An observational exploration of the evolution of angular momentum in close detached binary and single stars of solar type

This thesis explore the effects of tides in solar-type stars in close detached binary systems. Tidal interactions drive an exchange of stellar and orbital angular momentum. The cumulative effects of tidal interactions is referred to as tidal evolution. The characteristic signs of completed tidal evolution are: (1) Alignment of the stellar spin axes perpendicular to the orbital plane; (2) Synchronization of the rotation of the stars to the orbital motion; and (3) Circularization of the orbits.;This thesis contributes new observational data on the orbital periods and eccentricities of close solar-type binary stars, a new diagnostic to measure the degree of tidal circularization in a population of binary stars, rotation periods for the primary stars in 13 binaries with known orbital periods and eccentricities, and a diagnostic of the degree of tidal synchronization in a given binary star. Together, the new data and the new diagnostics produce results that challenge and constrain current theoretical models of tidal evolution.;This thesis presents an observation that stars in close binaries (stellar separation less than ∼ 5 AU), in the 150 million year open cluster M35, rotate on average faster than single stars or stars in wider binaries. This result suggests that a companion star within ∼ 5 AU does affect the rotational evolution of a solar-type star in a way that leads to on average faster rotation. In the framework of current models of angular momentum evolution of stars during their pre main-sequence phase, this result lent support to the idea that the lifetimes of circumstellar disks in such close binaries are shorter than for single stars or for stars in wider binaries.;Finally, this thesis presents an extensive time-series photometric survey of late-type stars M35, resulting in rotation periods for 310 cluster members. Distinct patterns in the distribution of stellar rotation periods with stellar color (mass) in offer strong support for a hydromagnetic mechanism recently proposed to explain the rotational evolution of late-type stars.