Electron excitation of the 1s22s22p52Po3/2-2Po1/2transition and analysis of the 1s22s2p6nl resonances for Ne II and Mg IV

Johnson, C. T.; Kingston, A E

doi:10.1088/0022-3700/20/21/023

Cited by 11 publications

(15 citation statements)

References 29 publications

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“…We are currently unable to explain this disagreement, as our measured strength of [Ne ii] 12.8 m agrees closely with the value reported by Dinerstein et al (2003), as do our derived electron temperature and density values. We also employed a collision strength of 0.318 (Griffin et al 2001), which agrees closely with their value of 0.306 taken from Johnson & Kingston (1987). On the other hand, the close agreement in the case of sulfur is strong evidence that the ionization stages above S +3 in DdDm-1 are relatively unpopulated.…”

Section: Numerical Analysissupporting

confidence: 60%

A Multiwavelength Analysis of the Halo Planetary Nebula DdDm‐1

Henry

Kwitter

Dufour

et al. 2008

ApJ

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We present new HST optical imagery as well as new UVand IR spectroscopic data obtained with the Hubble Space Telescope and Spitzer Space Telescope, respectively, of the halo planetary nebula DdDm-1. For the first time we present a resolved image of this object, which indicates that the morphology of DdDm-1 can be described as two orthogonal elliptical components in the central part surrounded by an extended halo. The extent of the emission is somewhat larger than was previously reported in the literature. We combine the spectral data with our own previously published optical measurements to derive nebular abundances of He, C, N, O, Ne, Si, S, Cl, Ar, and Fe. The metallicity, as gauged by oxygen, is found to be 0.60 dex below the solar value, confirming DdDm-1's status as a halo PN. In addition, we find that Si and Fe are markedly underabundant, suggesting their depletion onto dust. The very low C/O ratio suggests that the chemistry of the nebula should be consistent with an oxygen-rich environment. With regard to the unexpectedly low S abundance relative to O often seen in PNe, we find that the sulfur abundance of DdDm-1 is only slightly below the value expected based on the normal lockstep behavior between S and O observed in H ii regions and blue compact galaxies. We performed a photoionization model analysis from which we inferred a central star effective temperature and luminosity of 55,000 K and 1000 L , respectively, implying an initial progenitor mass of <1 M . Finally, we report on a new radial velocity determination from echelle observations.

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Section: Numerical Analysissupporting

confidence: 60%

A Multiwavelength Analysis of the Halo Planetary Nebula DdDm‐1

Henry

Kwitter

Dufour

et al. 2008

ApJ

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“…This is within 3% of our results. The two-state R-matrix calculation [7] yields values of F for T=<40000 K. This is 6% lower than our result at 40000 K.…”

Section: Pacs: 3480dcontrasting

confidence: 88%

“…Our threshold value for/2 is 0.36. This is approximately 5% higher than the value 0.344 obtained by two-state R-matrix method [7]. This suggests that coupling between the states with configuration 2p431 and the states with configurations 2p s and 2 s 2 p 6 is weak.…”

Section: Pacs: 3480dmentioning

confidence: 60%

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Electron-impact excitation of the transition 1s 22s 22p 5(2 P 2/03−2 P 2/01) of Mg IV

