The changes in the UV emission lines of RR Telescopii from 1978 to 1993. I. The IUE SWP region

Abstract

Line emission intensities and FWHMs in the range 1175-1900 Angstroms have been measured on high resolution IUE spectra of RR Tel taken from 1978 to 1993. The variations observed in the emission line intensities show a rather strong correlation with the line ionization. The decrease is of a factor larger than three and up to ten for the low-ionization lines, and of a factor between two and three for the medium-high ionization lines. Instead, the high ionization lines have generally maintained their 1978 strength or have even increased it. For all lines no variation in the FWHM has been detected. Special attention has been paid to a very long exposure spectrum already studied by other authors for which we present new identifications and several comments. The presence of spurious emission features and camera artifacts is discussed. Based on observations with the International Ultraviolet Explorer (IUE) retrieved from the VILSPA data-bank. Tables 1 to 3 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/Abstract.html