Chianti—an atomic database for emission lines. xii. version 7 of the database
TL;DR: The CHIANTI spectral code consists of an atomic database and a suite of computer programs to calculate the optically thin spectrum of astrophysical objects and carry out spectroscopic plasma diagnostics as discussed by the authors.
Abstract: The CHIANTI spectral code consists of an atomic database and a suite of computer programs to calculate the optically thin spectrum of astrophysical objects and carry out spectroscopic plasma diagnostics. The database includes atomic energy levels, wavelengths, radiative transition probabilities, collision excitation rate coefficients, and ionization and recombination rate coefficients, as well as data to calculate free-free, free-bound, and two-photon continuum emission. Version 7 has been released, which includes several new ions, significant updates to existing ions, as well as Chianti-Py, the implementation of CHIANTI software in the Python programming language. All data and programs are freely available at http://www.chiantidatabase.org, while the Python interface to CHIANTI can be found at http://chiantipy.sourceforge.net.
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TL;DR: This version of the CHIANTI database includes a large amount of new data and ions, which represent a significant improvement in the soft X-ray, EUV and UV spectral regions, which several space missions currently cover.
Abstract: We present version 8 of the CHIANTI database. This version includes a large amount of new data and ions, which represent a significant improvement in the soft X-ray, extreme UV (EUV) and UV spectral regions, which several space missions currently cover. New data for neutrals and low charge states are also added. The data are assessed, but to improve the modelling of low-temperature plasma the effective collision strengths for most of the new datasets are not spline-fitted as previously, but are retained as calculated. This required a change of the format of the CHIANTI electron excitation files. The format of the energy files has also been changed. Excitation rates between all the levels are retained for most of the new datasets, so the data can in principle be used to model high-density plasma. In addition, the method for computing the differential emission measure used in the CHIANTI software has been changed.
487 citations
Cites background or methods from "Chianti—an atomic database for emis..."
...The experimental energies for this ion were assessed for version 7 (Landi et al. 2012), and have been taken from a variety of sources....
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...The important Fexvii data were released previously in CHIANTI version 7 (Landi et al. 2012)....
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TL;DR: AtomDB 2.0.2 as discussed by the authors is a database of atomic data and a plasma modeling code with a focus on X-ray astronomy, including new ionization balance data, state-selective recombination data, and updated collisional excitation data for many ions, including the iron L-shell ions from Fe+16 to Fe+23 and all of the hydrogen- and helium-like sequences.
Abstract: We describe the latest release of AtomDB, version 2.0.2, a database of atomic data and a plasma modeling code with a focus on X-ray astronomy. This release includes several major updates to the fundamental atomic structure and process data held within AtomDB, incorporating new ionization balance data, state-selective recombination data, and updated collisional excitation data for many ions, including the iron L-shell ions from Fe+16 to Fe+23 and all of the hydrogen- and helium-like sequences. We also describe some of the effects that these changes have on calculated emission and diagnostic line ratios, such as changes in the temperature implied by the He-like G-ratios of up to a factor of two.
458 citations
TL;DR: AtomDB 2.0.2 as mentioned in this paper is a database of atomic data and a plasma modeling code with a focus on X-ray astronomy, which includes several major updates to the fundamental atomic structure and process data held within AtomDB, incorporating new ionization balance data, state-selective recombination data, and updated collisional excitation data for many ions.
Abstract: We describe the latest release of AtomDB, version 2.0.2, a database of atomic data and a plasma modeling code with a focus on X-ray astronomy. This release includes several major updates to the fundamental atomic structure and process data held within AtomDB, incorporating new ionization balance data, state-selective recombination data, and updated collisional excitation data for many ions, including the iron L-shell ions from Fe$^{+16}$ to Fe$^{+23}$ and all of the hydrogen- and helium-like sequences. We also describe some of the effects that these changes have on calculated emission and diagnostic line ratios, such as changes in the temperature implied by the He-like G-ratios of up to a factor of 2.
344 citations
Additional excerpts
...0 (Kaastra et al. 1996), CHIANTI v7 (Landi et al. 2012) and AtomDB v1....
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TL;DR: Observations by the IRIS confirm that the photosphere is more complex than conventionally thought, but also provide insight into the energy conversion in the process of magnetic reconnection.
Abstract: The solar atmosphere was traditionally represented with a simple one-dimensional model. Over the past few decades, this paradigm shifted for the chromosphere and corona that constitute the outer atmosphere, which is now considered a dynamic structured envelope. Recent observations by the Interface Region Imaging Spectrograph (IRIS) reveal that it is difficult to determine what is up and down, even in the cool 6000-kelvin photosphere just above the solar surface: This region hosts pockets of hot plasma transiently heated to almost 100,000 kelvin. The energy to heat and accelerate the plasma requires a considerable fraction of the energy from flares, the largest solar disruptions. These IRIS observations not only confirm that the photosphere is more complex than conventionally thought, but also provide insight into the energy conversion in the process of magnetic reconnection.
337 citations
TL;DR: In this paper, the effects of both the new atomic data and the κ-distribution on the strong-line techniques used to determine chemical abundances in H II regions were explored.
