v_z,init versus t_init for star particles whose velocity changes by more than 5 km s⁻¹, color-coded by their velocity change. The solid black line is the mass-weighted average velocity of the full stellar population. Stars faster than the average tend to slow down, while those slower than the average tend to speed up, particularly for the fiducial and ldcloud simulations. The gravity from the accelerating dense cloud of gas is likely responsible for the blue (accelerating) star particles that are moving faster than the average stellar velocity.