On the Extraction of Optical Rotation Curves for Spiral Galaxies

Abstract

We discussed four different methods - the single, double and triple Gaussian fits, and the intensity weighted centroid fit - which extract rotation curves from several emission lines ([OII], Hβ, [OIII], and Hα) of spiral galaxies. Spatial extents and the shapes of rotation curves derived through various methods applying to each emission lines of a sample galaxy UGC 11635 are all in a good agreement with one another. Linewidths of Hβ and Hα measured from rotation profiles are in a good agreement with Hα linewidth of Courteau (1992). However, linewidths of [OII] seems to be much broader than Hα, and the profile of [OIII] does not follow the profile of Hα.