Theoretical D0 for NH(X 3Σ−)

Bauschlicher, Charles W.; Langhoff, Stephen R.

doi:10.1016/0009-2614(87)87218-4

Cited by 51 publications

(9 citation statements)

References 22 publications

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“…12 We adopt dissociation potentials of 3.47 and 4.39 eV (Huber & Herzberg 1979) for CH and OH, respectively. For NH we adopt 3.40 eV based on the theoretical calculations of Bauschlicher & Langhoff (1987) and the laboratory spectroscopy of Ervin & Armentrout (1987). Our analysis assumes classical plane-parallel stellar atmospheres and LTE, both for atomic and for molecular features.…”

Section: Discussionmentioning

confidence: 99%

New Extremely Metal‐Poor Stars in the Galactic Halo

Cohen

Christlieb

McWilliam

et al. 2008

ApJ

127

163

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We present a detailed abundance analysis based on high-resolution and high signal-to-noise spectra of eight extremely metal-poor (EMP) stars with ½Fe/H P À3:5 dex, four of which are new. Only stars with 4900 K < T eA < 5650 K are included. Two stars of the eight are outliers in each of several abundance ratios. The most metal-poor star in this sample, HE 1424À0241, has ½Fe/H $ À4 dex and is thus among the most metal-poor stars known in the Galaxy. It has highly anomalous abundance ratios unlike those of any other known EMP giant, with very low Si, Ca, and Ti relative to Fe, and enhanced Mn and Co, again relative to Fe. Only (low) upper limits for C and N can be derived from the nondetection of the CH and NH molecular bands. HE 0132-2429, another sample star, has excesses of N and Sc with respect to Fe. The strong outliers in abundance ratios among the Fe-peak elements in these C-normal stars, not found at somewhat higher metallicities (½Fe/H $ À3 dex), are definitely real. They suggest that at such low metallicities we are beginning to see the anticipated and long sought stochastic effects of individual supernova events contributing to the Fe-peak material within a single star. With spectra reaching well into the near-UV we are able to probe the behavior of copper abundances in such extreme EMP stars. A detailed comparison of the results of the analysis procedures adopted by our 0Z project compared to those of the First Stars VLT Large Project finds a systematic difference for ½Fe/H of $0.3 dex, our values always being higher.

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Section: Discussionmentioning

confidence: 99%

New Extremely Metal‐Poor Stars in the Galactic Halo

Cohen

Christlieb

McWilliam

et al. 2008

ApJ

127

163

View full text Add to dashboard Cite

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“…For CH and OH we use dissociation energies of 3.47 eV and 4.39 eV, respectively (Huber & Herzberg 1979). For NH we employ 3.37 eV (Bauschlicher & Langhoff 1987).…”

Section: Line Data and Analysis Techniquesmentioning

confidence: 99%

HE 1327−2326, an Unevolved Star with [Fe/H]<−5.0. II. New 3D−1D Corrected Abundances from a Very Large Telescope UVES Spectrum

Frebel

Collet

Eriksson

et al. 2008

Astrophysical Journal

157

184

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We present a new abundance analysis of HE 1327−2326, the currently most iron-poor star, based on observational data obtained with VLT/UVES. We correct the 1D LTE abundances for 3D effects to provide an abundance pattern that supersedes previous works, and should be used to observationally test current models of the chemical yields of the first-generation SNe. Apart from confirming the 1D LTE abundances found in previous studies before accounting for 3D effects, we make use of a novel technique to apply the 3D−1D corrections for CNO which are a function of excitation potential and line strength for the molecular lines that comprise the observable CH, NH, and OH features. We find that the fit to the NH band at 3360Å is greatly improved due to the application of the 3D−1D corrections. This may indicate that 3D effects are actually observable in this star. We also report the first detection of several weak Ni lines. The cosmologically important element Li is still not detected; the new Li upper limit is extremely low, A(Li) < 0.62, and in stark contrast with results not only from 1 Based on observations collected at the European Southern Observatory, Paranal, Chile (Proposal ID 075.D-0048).WMAP but also from other metal-poor stars. We also discuss how the new corrected abundance pattern of HE 1327−2326 is being reproduced by individual and integrated yields of SNe.

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“…experimental results. Besides the calculations employed to explore the title potential energy surface, 12,14,15 we have tabulated some of the best predictions 34,38 reported thus far.…”

Section: Extendedmentioning

confidence: 99%

Repulsive double many-body expansion potential energy surface for the reactions N(4S)+ H2⇌ NH(X3Σ–)+ H from accurate ab initio calculations

Poveda

Varandas

2005

Phys. Chem. Chem. Phys.

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A single-sheeted DMBE potential energy surface is reported for the reactions N(4S)+H2<-->NH(X3Sigma-)+H based on a fit to accurate multireference configuration interaction energies. These have been calculated using the aug-cc-pVQZ basis set of Dunning and the full valence complete active space wave function as reference, being semi-empirically corrected by scaling the two-body and three-body dynamical correlation energies. The topographical features of the novel global potential energy surface are examined in detail, including a conical intersection involving the two first 4A'' potential energy surfaces which has been transformed into an avoided crossing in the present single-sheeted representation.

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Theoretical D0 for NH(X 3Σ−)

Cited by 51 publications

References 22 publications

New Extremely Metal‐Poor Stars in the Galactic Halo

New Extremely Metal‐Poor Stars in the Galactic Halo

HE 1327−2326, an Unevolved Star with [Fe/H]<−5.0. II. New 3D−1D Corrected Abundances from a Very Large Telescope UVES Spectrum

Repulsive double many-body expansion potential energy surface for the reactions N(4S)+ H2⇌ NH(X3Σ–)+ H from accurate ab initio calculations

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