scholarly journals MBPT Results for Δn=0 Electric Dipole Transitions

1993 ◽  
Vol 155 ◽  
pp. 96-96
Author(s):  
G. Gaigalas ◽  
R. Kisielius ◽  
G. Merkelis ◽  
Z. Rudzikas ◽  
M. Vilkas
Keyword(s):  
Electric Dipole ◽  
Planetary Nebulae ◽  
Atomic Data ◽  
Atomic Lines

To identify spectra of Planetary Nebulae which usually have many atomic lines one needs very accurate theoretical atomic data.

scholarly journals Improved Neutron-Capture Element Abundances in Planetary Nebulae

2009 ◽  
Vol 26 (3) ◽  
pp. 339-344 ◽  
Author(s):  
N. C. Sterling ◽  
H. L. Dinerstein ◽  
S. Hwang ◽  
S. Redfield ◽  
A. Aguilar ◽  
...  
Keyword(s):  
Cross Sections ◽  
Planetary Nebulae ◽  
Asymptotic Giant Branch ◽  
Rate Coefficients ◽  
Atomic Data ◽  
Agb Stars ◽  
Iron Species ◽  
Element Abundances ◽  
Ionization Balance ◽  
Initial Results

AbstractSpectroscopy of planetary nebulae (PNe) provides the means to investigate s-process enrichments of neutron(n)-capture elements that cannot be detected in Asymptotic Giant Branch (AGB) stars. However, accurate abundance determinations of these elements present a challenge. Corrections for unobserved ions can be large and uncertain, since in many PNe only one ion of a given n-capture element has been detected. Furthermore, the atomic data governing the ionization balance of these species are not well-determined, inhibiting the derivation of accurate ionization corrections. We present initial results of a program that addresses these challenges. Deep high-resolution optical spectroscopy of ∼20 PNe has been performed to detect emission lines from trans-iron species including Se, Br, Kr, Rb and Xe. The optical spectral region provides access to multiple ions of these elements, which reduces the magnitude and importance of uncertainties in the ionization corrections. In addition, experimental and theoretical efforts are providing determinations of the photoionization cross sections and recombination rate coefficients of Se, Kr and Xe ions. These new atomic data will make it possible to derive robust ionization corrections for these elements. Together, our observational and atomic data results will enable n-capture element abundances to be determined with unprecedented accuracy in ionized nebulae.

scholarly journals Atomic data for IR and sub-mm wavelengths

2009 ◽  
Vol 5 (H15) ◽  
pp. 539-540
Author(s):  
Gillian Nave
Keyword(s):  
Interstellar Medium ◽  
Electric Dipole ◽  
Visible Region ◽  
Diagnostic Information ◽  
Atomic Data ◽  
Low Density ◽  
Potential Importance ◽  
Ground Term ◽  
Atomic Spectra

Atomic spectra in the infrared and sub-mm wavelength regions can be divided into two broad categories: electric dipole-allowed transitions, and forbidden lines due to transitions within the ground term or between low-lying levels of the same parity. Both are of potential importance in the interpretation of astrophysical spectra. Allowed transitions can provide diagnostic information for stellar photospheres, particularly for elements that are not accessible in the visible region. Electric-dipole forbidden lines are important diagnostics of low-density plasmas, such as nebulae and the interstellar medium. In order to interpret astrophysical spectra, accurate atomic data are required. This paper summarizes the techniques for measuring atomic data and lists the most important compilations and databases.

scholarly journals Atomic Data and Neutron-Capture Element Abundances in Planetary Nebulae

2016 ◽  
Vol 12 (S323) ◽  
pp. 74-81
Author(s):  
N. C. Sterling
Keyword(s):  
Neutron Capture ◽  
Milky Way ◽  
Planetary Nebulae ◽  
Atomic Data ◽  
Experimental Investigations ◽  
Agb Stars ◽  
Intermediate Mass ◽  
Element Abundances ◽  
Nearby Galaxies

AbstractNeutron(n)-capture elements are produced by s-process nucleosynthesis in low- and intermediate-mass AGB stars, and therefore can be enriched in planetary nebulae (PNe). In the last ten years, n-capture elements have been detected in more than 100 PNe in the Milky Way and nearby galaxies. In some objects, several different n-capture elements have been detected, providing valuable constraints to models of AGB nucleosynthesis and evolution. These detections have motivated theoretical and experimental investigations of the atomic data needed to derive accurate n-capture element abundances. In this review, I discuss the methods and results of these atomic data studies, and their application to abundance determinations in PNe.

