We present results of observations of the blue spectrum of the symbiotic system AG Peg at the final stage of its outburst when the luminosity and the mass-loss rate of its hot component decrease. The radial velocity data and the line fluxes have been obtained.
The radial velocities of the emission lines are compared with the radial velocity curves of the same elements during the orbital cycle, drawn on the basis of earlier observations, realized nine years ago (Tomov & Tomova 1992). It turns out that some of them differ considerably from the corresponding values of the curves, which in our opinion, is determined by dynamical change of the nebular environment. Balmer progression has not been established.
The profile of the lines H, H
and HeII 4686 consists
of two components:
a central narrow component and a broad component indicating stellar wind.
The comparison with earlier spectra (Tomov & Tomova 1992)
shows the width of the broad component has not changed, which means that
the wind velocity has had a constant value. The line fluxes of the broad
components have been calculated by means of the mass-loss rate, obtained on
the basis of contemporaneous UV observations. They are in agreement with
the observed fluxes which confirms this mass-loss rate and its decreasing by
a factor of 1.77 during this period of nine years.
The line fluxes of the more intensive among the narrow lines have also been obtained. A decrease of these fluxes by a mean factor of about 2 for all elements has been derived during this period.
Acknowledgements
The authors are grateful to the referee whose critical remarks contributed to improve the paper. N.T. and M.T. would like to thank their colleagues Dr. R. Zamanov and Dr. N. Markova for helpful discussions. This work was supported in part by Bulgarian National Scientific Foundation grant under contract F-466/94 with Ministry of Education, Science and Technology.