Ììì Úóðùøøóò Óó Ö Èøøøöò Ëô Ûûøø Ììññ Òò Ùððð Èöóññòòò 2. Measuring the Properties of Bars from Observations

Results from the modelling of bars in nearly 300 galaxies are used to test predictions from theoretical work on the evolution of bars. Correlations are found between bar ellipticity and boxiness, between bar strength and normalised size, between the normalised sizes of bars and bulges, and between normalised bar size and bulge-to-total ratio. Bars with different ellipticities follow parallel lines in the latter two correlations. These correlations suggest that, formed with different sizes and ellipticities, bars slow down and grow longer and stronger, in agreement with theoretical work. As a consequence, bar pattern speeds should become lower with time, and towards galaxies with more prominent bulges.