1995A&A...301..359M

Visual, NIR, and H_α surface photometry of the oval disk galaxy M94 (NGC4736) was performed to study the distribution of mass in old stars and the distribution of the warm emission line gas. The radial profile of the inner stellar disk is steeper than exponential and displays twisted and deformed isophotes. Dust is not responsible for these deviations. The investigation of a number of morphological models showed that M94 has a weak central stellar bar of 0.7kpc semi-major axis length which comprises about 14% of the total light within 20". By means of longslit spectroscopy the kinematics of gas and stars in this region were investigated. The stellar kinematics reveal the existence of a small spheroidal bulge with v/σ≃0.8. The stellar velocity field in this region is approximately axisymmetric, showing that the effects of the bar on the kinematics of the hot component are relatively small. The warm gas in the bar region shows global and local deviations from the stellar kinematics, but outside the central bar fits into the general HI velocity field. Model calculations of closed orbits for gas in the potential of the bar perturbation and axisymmetric disk and bulge predict large non-circular motions for cold gas in equilibrium flow. These do not fit the central H_α kinematics; rather it appears that the H_α gas must have large random motions and is not in a steady state, and that hydrodynamical effects due to a recent starburst play a role in the central region.