EXCITATION CONDITIONS IN THE UPPER ATMOSPHERE AS DETERMINED FROM A STUDY OF ATOMIC EMISSION LINES IN THE AURORAL SPECTRUM

1947 ◽  
Vol 25a (5) ◽  
pp. 293-301 ◽  
Author(s):  
William Petrie
Keyword(s):  
Oxygen Atom ◽  
Atomic Emission ◽  
Upper Atmosphere ◽  
Emission Lines ◽  
Excitation Temperature ◽  
Auroral Region ◽  
Line Intensities ◽  
Theoretical Line ◽  
Measured Line ◽  
Excitation Conditions

Vegard's identifications of a number of lines appearing in the auroral spectrum are discussed. The conclusion is reached that a good many of these lines may be attributed to the oxygen atom in several stages of ionization. It is shown how measured line intensities and theoretical line strengths are combined to give the excitation temperature of the auroral region. Preliminary results indicate that this temperature is in the range 3000° to 6000° K. The meaning of this result is discussed briefly.

scholarly journals Excitation of emission lines by fluorescence and recombination in IC 418

2011 ◽  
Vol 7 (S283) ◽  
pp. 350-351 ◽  
Author(s):  
Vladimir Escalante ◽  
Cristophe Morisset ◽  
Leonid Georgiev
Keyword(s):  
Central Star ◽  
Electron Excitation ◽  
Emission Lines ◽  
Synthetic Spectrum ◽  
Line Intensities ◽  
Almost All ◽  
Excitation Conditions ◽  
Photodissociation Region

AbstractWe predict intensities of lines of CII, NI, NII, OI and OII and compare them with a deep spectroscopic survey of IC 418 to test the effect of excitation of nebular emission lines by continuum fluorescence of starlight. Our calculations use a nebular model and a synthetic spectrum of its central star to take into account excitation of the lines by continuum fluorescence and recombination. The NII spectrum is mostly produced by fluorescence due to the low excitation conditions of the nebula, but many CII and OII lines have more excitation by fluorescence than recombination. In the neutral envelope, the NI permitted lines are excited by fluorescence, and almost all the OI lines are excited by recombination. Electron excitation produces the forbidden optical lines of OI, but continuum fluorescence excites most of the NI forbidden line intensities. Lines excited by fluorescence of light below the Lyman limit thus suggest a new diagnostic to explore the photodissociation region of a nebula.

scholarly journals Optical and Near–Infrared Spectroscopy of the Emission Line Young Stellar Object Gy 2-18 (HHL 31)

2000 ◽  
Vol 175 ◽  
pp. 498-501 ◽  
Author(s):  
Paolo Persi ◽  
Vito Francesco Polcaro ◽  
Joaquin Bohigas ◽  
Mauricio Tapia
Keyword(s):  
Stellar Wind ◽  
Near Infrared ◽  
Young Star ◽  
Emission Lines ◽  
Line Intensities ◽  
Near Ir ◽  
Hydrogen Recombination ◽  
Recombination Emission ◽  
Measured Line ◽  
Extended Reflection

AbstractWe present the results of optical and near–IR spectroscopy of the massive young star associated with the extended reflection nebula Gy 2-18 (HHL31). The optical spectrum between 4000-5000 Å suggests a B0-B2 classification for this object. In addition the Hα line profile indicate the presence of a consistent stellar wind with a velocity of the order of 1200 km/s. The near-IR spectrum is dominated by the presence of the hydrogen recombination emission lines (Pfund and Bracket series). The measured line intensities of these lines are in agreement with the presence of a strong stellar wind in Gy2-18.

Use of Normalized Relative Line Intensities for Qualitative and Semi-Quantitative Analysis in Inductively Coupled Plasma Atomic Emission Spectrometry Using a Custom Segmented-Array Charge-Coupled Device Detector. Part I: Principle and Feasibility

1995 ◽  
Vol 49 (10) ◽  
pp. 1478-1484 ◽  
Author(s):  
Luc Soudier ◽  
Jean-Michel Mermet
Keyword(s):  
Inductively Coupled Plasma ◽  
Major Element ◽  
Atomic Emission ◽  
Atomic Emission Spectrometry ◽  
Emission Spectrometry ◽  
Plasma Atomic Emission Spectrometry ◽  
Charge Coupled Device ◽  
Inductively Coupled ◽  
Line Intensities ◽  
Relative Line

A procedure is described to conduct qualitative analysis in inductively coupled plasma atomic emission spectrometry even in the presence of spectral interferences. This procedure is based on the use of both line correlation and normalized relative line intensities of given elements. When spectral interferences due to a major element are observed for an analyte, use of multiple linear regression of the normalized relative line intensities of both the analyte and the major element provides information about the certainty of the presence of the analyte and the relative concentration between the major element and the analyte. Direct peaking and automatic background correction are required for this procedure. In this instance, no information is necessary about the shape of the line profile. This procedure has been tested with an echelle grating-based dispersive system equipped with a custom segmented-array charge-coupled device detector.

