ON POSSIBLE VARIATIONS OF BASAL Ca II K CHROMOSPHERIC LINE PROFILES WITH THE SOLAR CYCLE

2013 ◽  
Vol 767 (1) ◽  
pp. 56 ◽  
Author(s):  
Alexei A. Pevtsov ◽  
Luca Bertello ◽  
Han Uitenbroek
Keyword(s):  
Solar Cycle ◽  
Line Profiles ◽  
Chromospheric Line

Variations in Ca-K line profiles and Ca-K line features as a function of latitude and solar cycle during the 20th century

2018 ◽  
Vol 13 (S340) ◽  
pp. 23-26 ◽  
Author(s):  
Jagdev Singh ◽  
M. Priyal ◽  
G. Sindhuja ◽  
B. Ravindra
Keyword(s):  
Solar Cycle ◽  
20Th Century ◽  
Intensity Distribution ◽  
Polar Regions ◽  
Line Profiles ◽  
Threshold Values ◽  
Latitude Belt ◽  
Negligible Amount ◽  
Complex Variation ◽  
Visible Disk

AbstractThe analysis of the Ca-K line spectra as a function of latitude and integrated over the visible disk obtained during the period of 1989–2011 at the Kodaikanal Solar Tower Telescope shows that the FWHM of the K1 distribution at different latitudes varies by negligible amount at about 60° latitude whereas it varies significantly at other latitudes. Findings, especially the fewer variations in mid-latitude belts as compared to polar regions and complex variation in the shift in the activity around 60° latitude belt, will have important implications on the modeling of solar dynamos. Further, we have generated a uniform set of digitized Ca-K line images by selecting images considering the intensity distribution of the images corrected for the instrumental vignetting for the data obtained at Kodaikanal during the 20th century. Then, we have determined the percentage of plage and network areas by using the intensity and area threshold values.

scholarly journals Optical instrumentation for chromospheric monitoring during solar cycle 25 at Paris and Côte d’Azur observatories

2020 ◽  
Vol 10 ◽  
pp. 31
Author(s):  
Jean-Marie Malherbe ◽  
Thierry Corbard ◽  
Kevin Dalmasse
Keyword(s):  
Solar Activity ◽  
Solar Cycle ◽  
Space Weather ◽  
Coronal Mass Ejections ◽  
Calibration Method ◽  
Line Profiles ◽  
Short Term ◽  
Optical Instruments ◽  
Dynamic Events

We present the observing program proposed by Paris and Côte d’Azur Observatories for monitoring solar activity during the upcoming cycle 25 and providing near real time images and movies of the chromosphere for space-weather research and applications. Two optical instruments are fully dedicated to this task and we summarize their capabilities. Short-term and fast-cadence observations of the chromosphere will be performed automatically at Calern observatory (Côte d’Azur), where dynamic events, as flare development, Moreton waves, filament instabilities and Coronal Mass Ejections onset, will be tracked. This new set of telescopes will operate in 2021 with narrow bandpass filters selecting Hα and CaII K lines. We present the instrumental design and a simulation of future images. At Meudon, the Spectroheliograph is well adapted to the long-term and low-cadence survey of chromospheric activity by recently improved and optimized spectroscopic means. Surface scans deliver daily (x, y, λ) datacubes of Hα, CaII K and CaII H line profiles. We describe the nature of available data and emphasize the new calibration method of spectra.

scholarly journals Modelling chromospheric line profiles in NGC 2808: evidence of mass loss from RGB stars

2006 ◽  
Vol 454 (2) ◽  
pp. 609-615 ◽  
Author(s):  
P. J. D. Mauas ◽  
C. Cacciari ◽  
L. Pasquini
Keyword(s):  
Mass Loss ◽  
Line Profiles ◽  
Chromospheric Line

scholarly journals Calcium K Line Profiles as a Function of Latitude and Solar Cycle Phase

1990 ◽  
Vol 142 ◽  
pp. 261-261
Author(s):  
Jagdev Singh
Keyword(s):  
Solar Cycle ◽  
Line Profile ◽  
Solar Minimum ◽  
Active Network ◽  
Cycle Phase ◽  
Line Profiles ◽  
Maximum Phase ◽  
Excess Emission ◽  
Limb Darkening ◽  
Network Component

The sun as a star has been studied by many observers by monitoring the calcium K line profile. Skumanich et al (1984) proposed a three component model of the solar cycle variability of calcium K emission using extant contrast and fractional area parameters for (1) cell (2) network and (3) plage components. The computed line profile agreed well with the observed one at the solar minimum by taking the contribution of only cell and network features and using extant limb-darkening laws. The occurrence of plages during the growth of the solar cycle was found to be insufficient to account for the increase in K emission and therefore, they introduced an additional network component, ‘Active network’ in excess of the quiet sun value to explain the observed excess emission during the maximum phase.

scholarly journals Modelling chromospheric line profiles as diagnostics of velocity fields inω Centauri red giant stars

2010 ◽  
Vol 526 ◽  
pp. A4 ◽  
Author(s):  
M. Vieytes ◽  
P. Mauas ◽  
C. Cacciari ◽  
L. Origlia ◽  
E. Pancino
Keyword(s):  
Velocity Fields ◽  
Line Profiles ◽  
Giant Stars ◽  
Red Giant Stars ◽  
Red Giant ◽  
Chromospheric Line

scholarly journals Calcium K-Line Profiles as a Function of Latitude and Solar Cycle Phase

1993 ◽  
Vol 141 ◽  
pp. 408-409
Author(s):  
Jagdev Singh
Keyword(s):  
Solar Cycle ◽  
High Resolution ◽  
Data Base ◽  
Differential Rotation ◽  
Large Data ◽  
Ionized Calcium ◽  
Cycle Phase ◽  
Line Profiles ◽  
Solar Image ◽  
Large Data Base

AstractHigh resolution spectra are being taken in ionized calcium K-line at different latitudes and integrated over the visible 180 degree longitude. These have been analysed to study the variability of the line parameters as a function of latitude. These spectra are being obtained on a regular basis and large data base will be used to study chromospheric rotation, differential rotation in chromosphere, activity and variability of K-line parameters as function of latitude and solar cycle phase. Further, an optical arrangement has been worked out to obtain the spectra along the latitudes of the solar image in the light integrated over longitudes. This involves the unidirectionally focusing of the image in N-S direction.

Calculated Coronal Magnetic Fields and Their Comparison with the Coronal Structures as Observed during Five Solar Eclipses

1994 ◽  
Vol 144 ◽  
pp. 559-564
Author(s):  
P. Ambrož ◽  
J. Sýkora
Keyword(s):  
Magnetic Field ◽  
Solar Cycle ◽  
Magnetic Fields ◽  
Solar Corona ◽  
Coronal Magnetic Field ◽  
Coronal Magnetic Fields ◽  
Solar Eclipses ◽  
Coronal Structures

AbstractWe were successful in observing the solar corona during five solar eclipses (1973-1991). For the eclipse days the coronal magnetic field was calculated by extrapolation from the photosphere. Comparison of the observed and calculated coronal structures is carried out and some peculiarities of this comparison, related to the different phases of the solar cycle, are presented.

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