A theoretical study of dielectronic recombination processes of C²⁺ions in planetary nebulae

Abstract

In the process of dielectronic recombination, an electron can be captured by a positive ion into doubly excited resonance states. These states can decay by autoionization or by radiative transitions which produce recombination lines. These lines are important to estimate the element abundances as well as the electron temperatures in planetary nebulae. The present paper reports a theoretical study by the R-matrix method for such processes of C2+ ions in planetary nebulae, which produce recombination lines λ5114 Å(4f′–3d′), λ4965 Å(3d′–3p′), λ4619 Å(4f′–3d′) and λ8794 Å(3d′–3p′). Our study is based on three sets of target orbitals, through which we elucidate the electron correlation and static polarization effects in the dielectronic recombination processes. The calculated energy level positions are used to indicate the degrees of our calculation convergence; especially those based on the set of target orbitals including the electron correlation and static polarization effects agree well with the experimental data within about 4%. For such recombination processes, the recommended radiative transition rates, autoionization rates and net recombination rate coefficients are also provided. We anticipate that the accuracy of our recommended recombination rate coefficients for the whole four dielectronic lines is about 7% within our theoretical model.

Relativistic eigenchannelR-matrix studies of the strong intrashell electron correlations in highly chargedAr13+ions

“…From the smooth MQDT parameters shown in Fig. 2, we can readily get resonant scattering matrices for 032508-5 autoionization with the channel projection method [20,21], from which we can obtain all related autoionization quantities [33][34][35][36][37][38][39][40][41]. Notably, eigenphase shifts, which are eigenvalues of resonant scattering matrices, are crucial for the determination of resonance properties [34,40,41].…”

Atomic and Molecular Aspects of Astronomical Spectra

“…The process is also important for evaluating the energy balance and degree of ionization in hot and cold plasmas as it contributes to the determination of state population and ionization balance at various ranges of temperature and electronic number density. DR can occur through numerous transitional autoionizing states; possibly the whole Rydberg series [19,23].…”

“…Peng et al [62] investigated theoretically the C ii recombination line λ8794 Å, which is important for determining carbon abundance in planetary nebulae, using the R-matrix method. In a similar study [23] they investigated dielectronic recombination processes of C 2+ ion in planetary nebulae where several C ii recombination lines were examined in the course of this study. García-Rojas et al [11,[92][93][94][95], Ercolano et al [96], Stasińska et al [97], Robertson-Tessi and Garnett [98], Wang and Liu [99], Sharpee et al [100], and Williams et al [101].…”

“…The study of transition lines of carbon and its ions in the spectra of astronomical objects, such as planetary nebulae [137][138][139], has implications for carbon abundance determination [9,52,56,58,117,140], probing the physical conditions in the interstellar medium [23,51], and element enrichment in the CNO cycle [59,140,141]. The lines span large parts of the electromagnetic spectrum and originate from various processes under different physical conditions.…”

Dielectronic recombination lines of C+

“…The study of atomic and ionic lines of carbon in the spectra of astronomical objects, such as planetary nebulae [1][2][3], has implications for carbon abundance determination [4][5][6][7][8][9], probing the physical conditions in the interstellar medium [10,11], and element enrichment in the CNO cycle [7,12,13]. The lines span large parts of the electromagnetic spectrum and originate from various processes under different physical conditions.…”