Fourier Deconvolution of Overlapping Line Pairs in Inductively Coupled Plasma-Atomic Emission Spectrometry

1989 ◽  
Vol 43 (1) ◽  
pp. 96-103 ◽  
Author(s):  
Eric H. Van Veen ◽  
M. Pieter Goudzwaard ◽  
Margaretha T. C. De Loos-Vollebregt ◽  
Leo De Galan
Keyword(s):  
Inductively Coupled Plasma ◽  
Gaussian Approximation ◽  
Signal To Noise Ratio ◽  
Detection Limits ◽  
Atomic Emission ◽  
Emission Lines ◽  
Emission Spectrometry ◽  
Plasma Atomic Emission Spectrometry ◽  
Spectral Window ◽  
Inductively Coupled

A deconvolution procedure utilizing Fourier transformation has been developed to reduce line overlap in ICP-AES. Line broadening is caused by physical processes and by instrumental broadening. Convenient deconvolution, however, turns out to be restricted to broadening common to the emission lines in the spectral window, i.e., to instrumental broadening. Deconvolution for the “true” instrumental broadening function and for a Gaussian approximation to this function yields similar results, but the former allows for fast automated data processing with regard to any spectral region and sample composition. A straightforward procedure is reported for the determination of this function independent of wavelength. At the present noise level, a twofold reduction in linewidth can be achieved for emission lines having a small physical width in comparison to the instrumental width. With data acquired from both a high- and a medium-resolution monochromator, results from overlapping line pairs show linear analytical curves and improved detection limits. Due to the decrease in signal-to-noise ratio on deconvolution, the detection limits measured for isolated lines cannot be attained.

scholarly journals Twenty years of observations of PM 1-188: Its chemical abundances and extraordinary kinematics

2021 ◽  
Author(s):  
Miriam Peña ◽  
Liliana Hernández-Martínez ◽  
Francisco Ruiz-Escobedo
Keyword(s):  
Chemical Composition ◽  
Planetary Nebula ◽  
Central Star ◽  
Emission Lines ◽  
Type I ◽  
Chemical Abundances ◽  
Line Intensities ◽  
Physical Conditions ◽  
The Past ◽  
Spectrophotometric Data

Abstract The analysis of 20 years of spectrophotometric data of the double shell planetary nebula PM 1-188 is presented, aiming to determine the time evolution of the emission lines and the physical conditions of the nebula, as a consequence of the systematic fading of its [WC 10] central star whose brightness has declined by about 10 mag in the past 40 years. Our main results include that the [O iii], [O ii], [N ii] line intensities are increasing with time in the inner nebula as a consequence of an increase in electron temperature from 11 000 K in 2005 to more than 14 000 K in 2018, due to shocks. The intensity of the same lines are decreasing in the outer nebula, due to a decrease in temperature, from 13 000 K to 7000 K, in the same period. The chemical composition of the inner and outer shells was derived and they are similar. Both nebulae present subsolar O, S and Ar abundances, while they are He, N and Ne rich. For the outer nebula the values are 12+log He/H = 11.13 ± 0.05, 12+log O/H = 8.04 ± 0.04, 12+log N/H = 7.87 ± 0.06, 12+log S/H = 7.18 ± 0.10 and 12+log Ar = 5.33 ± 0.16. The O, S and Ar abundances are several times lower than the average values found in disc non-Type I PNe, and are reminiscent of some halo PNe. From high resolution spectra, an outflow in the N-S direction was found in the inner zone. Position-velocity diagrams show that the outflow expands at velocities in the −150 to 100 km s−1 range, and both shells have expansion velocities of about 40 km s−1.

scholarly journals Density Diagnostics of Solar Emission Lines from the Nitrogen-like Mg VI Ion

1990 ◽  
Vol 142 ◽  
pp. 443-444
Author(s):  
P.K. Raju ◽  
R. Vasundhara
Keyword(s):  
Electron Density ◽  
Line Intensity ◽  
Emission Lines ◽  
Solar Plasma ◽  
Theoretical Line ◽  
Intensity Ratios ◽  
Density Diagnostics

The variation of theoretical line intensity ratios with electron density for Mg VI ion are presented. This study indicates that the line intensity ratios for Mg VI can be used to infer electron density for solar plasma.

scholarly journals IUE Spectra of The by Dra/Flare Star AU Mic

1983 ◽  
Vol 71 ◽  
pp. 249-250
Author(s):  
C.J. Butler ◽  
A.D. Andrews ◽  
J.G. Doyle ◽  
P.B. Byrne ◽  
J.L. Linsky ◽  
...  
Keyword(s):  
Light Curve ◽  
Emission Line ◽  
Flare Star ◽  
Emission Lines ◽  
Spectral Variation ◽  
Strong Emission ◽  
Line Intensities ◽  
The Mean ◽  
Phase Interval

A coordinated series of ground-based optical and IUE observations of BY Dra variables was undertaken to follow the spectral variation of these stars over one cycle. In the first series 20 LWR and 19 SWP trailed spectra were taken of AU Mic over a three day period 4-6 August 1980 .In Figure 1 we show the mean integrated fluxes for the strong emission lines in the SWP spectra of AU Mic over the observed phase interval of 0.14 to 0.8 together with an approximate V light curve determined by the FES on IUE. From comparison of the emission line intensities and FES magnitudes in Figure 1 several points emerge.

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