LOW-STATE PHASE-RESOLVED INFRARED SPECTROSCOPY OF VV PUPPIS

We present new five-color photometric and spectroscopic observations of the Algol system XX Cephei (V = 9.13, P = 2.3 days). This system is known to have a variable period. From analysis of both the period variations and the light curve we found no support for apsidal motion. However, there is a possible light-time effect. The period changes could also be episodic. Our spectroscopic analysis yielded a classification of A4. We found no evidence of features attributable to the cooler component or of active mass transfer. Our photometric solution, using the Wilson-Devinney modeling program, showed the system to be an Algol configuration with a mass ratio of 0.17. We determined the masses and radii, in solar units, to be M1 = 1.92, M2 = 0.33, R1 = 2.07, and R2 = 2.32, and the temperatures to be T1 = 8500 K and T2 = 4555 K. From the parallax given in the Hipparcos catalog, neglecting reddening, absolute magnitudes of MV = 1.73 and 4.43 were determined for the primary and secondary components, respectively.