrically determined absolute magnitudes, which correlate with v sin i and delta m<SUB>1</SUB>. The photometric calibrations are found to fit the lambda Boo stars, but should not be used for the group of evolved metallic-line A stars. The related gamma Dor variables and the pre-main-sequence delta Scuti variables are also discussed. Finally, the variables catalogued with periods longer than 0fd 25 are examined on a star-by-star basis in order to assign them to the proper delta Scuti, RR Lyrae or gamma Dor class. A search for massive, long-period delta Scuti stars similar to the triple-mode variable AC And is also carried out.