Photometric and Spectroscopic Observations of the Algol Type Binary V Triangle

Time-series, multi-color photometry and high-resolution spectra of the short-period eclipsing binary V Tri were obtained through observation. The completely covered light and radial velocity (RV) curves of the binary system are presented. All times of light minima derived from both photoelectric and CCD photometry were used to calculate the orbital period and new ephemerides of the eclipsing system. The analysis of the O - C diagram reveals that the orbital period is 0.58520481 days, decreasing at a rate of dP/dt = -7.80 x 10(-8) day yr(-1). The mass transfer between the two components and the light-time-travel effect due to a third body could be used to explain the period decrease. However, a semi-detached configuration with the lower-mass component filling and the primary nearly filling each of their Roche lobes was derived from the synthesis of the light and RV curves by using the 2015 version of the Wilson-Devinney code. We consider the period decrease to be the nonconservative mass transfer from the secondary component to the primary and the mass loss of the system, which was thought to be an EB type, while it should be an EA type (semi-detached Algol-type) from our study. The masses, radii, and luminosities of the primary and secondary are 1.60 +/- 0.07M(circle dot), 1.64 +/- 0.02 R-circle dot, and 14.14 +/- 0.73 L-circle dot and 0.74 +/- 0.02 M-circle dot, 1.23 +/- 0.02 R-circle dot, and 1.65 +/- 0.05 L-circle dot, respectively.