CHIANTI -- an atomic database for emission lines -- Paper XVIII. Version 11, advanced ionization equilibrium models: density and charge transfer effects

Abstract

Version 11 of the CHIANTI database and software package is presented. Advanced ionization equilibrium models have been added for low charge states of seven elements (C, N, O, Ne, Mg, Si and S), and represent a significant improvement especially when modelling the solar transition region. The models include the effects of higher electron density and charge transfer on ionization and recombination rates. As an illustration of the difference these models make, a synthetic spectrum is calculated for an electron pressure of 7$\times 10^{15}$ cm${}^{-3}$ K and compared with an active region observation from HRTS. Increases are seen of factors of two to five in the predicted radiances of the strongest lines in the UV from Si IV, C IV, and N V, compared to the previous modelling using the coronal approximation. Much better agreement (within 20\%) with the observation is found for the majority of the lines. The new atomic models better equip both those who are studying the transition region and those who are interpreting emission from higher density astrophysical and laboratory plasma. In addition to the advanced models, several ion datasets have been added or updated, and data for the radiative recombination energy loss rate have been updated.

arXiv comment19 pages, 5 figures, 1 table, submitted to ApJ

References in corpus (25)

• The Interface Region Imaging Spectrograph (IRIS)
• The chemical make-up of the Sun: A 2020 vision
• A Tale Of Two Spicules: The Impact of Spicules on the Magnetic Chromosphere
• CHIANTI -- an atomic database for emission lines -- Paper XVI: Version 10, further extensions
• The FIP and Inverse FIP Effects in Solar and Stellar Coronae
• Solar UV and X-Ray Spectral Diagnostics
• Dielectronic recombination data for dynamic finite-density plasmas I. Goals and methodology
• Radiative recombination data for modelling dynamic finite-density plasmas
• Element Abundances: A New Diagnostic for the Solar Wind
• The formation of IRIS diagnostics V. A quintessential model atom of C II and general formation properties of the C II lines at 133.5 nm
• Solar Transition-Region Lines Observed by the Interface Region Imaging Spectrograph: Diagnostics for the O IV and Si IV Lines
• Si IV Resonance Line Emission During Solar Flares: Non-LTE, Non-equilibrium, Radiation Transfer Simulations
• The Solar Upper Transition Region Imager (SUTRI) onboard the SATech-01 satellite
• A Si IV/O IV electron density diagnostic for the analysis of IRIS solar spectra
• Inelastic e+Mg collision data and its impact on modelling stellar and supernova spectra
• Suppression of Dielectronic Recombination Due to Finite Density Effects II: Analytical Refinement and Application to Density-dependent Ionization Balances and AGN Broad-line Emission
• Helium line emissivities in the solar corona
• Modelling ion populations in astrophysical plasmas: carbon in the solar transition region
• Modelling low charge ions in the solar atmosphere
• Effects of density on the oxygen ionisation equilibrium in collisional plasmas
• Modelling the chromosphere and transition region of Epsilon Eri (K2 V)
• Asteroseismology and Spectropolarimetry of the Exoplanet Host Star $\lambda$ Serpentis
• A benchmark study of atomic models for the transition region against quiet Sun observations
• The influence of photo-induced processes and charge transfer on carbon and oxygen in the lower solar atmosphere
• The electron energy-loss rate due to radiative recombination

Cited by in corpus (1)

• Reduced atomic models for large-scale computations: Fe XIII near-infrared lines