RY Persei: An early-type interacting close binary

We have analyzed photometric and spectroscopic data for the totally-eclipsing binary RY Persei. It is a semidetached binary of the Algol type. However, both the gainer (B4: V) and the loser (F7: II-III) are significantly more massive (6.25 and 1.6 M.), hotter, and more luminous (M(bol) about -3.3 and -0.2 mag, respectively) than a typical Algol system. As a possible result, the ionization level indicated by emission lines observed in the UV during total eclipse is unusually high. These lines also show evidence of CNO processing of circumstellar matter: the C IV and C II lines are weak compared to the very strong N V line. V,B photometric solutions are quite satisfactory, if the rapid rotation of the gainer (about 10 times the synchronous rate) is taken into account. On the contrary, IUE spectra show circumstellar structures in both continuum and absorption lines (and in emission lines in deep eclipse). RY Per straddles the border between permanent and transient accretion disks; it may be better to speak about a pseudo-photosphere. Because of its distance (about 840 pc) and low galactic latitude (-10.5 degrees), interstellar extinction is appreciable; our estimate is E(B-V)approximate to 0.18 mag. (C) 1997 American Astronomical Society.