#1  
Old 11-07-2020, 10:06 AM
Merlin66's Avatar
Merlin66 (Ken)
Spectroscopy Wizard

Merlin66 is offline
 
Join Date: Oct 2005
Location: St Leonards, Vic
Posts: 7,849
Quiz question for solar observers

This is addressed to all solar observers.
Have you ever heard of "veiled sunspots"???
(I'm translating a French solar observing book at the moment and came across this reference)
I did find the (very interesting) answer...what do you think???
(The answer, if not found, will be given later)
Reply With Quote
  #2  
Old 11-07-2020, 11:25 AM
PeterM
Like Solar

PeterM is offline
 
Join Date: Jun 2006
Posts: 1,761
Hmmm nope.
To do with detailed sketches from French (religious?) astronomers in 1870s & 1880s. Maybe with some artistic licence thrown in? Representation of hell?
I haven't got a clue but looking forward to reading more.
Reply With Quote
  #3  
Old 11-07-2020, 02:29 PM
Merlin66's Avatar
Merlin66 (Ken)
Spectroscopy Wizard

Merlin66 is offline
 
Join Date: Oct 2005
Location: St Leonards, Vic
Posts: 7,849
Peter,
Getting close.....
But what does a "veiled sunspot" mean?

Any other suggestions???
Reply With Quote
  #4  
Old 11-07-2020, 03:40 PM
Saturnine (Jeff)
Registered User

Saturnine is offline
 
Join Date: Jul 2008
Location: Wollongong
Posts: 1,375
I think that I've heard the term before but can't remember the explanation and not going to try guessing. Will wait for the answer,I could look it up but !!!
Reply With Quote
  #5  
Old 11-07-2020, 04:11 PM
AstroJunk's Avatar
AstroJunk (Jonathan)
Shadow Chaser

AstroJunk is offline
 
Join Date: Jan 2006
Location: Brisbane
Posts: 1,753
I had to look it up
Reply With Quote
  #6  
Old 12-07-2020, 10:30 AM
Merlin66's Avatar
Merlin66 (Ken)
Spectroscopy Wizard

Merlin66 is offline
 
Join Date: Oct 2005
Location: St Leonards, Vic
Posts: 7,849
Back in 1875 Father Secchi published his "Le Soleil". This was an up-to-date review of solar observing and solar knowledge.
He mentions, in Volume 1 his visual observations of sunspots.
He was convinced that he had seen the umbra of some sunspots covered by a faint pink veil of light. He includes many etchings of this phenomenon.


Notwithstanding his observations, this "pink veil" has not been recorded in modern times.
https://collection.crystalbridges.or...d-veiled-spots


A challenge to modern observers????
Reply With Quote
  #7  
Old 12-07-2020, 04:38 PM
astroron's Avatar
astroron (Ron)
Supernova Searcher

astroron is offline
 
Join Date: Mar 2005
Location: Cambroon Queensland Australia
Posts: 9,027
Quote:
Originally Posted by Merlin66 View Post
Back in 1875 Father Secchi published his "Le Soleil". This was an up-to-date review of solar observing and solar knowledge.
He mentions, in Volume 1 his visual observations of sunspots.
He was convinced that he had seen the umbra of some sunspots covered by a faint pink veil of light. He includes many etchings of this phenomenon.


Notwithstanding his observations, this "pink veil" has not been recorded in modern times.
https://collection.crystalbridges.or...d-veiled-spots


A challenge to modern observers????
Link not available.
Error 521 Ray ID: 5b1918fcffb516e1 • 2020-07-12 07:37:12 UTC
Web server is down.
Cheers
Reply With Quote
  #8  
Old 12-07-2020, 04:46 PM
Merlin66's Avatar
Merlin66 (Ken)
Spectroscopy Wizard

Merlin66 is offline
 
Join Date: Oct 2005
Location: St Leonards, Vic
Posts: 7,849
https://digitalcollections.nypl.org/...0-e00a18064a99
This should work.
I actually have a copy of Father Secchi’s book....I can scan the illustrations if needed.
Reply With Quote
  #9  
Old 12-07-2020, 05:16 PM
astroron's Avatar
astroron (Ron)
Supernova Searcher

astroron is offline
 
Join Date: Mar 2005
Location: Cambroon Queensland Australia
Posts: 9,027
Quote:
Originally Posted by Merlin66 View Post
https://digitalcollections.nypl.org/...0-e00a18064a99
This should work.
I actually have a copy of Father Secchi’s book....I can scan the illustrations if needed.
Thanks Ken
The pic came up just fine this time.
Very strange phenomenon indeed.
Cheers
Reply With Quote
  #10  
Old 12-07-2020, 06:02 PM
Merlin66's Avatar
Merlin66 (Ken)
Spectroscopy Wizard

Merlin66 is offline
 
Join Date: Oct 2005
Location: St Leonards, Vic
Posts: 7,849
Yeah, I can well understand why current solar observers may never have heard of “veiled sunspots”........
Reply With Quote
  #11  
Old 14-07-2020, 12:17 PM
N1 (Mirko)
Registered User

N1 is offline
 
Join Date: Oct 2013
Location: Dunners Nu Zulland
Posts: 1,275
Perhaps an artefact produced by the singlets/achromatic lenses they would have been using? It seems plausible that for the effect to become detectable, the umbra's image would have to be of a certain size, which would explain why only the bigger spot in the sketch has this feature.
Reply With Quote
  #12  
Old 14-07-2020, 03:43 PM
Merlin66's Avatar
Merlin66 (Ken)
Spectroscopy Wizard

Merlin66 is offline
 
Join Date: Oct 2005
Location: St Leonards, Vic
Posts: 7,849
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.
Reply With Quote
  #13  
Old 15-07-2020, 09:27 AM
N1 (Mirko)
Registered User

N1 is offline
 
Join Date: Oct 2013
Location: Dunners Nu Zulland
Posts: 1,275
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.
Reply With Quote
  #14  
Old 15-07-2020, 10:20 AM
Merlin66's Avatar
Merlin66 (Ken)
Spectroscopy Wizard

Merlin66 is offline
 
Join Date: Oct 2005
Location: St Leonards, Vic
Posts: 7,849
Mirko,
There's plenty of activity which can be observed in and around the sunspot umbra.
Light bridges, umbral spots are more obvious with G band (or Baader K-line) filters. You can also use a night-time Ha filter. Plenty of recorded data, but no record of "pink veils".
Secchi was convinced the pink glow was real.
Reply With Quote
  #15  
Old 15-07-2020, 11:59 AM
N1 (Mirko)
Registered User

N1 is offline
 
Join Date: Oct 2013
Location: Dunners Nu Zulland
Posts: 1,275
He also says the glow was similar to that of the prominences during a total eclipse, so it may very well result from emission at H alpha wavelengths.
Reply With Quote
Reply

Bookmarks

Thread Tools
Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT +10. The time is now 10:24 AM.

Powered by vBulletin Version 3.8.7 | Copyright ©2000 - 2020, Jelsoft Enterprises Ltd.
Advertisement
NexDome Observatories
Advertisement
Testar
Advertisement
Limpet Controller
Advertisement
Bintel
Advertisement
Astronomy and Electronics Centre
Advertisement