STUDIES OF LARGE-AMPLITUDE DELTA-SCUTI VARIABLES .2. DY HERCULIS

This is the second paper in a series on large-amplitude delta Scuti st ars intended to determine Baade-Wesselink radii and luminosities with precision. The first paper discussed our method of analysis and its ap plication to EH Librae; in this paper we discuss the observations and analysis of DY Herculis. Optical and infrared photometry and cross-cor related radial-velocity data have been obtained and analyzed. Fourier representations for the UBVRIJHK light curves and for the radial-veloc ity curves were used to derive a value for the minimum radius for each of 60 combinations of flux and color index. From these we adopt a mea n value for the minimum radius of R(min) = 2.77 +/- 0.20R.. When combi ned with effective temperatures from Breger et al. (1978), we find a m ean bolometric luminosity of (L(B)) = 21.70L. and a mean absolute magn itude of (M(B)) = 1.41. The radial excursion is 0.149R.. We use the sa me procedure to improve our results for EH Librae, deriving R(min) for each of 42 combinations of flux and color index, and obtain mean valu es of R(min) = 2.62 +/- 0.19R., (L(B)) = 24.56L. and (M(B)) = 1.27.