EDP Sciences
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Volume 367, Number 3, March I 2001
Page(s) 780 - 787
Section Extragalactic astronomy
DOI http://dx.doi.org/10.1051/0004-6361:20000500

A&A 367, 780-787 (2001)
DOI: 10.1051/0004-6361:20000500

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

L. C. Popovic, N. Stanic, A. Kubicela and E. Bon

Astronomical Observatory, Volgina 7, Belgrade, Yugoslavia

(Received 9 October 2000 / Accepted 6 December 2000 )

To investigate the structure of the Akn 120 emitting region we have analysed the spectral line profiles of H$_\alpha$, H$_\beta$, Ly$_\alpha$, 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 ($\approx$2500 km s-1) and approaching line-of-sight velocities, and the other has a smaller random velocity of emitters ($\approx$1000 km s-1) and receding line-of-sight velocities. Also, we discuss the long-term H$_\beta$ line shape variation in the spectra of Akn 120. The H$_\beta$ 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 H$_\beta$ and shelf (Fe II template) cause the H$_\beta$ 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: $i=10^\circ$; $R_{\rm inn}\approx 120{-}200 R_{\rm g}$, $R_{\rm out}\approx 1000 R_{\rm g}$.

Key words: galaxies: individual (Arakelian 120) -- galaxies: Seyfert -- line: profiles -- accretion, accretion disks

Offprint request: L. C. Popovic, lpopovic@aob.bg.ac.yu

SIMBAD Objects in preparation

© ESO 2001