Spectroheliography in CN light

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fulvio.mete
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Spectroheliography in CN light

Post by fulvio.mete »

For the first time in the amateur field (I think) a spectroheliogram of the solar disk in light of the molecular lines of Cyanogen (Cn) at 3882 and 3883Å. taken on april, 23, 7.34 UT with my Hires modified littrow spectrograph POSS2 and DMK 51 camera. Also the professional references about these lines and the significance of their presence in the chromosphere are small, so, if anyone in the forum has some references please let me know.

Fulvio Mete
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Sun Cn  3883 22_04_23 final web 2.jpg
Sun Cn 3883 22_04_23 final web 2.jpg (1.33 MiB) Viewed 997 times
Sun Cn  3883 22_04_23 final web.jpg
Sun Cn 3883 22_04_23 final web.jpg (338.65 KiB) Viewed 997 times


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Re: Spectroheliography in CN light

Post by marktownley »

I like it!


Image
http://brierleyhillsolar.blogspot.co.uk/
Solar images, a collection of all the most up to date live solar data on the web, imaging & processing tutorials - please take a look!
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Re: Spectroheliography in CN light

Post by highfnum »

nice


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Re: Spectroheliography in CN light

Post by p_zetner »

Very nice.
For the first time in the amateur field (I think) a spectroheliogram of the solar disk in light of the molecular lines of Cyanogen (Cn) at 3882 and 3883Å.
This is a bit of a bold claim and not quite accurate!

My latest CN image (2021) is posted in this thread:
viewtopic.php?f=8&t=35248

I was also lucky enough to catch a jet transit while imaging in the CN band with my spectroheliograph.
viewtopic.php?f=8&t=32326
(I'll also make a bold claim! I believe this may actually be the first capture of such a transit with a spectroheliograph.)

I think my earliest CN image was taken in 2015 but I may have an earlier version.
It is re-posted below and also appears in the book "Solar Astronomy" edited by Christian Vladrich.

Cheers.
Peter
Zetner_CH15 Fig01.png
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Re: Spectroheliography in CN light

Post by highfnum »

Most metal lines have a similar look
Except sodium
Anyone know why?


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Re: Spectroheliography in CN light

Post by p_zetner »

The subject of CN imaging has also been discussed in these two forum threads:

2022: https://solarchatforum.com/viewtopic.php?f=8&t=34502

2013: https://solarchatforum.com/viewtopic.php?f=8&t=9608

I believe the 2013 thread may have been my first reported CN image.
The actual images are absent from the thread because of a problem with the forum.
You might find the discussion worthwhile in both threads.


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Re: Spectroheliography in CN light

Post by fulvio.mete »

Thanks you for comments :my apologies to p_zetner, of whom I did not know the images in Cn. However, I would like to point out my assertion was doubtful.As I said before, I have been missing from the forum for many years so I was not up to date on the topics discussed.
In every case, I'm thanking p_zetner for useful informations about CN spectroheliograms in the threads indicates by him.


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Re: Spectroheliography in CN light

Post by Montana »

Great info from everyone :hamster: I love to see all these new and interesting bands. The CN looks very similar to Calcium band :bow :hamster:

Alexandra


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Re: Spectroheliography in CN light

Post by p_zetner »

No apologies necessary, Fulvio.
There is a lot of history on this forum which is why it is so useful.
Cheers.
Peter


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Re: Spectroheliography in CN light

Post by fulvio.mete »

Thanks, Alexandra for your reply: yes, ,the line has a sensitivity to magnetic fields similar to Ca II, the points to investigate, in my opinion are:
-The molecular population of CN belongs only to sun cromosphere?
- If so,at what height and temperature?
Sincerely, I'm not a professional physicist , and I'd be interested to explore these two points.


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Re: Spectroheliography in CN light

Post by fulvio.mete »

Thanks, Peter, for your reply: I've just downloaded the design of your spectrograph that seems very interesting.


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Re: Spectroheliography in CN light

Post by p_zetner »

Hi Fulvio.

Concerning your questions
The molecular population of CN belongs only to sun cromosphere?
- If so,at what height and temperature?
Molecules are formed mainly in the outer layers of the photosphere (low chromosphere). Their formation is generally highly temperature sensitive so they “live” in the cooler regions including the upper photosphere and sunspot umbrae.

With regard to the increased contrast in faculae and network (magnetic) bright points, here is a quote from “The role of the Fraunhofer lines in solar brightness variability” A. I. Shapiro et.al. A&A 581, A116 (2015):

“The amplification of facular contrast by molecular lines is due to the strong sensitivity of molecular concentrations to temperature changes. Molecular concentrations are lower in faculae which are generally warmer than the quiet Sun surroundings. Consequently, the molecular lines in the facular spectrum are weaker than in the spectrum of the quiet Sun, which leads to the enhancement of the contrast…….The CN violet system and CH G-band induce a comparable amplification of the facular brightness contrast even though the CH G-band is more pronounced in the solar spectrum. This is partly caused by the relatively high dissociation energy of the CN molecule (7.72 eV), which is larger than that of CH (4.25 eV). As a consequence the CN concentration is more sensitive to temperature changes than the CH concentration (see e.g. the discussion of the chemical equilibrium calculations in Berdyugina et al. 2003).”

With regard to imaging possibilities in molecular bands, here is a quote from “The molecular Zeeman effect and diagnostics of solar and stellar magnetic fields II. Synthetic Stokes profiles in the Zeeman regime”. S. V. Berdyugina et.al. A&A 412, 513–527 (2003):

“Imaging in molecular bands can help in studying the spatial fine structure of the photosphere and sunspots. In the photosphere, the best contrast of temperature inhomogeneities with respect to the average brightness of the photosphere is expected to be observed in the CN violet band head at 388.3nm. The CH and OH bands at 430.0nm and 313.0nm, respectively, produce similar results. In a penumbra, the best contrast is achieved in the CN and OH bands. For imaging umbral inhomogeneities, the TiO band head at 7055 Å is found to be very promising.”

Regards.
Peter


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Re: Spectroheliography in CN light

Post by fulvio.mete »

Thanks for your reply and infos, Peter: this field of spectroheliography seems promising and interesting.
Regards
Fulvio Mete


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