The structure of the Akn 120 emitting region: The line shapes and long-term H$\mathsf{_\beta}$ line profile variation

To investigate the structure of the Akn 120 emitting region we have analysed the spectral line profiles of Hα , Hβ , Lyα , C III[1909], C IV[1549] and Mg II[2798] lines using a Gaussian-decomposition approach. The decomposed shape of the Akn 120 lines indicates three separated broad line-emitting regions, in two of them, the systematic motions of emitting gas are present. It seems that one of the two regions has a high random velocity of emitters (≈ 2500 km s-1 ) and approaching line-of-sight velocities, and the other has a smaller random velocity of emitters (≈ 1000 km s-1 ) and receding line-of-sight velocities. Also, we discuss the long-term Hβ line shape variation in the spectra of Akn 120. The Hβ line (from 96 spectra) was fitted with three broad and one narrow Gaussians through the entire period considered (1977-1990). The central broad as well as blue component of Hβ and shelf (Fe II template) cause the Hβ line shape variation. Besides the Gaussian decomposition of the shapes of the three hydrogen lines we propose here a disk model with two more regions located symmetrically to the disk plane. Using the fitting method with the disk model we obtained the parameters of the disk: ; , .