Abstract: Recently, Nicholls et al, inspired by in situ observations of solar system astrophysical plasmas, suggested that the electrons in H II regions are characterized by a κ-distribution of energies rather than a simple Maxwell-Boltzmann distribution Here, we have collected together new atomic data within a modified photoionization code to explore the effects of both the new atomic data and the κ-distribution on the strong-line techniques used to determine chemical abundances in H II regions By comparing the recombination temperatures (T {sub rec}) with the forbidden line temperatures (T {sub FL}), we conclude that κ ∼ 20 While representing only a mild deviation from equilibrium, this result is sufficient to strongly influence abundances determined using methods that depend on measurements of the electron temperature from forbidden lines We present a number of new emission line ratio diagnostics that cleanly separate the two parameters determining the optical spectrum of H II regions—the ionization parameter q or U and the chemical abundance, 12+log(O/H) An automated code to extract these parameters is presented Using the homogeneous data set from van Zee et al, we find self-consistent results between all of these different diagnostics The systematic errors between different line ratio diagnostics are much smallermore » than those found in the earlier strong-line work Overall, the effect of the κ-distribution on the strong-line abundances derived solely on the basis of theoretical models is rather small« less
319 citations
Cites methods from "Chianti—an atomic database for emis..."
...The temperature coordinates were normalised in a fashion similar to that used in CHIANTI 7.1 (Dere et al. 1997; Landi et al. 2012) and originally proposed by Burgess & Tully (1992), but here we use a more direct scaled temperature coordinate x = T/(T +TC), where T is the temperature and TC is a…...
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References
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TL;DR: The CHIANTI database as mentioned in this paper is a set of atomic data and transition probabilities necessary to calculate the emission line spectrum of astrophysical plasmas, including atomic energy levels, atomic radiative data such as wavelengths, weighted oscillator strengths and A values, and electron collisional excitation rates.
Abstract: CHIANTI consists of a critically evaluated set of atomic data and transition probabilities necessary to calculate the emission line spectrum of astrophysical plasmas. The data consist of atomic energy levels, atomic radiative data such as wavelengths, weighted oscillator strengths and A values, and electron collisional excitation rates. A set of programs that use these data to calculate the spectrum in a desired wavelength range as a function of temperature and density is also provided. A suite of programs has been developed to carry out plasma diagnostics of astrophysical plasmas. The state-of-the-art contents of the CHIANTI database will be described and some of the most important results obtained from the use of the CHIANTI database will be reviewed.
2,116 citations
"Chianti—an atomic database for emis..." refers background in this paper
...CHIANTI was first released in 1996 (Dere et al. 1997) and it covered wavelengths larger than 50 Å....
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TL;DR: Superstructure as mentioned in this paper is a general-purpose automatic atomic-structure program that uses multi-configuration type expansions to calculate term energies, intermediate-coupling energy levels, term coupling coefficients, and cascade coefficients.
781 citations
"Chianti—an atomic database for emis..." refers methods in this paper
...The radiative decay rates in the previous CHIANTI model were from an unpublished calculation by the CHIANTI team (Landi et al. 1999) carried out with SUPERSTRUCTURE (Eissner et al. 1974), and the forbidden transition rates have now been replaced with the values from Merkelis et al. (1999)....
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...Ni xv collision excitation rates in the previous version of CHIANTI had not been changed since version 1, and consisted of distorted wave calculations carried out using the UCL (University College London) suite of codes (Eissner & Seaton 1972) with an atomic model that included the four lowest configurations; radiative data also came from an unpublished calculation carried out with SUPERSTRUCTURE using a 35 configuration atomic model....
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01 Jan 2005
TL;DR: The Atomic Spectra Database (ASD) as discussed by the authors is a large-scale database of tens of thousands of spectral lines and energy levels at the National Institute of Standards and Technology (NIST).
Abstract: Accurate atomic data have great importance in astrophysics, plasma research, and other fields of physics. For more than 10 years, the Atomic Spectra Database (ASD) at the National Institute of Standards and Technology has served as a convenient and robust source of critically evaluated data on tens of thousands of spectral lines and energy levels. The recent upgrade of the ASD represents a significant new step in the development of dynamic databases providing powerful tools for data analysis and manipulation. We present a detailed description of ASD 3.0 emphasizing numerous advanced features and options for data search and presentation.
743 citations
TL;DR: The CHIANTI database as mentioned in this paper provides a set of atomic data for the interpretation of astrophysical spectra emitted by collisionally dominated, high temperature, optically thin sources.
Abstract: Aims. The goal of the CHIANTI atomic database is to provide a set of atomic data for the interpretation of astrophysical spectra emitted by collisionally dominated, high temperature, optically thin sources. Methods. A complete set of ground level ionization and recombination rate coefficients has been assembled for all atoms and ions of the elements of H through Zn and inserted into the latest version of the CHIANTI database, CHIANTI 6. Ionization rate coefficients are taken from the recent work of Dere (2007, A&A, 466, 771) and recombination rates from a variety of sources in the literature. These new rate coefficients have allowed the calculation of a new set of ionization equilibria and radiative loss rate coefficients. For some ions, such as Fe viii and Fe ix, there are significant differences from previous calculations. In addition, existing atomic parameters have been revised and new atomic parameters inserted into the database. Results. For each ion in the CHIANTI database, elemental abundances, ionization potentials, atomic energy levels, radiative rates, electron and proton collisional rate coefficients, ionization and recombination rate coefficients, and collisional ionization equilibrium populations are provided. In addition, parameters for the calculation of the continuum due to bremsstrahlung, radiative recombination and two-photon decay are provided. A suite of programs written in the Interactive Data Language (IDL) are available to calculate line and continuum emissivities and other properties. All data and programs are freely available at http://wwwsolar.nrl.navy.mil/ chianti
513 citations
"Chianti—an atomic database for emis..." refers background in this paper
...Since the latest release (Dere et al. 2009), many new atomic physics calculations were published that improved the data sets for several ions in CHIANTI, or provided new data for transitions unavailable in the literature before....
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