  The method of gyrochronology relates the age of its star to its rotation
period. However, recent evidence of deviations from gyrochronology relations
was reported in the literature. Here, we study the influence of tidal
interaction between a star and its companion on the rotation velocity of the
star, in order to explain peculiar stellar rotation velocities. The interaction
of a star and its planet is followed using a comprehensive numerical framework
that combines tidal friction, magnetic braking, planet migration, and detailed
stellar evolution models from the GARSTEC grid. We focus on close-in companions
from 1 to 20 M$_{Jup}$ orbiting low-mass, 0.8 and 1 M$_{\odot}$, main-sequence
stars with a broad metallicity range from [Fe/H] = -1 to solar. Our simulations
suggest that the dynamical interaction between a star and its companion can
have different outcomes, which depend on the initial semi-major axis and the
mass of the planet, as well as the mass and metallicity of its host star. In
most cases, especially in the case of planet engulfment, we find a catastrophic
increase in stellar rotation velocity from 1 kms$^{-1}$ to over 40 kms$^{-1}$,
while the star is still on the main-sequence. The main prediction of our model
is that low-mass main-sequence stars with abnormal rotation velocities should
be more common at low-metallicity, as lower [Fe/H] favours faster planet
engulfment, provided occurrence rate of close in massive planets is similar at
all metallicities. Our scenario explains peculiar rotation velocities of
low-mass main-sequence stars by the tidal interaction between the star and its
companion. Current observational samples are too small and incomplete, and thus
do not allow us to test our model.