Mohan

Baluja

1989

Z Phys D - Atoms, Molecules and Clusters

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Effective collision strengths for electron-impact excitation of the ground state fine structure transition 2P~2-2P~}2 have been calculated by using the R-matrix method. Twelve lowest target states, represented by configuration interaction wavefunctions are included in the scattering calculations. M1 and E2 transition probabilities are also calculated by employing the Breit-Pauli Hamiltonian. PACS: 34.80.DThe emission line of Mg IV arising due to the fine structure transition 2s22pS2P3~2-2P~°2 has been observed in the high excitation planetary nebula NGC 7027. The observed absolute wavelength for this transition is 4.49 gm [1,2]. The abundance of Mg IV depends almost inversely on the effective collision strength F(2P3~2 -2P1~2 ) [3].Previous calculations for this transition in Mg IV have been performed in the Distorted-Wave approximation [4]. In a hybrid approach [5], the exact resonance approximation was used to calculate the pwave contribution to collision strength f2, and distorted-wave approximation was used for other partial waves. Calculations in a five-state close coupling approximation [6] have also been carried out. These five states having configurations 2p 5, 2s2p 6, 2p43s and 2p43 d were represented by configuration interaction (CI) wavefunctions. Recently a two-state calculation [7] using the R-matrix method [8] has also been reported. This calculation included the states 2p 5 and 2s2p 6 and represented them by CI wavefunctions. Since n = 3 levels are well separated from n = 2 levels, the inclusion of n = 3 levels in any scattering calculations is not expected to be significant for the calculations of F at low electron temperatures.In the present work we have performed a twelvestate calculation using the R-matrix method [8] where the single-configuration function {¢i} are constructed from one-electron orbitals whose angular momenta are coupled to form a total L and S common to all M configurations. The {c~i} specifies the coupling. The radial part of each orbital is expressed as a sum of Slater-type orbitals. The details of these CI wavefunctions have been given elsewhere [9] which were used to calculate effective collision strengths F for transitions in Mg IV from its ground state 2pO to the eleven lowest-excited states.We have calculated the M1 and E2 transition probabilities for t h e 2P3~ 2 -2.Pl~ 2 transition by transforming the LS coupled CI wavefunction of (1) to a J-dependent CI expansion of the formwhere the sum over i is over all those LS states which have the same J value. {/~i} specifies the coupling scheme in the J-dependent case. The set of {bi} in (2) are components of the appropriate eigenvector of the Hamiltonian matrix with basis {~bi}. The Hamil-

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“…To date, close-coupling calculations of electron-impact excitation of Ne + have been restricted to the fine-structure transition: 2s 2 2p 5 2 P 3/2 → 2 P 1/2 . Johnson and Kingston [2] and later Saraph and Tully [3] employed large configuration-interaction (CI) expansions of the target, but included only the two LS terms 2s 2 2p 5 2 P and 2s2p 6 2 S in their close-coupling expansion; they then employed the program JAJOM [4] to transform the scattering matrices from LS to intermediate coupling and thereby determine the collision strengths for the finestructure transition.…”

Section: Introductionmentioning

confidence: 99%

Electron-impact excitation of Ne⁵⁺

Mitnik¹,

Griffin²,

Badnell³

2001

J. Phys. B: At. Mol. Opt. Phys.

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We present the results of a 61-term, 138-level intermediate-coupling frametransformation R-matrix close-coupling calculation of the electron-impact excitation of fluorine-like Ne + . All levels of the 2s 2 2p 5 , 2s2p 6 , 2s 2 2p 4 3 and 2s 2 2p 4 4 configurations that lie below the ionization limit are included in the close-coupling expansion. With the exception of several R-matrix calculations of excitation between the fine structure levels of 2s 2 2p 5 2 P, this represents the first close-coupling calculation for this ion. Here we describe this calculation and present radiative rates and effective collision strengths for a selected number of the 9453 transitions resulting from this work. The full set of data is available at the Oak Ridge National Laboratory Controlled Fusion Atomic Data Center Web site.

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Electron excitation of the 1s²2s²2p⁵²P^o_3/2-²P^o_1/2transition and analysis of the 1s²2s2p⁶nl resonances for Ne II and Mg IV

Cited by 11 publications

References 29 publications

A Multiwavelength Analysis of the Halo Planetary Nebula DdDm‐1

A Multiwavelength Analysis of the Halo Planetary Nebula DdDm‐1

Electron-impact excitation of the transition 1s 22s 22p 5(2 P 2/03−2 P 2/01) of Mg IV

Electron-impact excitation of Ne⁵⁺

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Electron excitation of the 1s22s22p52Po3/2-2Po1/2transition and analysis of the 1s22s2p6nl resonances for Ne II and Mg IV

Cited by 11 publications

References 29 publications

A Multiwavelength Analysis of the Halo Planetary Nebula DdDm‐1

A Multiwavelength Analysis of the Halo Planetary Nebula DdDm‐1

Electron-impact excitation of the transition 1s 22s 22p 5(2 P 2/03−2 P 2/01) of Mg IV

Electron-impact excitation of Ne5+

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Electron excitation of the 1s²2s²2p⁵²P^o_3/2-²P^o_1/2transition and analysis of the 1s²2s2p⁶nl resonances for Ne II and Mg IV

Electron-impact excitation of Ne⁵⁺