scholarly journals The Solar Photospheric Nitrogen Abundance: Determination with 3D and 1D Model Atmospheres

2009 ◽  
Vol 26 (3) ◽  
pp. 345-350 ◽  
Author(s):  
E. Maiorca ◽  
E. Caffau ◽  
P. Bonifacio ◽  
M. Busso ◽  
R. Faraggiana ◽  
...  
Keyword(s):  
Local Thermodynamic Equilibrium ◽  
Spectral Lines ◽  
Solar Photosphere ◽  
Radiation Hydrodynamics ◽  
1D Model ◽  
Nitrogen Abundance ◽  
Width Measurements ◽  
Hydrodynamical Modelling ◽  
Abundance Determination

AbstractWe present a new determination of the solar nitrogen abundance making use of 3D hydrodynamical modelling of the solar photosphere, which is more physically motivated than traditional static 1D models. We selected suitable atomic spectral lines, relying on equivalent width measurements already existing in the literature. For atmospheric modelling we used the co5bold 3D radiation hydrodynamics code. We investigated the influence of both deviations from local thermodynamic equilibrium (non-LTE effects) and photospheric inhomogeneities (granulation effects) on the resulting abundance. We also compared several atlases of solar flux and centre-disc intensity presently available. As a result of our analysis, the photospheric solar nitrogen abundance is A(N) = 7.86 ± 0.12.

scholarly journals Determination of Stark parameters by cross-calibration in a multi-element laser-induced plasma

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Hao Liu ◽  
Benjamin S. Truscott ◽  
Michael N. R. Ashfold
Keyword(s):  
Free Choice ◽  
Local Thermodynamic Equilibrium ◽  
Spectral Lines ◽  
Stark Broadening ◽  
Laser Induced Plasma ◽  
Model Free ◽  
Charge States ◽  
Cross Calibration

Abstract We illustrate a Stark broadening analysis of the electron density N e and temperature T e in a laser-induced plasma (LIP), using a model free of assumptions regarding local thermodynamic equilibrium (LTE). The method relies on Stark parameters determined also without assuming LTE, which are often unknown and unavailable in the literature. Here, we demonstrate that the necessary values can be obtained in situ by cross-calibration between the spectral lines of different charge states, and even different elements, given determinations of N e and T e based on appropriate parameters for at least one observed transition. This approach enables essentially free choice between species on which to base the analysis, extending the range over which these properties can be measured and giving improved access to low-density plasmas out of LTE. Because of the availability of suitable tabulated values for several charge states of both Si and C, the example of a SiC LIP is taken to illustrate the consistency and accuracy of the procedure. The cross-calibrated Stark parameters are at least as reliable as values obtained by other means, offering a straightforward route to extending the literature in this area.

Mega (metal-poor) not so much : Non-LTE spectroscopic stellar parameters and abundance determination of Ultra metal-poor stars

2017 ◽  
Vol 13 (S334) ◽  
pp. 259-262 ◽  
Author(s):  
Rana Ezzeddine ◽  
Tatyana Sitnova ◽  
Anna Frebel ◽  
Lyudmilla Mashonkina ◽  
Bertrand Plez
Keyword(s):  
Thermodynamic Equilibrium ◽  
Local Thermodynamic Equilibrium ◽  
Chemical Species ◽  
First Stars ◽  
Absolute Value ◽  
Non Local ◽  
Abundance Determination

AbstractWe present Non-Local Thermodynamic Equilibrium (Non-LTE) abundance corrections for Mg, Ca, and Fe in 12 ultra metal-poor (UMP) stars ([Fe/H] < −4.00). We show that they increase in absolute value toward the lower metallicity up to 0.45 dex for Mg, 0.30 dex for Ca, and 1.00 dex for Fe. This represents a first step toward a full Non-LTE analysis of chemical species in the UMP stars that will enable us to put useful constraints on the properties of the “First” stars.

scholarly journals Iron abundance determination for the solar-like stars HR 4345 and HR 6573

2004 ◽  
pp. 41-45 ◽  
Author(s):  
Oliver Vince ◽  
Istvan Vince
Keyword(s):  
Software Package ◽  
Input Data ◽  
Spectral Lines ◽  
Software Packages ◽  
Iron Abundance ◽  
Microturbulent Velocity ◽  
Abundance Determination

Using the BLACKWELL software package written by R.O. Gray, the iron abundance of the solar-like stars HR 4345 and HR 6573 has been determined. The method is based on determination of the minimum dispersion (or the region of least confusion) of the iron abundance versus microturbulent velocity functions for some selected spectral lines of neutral iron. The input data used by BLACKWELL are the observed equivalent widths of several spectral lines of neutral iron. They are obtained from spectra observed at the Observatoire de Haute-Provence, France, with the 1.52-m telescope and Aurelie spectrograph. Reduction of the raw spectra and the measurement of the equivalent widths of spectral lines are carried out using IRAF and SPE software packages. The measured values of iron abundances of HR 4345 and HR 6573 are 7.72?0.03 and 7.63?0.05 respectively.

scholarly journals The Semiclassical Limit of the Gailitis Formula Applied to Electron Impact Broadening of Spectral Lines of Ionized Atoms

Atoms ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 29
Author(s):  
Sylvie Sahal-Bréchot
Keyword(s):  
Electron Impact ◽  
Classical Limit ◽  
Semiclassical Limit ◽  
Spectral Lines ◽  
Stark Broadening ◽  
Feshbach Resonances

The present paper revisits the determination of the semi-classical limit of the Feshbach resonances which play a role in electron impact broadening (the so-called “Stark“ broadening) of isolated spectral lines of ionized atoms. The Gailitis approximation will be used. A few examples of results will be provided, showing the importance of the role of the Feshbach resonances.

