Short-term emission line and continuum variations in Mrk 110

¹ Universitäts-Sternwarte Göttingen, Geismarlandstraße 11, 37083 Göttingen, Germany
² Department of Astronomy and McDonald Observatory, University of Texas at Austin, Austin, TX 78712, USA
³ Department of Astronomy, San Diego State University, San Diego, CA 92182, USA

Corresponding author: W. Kollatschny, wkollat@uni-sw.gwdg.de

Received: 19 July 2001
Accepted: 19 September 2001

Abstract

We present results of a variability campaign of Mrk 110 performed with the 9.2-m Hobby-Eberly Telescope (HET) at McDonald Observatory. The high spectra cover most of the optical range. They were taken from 1999 November through 2000 May. The average interval between the observations was 7.3 days and the median interval was only 3.0 days. Mrk 110 is a narrow-line Seyfert 1 galaxy. During our campaign the continuum flux was in a historically low stage. Considering the delays of the emission lines with respect to the continuum variations we could verify an ionization stratification of the BLR. We derived virial masses of the central black hole from the radial distances of the different emission lines and from their widths. The calculated central masses agree within 20% . Furthermore, we identified optical Hei singlet emission lines emitted in the broad-line region. The observed line fluxes agree with theoretical predictions. We show that a broad wing on the red side of the [Oiii]λ5007 line is caused by the Hei singlet line at 5016 Å.