The variability of the spectrum of Arakelian 120. II - Evidence for a small broad line emitting region

Abstract

view Abstract Citations (103) References (33) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The variability of the spectrum of Arakelian 120. II. Evidence for a small broad line emitting region. Peterson, B. M. ; Meyers, K. A. ; Carpriotti, E. R. ; Foltz, C. B. ; Wilkes, B. J. ; Miller, H. R. Abstract The results of four years of spectroscopic and photometric observations of the Seyfert galaxy Akn 120 are reported. The observations were carried out using the image dissector scanner attached to the Perkins 1.8-meter reflector telescope at Lowell Observatory, as well as the photon-counting Reticon dstector attached to the Steward Observatory 2.3-meter telescope. The main conclusions of the observations were: (1) the cloud features of the broad-line emitting (BLR) region of Akn 120 were optically thick due to the variation of the Balmer emission with continuum; (2) no perceptible time delay was observed between the continuum variations and H-beta variations; (3) estimates of the ionizing flux of Akn 120 led to a BLR radiation which was two orders of magnitude too large, assuming a conventional electron density of 10 to the 9th per cubic cm; and (4) the broad Balmer lines in Akn 120 were displaced redward from the systemic velocity by about 400 km/s, implying a gravitational redshift. A mass of about 7 x 10 to the 8th solar mass was estimated for the central object of Akn 120, and the emission line widths of the entire system were found to be consistent with equipartition in the BLR. A complete list of the observational parameters is given in a table. Publication: The Astrophysical Journal Pub Date: May 1985 DOI: 10.1086/163142 Bibcode: 1985ApJ...292..164P Keywords: Astronomical Spectroscopy; Periodic Variations; Radiant Flux Density; Seyfert Galaxies; Spectral Energy Distribution; Spectral Line Width; Electron Density (Concentration); Emission Spectra; Galactic Nuclei; H Beta Line; Luminous Intensity; Red Shift; Astrophysics full text sources ADS | data products SIMBAD (4) NED (4)