bulge contributes significantly to the profile. Because of this, the σ − drop is not properly reproduced (S´ ersic profiles do possess a slight central decline in the velocity dispersion – see Ciotti 1991 – but this feature cannot reproduce the observed σ − drop). Thus, we posit that either an additional nuclear component is responsible for the σ − drop, or that bar formation in this scenario would generate gas inflow that could reproduce the σ − drop. The disc contribution to the velocity dispersion is comparatively muted, resulting in a lower overall disc dispersion. From Fig. 8, we see that scenario E behaves differently than the other scenarios. These models have lower M$_{d}$ and Q$_{min}$ but Fig. 9 shows that these models have high X$_{min}$ . Addi- tionally, Q$_{min}$ is reached at larger radii than in the other scenarios (typically, at ∼ 2 − 2 . 5 R$_{d}$ ), and they have more massive bulges ( § 6.4), which may also help inhibit the bar instability. As before, we selected several models and tested them for bar stability; the results are shown in the bottom right panel of Fig. 10. While these models quickly form spiral structure, bar formation is gradual at the low X$_{min}$ end of the best fit region and there is no evidence of bar formation at larger X$_{min}$ , despite the very low Q$_{min}$ . Because these simulations do not include gas, it is not possible to simulate possible bar destruction by gas inflow, but we can examine the length of the bar that forms. In Fig. 12 we plot the bar strength A as a function of radius at different times for the lowest − X model. This plot provides an estimate of the bar length of ∼ 1 . 5 kpc at 1 . 5 − 2 Gyr, which is consistent with the location of the Type II hump. We conclude that scenario E is a realistic scenario for the formation of the bar. In this section we delineate numerous other results that can be gleaned from the model. Because scenarios KG and KL are ruled out, we focus mainly on the results for scenarios K and E. We begin by comparing the photometric and dispersion scale lengths. We find from scenario K that the dispersion scale length is significantly larger than the photometric scale length, as seen in Fig. 13. The mean R$_{σ}$ = 2 . 6 kpc is also considerably larger than the best fit R$_{σ}$ of 1.16 kpc found in § 2, while the photometric scale length is slightly less than the ‘fit by eye’ value of 1 kpc from B89. Note that the dispersion scale length is poorly constrained owing to the size of the error bars in the velocity dispersion data, and that a wide range 19 6.1. The disc 6. Further results