Bowen excitation of N III lines in symbiotic stars

Abstract

Abstract. We present a semi-empirical equation for prediction of the strengths of those N III lines that are generated by the Bowen mechanism and observed in spectra of symbiotic stars. The equation assumes that the Bowen mechanism is the only source populating the 3d state in N III, and comparisons with observations of the 3s-3p and 3p-3d transitions serve as a test of this assumption. In an ongoing study of symbiotic stars the equation has been applied to two symbiotic novae, RR Tel and AG Peg, by comparing the predicted N III line strengths to observed line intensities. It is clear that besides the Bowen mechanism there is another process, most likely radiative recombination, that contributes to the N III 3d population in AG Peg and is the main population process of this state in RR Tel. It is also clear that a second, not previously considered, N III channel, 2p 2 P 1/2 -3d 2 D 3/2 at 374.198 Å, is pumped by O III in both RR Tel and AG Peg.

The He$\rm_{II}$ Fowler lines and the O$\rm_{III}$ and N$\rm_{III}$ Bowen fluorescence lines in the symbiotic nova RR Telescopii

“…Concerning other physical processes such as radiative recombination as the main population process of the 3d 2 D J levels (see also the considerations by KB91 and Eriksson et al 2005 in Sect. 6.1), we have checked in detail the possible presence of recombination lines of N iii in the RR Tel spectrum.…”

Radiation processes in the Seyfert galaxy NGC 4151

“…Pumping to the y 4 H 11/2 ( ( 3 G)4p 4 H 11/2 ) by the C IV resonance doublet was the first observed PAR process involving Fe II observed in symbiotic stars (Johansson 1983). Now pumping to the Fe II y 4 H 11/2 and ( 3 F)4p 4 G 9/2 levels has been observed in several objects (Eriksson et al 2004). It is therefore not surprising that Eq.…”

“…To estimate the possibility of pumping, to a certain degree the atomic properties of the pumping channel as well as the nature of the pumping line have to be taken into account. I used the same equation as Eriksson et al (2005) to estimate the relative pumping rates through the channels pumped by the same line,…”

The nature of ultraviolet spectra of AG Pegasi and other symbiotic stars: locations, origins, and excitation mechanisms of emission lines

“…Also, two emission lines, O III λ3341.73, 3300.34 are observed as secondary decays from 2p3s 3 P-2p3p 3 S transitions. It is not only the 3 P 2 level that is populated by PAR in AG Peg, the two other fine structure levels, 3 P 1 and 3 P 0 , are also populated through channels within 2p 2 3 P-2p3d 3 P between 303.41 Å and 303.80 Å (Eriksson et al 2005). From the three emission lines corresponding to 2p3p 3 S-2p3d 3 P (Fig.…”