Abstract
We numerically study the dynamical evolution of collapsing and star-forming gas. Efficiency of star formation during collapse is found to affect greatly the formation of non-axisymmetric structures such as bars and clumps developed after the completion of star formation. Effective consumption of gas by star formation greatly promotes the formation of a stellar bar because it reduces the formation of massive gas clumps which can suppress the formation of a stellar bar. This crucial role of the star formation does not depend strongly on other fundamental parameters such as the initial total angular momentum of the system and the fraction of initial gas mass.
