Extended theoretical transition data in C i–iv

Abstract

Accurate atomic data are essential for opacity calculations and for abundance analyses of the Sun and other stars. The aim of this work is to provide accurate and extensive results of energy levels and transition data for C i – iv. The Multiconfiguration DiracâHartreeâFock and relativistic configuration interaction methods were used in the present work. To improve the quality of the wave functions and reduce the relative differences between length and velocity forms for transition data involving high Rydberg states, alternative computational strategies were employed by imposing restrictions on the electron substitutions when constructing the orbital basis for each atom and ion. Transition data, e.g., weighted oscillator strengths and transition probabilities, are given for radiative electric dipole (E1) transitions involving levels up to 1s22s22p6s for C i, up to 1s22s27f for C ii, up to 1s22s7f for C iii, and up to 1s28g for C iv. Using the difference between the transition rates in length and velocity gauges as an internal validation, the average uncertainties of all presented E1 transitions are estimated to be 8.05%, 7.20%, 1.77%, and 0.28%, respectively, for C i – iv. Extensive comparisons with available experimental and theoretical results are performed and good agreement is observed for most of the transitions. In addition, the C i data were employed in a reanalysis of the solar carbon abundance. The new transition data give a line-by-line dispersion similar to the one obtained when using transition data that are typically used in stellar spectroscopic applications today.

The chemical make-up of the Sun: A 2020 vision

“…The [C i] result is drawn from the 3D non-LTE analysis of the 872.7 nm line from Amarsi et al ( 2019), although we note that this low-excitation line is wellreproduced in 3D LTE. The C i result is based on the 14 lines also analysed in this 3D non-LTE study; here, the result has increased by 0.03 dex in light of new g f -values from large-scale atomic structure calculations by Li et al (2021). The molecular results are based on new 3D LTE calculations of 39 lines in the C 2 Swan system, and CH lines which were divided into 51 fundamental rovibrational (dν = 1) lines and seven electronic lines in the CH A-X system.…”

The solar carbon, nitrogen, and oxygen abundances from a 3D LTE analysis of molecular lines

“…A comparison can be found in Asplund et al (2021); the main findings are summarised here. Due to several different updates, in particular a systematic shift in the transition probabilities for C i (Li et al 2021), the various carbon abundance indicators all now point to a value of around 8.46 dex, which is 0.03 dex larger than the value advocated by Asplund et al (2009). For oxygen, the agreement is also very satisfactory, with the [O i] lines and O i lines indicating on average slightly higher and lower 1.…”

“…It is illuminating to compare the molecular results derived here with atomic results present in the literature. Recently, 3D non-LTE studies of C i (Amarsi et al 2019;Li et al 2021), N i (Amarsi et al 2020a), and O i (Amarsi et al 2018) lines have been carried out. These studies are based on the same model atmosphere as that used here.…”

“…2.3) is 5773 K, with a standard deviation of 16 K, in excellent agreement with the nominal solar value of 5772 K (Prša et al 2016). The model is the same as that used already in the 3D non-LTE analyses of O i lines (Amarsi et al 2018), where it is discussed in more detail; as well as of C i and N i lines (Amarsi et al 2019;Li et al 2021;Amarsi et al 2020a). It was also used in the 3D non-LTE analyses of the sodium, magnesium, potassium, calcium, and iron abundances, presented in Asplund et al (2021).…”

“…Secondly, a number of accurate, complementary results have become available, and it is important to verify that consistent results are obtained. These include 3D non-LTE elemental abundances based on C i (Amarsi et al 2019;Li et al 2021), N i (Amarsi et al 2020a), andO i (Amarsi et al 2018). Lastly, the 3D model atmosphere has been updated, as summarised in Table 1 of Asplund et al (2021); in particular, the newer model was constructed with the composition of (Asplund et al 2009), rather than the more metal-poor composition of (Asplund et al 2005a).…”