Lenticular galaxy
Sérsic decomposition

The surface brightness profiles of lenticular galaxies are well described by the sum of a Sérsic model for the spheroidal component plus an exponentially declining model (Sérsic index of n ≈ 1) for the disk, and often a third component for the bar. Sometimes there is an observed truncation in the surface brightness profiles of lenticular galaxies at ~ 4 disk scalelengths. These features are consistent with the general structure of spiral galaxies. However, the bulge component of lenticulars is more closely related to elliptical galaxies in terms of morphological classification. This spheroidal region, which dominates the inner structure of lenticular galaxies, has a steeper surface brightness profile (Sérsic index typically ranging from n = 1 to 4) than the disk component. Lenticular galaxy samples are distinguishable from the diskless (excluding small nuclear disks) elliptical galaxy population through analysis of their surface brightness profiles.
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