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Old 15-07-2020, 09:27 AM
N1 (Mirko)
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Quote:
Originally Posted by Merlin66 View Post
Father Secchi discusses the possibility of archromatic artifacts (Le Soleil, Volume 1, pages 104-109) and concludes they are real - similar (in his words) to the pink flames seen at the edge of the moon's disk during totality.
There are four or five different illustrations (from 1866) which show the "voiles roses" in different sized sunspots.
I does seem strange that Newcomb's reference work " Popular Astronomy", 1892 nor the Flammarion & Gore "Popular Astronomy" circa 1900 fail to mention this phenomenon.
However, C.A.Young in his definitive "The Sun", 1882, does make mention (p117)
"....there are also fainter veils of a substance less brilliant, but sometimes rose-colored, which seem to float above the umbra."

He doesn't provide any further information or references.
Hi Ken, so we don't know how exactly he concludes they are real e.g. based on positive evidence, or just based on his assessment that it's not CA?

Thinking about this some more - An AR's appearance differs greatly depending on the wavelength(s) it's observed at. So some visible light emanating from above the umbral regions is not entirely implausible. For example, part of a filament stretched across a sunspot's umbra (is that even possible?) may just be detectable if the area below is dark enough.
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