Radial and nonradial periods of Delta Scuti

Five periods have been discussed by Smith (1981) for the prototype variable star delta Scuti. The main one, at 0.193772 day, has long been identified as the radial fundamental mode. The others have not been clearly understood, but the second radial overtone is probably the correct identification for the 0.116366 day period. The other three at 0.186891, 0.189435, and 0.211157 day seem to be nonradial modes because of their long periods. The first of these seems to have l = 2 and m = -2 as observed by Smith. Table 1 gives these observed periods. Based on the Fitch (1981) nonradial pulsation constants, the 4.48 hour (.187 day) period seems to be a p1 mode, but as we shall see, we find that this identification is not very certain. The goal of this paper is to use our nonradial nonadiabatic computing program to predict periods in this range for a model matching the observed parameters of delta Scuti and to identify all five periods