  We study the formation and evolution of the tidal tail released from a young
Pleiades-like star cluster, due to expulsion of primordial gas in a realistic
gravitational field of the Galaxy. The tidal tails (as well as clusters) are
integrated from their embedded phase for 300 Myr. We vary star formation
efficiencies (SFEs) from 33% to 100% and the timescales of gas expulsion as
free parameters, and provide predictions for the morphology and kinematics of
the evolved tail for each of the models. The resulting tail properties are
intended for comparison with anticipated Gaia observations in order to
constrain the poorly understood early conditions during the gas phase and gas
expulsion. The simulations are performed with the code Nbody6 including a
realistic external gravitational potential of the Galaxy, and an analytical
approximation for the natal gaseous potential. Assuming that the Pleiades
formed with rapid gas expulsion and an SFE of $\approx 30$%, the current
Pleiades are surrounded by a rich tail extending from $\approx 150$ to $\approx
350$ pc from the cluster and containing 0.7 to 2.7 times the number of stars in
the present-day cluster. If the Pleiades formed with an SFE close to 100%, then
the tail is shorter ($\lesssim 90$ pc) and substantially poorer, containing
only $\approx 2$% of the number of present-day cluster stars. If the Pleiades
formed with an SFE of $\approx 30$%, but the gas expulsion was adiabatic, the
tail signatures are indistinguishable from the case of the model with 100% SFE.
The model takes into account the estimated contamination due to the field stars
and the Hyades-Pleiades stream, which constitutes a more limiting factor than
the accuracy of the Gaia measurements.