Measurement and analysis of species distribution in laser-induced ablation plasma of an aluminum-magnesium alloy

2021 ◽  
Author(s):  
Junxiao Wang ◽  
Shuqing Wang ◽  
Lei Zhang ◽  
Maogen Su ◽  
Duixiong Sun ◽  
...  
Keyword(s):  
Species Distribution ◽  
Laser Energy ◽  
Integral Intensity ◽  
Spectral Lines ◽  
Imaging Method ◽  
Measurement And Analysis ◽  
Ablation Plasma ◽  
Spatio Temporal ◽  
Differential Imaging

Abstract We proposed a theoretical spatio-temporal imaging method, which was based on the thermal model of laser ablation and the two-dimensional axisymmetric multi-species hydrodynamics model. By using the intensity formula, the integral intensity of spectral lines could be calculated and the corresponding images of intensity distribution could be drawn. Through further image processing such as normalization, determination of minimum intensity, combination and color filtering, a relatively clear species distribution image in the plasma could be obtained. Using the above method, we simulated the plasma ablated from Al-Mg alloy by different laser energies under 1 atm argon, and obtained the theoretical spatio-temporal distributions of Mg I, Mg II, Al I, Al II and Ar I species, which are almost consistent with the experimental results by differential imaging. Compared with the experimental decay time constants, the consistency is higher at low laser energy, indicating that our theoretical model is more suitable for the plasma dominated by laser-supported combustion wave.

Determination of Al, Cu, Ni in Zr-Based Amorphous Alloy by Inductively Coupled Plasma Atomic Emission Spectrometry

2015 ◽  
Vol 1095 ◽  
pp. 218-221
Author(s):  
Lan Ma ◽  
Guang He Qin ◽  
Qiong Yu ◽  
Jing Zhou
Keyword(s):  
Amorphous Alloy ◽  
Inductively Coupled Plasma ◽  
Atomic Emission ◽  
Spectral Lines ◽  
Atomic Emission Spectrometry ◽  
Emission Spectrometry ◽  
Plasma Atomic Emission ◽  
Plasma Atomic Emission Spectrometry ◽  
Inductively Coupled

A Method was studied for the determination of Al、Cu、Ni in Zr-based amorphous alloy by inductively coupled plasma atomic emission spectrometry (ICP-AES). Samples were dissolved by hydrochloric acid,nitric acid and hydrofluoric acid,analytical spectral lines for aluminum,copper,nickle are 308.215nm,327.396nm and 231.604nm.Interference of zinc was eliminated by the matrix-matching method, the experiments were done with optimized Operating Parameters. The correlation coefficients of the calibration curve are all 0.999,detection limits are 0.0010%,0.005% and 0.0006% respectively,and the range of recovery is 98%-104%.

(F)UV Spectroscopy of K648: Abundance Determination of Trace Elements

2010 ◽  
Author(s):  
S. J. Mohamad-Yob ◽  
M. Ziegler ◽  
T. Rauch ◽  
K. Werner ◽  
Klaus Werner ◽  
...  
Keyword(s):  
Trace Elements ◽  
Uv Spectroscopy ◽  
Abundance Determination

scholarly journals On the violation of local thermodynamic equilibrium in the plasma jet of an argon arc two-jet plasmatron

2019 ◽  
Vol 85 (1II)) ◽  
pp. 145-150
Author(s):  
A. S. Cherevko ◽  
A. A. Morozova
Keyword(s):  
Energy Level ◽  
Equilibrium State ◽  
Thermodynamic Equilibrium ◽  
Local Thermodynamic Equilibrium ◽  
Plasma Jet ◽  
Saha Equation ◽  
Radiation Processes ◽  
Unconventional Method

The degree and nature of the violation of local thermodynamic equilibrium (LTE) in the analytical zone of a plasma jet generated by an argon arc two-jet plasmatron (TJP) was estimated using an unconventional method based on determination of the nonequilibrium parameterbiequal to the ratio of the experimentally determined actual population of the energy level (ni) of the element to the population of the same level calculated from the Saha equation (nis). Partial ionizing deviation of plasma under study from the equilibrium state takes place only when low-lying atomic levels are overpopulated. The distinct dependence ofbion the ionization potential of the considered element (e.g., Ca, Mg, and Be) is shown. The results were interpreted in the light of the increasing role of radiation processes upon excitation of spectra in the argon arc two-jet plasmatron.

scholarly journals Determination of metallicity of the HR7914 solar-like star

2003 ◽  
pp. 69-74 ◽  
Author(s):  
Oliver Vince ◽  
Istvan Vince
Keyword(s):  
Spectral Line ◽  
Stellar Atmosphere ◽  
Astronomical Observatory ◽  
Program Package ◽  
Spectral Lines ◽  
Iron Abundance ◽  
Microturbulent Velocity

By using the Blackwell program package by R.O. Gray, the metallicity of the HR7914 solar-like star was determined. The program package utilizes measured equivalent widths of several chosen neutral iron spectral lines from the observed spectra, appropriate atomic and spectral line parameters and adequate Kurucz?s stellar atmosphere models. The method is based on determination of the minimum dispersion of the iron abundance versus microturbulent velocity functions for the selected neutral iron spectral lines. The spectra were observed at National Astronomical Observatory Rozhen (NAO Rozhen), Bulgaria, using the 2m-telescope and Coude spectrograph. They were reduced with the IRAF program package. The measurement of the spectral line parameters was done with the SPE program package. The metallicity of the HR7914 solar-like star was determined to be 0.02.

Sign in / Sign up

Export Citation Format

Share Document