δ Scuti and related stars: Analysis of the R00 Catalogue

¹ Instituto de Astrofísica de Andalucía, CSIC, PO Box 3004, 18080 Granada, Spain
² Institut für Astronomie, Universität Wien, Türkenschanzstr. 17, 1180, Austria

E. Rodríguez

Received: 21 September 2000
Accepted: 3 November 2000

Abstract

We present a comprehensive analysis of the properties of the pulsating δ Scuti and related variables based mainly on the content of the recently published catalogue by Rodríguez et al. ([CITE], 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 δ Scuti pulsators situated in eclipsing binary systems. The location of the δ Scuti variables in the H-R diagram is discussed on the basis of HIPPARCOS parallaxes and uvbyβ photometry. New borders of the classical instability are presented. In particular, the properties of the δ Scuti pulsators with nonsolar surface abundances (SX Phe, λ Boo, ρ Pup, δ Del and classical Am stars subgroups) are examined. The Hipparcos parallaxes show that the available photometric uvbyβ absolute magnitude calibrations by Crawford can be applied correctly to δ Scuti variables rotating faster than 100 km s with normal spectra. It is shown that systematic deviations exist for the photometrically determined absolute magnitudes, which correlate with and . The photometric calibrations are found to fit the λ Boo stars, but should not be used for the group of evolved metallic-line A stars. The related γ Dor variables and the pre-main-sequence δ Scuti variables are also discussed. Finally, the variables catalogued with periods longer than 025 are examined on a star-by-star basis in order to assign them to the proper δ Scuti, RR Lyrae or γ Dor class. A search for massive, long-period δ Scuti stars similar to the triple-mode variable AC And is also carried out.