Reinvestigation of Rotational-Line Intensity Factors in Diatomic Spectra

Whiting, E. E.; Nicholls, R. W.

doi:10.1086/190286

Cited by 135 publications

(52 citation statements)

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“…In the case of C 2 , rotational levels shift up or down in energy depending on the parity. The normalization of Einstein coefficients was according to Whiting & Nicholls (1974), but without the Λ-doubling perturbation, which is consistent with Trujillo Bueno et al (2006) and differs by factor of two from Berdyugina & Fluri (2004). Using numerical values was easier with our approach but the result of both methods would be similar.…”

Section: Basic Assumptionssupporting

confidence: 84%

Solar turbulent magnetic fields: Non-LTE modeling of the Hanle effect in the C₂molecule

Kleint

Шапиро

Berdyugina

et al. 2011

A&A

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Context. Scattering polarization measurements contain a wealth of information that needs a thorough interpretation. This often requires accounting for the non-local origin of photons with different frequencies and at different limb positions. Currently, modeling scattering polarization in several molecular C 2 lines simultaneously is only successful for lines with similar quantum numbers. More sophisticated models are needed to understand the dependence on quantum numbers and to reliably derive the strength of the turbulent magnetic fields using the differential Hanle effect. Aims. We have developed a non-LTE analyzing technique for the C 2 lines to determine the strength of turbulent magnetic fields and have applied it to observations obtained during our synoptic program at the Istituto Ricerche SOlari Locarno (IRSOL). Methods. The influence of magnetic fields on scattering polarization can be interpreted differentially, i.e., by comparing several spectral lines within one spectral region. Through the application of the differential Hanle effect and non-LTE 1D radiative transfer, we are able to infer a magnetic field strength from the photospheric C 2 lines around 5141 Å. Compared to previous models we include the effect of collisions and investigate their dependence on the total angular momentum number J. Results. We carry out a detailed parameter study to investigate the influence of model parameters on the resulting scattering polarization. A good fit can now be obtained for spectral lines from different C 2 triplets. For the 78 measurements obtained during the solar minimum in 2007-2009 we infer a mean magnetic field strength of 7.41 G with a standard deviation of 0.76 G.

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Section: Basic Assumptionssupporting

confidence: 84%

Solar turbulent magnetic fields: Non-LTE modeling of the Hanle effect in the C₂molecule

Kleint

Шапиро

Berdyugina

et al. 2011

A&A

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“…In addition to C 2 , the spectral regions studied also include MgH molecular features that may contribute to the continuum formation. The oscillator strengths of C 2 and MgH lines were revised according to the normalisation of the Hönl-London factors (Whiting & Nicholls 1974).…”

Section: Carbon Abundance From Spectral Synthesismentioning

confidence: 99%

Accurate and homogeneous abundance patterns in solar-type stars of the solar neighbourhood: a chemo-chronological analysis

Silva

Mello

Milone

et al. 2012

A&A

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Aims. We report the derivation of abundances of C, Na, Mg, Si, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sr, Y, Zr, Ba, Ce, Nd, and Sm in a sample of 25 solar-type stars of the solar neighbourhood, correlating the abundances with the stellar ages, kinematics, and orbital parameters. Methods. The spectroscopic analysis, based on data of high resolution and high signal-to-noise ratio, was differential to the Sun and applied to atomic line equivalent widths supplemented by the spectral synthesis of C and C 2 features. We also performed a statistical study by using the method of tree clustering analysis, searching for groups of stars sharing similar elemental abundance patterns. We derived the stellar parameters from various criteria, with average errors of 30 K, 0.13 dex, and 0.05 dex, respectively, for T eff , log g, and [Fe/H]. The average error of the [X/Fe] abundance ratios is 0.06 dex. Ages were derived from theoretical HR diagrams and membership of the stars in known kinematical moving groups.

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“…The g f of C 2 and MgH lines from the Kurucz database were revised according to the normalisation of the Hönl-London factors (Whiting & Nicholls 1974). The g f values of atomic and other molecular lines were also revised when needed to fit the solar spectrum, taken as a reference in our differential chemical analysis.…”

Section: Carbon Abundance From Spectral Synthesismentioning

confidence: 99%

Homogeneous photospheric parameters and C abundances in G and K nearby stars with and without planets

Silva

Milone

Reddy

2010

A&A

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Aims. We present a determination of photospheric parameters and carbon abundances for a sample of 172 G and K dwarf, subgiant, and giant stars with and without detected planets in the solar neighbourhood. The analysis was based on high signal-to-noise ratio and high resolution spectra observed with the ELODIE spectrograph (Haute Provence Observatory, France) and for which the observational data were publicly available. We intend to contribute precise and homogeneous C abundances in studies that compare the behaviour of light elements in stars with and without planets. This will bring new arguments to the discussion of possible anomalies that have been suggested and will contribute to a better understanding of different planetary formation process. Methods. The photospheric parameters were computed through the excitation potential, equivalent widths, and ionisation equilibrium of iron lines selected in the spectra. Carbon abundances were derived from spectral synthesis applied to prominent molecular head bands of C 2 Swan (λ5128 and λ5165) and to a C atomic line (λ5380.3). Careful attention was drawn to carry out this homogeneous procedure and to compute the internal uncertainties. [Fe/H] shows no difference in the behaviour of planet-host stars in comparison with stars for which no planet was detected, for both dwarf and giant subsamples. This result agrees with the hypothesis of a primordial origin for the chemical abundances presently observed instead of self-enrichment during the planetary system formation and evolution. Additionally, giant stars are clearly depleted in [C/Fe] (by about 0.14 dex) when compared with dwarfs, which is probably related to evolution-induced mixing of H-burning products in the envelope of evolved stars. Subgiant stars, although in small number, seem to follow the same C abundance distribution as dwarfs. We also analysed the kinematics of the sample stars that in their majority are members of the Galaxy's thin disc. Finally, comparisons with other analogue studies were performed and showed good agreement within the uncertainties. Results. The distribution of [C/Fe] as a function of

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Reinvestigation of Rotational-Line Intensity Factors in Diatomic Spectra

Cited by 135 publications

References 0 publications

Solar turbulent magnetic fields: Non-LTE modeling of the Hanle effect in the C₂molecule

Solar turbulent magnetic fields: Non-LTE modeling of the Hanle effect in the C₂molecule

Accurate and homogeneous abundance patterns in solar-type stars of the solar neighbourhood: a chemo-chronological analysis

Homogeneous photospheric parameters and C abundances in G and K nearby stars with and without planets

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Reinvestigation of Rotational-Line Intensity Factors in Diatomic Spectra

Cited by 135 publications

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Solar turbulent magnetic fields: Non-LTE modeling of the Hanle effect in the C2molecule

Solar turbulent magnetic fields: Non-LTE modeling of the Hanle effect in the C2molecule

Accurate and homogeneous abundance patterns in solar-type stars of the solar neighbourhood: a chemo-chronological analysis

Homogeneous photospheric parameters and C abundances in G and K nearby stars with and without planets

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Solar turbulent magnetic fields: Non-LTE modeling of the Hanle effect in the C₂molecule

Solar turbulent magnetic fields: Non-LTE modeling of the Hanle effect in the C₂molecule