  In this work, we study whether the engulfment of a brown dwarf (BD) by a
solar-like main-sequence (MS) star can significantly alter the structure of the
star and the Li content on its surface. We perform 3D Smoothed Particle
Hydrodynamics simulations of the engulfment of a BD with masses 0.01 and 0.019
Msun, onto an MS star of 1 Msun and solar composition, in three different
scenarios: a head-on collision, a grazing collision, and a merger. We study the
dynamics of the interaction in detail, and the relevance of the type of
interaction and the mass of the BD on the final fate of the sub-stellar object
and the host star in terms of mass loss of the system, angular momentum
transfer, and changes in the Li abundance in the surface of the host star. We
found that most of the BD mass is diluted in the denser region of the MS star.
Only in the merger scenario a significant fraction (40%) of the BD material
would remain in the outer layers. We find a clear increase in the surface
rotational velocity of the host star after the interaction, ranging between 25
km/s (grazing collision) to 50 km/s (merger). We also find a significant mass
loss from the system (1e-4 - 1e-3 Msun) due to the engulfment, which in the
case of the merger, may form a circumstellar disk-like structure. Assuming that
neither the depth of the convective envelope of the host star nor its mass
content are modified during the interaction, a small change in the surface Li
abundance in the head-on and grazing collisions is found. However, in the
merger we find large Li enhancements, by factors 20-30, depending on the BD
mass. Some of these features could be detected observationally in the host star
provide they remain long enough time.
