Astron. Astrophys. 361, 977-981 (2000)

New forbidden and fluorescent Fe III lines identified in HST spectra of Carinae ^*

S. Johansson ¹, T. Zethson ¹, H. Hartman ¹, J.O. Ekberg ¹, K. Ishibashi ^2,3, K. Davidson ² and T. Gull <sup>3

1</sup> Department of Physics, Lund University, P.O. Box 118, 22100 Lund, Sweden (sveneric.johansson, torgil.zethson, henrik.hartman, jan_olof.ekberg@fysik.lu.se)
² Astronomy Department, University of Minnesota, 116 Church St. SE, Minneapolis, MN 55455, USA (bish@howdy.gsfc.nasa.gov; kd@ea.spa.umn.edu)
³ NASA/Goddard Space Flight Center, Code 681, Greenbelt, MD 20771, USA (gull@sea.gsfc.nasa.gov)

Received 21 March 2000 / Accepted 6 July 2000

Abstract

We discuss the origin of eight emission lines in the spectra of gas blobs close to the central star of Carinae. The spectra have been obtained with the Goddard High Resolution Spectrograph (GHRS) and the Space Telescope Imaging Spectrograph (STIS) onboard the Hubble Space Telescope . Between 2400 and 2500 Å five narrow lines are identified as new forbidden lines of doubly ionized iron, [Fe III]. We present gA-value data for the corresponding transitions, which combine two different metastable configurations of Fe III. An anomalous intensity of the narrow Fe III line (UV 34) at 1914 Å is explained as fluorescence due to HLy pumping. A level mixing of about 1% increases the f-value of the pumped excitation channel by more than two orders of magnitude, which makes the pumping efficient and the fluorescence significant. We introduce a new designation for fluorescence lines photoexcited by an accidental resonance, eg. Fe III in the case of doubly ionized iron.

Key words: atomic processes line: identification stars: individual: j Car stars: variables: general ultraviolet: stars

* Based on observations with the NASA/ESA Hubble Space Telescope, and supported by grant numbers GO-6501 and GO-7302 from the Space Telescope Science Institute. The STScI is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555.

Send offprint requests to: S. Johansson

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Contents

• 1. Introduction
• 2. New forbidden [Fe III] lines
• 3. New fluorescent Fe III lines
• 4. Conclusion
• Acknowledgements
• References

© European Southern Observatory (ESO) 2000

Online publication: October 10, 2000
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