STUDIES OF LARGE AMPLITUDE DELTA SCUTI VARIABLES: I. A CASE STUDY OF EH LIBRAE

Abstract

ABSTRACT This is the first of a short series of papers on large-amplitude delta Scuti variables. The determination of Baade-Wesselink radii and luminosities for pulsating stars is a long-standing and highly desired goal since such quantiites provide necessary ingredients to produce standard candles. In a modest contribution towards attaining this continuing goal, we are determining the radii and luminosities of a selection of the large-amplitude delta Scuti stars. Optical and infrared photometry and cross-correlated radial velocity data have been obtained for the large-amplitude delta Scuti stars DY Herculis, EH Librae, and DY Pegasi. Fourier representations for B, V, I and J light curves and for the radial velocity curves were used in Baade-Wesselink analysis to derive minimum radii over the pulsation cycles. The resulting radii and their errors, mean bolometric luminosity and mean absolute bolomentric magnitudes will be discussed here and in the papers to follow. The Baade-Wesselink analysis yielded Rmin = 2.54 Rsun ± 0.35 Rsun, for EH Librae with a radius excursion of 0.098 Rsun. When combined with Joner's (1986) effective temperature, we found a mean bolometric luminosity of 22.2 Lsun and a mean absolute bolometric magnitude of 1.38.