EDP Sciences
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Volume 412, Number 3, December IV 2003
Page(s) 771 - 776
Section Formation, structure and evolution of stars
DOI http://dx.doi.org/10.1051/0004-6361:20031613

A&A 412, 771-776 (2003)
DOI: 10.1051/0004-6361:20031613

Anomalously bright UV lines of Fe II as a probe of gas condensations in the vicinity of hot stars

S. Johansson1 and V. S. Letokhov2, 1

1  Lund Observatory, Lund University, PO Box 43, 22100 Lund, Sweden
    e-mail: Vladilen.Letokhov@astro.lu.se
2  Institute of Spectroscopy, Russian Academy of Sciences, Troitsk, Moscow region 142190, Russia

(Received 26 May 2003 / Accepted 13 October 2003)

Two UV lines of Fe II at 2507/2509 Å are extremely bright in spatially resolved HST/STIS spectra of dense gas condensations (the so called Weigelt blobs) close to the central star of $\eta$ Carinae. The lines also appear unresolved in HST/FOS spectra of the star AE And. Under normal conditions the lines should hardly be observable. Based on recent studies of the formation of the $\lambda\lambda$2507/2509 lines as part of a radiative cycle driven by HLy $\alpha$ pumping and including stimulated emission we propose the possibility of using them as a probe of non-homogeneities in gas condensations located outside hot, massive stars.

Key words: atomic processes -- line: formation -- radiation mechanisms: non-thermal -- stars: individual: $\eta$ Car, AE And

Offprint request: S. Johansson, sveneric.johansson@astro.lu.se

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