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Session 19 - Hot Stars.
Display session, Monday, January 15
North Banquet Hall, Convention Center
The rich emission line spectrum of the bright symbiotic nova RR Tel provides one of the best laboratories for determining empirical values of atomic parameters, including branching ratios, Einstein A-values and electron collision strengths. In addition to providing atomic parameters not measurable in the laboratory, the observations also test recent theoretical calculations of these parameters. In July 1995 we obtained high quality low and medium resolution, large aperture spectra of RR Tel using the Goddard High Resolution Spectrograph (GHRS) on board the Hubble Space Telescope. These spectra sample wavelengths from 1100 Å\ to 2680 Å\ and contain numerous lines of astrophysical interest which will be used to derive empirical atomic data (e.g. branching ratios in C II], N III], O III] and O IV]) as well as lines from which the local temperature and density can be determined. The GHRS spectra have greater dynamic range and lower background noise than available high resolution IUE data, permitting detailed evaluation of spectral diagnostics even for the weak emission features from some intercombination and forbidden transitions. In this paper we show examples of the spectra, discuss the atomic transitions for which atomic data will be derived and describe the methods used in determining these parameters. RR Tel and AG Peg, both of which have been observed with the GHRS, are fundamental for studying time variability of spectra of a symbiotic nova and the GHRS observations will be compared with previous IUE results to investigate this variability. We will also discuss the observed flows and turbulence found from the line profiles as well as the shape of the UV continuum.
Support for this work was provided by NASA through grant number GO-05863.01-94A from the Space Telescope Science Institute, which is operated by the Association of Universities for research in Astronomy, Inc., under NASA contract NAS5-26555.
