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Next: Wind absorption lines Up: HST-UV spectroscopy: results and Previous: Interstellar absorption lines

Photospheric absorption lines

The spectra of these Seyferts are also rich in absorption features formed in the photospheres of massive stars. The most prominent lines are SV 1#11501, CIII 1#11426,1428, SiIII 1#11417 and SiIII 1#11341-1343+PIII 1#11344. These lines are strong in late O and early B stars (Walborn, Bohlin, & Panek 1985; Walborn, Parker, & Nichols 1995). They have been detected in the prototype starburst galaxy NGC 7714 (González Delgado et al 1998, in preparation). These are not resonances lines, and therefore they cannot be formed in the interstellar medium. The measured equivalent widths of these lines are given in Table 3. Their strength indicates that O and early B stars are the dominant population in the UV spectrum of these Seyfert galaxies.

Another possible feature that could be associated with the starburst is the photospheric lines SiIII 1#11294,1296. These lines are very strong in early B supergiants. We note in our UV spectra that the absorption feature around 1300 Å is stronger and broader than the other interstellar absorption lines, indicating that the interstellar lines OI+SiII 1#11303 could be contaminated by SiIII. These SiIII lines have been detected in the super star-cluster in NGC 1705 (Heckman & Leitherer 1997).


next up previous
Next: Wind absorption lines Up: HST-UV spectroscopy: results and Previous: Interstellar absorption lines
Rosa Gonzalez
1998-06-20