A REANALYSIS OF THE SWP-HI IUE OBSERVATIONS OF CAPELLA

We have reanalyzed the numerous high-resolution, far-ultraviolet obser vations of Capella (G8 III + G1 III) made by the International Ultravi olet Explorer in its 16 yr lifetime. Our purpose was to search for lon g-term profile variations in Capella's ultraviolet emission lines and to complement the analysis of Goddard High Resolution Spectrograph (GH RS) observations of Capella, discussed in a companion paper (Linsky et al. 1995). We implemented a state-of-the-art photometric correction a nd spectral extraction procedure to improve S/N and control potential sources of systematic errors. Nevertheless, we were unable to find com pelling evidence for any significant long-term line profile variations . Previous work has shown that the G8 primary star is only a minor con tributor to the high-excitation transition region lines but is a signi ficant contributor to the low-excitation chromospheric lines. We have found exceptions to this rule, however. We find that the G8 star is re sponsible for a significant portion of Capella's N V lambda lambda 123 9, 1243 emission, but is not a large contributor to the S I lambda 129 6, Cl I lambda 1352, and O I] lambda 1356 lines. We suggest possible e xplanations for these behaviors. We also find evidence that the He II lambda 1640 emission from the G1 star is from the transition region, w hile the He II lambda 1640 emission from the G8 star is chromospheric, consistent with the findings of Linsky et al. (1994). The C II lambda 1336 line shows a weak central reversal. It is blueshifted by about 9 km s(-1) with respect to the centroid of the emission from the G1 sta r. While the central reversal of the C II line is blueshifted, the cen tral reversal of the Si III lambda 1207 line discussed by Linsky et al . (1994) is not.