1998PASP..110..433W

This is the third in a series of papers on large-amplitude δ Scuti and related stars intended to determine Baade-Wesselink radii and luminosities with precision. The first two papers discussed our method of analysis and its application to the δ Scuti variables EH Librae and DY Herculis; in the present paper we discuss the observations and analysis of the SX Phoenicis variable DY Pegasi. Optical (BVI) and infrared (JH) photometry and cross-correlated radial velocity data have been obtained and analyzed. Fourier representations for the BVIH light curves and for the radial velocity curve were used to derive a value for the minimum radius for each of 22 combinations of flux and color index, from which we obtain a mean value for the minimum radius of R_min=2.09±0.25 R_☉. When combined with effective temperatures from Burki & Meylan, we find a mean bolometric luminosity of <L_bol≥11.34 L_☉ and a mean absolute magnitude of <M_bol≥2.11. The radial excursion (R_max-R_min) is 0.073 R_☉.