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

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.

Ca II Emission from Late-type Stars

1983 ◽  
Vol 5 (2) ◽  
pp. 152-157 ◽  
Author(s):  
L. E. Cram
Keyword(s):  
Line Profile ◽  
Strong Correlation ◽  
Velocity Fields ◽  
Line Profiles ◽  
Late Type ◽  
Wide Range ◽  
Cool Stars ◽  
Visual Magnitude ◽  
The Absolute ◽  
Emission Core

Two recent observational surveys of the Ca II resonance lines (Zarro and Rodgers 1983; Linsky et al. 1979) illustrate the great diversity of line profile shapes found in the spectra of cool stars. This diversity reflects a corresponding wide range in the underlying chromospheric properties of the stars. There are, however, three well-marked systematic trends in the shapes of Ca II line profiles which presumably reflect systematic trends in chromospheric properties. One of these, the Wilson-Bappu effect (Wilson and Bappu 1957), describes the strong correlation betweeen the width of the emission core (see Figure 1) and the absolute visual magnitude of the star. Despite much work, it is still not clear whether this is due primarily to systematic changes of velocity fields (e.g. Hoyle and Wilson 1958) or optical depths (e.g. Jefferies and Thomas 1959) in stellar chromospheres.

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 Reappraising Transition Region Line Widths in Light of Recent Alfvén Wave Discoveries

2008 ◽  
Vol 673 (2) ◽  
pp. L219-L223 ◽  
Author(s):  
Scott W. McIntosh ◽  
Bart De Pontieu ◽  
Theodore D. Tarbell
Keyword(s):  
Transition Region ◽  
Alfven Wave ◽  
Line Widths ◽  
Region Line

scholarly journals Spectroscopic Analysis of HR 1099

1991 ◽  
Vol 130 ◽  
pp. 449-451
Author(s):  
I.S. Savanov ◽  
I. Tuominen
Keyword(s):  
Spectroscopic Analysis ◽  
Theoretical Calculations ◽  
Wavelength Region ◽  
Surface Imaging ◽  
Line Profiles ◽  
Late Type ◽  
Synthetic Spectra ◽  
Solar Abundances

AbstractWe have calculated synthetic spectra for HR 1099 for the wavelength region λ6425-6445 Å, which includes the Cal λ6439 Å and FeI λ6430 Å lines, often used for the surface imaging of rapidly rotating late-type stars. The best agreement between the theoretical and observed spectra can be achieved with solar abundances in the both components of the system, except for Ca in the primary. Theoretical calculations give the possibility of estimating the influence of microturbulence, damping and blending on Ca I and Fe I line profiles.

Transition region line-shifts in the rebound shock spicule model

1994 ◽  
Vol 70 (1-2) ◽  
pp. 103-106 ◽  
Author(s):  
V. H. Hansteen ◽  
�. Wikst�l
Keyword(s):  
Transition Region ◽  
Region Line

A model for maser line profiles of late-type stars

1987 ◽  
Vol 122 ◽  
pp. 249-251
Author(s):  
J.R.D. Lépine
Keyword(s):  
Simple Model ◽  
Spherically Symmetric ◽  
Type Ii ◽  
Line Profiles ◽  
Late Type ◽  
Maser Line ◽  
Expanding Shells

The profiles of maser lines from spherically symmetric expanding shells are computed with the help of a simple model. It is shown that a beaming effect must be taken into account in order to correctly account for the OH profiles of type II OH stars.

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.

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