| Issue |
A&A
Volume 452, Number 1, June II 2006
|
|
|---|---|---|
| Page(s) | 253 - 256 | |
| Section | Interstellar and circumstellar matter | |
| DOI | https://doi.org/10.1051/0004-6361:20054375 | |
| Published online | 17 May 2006 | |
Resonance-enhanced two-photon ionization (RETPI) of Si II and an anomalous, variable intensity
of the 
1892 Si III] line in the Weigelt blobs of η Carinae
1
Lund Observatory, Lund University, PO Box 43, 22100, Lund, Sweden e-mail: sveneric.johansson@astro.lu.se
2
Institute of Spectroscopy, Russian Academy of Sciences, 142190 Troitsk, Moscow region, Russia
Received:
19
October
2005
Accepted:
21
February
2006
Context.The Si III] 1892 Å intercombination line shows an anomalously high intensity in spectra of the radiation-rich Weigelt blobs in the vicinity of Eta Carinae. The line disappears during the 100 days long spectral events occurring every 5.5 years.
Aims.The aim is to investigate whether resonance-enhanced two-photon ionization (RETPI) is a plausible excitation mechanism for the Si III] λ1892 line.
Methods.The possible intensity enhancement of the λ1892 line is investigated as regards quasi-resonant intermediate energy levels of Si II.
Results.The RETPI mechanism is effective on 
in the radiation-rich Weigelt
blobs where the two excitation steps are provided by the two intense hydrogen lines Lyα and Lyγ.
Key words: atomic processes / radiation mechanisms: non-thermal / HII regions / stars: individual: η Carinae
© ESO, 2006
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