A comparison of computed and observed line profiles and flash intensities in the photosphere-chromosphere transition region

Solar Physics ◽  
1970 ◽  
Vol 15 (2) ◽  
pp. 322-337 ◽  
Author(s):  
E. L. J. Van Dessel
Keyword(s):  
Transition Region ◽  
Line Profiles

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.

scholarly journals Enhanced Turbulence and Heating Observed Preceding the Impulsive Phase in a Solar Flare

1989 ◽  
Vol 104 (2) ◽  
pp. 231-234
Author(s):  
Chung-Chieh Cheng ◽  
K.G. Widing
Keyword(s):  
Solar Flare ◽  
Transition Region ◽  
Normal Incidence ◽  
Impulsive Phase ◽  
Energetic Particles ◽  
Line Profiles ◽  
Chromospheric Evaporation

AbstractWe studied the unique EUV spectra of the 21 Jan. 1974 flare observed by the NRL Normal-Incidence Slit Spectrometer (SO 82B) onboard the Skylab. The results show that the pre-impulsive transition region plasmas exhibited enhanced turbulence and heating before the acceleration of energetic particles. The absence of blue-shifted components in the Fe XXI line profiles shows that the chromospheric evaporation is not important in this flare.

scholarly journals Measurements of Mass Flow in the Transition Region and Inner Corona

1980 ◽  
Vol 91 ◽  
pp. 375-378
Author(s):  
Gary J. Rottman
Keyword(s):  
Transition Region ◽  
Mass Flow ◽  
Spectral Resolution ◽  
Solar Disk ◽  
Velocity Fields ◽  
Emission Lines ◽  
High Spectral Resolution ◽  
Sounding Rocket ◽  
Line Profiles ◽  
Euv Emission

A recent sounding rocket experiment has provided high spectral resolution line profiles across the solar disk. The objective of this experiment is to provide information on the systematic velocity fields at the base of the corona by observing the displacement, width and shape of EUV emission lines.

scholarly journals Semi-empirical model atmospheres for the chromosphere of the sunspot penumbra and umbral flashes

2019 ◽  
Vol 627 ◽  
pp. A46 ◽  
Author(s):  
Souvik Bose ◽  
Vasco M. J. Henriques ◽  
Luc Rouppe van der Voort ◽  
Tiago M. D. Pereira
Keyword(s):  
Transition Region ◽  
Empirical Model ◽  
Solar Chromosphere ◽  
Line Profiles ◽  
Frequency Redistribution ◽  
Lower Transition ◽  
Semi Empirical ◽  
Complete Frequency ◽  
Imaging Spectrograph ◽  
Sunspot Penumbra

Context. The solar chromosphere and the lower transition region are believed to play a crucial role in the heating of the solar corona. Models that describe the chromosphere (and the lower transition region), accounting for its highly dynamic and structured character are, so far, found to be lacking. This is partly due to the breakdown of complete frequency redistribution (CRD) in the chromospheric layers and also because of the difficulty in obtaining complete sets of observations that adequately constrain the solar atmosphere at all relevant heights. Aims. We aim to obtain semi-empirical model atmospheres that reproduce the features of the Mg II h&k line profiles that sample the middle chromosphere with focus on a sunspot. Methods. We used spectropolarimetric observations of the Ca II 8542 Å spectra obtained with the Swedish 1 m Solar Telescope and used NICOLE inversions to obtain semi-empirical model atmospheres for different features in and around a sunspot. These were used to synthesize Mg II h&k spectra using the RH1.5D code, which we compared with observations taken with the Interface Region Imaging Spectrograph (IRIS). Results. Comparison of the synthetic profiles with IRIS observations reveals that there are several areas, especially in the penumbra of the sunspot, where most of the observed Mg II h&k profiles are very well reproduced. In addition, we find that supersonic hot down-flows, present in our collection of models in the umbra, lead to synthetic profiles that agree well with the IRIS Mg II h&k profiles, with the exception of the line core. Conclusions. We put forward and make available four semi-empirical model atmospheres. Two for the penumbra, reflecting the range of temperatures obtained for the chromosphere, one for umbral flashes, and a model representative of the quiet surroundings of a sunspot.

scholarly journals Evaluating Possible Heating Mechanisms Using the Transition Region Line Profiles of Late‐Type Stars

1997 ◽  
Vol 478 (2) ◽  
pp. 745-765 ◽  
Author(s):  
Brian E. Wood ◽  
Jeffrey L. Linsky ◽  
Thomas R. Ayres
Keyword(s):  
Transition Region ◽  
Line Profiles ◽  
Late Type ◽  
Region Line

scholarly journals Non-Maxwellian Analysis of the Transition-region Line Profiles Observed by theInterface Region Imaging Spectrograph

2017 ◽  
Vol 842 (1) ◽  
pp. 19 ◽  
Author(s):  
Jaroslav Dudík ◽  
Vanessa Polito ◽  
Elena Dzifčáková ◽  
Giulio Del Zanna ◽  
Paola Testa
Keyword(s):  
Transition Region ◽  
Line Profiles ◽  
Imaging Spectrograph ◽  
Region Line

Structuring, Motions and Shapes of Corona Emission Line Profiles

1994 ◽  
Vol 144 ◽  
pp. 421-426
Author(s):  
N. F. Tyagun
Keyword(s):  
Emission Line ◽  
Filling Factor ◽  
Direct Relationship ◽  
Coronal Plasma ◽  
Line Of Sight ◽  
Line Profiles ◽  
The Difference ◽  
Yellow Line ◽  
Red Line

AbstractThe interrelationship of half-widths and intensities for the red, green and yellow lines is considered. This is a direct relationship for the green and yellow line and an inverse one for the red line. The difference in the relationships of half-widths and intensities for different lines appears to be due to substantially dissimilar structuring and to a set of line-of-sight motions in ”hot“ and ”cold“ corona regions.When diagnosing the coronal plasma, one cannot neglect the filling factor - each line has such a factor of its own.

The Interpretation of Line Profiles

1977 ◽  
Vol 36 ◽  
pp. 191-215
Author(s):  
G.B. Rybicki
Keyword(s):  
Magnetic Fields ◽  
Atomic Physics ◽  
Velocity Fields ◽  
Spectral Lines ◽  
Inhomogeneous Structure ◽  
The Sun ◽  
Line Profiles ◽  
Physical Phenomena

Observations of the shapes and intensities of spectral lines provide a bounty of information about the outer layers of the sun. In order to utilize this information, however, one is faced with a seemingly monumental task. The sun’s chromosphere and corona are extremely complex, and the underlying physical phenomena are far from being understood. Velocity fields, magnetic fields, Inhomogeneous structure, hydromagnetic phenomena – these are some of the complications that must be faced. Other uncertainties involve the atomic physics upon which all of the deductions depend.

Hydrogen line profiles at low densities

1984 ◽  
Vol 9 (4) ◽  
pp. 697-704 ◽  
Author(s):  
C. Stehlé ◽  
N. Feautrier
Keyword(s):  
Line Profiles ◽  
Hydrogen Line
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