scholarly journals Populations of Hydrogen-like Atoms or Ions and Radio Recombination Lines (RRL's) Interpretation

2002 ◽  
Vol 199 ◽  
pp. 351-352
Author(s):  
N.I. Rovenskaya
Keyword(s):  
Thermal Radiation ◽  
Electron Density ◽  
Hii Regions ◽  
Kinetic Temperature ◽  
Line Radiation ◽  
Continuum Radiation ◽  
Radio Recombination Lines ◽  
The Continuum

The problem of non-LTE populations has been considered in terms of the departure coefficients ∂bn/∂n as functions of the kinetic temperature Te, the electron density Ne, the continuum radiation flow Ic and the ratios of IHnα, IHnβ, IHnδ and IHnε (the line radiation flows). The ratio of IHnα/IHnβ are sensitive to the thermal radiation from HII regions. Characterized by the relation of ∂2bn/∂n2 > 0, the populations are shown to be inhabited radiatively.

scholarly journals 5 GHz Continuum Radiation from Southern Hemisphere Galactic HII Regions

1968 ◽  
Vol 21 (6) ◽  
pp. 881 ◽  
Author(s):  
FF Gardner ◽  
M Morimoto
Keyword(s):  
Southern Hemisphere ◽  
Hii Regions ◽  
Radio Sources ◽  
Positional Accuracy ◽  
Continuum Radiation ◽  
Thermal Radio ◽  
5 Ghz ◽  
Better Than ◽  
The Continuum

The continuum radiation from about 36 southern thermal radio sources has been surveyed at 6 cm wavelength with a beamwidth of 4'�2 arc, and maps are shown for 28 of these. The positional accuracy is better than l' arc.

scholarly journals Radio Observations of Hii Regions in M33

1974 ◽  
Vol 60 ◽  
pp. 227-228
Author(s):  
F. P. Israel ◽  
P. C. van der Kruit
Keyword(s):  
Radio Telescope ◽  
Hii Regions ◽  
Radio Sources ◽  
Orion Nebula ◽  
Radio Observations ◽  
Continuum Radiation ◽  
The Continuum

The Westerbork Synthesis Radio Telescope was used to map the continuum radiation of M33 at 1415 MHz. Of 67 radio sources with fluxes S> 1.8 mJy (3σ), 60% coincide with Hα sources. These are all intrinsically stronger than 4 × the Orion nebula, i.e., they are giant Hiiregions. The two strongest sources, NGC 604 (58 mJy) and NGC 595 (20 mJy), are similar to W51.

scholarly journals 35. Optical emission from the Crab nebula in the continuous spectrum

1957 ◽  
Vol 4 ◽  
pp. 201-204
Author(s):  
I. S. Shklovsky
Keyword(s):  
Thermal Radiation ◽  
Continuous Spectrum ◽  
Crab Nebula ◽  
Optical Emission ◽  
Kinetic Temperature ◽  
Continuous Emission ◽  
The Crab Nebula

All conclusions concerning the nature of the Crab nebula up to the present have been based upon the interpretation of its continuous spectrum given by Baade and Minkowski in their well-known studies ([1, 2]; see also [3, 4]), It was suggested that its continuous emission is a thermal radiation caused by the extremely hot amorphous mass of this nebula. A consequence of this interpretation is that the mass of the envelope is of the order of 10–20 solar masses and the kinetic temperature is extremely high. The filamentary part of the nebula possesses more or less ordinary characteristics.

Transient Light Emissions from a Laser Perturbed Plasma

1972 ◽  
Vol 50 (19) ◽  
pp. 2338-2347 ◽  
Author(s):  
H. A. Baldis ◽  
R. A. Nodwell ◽  
J. Meyer
Keyword(s):  
Laser Pulse ◽  
Electron Density ◽  
Laser Light ◽  
Line Emission ◽  
Argon Plasma ◽  
Stark Broadening ◽  
Excited Atoms ◽  
Electron Density Gradient ◽  
Transient Plasma ◽  
The Continuum

The interaction between a 20 MW Q-switched ruby laser pulse and a partially ionized argon plasma has been studied experimentally. When the focused laser pulse is fired into the plasma, a transient emission from the plasma may be observed both in the continuum and line emission. From measurements of the absolute intensities of this transient radiation, estimates have been made of the population density of the excited atoms and of the electron densities. The Stark broadening of the Ar II lines has also been measured to obtain the electron density in the transient plasma and data obtained in this way are consistent with those obtained from the continuum radiation. During the time when the laser light is incident on the plasma the Ar II lines show a strong asymmetry which disappears quickly after the laser pulse has terminated. This asymmetry can be explained in terms of the electron density gradient present in the expanding perturbed plasma.

scholarly journals Birthrate of PN

1983 ◽  
Vol 103 ◽  
pp. 424-425 ◽  
Author(s):  
D.C.V. Mallik
Keyword(s):  
Electron Density ◽  
Surface Density ◽  
Planetary Nebulae ◽  
Number Density ◽  
Continuum Radiation ◽  
Complete Catalogue

Recent observations of planetary nebulae have called into question the Shklovsky method of measuring distances. For those planetaries for which independent distance and electron density determinations are available, it is found that the ionized mass and the radius are linearly correlated (Maciel and Pottasch, 1980) and also that the ionized masses increase with decreasing electron density (Pottasch, 1981). These relations imply that the nebulae are optically thick in Ly continuum radiation and the distances based on the Shklovsky method are overestimates. Using an empirically determined mass-radius relationship Maciel and Pottasch have obtained new distances for the nebulae in the catalogue of Milne and Aller (1975). We have used the more complete catalogue of Cahn and Kaler (1971) to obtain distances corrected for possible variations in the ionized mass and have compiled a new list of local planetaries. We obtain a surface density of 15 ± 3 kpc−2 and a planar number density of 44 ± 4 kpc−3.

scholarly journals Density Irregularity of the Inner Corona determined from Simultaneous Measurements of the XUV and the K Coronal Brightness

1990 ◽  
Vol 142 ◽  
pp. 253-254
Author(s):  
M. Guhathakurta ◽  
G.J. Rottmann ◽  
R.R. Fisher ◽  
F.Q. Orrall
Keyword(s):  
Electron Density ◽  
White Light ◽  
Light Emission ◽  
Solar Limb ◽  
Position Angle ◽  
Thomson Scattering ◽  
White Light Emission ◽  
Kinetic Temperature ◽  
Data Sets ◽  
Chemical Abundance

In this paper we report preliminary results from a study of the inner corona based on the direct comparison of XUV resonance emission line λ174.53 FeX with that of the white-light emission from the K corona. The data sets were obtained 17718th of March, 1988, during a total solar eclipse of the sun and consists of co-spatial and co-temporal measurements of these two quantities as a function of position angle and height above the solar limb. The local emission of a coronal resonance line is proportional to the electron density squared, the chemical abundance, and the electron kinetic temperature, while the white-light emission (arising from Thomson scattering by electrons) depends directly on the electron density and the local radiation field. Taken together these measurements yield an estimate of the quantity where n is the electron density. This quantity, called “X the coronal irregularity factor” by C.W. Allen, is found to be >1.

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