The origin of the anomalous intensity ratio between very bright UV FeII lines and their satellites in gaseous condensations close to the starηCarinae

Time variations of the narrow Fe II and H I spectral emission lines from the close vicinity of η Carinae during the spectral event of 2003

“…However, the penetration depth of this spectrally narrow radiation is restricted by the high optical density of absorption in the Lyα transition, and the significant (±2.5 Å) detuning of the Fe  absorption lines relative to Lyα. This matter was considered by Klimov et al (2002). The situation is more clear when one consider the Lyα radiation generated in the stellar wind in the geometry shown in Fig.…”

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

“…It should be emphasized that the hydrogen density N H << 10 13 cm −3 , which means that collisions do not contribute to the depletion of the long-lived Fe II states. In our initial model (Johansson & Letokhov 2001a,b;Klimov et al 2002), the accumulation of Fe + ions in the "pseudo-metastable" states leads to a noticeable optical thickness of the λλ2507/09 lines. The model is based on depletion of these levels by absorption, i.e.…”

“…These conditions are qualitatively illustrated in Fig. 3 by means of two main parameters -the distance R b from the central star in terms of its photosphere radius r s and the critical (minimal) hydrogen density N H for the given distance R. The hydrogen density N H should exceed some critical value N cr 0 (Klimov et al 2002):…”

“…Equation (1) (Johansson & Letokhov 2001b;Klimov et al 2002) in the Weigelt blobs, located at a distance R b ≈ (10 2 −10 3 )r s from the central star in η Car, where r s is the stellar radius. Another important and critical requirement is that R b is small enough to provide for a high spectral temperature of Lyα, T α , at a frequency matching the Fe II pumping channel.…”

“…The first source is the H II region produced by absorption of the Lyman continuum from the star, which is transferred into intense radiation in the immediate vicinity of the H I region containing Fe II. This source has been discussed earlier (Klimov et al 2002). To compensate for the wavelength detuning of 2.4 Å between Lyα and the absorbing Fe II channel by diffusion Doppler broadening, it is necessary that the optical density τ 0 (Lyα) of the H I region is about 2 ×10 8 as estimated by Hamann et al (1999).…”