Abstract

Data from 217 pairs of BV photometric observations of U Peg, obtained with a single-channel photomultiplier photometer on the 60-cm reflector at Beijing Observatory during 1978, are presented in tables and graphs and discussed in comparison with previous observations. Four minima times are determined; a secular period decrease of 4.16 msec/yr is calculated from for the period 1896-1978; and a 17-yr oscillation with semiamplitude 0.00323 d is identified and attributed to the light-time effect of a main-sequence type-M6 third body of 0.16 solar mass. Interpretation of the 1978 light curves and those obtained by Binnendijk (1960) in 1958 indicates an overcontact of about 9 percent, a photometric mass ratio m2/m1 between 2.5 and 3, a gamma velocity of -40 km/sec, and dimensions 0.6 solar mass and 0.8 solar radius for the first component and 1.3 solar mass and 1.4 solar radius for the second component.