Forum Springer Astron. Astrophys.
Forum Whats New Search Orders

Astron. Astrophys. 320, 405-414 (1997)

Table of Contents
Available formats: HTML | PDF | (gzipped) PostScript

[O III ] [FORMULA] 5007 wing variations and changes of Fe II optical multiplets in NGC 5548 *

S.G. Sergeev , V.I. Pronik , Yu.F. Malkov and K.K. Chuvaev **

Crimean Astrophysical Observatory, P/O Nauchny, 334413 Crimea, Ukraine

Received 4 October 1995 / Accepted 5 August 1996


The variations of the [FORMULA] [FORMULA]  5007 line profile in NGC 5548 are examined from CCD spectra obtained at the Ohio State University and Crimean Astrophysical Observatory in December 1988 - October 1994. We have found the total flux of [FORMULA] [FORMULA]  5007 line to be variable, so the spectral calibration based on the assumption of non-variability of [FORMULA] [FORMULA]  5007 line is not absolutely correct. The variations are much more pronounced in the far wings of the line profile ([FORMULA] 1100 km s-1). Assuming the central part of the line profile is non-variable, we analyzed the variations of the red and blue wings relative to the profile center. We have found that these variations can be explained in terms of a reaction to the ionizing radiation changes with a transfer function spreading up to several hundred days. Perhaps, the "real" constant flux is localized in the narrow [FORMULA] line which belongs to the NLR and has a transfer function of about several hundred years, while the broad wings are emitted from the outer BLR. These wings may belong to [FORMULA] [FORMULA]  5018 and/or [FORMULA] [FORMULA]  5007. The transfer function of the blue wing is narrower, with a peak shifted to the zero lag by [FORMULA] 200 days relative to the transfer function of the red wing. Both wings, and especially the blue wing, show weak reaction near the zero lag. These facts must exclude both pure radial and round motion, but may suggest a lack of emitting gas near the line of sight and the presence of an outflow component. The [FORMULA] [FORMULA]  5169 line shows similar behavior to the [FORMULA] [FORMULA]  5007 wings. It confirms [FORMULA] [FORMULA]  5018 is the main contributor to the [FORMULA] wings or that the broad [FORMULA] is emitted at the same distance from the central engine as the [FORMULA]. The assumption about the presence of "short" and "long" lag spectral components, one of which varies similarly to the H [FORMULA] line and the other similarly to the [FORMULA] [FORMULA]  5007 wings, permits us to separate these components. The decomposition of the spectra shows that all observed [FORMULA] multiplets have a high lag value of the order of several hundred days, pointing to the typical size of the region which emits these lines. The decomposition also shows that there is a short lag component in the red wing of [FORMULA] [FORMULA]  5007 line. According to the centroid of this line ([FORMULA] 5032 Å) it may be identified with the [FORMULA] [FORMULA]  5041, 5056 or He I [FORMULA]  5016, 5048.

Key words: galaxies: active – galaxies: individual: NGC 5548 – galaxies: Seyfert – lines: profiles

* Table 2 is only available in electronic form at the CDS via anonymous ftp
** Deceased, 15 November 1994

Send offprint requests to: S.G. Sergeev

© European Southern Observatory (ESO) 1997

Online publication: June 30, 1998