ATOMIC DATA AND SPECTRAL LINE INTENSITIES FOR Mg VI

Bhatia, A. K.; Young, Peter R.

doi:10.1006/adnd.1997.0766

Cited by 10 publications

(9 citation statements)

References 23 publications

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“…A values were obtained from a 4 configuration model of Mg VI used in Superstructure, produced for the CHIANTI database by P. R. Young. Effective collision strengths were from Bhatia & Young (1998).…”

Section: N-like Ionsmentioning

confidence: 99%

ADAS analysis of the differential emission measure structure of the inner solar corona

Lanzafame

Brooks

Lang

et al. 2002

A&A

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Abstract. The differential emission measure (DEM) of a solar active region is derived from SERTS-89 rocket data between 170 and 450Å . The integral inversion to infer the DEM distribution from spectral line intensities is performed by the data adaptive smoothing approach (Thompson 1990(Thompson , 1991. Our analysis takes into account the density dependence of both ionisation fractions and excitation coefficients according to the collisional-radiative theory as implemented in ADAS, the Atomic Data and Analysis Structure (McWhirter & Summers 1984;Summers 1994;Summers 2001). Our strategy aims at checking, using observational data, the validity and limitations of the DEM method used for analysing solar EUV spectra. We investigate what information it is possible to extract, within defined limitations, and how the method can assist in a number of cases, e.g. abundance determination, spectral line identification, intensity predictions, and validation of atomic cross-sections. Using the above data and theory, it is shown that a spurious multiple peak in the DEM distribution between log(Te) = 6.1 and 6.7, where Te is the electron temperature, may derive from an inaccurate treatment of the population densities of the excited levels and ionisation fractions or from using an integral inversion technique with arbitrary smoothing. Therefore, complex DEM structures, like those proposed for solar and stellar coronae by several authors, must be considered with caution. We address also the issue of systematic differences between iso-electronic sequences and show that these cannot be unambiguously detected in the coronal lines observed by SERTS. Our results indicate that a substantial improvement is required in the atomic modelling of the complex element Fe. The elemental abundance ratio Si/Ne is found to be close to its photospheric value. The same result may be true for the Fe/Ne abundance, but this latter result is uncertain because of the problems found with Fe.

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Section: N-like Ionsmentioning

confidence: 99%

ADAS analysis of the differential emission measure structure of the inner solar corona

Lanzafame

Brooks

Lang

et al. 2002

A&A

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“…The new Distorted Wave calculations of Bhatia & Young (1998) have been fitted and replace the data of Bhatia & Mason (1980b) in the database. The new calculations include the configurations 2s 2 2p 3 , 2s2p 4 , 2p 5 and 2s 2 2p 2 3s and were computed at several values of the incoming electron energy.…”

Section: Mg VImentioning

confidence: 99%

“…The new calculations include the configurations 2s 2 2p 3 , 2s2p 4 , 2p 5 and 2s 2 2p 2 3s and were computed at several values of the incoming electron energy. Radiative data are also taken from Bhatia & Young (1998). The level energies of Edlen (1984) are used for the 2s 2 2p 3 , 2s2p 4 and 2p 5 configurations, while the 2s 2 2p 2 3s energies are from the NIST database (Martin et al 1995).…”

Section: Mg VImentioning

confidence: 99%

CHIANTI – an atomic database for emission lines

Landi

Landini

Dere

et al. 1999

Astron. Astrophys. Suppl. Ser.

109

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Abstract. CHIANTI provides a database of atomic energy levels, wavelengths, radiative transition probabilities and electron excitation data for a large number of ions of astrophysical interest. This database allows the calculation of theoretical line emissivities necessary for the analysis of optically thin emission line spectra, and includes also a suite of IDL (Interactive Data Language) programs to calculate optically thin synthetic spectra and to perform spectral analysis and plasma diagnostics.The first version (1.0) of the CHIANTI database was released in 1996 (Dere et al. 1997) and has been extensively used for analysis of line spectra from astrophysical sources by the scientific community.The present paper describes the first major update to the CHIANTI database which will subsequently be labeled version 2.0. The update consists of the addition of a large number of new ions, the revision of existing data for some ions and the inclusion of an IDL procedure to calculate the continuum.The CHIANTI atomic database and supporting IDL routines are freely available through the internet.

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“…In astrophysical plasma applications, however, the majority of required radiative decay rates and collisional rate coefficients are derived from the A&A 548, A27 (2012) calculations. Previous theoretical calculations for electron impact excitation collision strengths include the distorted-wave calculations of Bhatia & Mason (1980), Bhatia & Young (1998), Landi & Bhatia (2007), and Zhang & Sampson (1999) and in the R-matrix calculations of Ramsbottom & Bell (1997). The distorted-wave calculations were carried out at a few selected incident electron energies and did not include resonances in the collision strengths.…”

Section: Introductionmentioning

confidence: 99%

“…The distorted-wave calculations were carried out at a few selected incident electron energies and did not include resonances in the collision strengths. Bhatia & Young (1998) and Ramsbottom & Bell (1997) considered the 12 lowest LS states of the 2s 2 2p 3 , 2s2p 4 , 2p 5 , and 2s 2 2p 2 3s configurations, while Landi & Bhatia (2007) included 74 fine-structure levels of the n = 2 and n = 3 states in their calculations.…”

Section: Introductionmentioning

confidence: 99%

Oscillator strengths and effective collision strengths for electron excitation of Mg VI

Tayal

2012

A&A

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Aims. Electron impact excitation collision strengths and oscillator strengths for the astrophysically important lines in Mg VI are reported. Thermally averaged collision strengths are presented as a function of electron temperature for application to solar and other astrophysical plasmas. Methods. The collision strengths were calculated in a close-coupling approximation using the B-spline Breit-Pauli R-matrix method. The multiconfiguration Hartree-Fock method with term-dependent, non-orthogonal orbitals was employed for an accurate representation of the target wave functions. The close-coupling expansion includes 74 bound levels of Mg VI covering the n = 2 and n = 3 terms. The present calculations led to a total of 2701 forbidden, intercombination, and allowed transitions between fine-structure levels. The effective collision strengths were obtained by averaging the electron collision strengths over a Maxwellian distribution of velocities.Results. The accuracy of present oscillator strengths is evaluated by the agreement between the length and velocity formulations combined with the agreement between the calculated and measured excitation energies. The calculated excitation energies are in excellent agreement with experiments and other extensive configuration-interaction calculations. The oscillator strengths for all E1 transitions are listed. The effective collision strengths are tabulated for all 2701 transitions among the 74 fine-structure levels at 11 electron temperatures in the range from 10 000 to 200 000 K. The present results are compared with other close-coupling and distorted-wave calculations. Overall good agrement is generally found with the calculations by Ramsbottom & Bell and by Landi & Bhatia for many transitions, but significant differences are also noted for some transitions.

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ATOMIC DATA AND SPECTRAL LINE INTENSITIES FOR Mg VI

Cited by 10 publications

References 23 publications

ADAS analysis of the differential emission measure structure of the inner solar corona

ADAS analysis of the differential emission measure structure of the inner solar corona

CHIANTI – an atomic database for emission lines

Oscillator strengths and effective collision strengths for electron excitation of Mg VI

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