Bars are the most important features that redistribute angular momentum and drive secular evolution in disk galaxies. We have derived the distribution of bar strengths in spirals and the Fourier properties of early-type galaxy bars in order to evaluate recent models of bar-halo angular momentum transfer and external gas accretion. A few results are presented here.

We use sticky-particle simulations to estimate the bar pattern speeds in disk galaxies over a wide range of Hubble types. For early types our results agree with the fast rotation found in previous kinematical measurements, while for later types significantly slower bars are found. Slow bars tend to be small, and favor less luminous galaxies, for a given bulge-to-total ratio.

We have applied the Tremaine-Weinberg method to the SB(r)b galaxy NGC 2523 and the SB(r)0/a galaxy NGC 4245 using the Calcium Triplet in order to determine their bar pattern speeds. Assuming an inclination of 53° and a distance of 49.5 Mpc, the pattern speed of NGC 2523 is 26.2 ± 6.1 km s−1 kpc−1. The pattern speed of NGC 4245 is 75.3 ± 31.2 km s−1 kpc−1, assuming an inclination of 35.4° and a distance of 12.7 Mpc. The ratio of the corotation radius to the bar radius of NGC 2523 and NGC 4245 is 1.3 ± 0.3 and 1.1 ± 0.5, respectively.