  Short-period binary star systems dissipate orbital energy through tidal
interactions that lead to tighter, more circular orbits. When at least one star
in a binary has evolved off of the main sequence, orbital circularization
occurs for longer-period (~100 day) systems. Past work by (Verbunt & Phinney
1995) has shown that the orbital parameters and the circularization periods of
a small sample of binary stars with evolved-star members can be understood
within the context of standard tidal circularization theory. Using a sample of
binaries with subgiant, giant, and red clump star members that is nearly an
order of magnitude larger, we reexamine predictions for tidal circularization
of binary stars with evolved members. We confirm that systems predicted by
equilibrium-tide theory to have circular orbits generally have negligible
measured eccentricities. The circularization period is correlated with the
surface gravity (i.e. size) of the evolved member, indicating that the
circularization timescale must be shorter than the evolutionary timescale along
the giant branch. A few exceptions to the conclusions above are mentioned in
the discussion: Some of these exceptions are likely systems in which the
spectrum of the secondary biases the radial velocity measurements, but four
appear to be genuine, short-period, moderate-eccentricity systems.
