Chromosphere activity: relations with Solar cycles (SC)
Serge Koutchmy1 , Ehsan Tavabi2 and Rayhane Sadeghi2
1Institut d’Astrophysique de Paris, Sorbonne Universit´es, UMR 7095, CNRS and UPMC, 75014 Paris, France,
2Physics Department, Payame Noor University, 19395-3697, Tehran, Iran.
Abstract
The forthcoming solar cycle (SC)#25 was believed to be rather low when using the sunspot number (SN) as a measurement of the level of activity. The most popular prediction was made by the panel of NASA in 2019, including works based on extrapolations of dynamo-type models. We however discovered that using different observations to measure the level of polar regions activity several years before the start of SC#25 and also after the start of the SC#25 in 2020, the height of the SC#25 could be high. The polar regions activity we considered seems related to the polar coronal holes (CH) activity and it is found significantly higher before the SC#25 that it was before the SC#24 and accordingly, we suggest that the SN cycle could indeed be much higher than during the SC#24 that was a low SN height cycle.
Keywords: solar cycle, cycle 25, polar regions activity, polar faculae, X- rays bright points, macro-spicules, polar mini ejections, chromospheric prolateness
Method
The images were obtained from 2010 to 2022, for 13 years data from the area above the coronal holes in the north pole of the Sun, from the release of 304 A due to the Helium 2 resonance line formed at about 50,000 K, taken by the SDO (approx. 2340 data). The cadence between frames is 12 seconds (images every minute), in FITS protocol. After obtaining and summing the images on the disk, we attended them using MATLAB, then we compressed the areas above the coronal holes in the South and North Poles regions to the extent of one column (see Figure). The graphs related to these data were plotted (15 data on the 15th day of every month)and measured the width at half the height of the maximum exactly at the first maximum. We recorded them as the width of the chromosphere at this point of the poles of the Sun. This thickness actually shows the width of the area above the coronal cavity where the magnetic field lines and as a result plasma and coronal mass escape into the space, and by measuring and studying it, we can find out the extent of the sun's magnetic activity in that area.
TR Thickness in Solar Maximum and minimums
Partial frames in R-Theta coordinate, extracted image of a typical three polar regions at time of minimum and maximum activity (2010 minimum, 2014 maximum and 2017 minimum) to demonstrate the ”abnormal” thickness of the 304 emissions (due to the HeII resonance line formed around 80 000K). Such extensions were measured during more than a full solar cycle (24th) in both the South and the North regions. Extensions are believed to be due to many ejection events in nearly radial directions called macro-spicules, in contrast to spicules seen everywhere, including regions outside the coronal hole regions. AIA filtergrams of the NSO NASA mission were used after summing original frames for 10 min include 50 successive frames.
Comparison of SN with the TR thickness
The results of measuring the FWHM of the 304 A shell for the last SC#24. Again in both hemisphere we recorded a more important activity reflected by the FWHM thickness of the 304 A shell before the SC25 compared to the level recorded before the SC#24. Apparent ”thicknesses” Variations of the transition region polar regions shells as measured using the 304 emissions (He II) from AIA/SDO. Both the North (N) in red and the South (S) in black poles are showing an extended shell of macro-spicules activity at years of the solar minima but during the last period around 2019, an enhanced activity is recorded suggesting that the next SC#25 will be high. In black line the “sn” during the same period of time.
Dynamical aspect of polar jets
After 2013, the IRIS spects. give us the ability to measure the some dynamical features properties of solar jets, Using Doppler map we found a several rotational macro-spicules in polar region, by looking to the spects. of Si IV (1394 A) and Mg II h & k (2800 A) the tilted angle of Doppler shift is detected, according the results of Machin learning method, the polar jets rotational motion (as their apparent motion and as their population) are significantly higher in solar minimum activity.
References
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Kitiashvili I.N., 2020. Solar and Stellar Magnetic Fields: Origins and Manifestations Proceedings IAU Symposium No. 354, A.G. Kosovichev, K. Strassmeier, and M. Jardine, eds.,pp. 147-156.
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Summery and conclusions
Extensions in polar regions we studied are believed to be due to ejection events at TR temperatures in nearly radial directions. They were called macrospicules in the time of the SkyLab observations made in CIV line emissions, in contrast to spicules seen lower everywhere around the disk at lower temperatures, including regions outside the coronal hole regions. High quality AIA 304 A filtergrams of the Hell resonance line from the SDO NASA mission are now available and they were used after summing original frames for 10 min in order to improve the signal/noise ratio. We also worked in polar coordinates in order to more easily and more precisely measure the effective thickness (FWHM) of the polar regions of 304 A emissions, including the so-called "abnormal" thickness of the fringe above CHs, for an illustration of the different steps used to deduce these FWHM. In above figure we show the results of measuring the FWHM of the 304 A shell for the last SC24. Again in both hemisphere we recorded a more important activity reflected by the FWHM thickness of the 304 A shell before the SC25 compared to the level recorded before the SC24.
Acknowledgements. In memory of my dear Serge, who was alive when the abstract was submitted. We acknowledge the HMI and AIA/SDO mission of NASA consortium for the easy access of calibrated data.