Hercules A

Hercules A
Radio-Optical View of the Galaxy Hercules A - Many thanks to: NASA, ESA, S. Baum and C. O'Dea (RIT), R. Perley and W. Cotton (NRAO/AUI/NSF), and the Hubble Heritage Team (STScI/AURA)

Thursday, October 8, 2015

About the evolution of the Sun active regions

As the days go by, I frequently show details of active region magnetograms images and charts, and other data, for active regions I think may be suspect of initiating the radio events we study.

I started studying solar radio emission in 1966, I am not finished yet :)

The degree of activity frequently varies much from day to day and is a complex subject studied for many decades.

Lidia van Driel-Gesztelyi and Lucie May Green have published last month a "Living Review of Solar Physics" titled:

"Evolution of Active Regions" , 98 pages, including 17 pages of references, free to download at:



Section 6 studies the case of AR 7978, "...subjected to the most comprehensive analysis of any AR..." as it evolved over a 6 month period.

Appendix A is a very good summary of Sunspot classifications, including the McIntosh and Hale methods.

I leave you repeating their quote from a poem by Laszlo Detre :

“  A Solar Physicist’s Lament  ....

It looks as if many a sunny day
Will pass along on its way
Before we solve it all...  "