Coronal and Transition Region Structure in the RS Canum Venaticorum Binaries V711 Tauri, AR Lacertae, and II Pegasi. I. Data Analysis and Emission Measure Distributions

1998 ◽  
Vol 497 (2) ◽  
pp. 883-895 ◽  
Author(s):  
N. W. Griffiths ◽  
C. Jordan
Keyword(s):  
Data Analysis ◽  
Transition Region ◽  
Emission Measure ◽  
Rs Canum Venaticorum Binaries

Helium line emission: its relation to atmospheric structure

1980 ◽  
Vol 297 (1433) ◽  
pp. 541-554 ◽  
Keyword(s):  
Temperature Gradient ◽  
Transition Region ◽  
Scaling Laws ◽  
Coronal Holes ◽  
Emission Measure ◽  
Line Emission ◽  
Electron Pressure ◽  
Steep Temperature Gradient ◽  
Region Temperature ◽  
Higher Temperature

A brief review is given of observations of the resonance lines of He I and He II and their interpretation. As discussed in a previous paper, the helium lines are anomalously strong in the quiet Sun when compared with other transition region lines. The enhancement can be brought about by the transient excitation of the lines by electrons of higher temperature than that which determines the ion population. The variation in the intensity of the helium lines relative to those of other transition region lines appears to be related to variations in the temperature gradient between different parts of the atmosphere. To relate the degree of enhancement to other observable parameters, such as electron pressure and absolute line intensities, and thus to the structure of the atmosphere, a method for analysing the emission measure distribution previously developed in the context of the quiet atmosphere and active region loops is applied also to coronal holes. It is proposed that the non-thermal ion motions observed in the transition region can provide the required mechanism for transporting the helium ions across the steep temperature gradient. By making a simple model, an expression is developed which relates the helium enhancement to the non-thermal motions, the transition region temperature gradient and the electron pressure. The scaling laws implied can be tested against further observations when they become available.

Emission Measure of Prominence-Corona Transition Region

1994 ◽  
Vol 144 ◽  
pp. 357-360 ◽  
Author(s):  
S. Pojoga
Keyword(s):  
Transition Region ◽  
Extreme Ultraviolet ◽  
Emission Measure ◽  
Spatial Distributions ◽  
Line Intensities ◽  
Homogeneous Area

AbstractExtreme ultraviolet line intensities obtained with the HCO spectrometer on Skylab are used to study the prominence-corona transition region. The spatial distributions of intensities as well as of EM are found from an almost homogeneous area in a prominence. A possible interpretation is given for the different shape of the EM curves in accordance with different models of subresolution structure.

Temperature and Emission-Measure Profiles along Long-lived Solar Coronal Loops Observed with the [ITAL]Transition Region and Coronal Explorer[/ITAL]

1999 ◽  
Vol 517 (2) ◽  
pp. L155-L158 ◽  
Author(s):  
Dawn D. Lenz ◽  
Edward E. DeLuca ◽  
Leon Golub ◽  
Robert Rosner ◽  
Jay A. Bookbinder
Keyword(s):  
Transition Region ◽  
Emission Measure ◽  
Coronal Loops ◽  
Solar Coronal

scholarly journals Non-Static Structure of the Chromosphere-Corona Transition Region

1974 ◽  
Vol 56 ◽  
pp. 91-91
Author(s):  
Philippe Delache
Keyword(s):  
Transition Region ◽  
Mass Flux ◽  
Thermal Emission ◽  
Emission Measure ◽  
Radio Spectrum ◽  
List Type ◽  
Static Structure ◽  
One Dimensional ◽  
Spatially Resolved ◽  
Theoretical Predictions

The emission measure Ne2 dh, which is so useful in reducing XUV as well as radio data, is redefined as f(T) dT where f(T) is called ‘thermal emission measure’. Theoretical predictions for f(T) on the basis of a simple, one dimensional, steadily expanding atmosphere are presented. Depending upon the boundary conditions, and essentially upon the mass flux, two very different behaviours show up.(1)With a mass flux compatible with an extrapolation of the solar wind flux, f(T) would correspond to a transition region controlled by a constant conductive flux. It can be fitted, as was shown e.g. by Athay (1966), with the XUV observations of the integrated disk for lines formed at temperatures higher than about 2 × 105 K.(2)But only with a mass flux enhanced by a factor of 50 to 100, can we interpret the radio spectrum and the XUV observations of lines formed at temperatures less than 2 × 105 K.The suggestion is made that a single model can reconcile both behaviours: below 2 × 105 K the emitting region is squeezed so that it covers 1–2% of the surface that it occupies at higher temperatures where all structures begin to merge, filling the whole corona. This variation with height compares with usual models derived from spatially resolved observations; as usual the underlying magnetic field is expected to support this channelling.

THE EMISSION MEASURE OF THE SOLAR LOWER TRANSITION REGION (2 × 104-2 × 105K)

2009 ◽  
Vol 693 (2) ◽  
pp. 1474-1483 ◽  
Author(s):  
U. Feldman ◽  
I. E. Dammasch ◽  
E. Landi
Keyword(s):  
Transition Region ◽  
Emission Measure ◽  
Lower Transition

scholarly journals Kappa-distributions and Temperature Structure of the Prominence-Corona Transition Region

2013 ◽  
Vol 8 (S300) ◽  
pp. 408-409 ◽  
Author(s):  
Elena Dzifčáková ◽  
Šimon Mackovjak ◽  
Petr Heinzel
Keyword(s):  
Transition Region ◽  
Emission Measure ◽  
Emission Lines ◽  
Temperature Structure ◽  
Formation Temperature ◽  
Differential Emission Measure ◽  
Line Intensities ◽  
Temperature Ranges

AbstractThe influence of the electron κ - distributions on the differential emission measure (DEM) of the prominence-corona transition region (PCTR) derived from observed line intensities has been investigated. An important consequence of the κ - distribution is formation of the emission lines in much wider temperature ranges. The implications for the formation temperature of the observed SDO/AIA band emissions are shown.

Effects of Ambipolar Diffusion on Prominence Thread Models

1994 ◽  
Vol 144 ◽  
pp. 315-321 ◽  
Author(s):  
M. G. Rovira ◽  
J. M. Fontenla ◽  
J.-C. Vial ◽  
P. Gouttebroze
Keyword(s):  
Energy Balance ◽  
Transition Region ◽  
Ambipolar Diffusion ◽  
Line Profiles ◽  
Balance Equations ◽  
Model Calculations ◽  
Partial Frequency ◽  
Frequency Redistribution ◽  
Partial Frequency Redistribution ◽  
Theoretical Structure

AbstractWe have improved previous model calculations of the prominence-corona transition region including the effect of the ambipolar diffusion in the statistical equilibrium and energy balance equations. We show its influence on the different parameters that characterize the resulting prominence theoretical structure. We take into account the effect of the partial frequency redistribution (PRD) in the line profiles and total intensities calculations.

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