2007AJ....134..179Y

We present a detailed period analysis of TY Bootis, based on all available light minimum times covering about 80 years. We discovered that there exists a cyclic variation overlaying a secular period decrease from the distorted (O-C) diagram. A long-term decrease with a sinusoidal oscillation (i.e., \formref eq. [2]) or with a light-time effect (i.e., \formref eq. [3]) may be reasonable due to the smaller difference between their sum of residuals. The sinusoidal change with a period of 59.7 yr for \formref equation (2) can be attributed to either a light-time effect or cyclic magnetic activity of both components. For the assumed third body, the period and eccentricity of the light-time orbit are P₃=58.6 yr and e'=0.1744, respectively. If the existence of an additional unseen body is true, this binary may be a tertiary system. The long-term orbital period decrease suggests that TY Boo is undergoing a mass transfer from the primary component to the secondary component at a rate of dm/dt=-3.15x10^–8 M_☉/yr for \formref equation (2) or dm/dt=-2.90x10^–8 M_☉/yr for \formref equation (3). As its mass transfers, accompanied by angular momentum loss due to mass outflow L₂, this binary will evolve into a deep contact configuration.