Issue |
A&A
Volume 464, Number 2, March III 2007
|
|
---|---|---|
Page(s) | 715 - 734 | |
Section | Stellar atmospheres | |
DOI | https://doi.org/10.1051/0004-6361:20066175 | |
Published online | 02 January 2007 |
The He
Fowler lines and the O
and
N
Bowen fluorescence lines in the symbiotic nova RR Telescopii
1
INAF – Osservatorio Astronomico di Trieste, via Tiepolo 11, 34143 Trieste, Italy e-mail: selvelli@ts.astro.it
2
CIFIST Marie Curie Excellence Team
3
Observatoire de Paris, GEPI, 5 place Jules Janssen, 92195 Meudon, France
Received:
3
August
2006
Accepted:
17
December
2006
Aims.A detailed study of the and
Bowen
lines in the spectrum of RR Tel.
Methods.Absolute intensities for the ,
,
and
emission lines have been obtained from STIS, UVES, FEROS and IUE data, after
re-calibration of UVES and FEROS on the STIS scale.
Results.A new measure of reddening ( ~ 0.00) has been obtained from the comparison between
the observed and the theoretical intensity decrement for 20 emission
lines of the
Fowler (n
3) series. This value
has been confirmed by the STIS and IUE continuum distribution, and by
the value of nH from the damped profile of the IS H Ly-α line.
We have obtained very accurate measurements for about thirty Bowen
lines of
and a precise determination of the efficiency in
the O1 and O3 excitation channels (18% and 0.7%, respectively).
The relative
intensities are in good agreement with the
predictions by Froese Fischer (1994). A detailed study of the decays from
all levels involved in the Bowen mechanism has lead to the detection of two new
Bowen lines near λ 2190. High resolution IUE data
have shown a nearly linear decline with time, from 1978 to 1995, in the
efficiency of the O1 and O3 processes, with a steeper slope for the O3 channel. A detailed
study of the
λ 4640 lines and of their excitation
mechanism has shown that, recombination and continuum fluorescence being
ruled out, line fluorescence remains the only viable mechanism to pump the
3d
and 3d
levels of
. We point out
the important role of multiple scattering in the resonance lines of
and
near λ 374 and show that
the observed
line ratios and intensities can be explained in terms of line
fluorescence by the three resonance lines of
at λλ 374.432,
374.162 and 374.073 under optically thick conditions.
Key words: stars: novae, cataclysmic variables / stars: binaries: symbiotic / ultraviolet: stars / atomic processes / radiative transfer
© ESO, 2007
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