scholarly journals Atomic data and the density structures of planetary nebulae

2021 ◽  
Author(s):  
Leticia Juan de Dios ◽  
Mónica Rodríguez
Keyword(s):  
Electron Density ◽  
Planetary Nebulae ◽  
Atomic Data ◽  
The Impact

Abstract We study the density structures of planetary nebulae implied by four diagnostics that sample different regions within the nebulae: [S ii] λ6716/λ6731, [O ii] λ3726/λ3729, [Cl iii] λ5518/λ5538, and [Ar iv] λ4711/λ4740. We use a sample of 46 objects with deep spectra that allow the calculation of the electron density from these four diagnostics, and explore the impact that different atomic data have on the results. We compare the observational results with those obtained from photoionization models characterized by three different density structures. We conclude that the atomic data used in the calculations of electron density fully determine the density structures that are derived for the objects. We illustrate this by selecting three combinations of atomic data that lead to observational results that are compatible with each of the three different density structures explored with the models.

scholarly journals Flux Ratio [Ne v] 14.3/24.3 as a Test of Collision Strengths

2004 ◽  
Vol 217 ◽  
pp. 190-191
Author(s):  
R.H. Rubin
Keyword(s):  
Electron Density ◽  
Flux Ratio ◽  
Planetary Nebulae ◽  
Atomic Data ◽  
Line Flux ◽  
Astronomical Data ◽  
Data Collision

From ISO [Ne v] 14.3/24.3 μm line flux ratios, we find that 10 out of 20 planetary nebulae (PNs) have measured ratios below the low-electron density (Ne) theoretical predicted limit. Such astronomical data serve to provide important tests of atomic data, collision strengths in this case. In principle, well-calibrated measurements of the [Ne v] 14.3/24.3 flux ratio could improve upon the existing atomic data.

Energies, wavelengths, transition probabilities, and oscillator strengths for electric dipole transitions of Na-like and Mg-like mercury

2018 ◽  
Vol 96 (10) ◽  
pp. 1098-1103
Author(s):  
Gülay Günday Konan ◽  
Leyla Özdemir
Keyword(s):  
Electric Dipole ◽  
Quantum Electrodynamics ◽  
Transition Probabilities ◽  
Experimental Results ◽  
Oscillator Strengths ◽  
Atomic Data ◽  
Theoretical Results

We have reported atomic data including energies and electric dipole (E1) transition parameters, such as wavelengths, transition probabilities (or rates), and weighted oscillator strengths, for Na-like and Mg-like mercury (Hg69+ and Hg68+) using the AUTOSTRUCTURE atomic code, which includes Breit and quantum electrodynamics effects as well as correlation developed by Badnell. We have compared our results with the available theoretical results in the literature. Also, we have presented new results where no other theoretical and experimental results are available.

scholarly journals The Belgian repository of fundamental atomic data and stellar spectra (BRASS)

2019 ◽  
Vol 624 ◽  
pp. A60 ◽  
Author(s):  
M. Laverick ◽  
A. Lobel ◽  
P. Royer ◽  
T. Merle ◽  
C. Martayan ◽  
...  
Keyword(s):  
Quality Assessment ◽  
Large Scale ◽  
Spectral Lines ◽  
Oscillator Strengths ◽  
Atomic Data ◽  
Chemical Abundance ◽  
Stellar Spectra ◽  
Atomic Lines ◽  
The Universe ◽  
Selection Of

