  For most hot Jupiters around main-sequence Sun-like stars, tidal torques are
expected to transfer angular momentum from the planet's orbit to the star's
rotation. The timescale for this process is difficult to calculate, leading to
uncertainties in the history of orbital evolution of hot Jupiters. We present
evidence for tidal spin-up by taking advantage of recent advances in planet
detection and host-star characterization. We compared the projected rotation
velocities and rotation periods of Sun-like stars with hot Jupiters and
spectroscopically similar stars with (i) wider-orbiting giant planets, and (ii)
less massive planets. The hot Jupiter hosts tend to spin faster than the stars
in either of the control samples. Reinforcing earlier studies, the results
imply that hot Jupiters alter the spins of their host stars while they are on
the main sequence, and that the ages of hot-Jupiter hosts cannot be reliably
determined using gyrochronology.
