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1987
Forbidden emission lines cannot be observed in terrestrial environments. They arise when downward transitions occur from metastable energy levels in neutral or ionised atoms. The transition probabilities are very much lower than for normal permitted transitions, so that lifetimes in the excited state may exceed 1 second. In terrestrial environments the
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Forbidden emission lines cannot be observed in terrestrial environments. They arise when downward transitions occur from metastable energy levels in neutral or ionised atoms. The transition probabilities are very much lower than for normal permitted transitions, so that lifetimes in the excited state may exceed 1 second. In terrestrial environments the
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2003
In this chapter, we will review the sometimes arcane, frequently confusing, notations that are used to classify atomic and molecular transitions and spectra. A basic understanding of these is essential, since it is through the atomic and molecular lines that we ultimately derive our understanding about the physical conditions in, and chemical ...
Michael A. Dopita, Ralph S. Sutherland
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In this chapter, we will review the sometimes arcane, frequently confusing, notations that are used to classify atomic and molecular transitions and spectra. A basic understanding of these is essential, since it is through the atomic and molecular lines that we ultimately derive our understanding about the physical conditions in, and chemical ...
Michael A. Dopita, Ralph S. Sutherland
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Emission Cores in H and K Lines
Solar Physics, 1968Profiles of the Hand K lines of Mgn and the K line of Can are computed using a two-level atom for five model atmospheres distinguished from each other mainly by the location of the temper ature minimum. In the five models the temperature minimum and the chromospheric temperature are adjusted to give best agreement between computed and observed ...
R. Grant Athay, A. Skumanich
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Helium shells and faint emission lines from slitless flash spectra [PDF]
Journal of Advanced Research, 2013 At the time of the two last solar total eclipses of August 1st, 2008 in Siberia and July 11th, 2010 in French Polynesia, high frame rate CCD flash spectra were obtained. These eclipses occurred in quiet Sun period and after.
Serge Koutchmy, Cyril Bazin
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1990
Active galaxies are distinguished from other galaxies in that they show indications of having energy output not related to ordinary stellar processes. The activity is centered in a small nuclear region and associated with strong emission lines. The nuclei of such galaxies are named Active Galactic Nuclei (hereafter AGNs). This group of objects includes
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Active galaxies are distinguished from other galaxies in that they show indications of having energy output not related to ordinary stellar processes. The activity is centered in a small nuclear region and associated with strong emission lines. The nuclei of such galaxies are named Active Galactic Nuclei (hereafter AGNs). This group of objects includes
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The Origin of the Emission Lines
1970The spectra of the nebulae are completely different from the spectra of their central stars. In particular, the energy emitted by a nebula in the different lines is considerably greater than the energy of the corresponding regions in the spectrum of the star. Nevertheless, the luminosity of a nebula is entirely due to the radiation of its central star,
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Emission-Line Variability and Distance of Quasars
Science, 1967The radius of the line-emitting region in quasars is larger than 1 parsec for the cosmological hypothesis and smaller than 1 parsec for the local hypothesis. Variability in emission lines has been reported but not proved beyond doubt. Its time scale would be a direct observational indicator of this radius and would add an important element to the ...
J, Pfleiderer, M, Grewing
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1997
The spectra of the purely gaseous nebulae are completely different from the spectra of their central stars. The discrepancy is expressed in the structure of the spectra itself as well as in the intensities in certain of its parts. In the visual band the spectrum of the nebula consists of a number of very intense emission lines with a hardly noticeable ...
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The spectra of the purely gaseous nebulae are completely different from the spectra of their central stars. The discrepancy is expressed in the structure of the spectra itself as well as in the intensities in certain of its parts. In the visual band the spectrum of the nebula consists of a number of very intense emission lines with a hardly noticeable ...
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2007
When we consider the radiation fields of stellar envelopes exposed to the photospheric UV radiation, the basic feature is their anisotropic nature. The degree of anisotropy is expressed by the geometrical dilution factor, W, defined as the ratio of the solid angle, ω, of the photosphere seen from a point of interest, P, relative to the total solid ...
Tomokazu Kogure, Kam-Ching Leung
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When we consider the radiation fields of stellar envelopes exposed to the photospheric UV radiation, the basic feature is their anisotropic nature. The degree of anisotropy is expressed by the geometrical dilution factor, W, defined as the ratio of the solid angle, ω, of the photosphere seen from a point of interest, P, relative to the total solid ...
Tomokazu Kogure, Kam-Ching Leung
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2012
>The force acting on a charge e moving non-relativistically with a velocity v of magnitude v in a uniform magnetic field B is the Lorentz force.
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>The force acting on a charge e moving non-relativistically with a velocity v of magnitude v in a uniform magnetic field B is the Lorentz force.
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