Context. Fundamental atomic transition parameters, such as oscillator strengths and rest wavelengths, play a key role in modelling and understanding the chemical composition of stars in the universe. Despite the significant work under way to produce these parameters for many astrophysically important ions, uncertainties in these parameters remain large and can limit the accuracy of chemical abundance determinations.Aims. The Belgian repository of fundamental atomic data and stellar spectra (BRASS) aims to provide a large systematic and homogeneous quality assessment of the atomic data available for quantitative spectroscopy. BRASS shall compare synthetic spectra against extremely high-quality observed spectra, at a resolution of ∼85 000 and signal-noise ratios of ∼1000, for approximately 20 bright BAFGK spectral-type stars, in order to critically evaluate the atomic data available for over a thousand potentially useful spectral lines.Methods. A large-scale homogeneous selection of atomic lines is performed by synthesising theoretical spectra of literature atomic lines for FGK-type stars including the Sun, resulting in a selection of 1091 theoretically deep and unblended lines in the wavelength range 4200–6800 Å, which may be suitable for quality assessment. Astrophysical log(g f) values are determined for the 1091 transitions using two commonly employed methods. The agreement of these log(g f) values are used to select well-behaved lines for quality assessment.Results. We found 845 atomic lines to be suitable for quality assessment, of which 408 were found to be robust against systematic differences between analysis methods. Around 53% of the quality-assessed lines were found to have at least one literature log(g f) value in agreement with our derived values, though the remaining values can disagree by as much as 0.5 dex. Only ∼38% of Fe Ilines were found to have sufficiently accurate log(g f) values, increasing to ∼70–75% for the remaining Fe-group lines.

scholarly journals Sulfur, Chlorine & Argon Abundances in Galactic PNe

2003 ◽  
Vol 209 ◽  
pp. 372-372
Author(s):  
Karen B. Kwitter ◽  
Richard B.C. Henry
Keyword(s):  
Near Infrared ◽  
Planetary Nebulae ◽  
Companion Paper ◽  
Extensive Study ◽  
Atomic Data ◽  
Stellar Abundances ◽  
Intermediate Mass Stars ◽  
The Galaxy ◽  
First Results ◽  
Full Analysis

We report first results from our extensive study of S, Cl and Ar abundances in a large sample (>60) of primarily Type II planetary nebulae (PNe) in the Galaxy (see Kwitter & Henry 2001, ApJ, 562, 804). Ratios of S/O, Cl/O, and Ar/O constitute important tests of differential nucleosynthesis of these elements and serve as strict constraints on massive star yield predictions. The use of PNe to measure the original stellar abundances of S, Cl, and Ar is possible because PN progenitors, intermediate-mass stars between 1 and 8M⊙, lack sufficient mass to synthesize these elements. Therefore, their abundances measured in the nebulae at present reflect accurately the original stellar abundances.Here we present results from new ground-based optical spectra of planetary nebulae extending from 3600–9600Å. The observed spectral range includes the strong near-infrared lines of [S III] λλ9069,9532, which allowed us to extensively test their effectiveness as an indicator of S++. We find that the S++ abundances derived from these lines are quite consistent with those derived from the λ6312 line when the latter is well measured. In addition, we find that the atmospheric absorption affecting the near-infrared lines can be minimized by using in the calculation whichever of the pair is less affected: if the observed ratio of λ9532/λ9069 exceeds 2.48, the theoretical value, we use λ9532; if we observe a ratio <2.48, we use λ9069 instead. We also introduce a new, model-tested ionization correction factor for sulfur that includes the latest atomic data and the effects of matter-boundedness.For the northern subsample we find the following averages: S/O=1.2E-2±0.71E-2, Cl/O=3.3E-4±1.6E-4, Ar/O=5.0E-3±1.9E-3.Subsequent papers in this series will present the full analysis and compare our derived abundances of S, Cl, and Ar with nucleosynthesis predictions from massive stars. (A companion paper in this volume by Milingo, Henry & Kwitter discusses the southern subset observed at CTIO; see also Milingo, J.B., Kwitter, K.B., Henry, R.B.C., & Cohen, R.E. 2002, ApJS, in press; Milingo, J.B., Henry, R.B.C., & Kwitter, K.B. 2002, ApJS, 2002, in press.)

scholarly journals The systematic uncertainties introduced by atomic data in nebular abundance determinations

2016 ◽  
Vol 12 (S323) ◽  
pp. 343-344
Author(s):  
Leticia Juan de Dios ◽  
Mónica Rodríguez
Keyword(s):  
Systematic Uncertainty ◽  
Planetary Nebulae ◽  
Data Selection ◽  
Atomic Data ◽  
Chemical Abundances ◽  
Physical Conditions ◽  
Systematic Uncertainties

AbstractAtomic data selection is one important source of systematic uncertainty since there are important variations between the values provided by different authors. We explore the effect of using different atomic data in the determination of physical conditions and chemical abundances in a sample of Galactic planetary nebulae and Hii regions. We find that the available datasets introduce significant differences in the results, especially at densities above 104 cm−3, where O/H and N/O reach uncertainties higher than a factor of 4.

Sign in / Sign up

Export Citation Format

Share Document