Atomic Data Assessment with PyNeb

PyNeb is a Python package widely used to model emission lines in gaseous nebulae. We take advantage of its object-oriented architecture, class methods, and historical atomic database to structure a practical environment for atomic data assessment. Our aim is to reduce the uncertainties in the parame...

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Bibliographic Details
Published in:Atoms 2020-12, Vol.8 (4), p.66
Main Authors: Morisset, Christophe, Luridiana, Valentina, García-Rojas, Jorge, Gómez-Llanos, Verónica, Bautista, Manuel, Mendoza, Claudio
Format: Article
Language:English
Subjects:
astrophysical software
atomic data assessment
atomic databases
Atomic structure
Data analysis
Datasets
Electron density
Electron impact
Energy
Historical structures
Isoelectronic sequence
nebular modeling
Planetary nebulae
Plasma
plasma diagnostics
Position measurement
Temperature
Uncertainty
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Summary:PyNeb is a Python package widely used to model emission lines in gaseous nebulae. We take advantage of its object-oriented architecture, class methods, and historical atomic database to structure a practical environment for atomic data assessment. Our aim is to reduce the uncertainties in the parameter space (line ratio diagnostics, electron density and temperature, and ionic abundances) arising from the underlying atomic data by critically selecting the PyNeb default datasets. We evaluate the questioned radiative-rate accuracy of the collisionally excited forbidden lines of the N- and P-like ions (O ii, Ne iv, S ii, Cl iii, and Ar iv), which are used as density diagnostics. With the aid of observed line ratios in the dense NGC 7027 planetary nebula and careful data analysis, we arrive at emissivity ratio uncertainties from the radiative rates within 10%, a considerable improvement over a previously predicted 50%. We also examine the accuracy of an extensive dataset of electron-impact effective collision strengths for the carbon isoelectronic sequence recently published. By estimating the impact of the new data on the pivotal [N ii] and [O iii] temperature diagnostics and by benchmarking the collision strength with a measured resonance position, we question their usefulness in nebular modeling. We confirm that the effective-collision-strength scatter of selected datasets for these two ions does not lead to uncertainties in the temperature diagnostics larger than 10%.
ISSN:2218-2004
2218-2004
DOI:10.3390/atoms8040066