On the disappearance of a small sunspot group

Solar Physics ◽  
1982 ◽  
Vol 81 (1) ◽  
pp. 33-46 ◽  
Author(s):  
Steven G. Wallenhorst ◽  
Kenneth P. Topka
Keyword(s):  
Sunspot Group ◽  
Small Sunspot

On the Dynamics of the Largest Active Region of the Solar Cycle 24

2017 ◽  
Vol 13 (S335) ◽  
pp. 32-35
Author(s):  
Ranadeep Sarkar ◽  
Nandita Srivastava ◽  
Sajal Kumar Dhara
Keyword(s):  
Magnetic Field ◽  
Solar Cycle ◽  
Active Region ◽  
Comparative Study ◽  
Lorentz Force ◽  
Sunspot Group ◽  
Solar Dynamics Observatory ◽  
Solar Cycle 24 ◽  
Solar Dynamics ◽  
Cycle 24

AbstractWe have studied the dynamics of the solar active region (AR) NOAA 12192 using full-disc continuum images and the vector magnetograms observed by the Helioseismic and Magnetic Imager (HMI) onboard Solar Dynamics Observatory (SDO). AR 12192 is the largest region of the solar cycle 24. It underwent a noticeable growth and produced 6 X-class, 22 M-class and 53 C-class flares during its disc passage. But the most peculiar fact of this AR is that it was associated with only one CME in spite of producing several X-class flares. In this work, we present the area evolution of this giant sunspot group during the first three rotations when it appeared as AR 12172, AR 12192 and AR 12209, respectively. We have also attempted to make a comparative study of the flare-related photospheric magnetic field and Lorentz force changes for both the eruptive and non-eruptive flares produced by AR 12192.

The Great Sunspot Group of February 1946

1946 ◽  
Vol 58 ◽  
pp. 86 ◽  
Author(s):  
Seth B. Nicholson ◽  
Joseph O. Hickox
Keyword(s):  
Sunspot Group

An Observation of the Longitudinal Magnetic Field in a Sunspot Group.

1964 ◽  
Vol 139 ◽  
pp. 1336 ◽  
Author(s):  
Richard G. Teske ◽  
Helen W. Dodson ◽  
E. Ruth Hedeman
Keyword(s):  
Magnetic Field ◽  
Sunspot Group ◽  
Longitudinal Magnetic Field

Sudden Disappearance of a Small Sunspot Associated with the 2002 February 20 M2.4 Flare

2002 ◽  
Vol 580 (2) ◽  
pp. L177-L180 ◽  
Author(s):  
Haimin Wang ◽  
Haisheng Ji ◽  
Edward J. Schmahl ◽  
Jiong Qiu ◽  
Chang Liu ◽  
...  
Keyword(s):  
Small Sunspot

scholarly journals The Main Component Analysis of the Longitudinal Distribution of Solar Activity

1991 ◽  
Vol 130 ◽  
pp. 275-276
Author(s):  
Ladislav Hejna ◽  
Hubertus Wöhl
Keyword(s):  
Time Series ◽  
Solar Activity ◽  
Sunspot Group ◽  
Component Analysis ◽  
Longitudinal Distribution ◽  
Sunspot Activity ◽  
Significant Feature ◽  
Solar Cycles ◽  
Main Component Analysis ◽  
Main Component

Abstract In this contribution, preliminary results of the main component analysis of Bartels diagram of time series of daily values of sunspot group numbers for solar cycles 18, 19 and 20 are presented. The results obtained suggest that the most significant feature in the longitudinal distribution of sunspot activity is the existence of preferred solar hemispheres alternating with a mean period of 2.5 Bartels rotations.

scholarly journals Remeasurement of Solar Observing Optical Network sunspot areas

2020 ◽  
Vol 497 (1) ◽  
pp. 1110-1114
Author(s):  
P J Meadows
Keyword(s):  
United States ◽  
Solar Cycle ◽  
Air Force ◽  
United States Air Force ◽  
Sunspot Group ◽  
Optical Network ◽  
The United States ◽  
Solar Cycle 24 ◽  
Cycle 24

ABSTRACT The United States Air Force solar observing optical network (SOON) sunspot areas have been reported by several researchers over many years to be underestimated by as much as 50 per cent. Here, the areas of sunspots from scanned SOON disc drawings have been accurately remeasured for a period of two months from 2014 October and November – this being near the peak of Solar Cycle 24 and which includes the largest sunspot group of that cycle. The remeasured sunspot areas are now comparable with areas in sunspot catalogues.

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