  Convection plays an essential role in the emerging intensity for many stars
that will be observed by Gaia. Convective-related surface structures affect the
shape, shift, and asymmetry of absorption lines, the phocentric and photometric
variability causing bias in Gaia measurements. Regarding the importance of Gaia
mission and its goals, it is mandatory to have the best models of the observed
stars. 3D time-dependent hydrodynamical simulations of surface convection are
crucial to model the photosphere of late type stars in a very realistic way.
These simulations are an important tool to correct the radial velocities and
better estimates the parallaxes and photometric variability.
