The multimode pulsation of the delta Scuti star V784 Cassiopeae

We present an analysis of new Johnson and Stromgren photometric and medium-resolution spectroscopic observations of the delta Scuti type variable star V784 Cassiopeae. The data were obtained in three consecutive years between 1999 and 2001. The period analysis of the light curve resulted in the detection of four frequencies ranging from 9.15 d(-1) to 15.90 d(-1), while there is a suggestion for more, unresolved frequency components, too. The mean Stromgren indices and Hipparcos parallax were combined to calculate the following physical parameters: [T-eff] = 7100 +/- 100 K, log g = 3.8 +/- 0.1, M-bol = 1(.)(m)50 +/- 0(.)(m)15. The position of the star in the HR diagram was used to derive evolutionary mass and age yielding to a consistent picture of an evolved delta Scuti star with a mixture of radial plus non-radial modes.