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# 4. Comparison with similar work

## 4.1. Work using the Inclined Thin Disk approximation

Because the results of Simien & Michard (1990), were derived from photographs of relatively poor resolution, it was not found possible to make significant comparisons with the present results: indeed the observed , e4 and e6 parameters in our "old" paper were obviously strongly affected by seeing for the two objects in common.

More significant comparisons are feasible for the Heidelberg results (Scorza & Bender 1995). It is to be noted that their assumptions are similar to ours, plus the one of constant , and that their criteria for finding the solution are essentially equivalent to our technique. We have three objects in common, i.e. NGC 3115, 3377 and 3585.

As an example, the comparison for NGC 3115 is shown in Fig. 2 (click here) for the MajA total and disk SuBr's (after an ad hoc correction to bring the data to a common magnitude scale). The disk profiles are in fair agreement, although their disk is chosen flatter. Note that we both use for the inner region the same CFHT frame obtained by Nieto in 1989.

The agreement is still better for NGC 3585, where our value is constant and nearly equal to the one of Scorza and Bender. On the other hand, the agreement is much worse for NGC 3377, probably in view of the relatively large difference in the values, the galaxy beeing more inclined and the disk thinner in our model.

Figure 2: Comparison between the disk profile of NGC 3115 derived by Scorza & Bender (1995) (open symbols) and our results (full symbols). Total SuBr: squares; disk SuBr: stars

## 4.2. Work using the Edge-on Very Thin Disk assumption

From our models it is possible to calculate the SuBr at the tips of any MinA, induced by each component. The fractional SuBr, indeed expressed in terms of the total and noted and , can also be obtained: their sum should be close to 1, and one should have near zero if our models are to support the assumption that the MinA SuBr of the disk is negligible. Table 2 (click here) gives the calculated for 6 galaxies treated with this assumption by Seifert & Scorza (1996) plus NGC 3377. The values of the fractional disk SuBr are given for the MinA of 9 bulge contours, specified by the values a of their MajA in arcsec. It appears from Table 2 (click here), that the Edge-on Very Thin Disk assumption is valid for NGC 3377 and nearly so for NGC 3115. For the later however, the structure termed "nuclear disk" by Scorza and Bender is not very thin according to our solution, and therefore has some effect on the MinA SuBr's. The assumption is in disagreement with our models for disk dominated S0's, such as NGC 2549, 4350 (but in its outermost parts), 5308, 5422 and 3098 to a lesser extent. As a consequence, part of the MinA light, actually coming from the disk in our models, will be mistaken for bulge light in the here discussed approximation: this will lead to overestimating the bulge light and underestimating the disk. The total and disk SuBr profiles found by Seifert & Scorza (1996) for NGC 2549 and 4350 are compared with our results in Fig. 3 (click here). The large and expected difference in the disk SuBr is striking. Note however that some specific disk features of interest (rings or "dubble disks") found in Seifert and Scorza treatment, are confirmed in our solution as seen for instance in the case of NGC 2549.

Figure 3: Comparison between the disk profiles derived by Seifert & Scorza (1996) (open symbols) and our results (full symbols) for two S0 galaxies. Total SuBr: squares; disk SuBr: stars

 a 3 5 10 20 30 40 50 60 2549 0.1 0.1 0.26 0.23 0.36 0.32 0.22 0.16 3098 0.23 0.25 0.13 0.07 0.05 - - - 3115 0.2 0.21 0.07 0.04 0.01 - - - 3377 0.04 0.02 0.02 0.01 - - - - 4350 0.08 0.11 0.53 0.52 0.48 0.35 0.12 0.01 5308 0.18 0.25 0.45 0.54 0.72 0.84 0.55 0.35 5422 0.1 0.18 0.27 0.32 0.52 0.61 0.43 0.27
Table 2: Fractional disk contributions to MinA SuBr's from our models

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