Mg (b2) absorption line

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Merlin66
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Mg (b2) absorption line

Post by Merlin66 »

It was mentioned that the latest Quark is designed to observe the Mg I (b2) absorption line in the solar spectrum.
http://daystarfilters.com/Quark/MgIQuark.shtml
This line is the middle of the Mg I Triplet at 5172.8A, the b1, b2, b3 etc. comes from Fraunhofer's recording of the more prominent lines in the early 1800.
https://www.wikiwand.com/en/Fraunhofer_lines

Mg I (b2) is in the green region of the solar spectrum.
http://fermi.jhuapl.edu/liege/s02_0002.html
Mg I triplet and Na doublet
Mg I triplet and Na doublet
Mg(b2)_wide.JPG (66.53 KiB) Viewed 626 times
Detail of Mg I (b2)
Detail of Mg I (b2)
Mg (b2).JPG (111.62 KiB) Viewed 626 times
The b2 line has extended wings with a deep core and the main line is <1.5A.
Should be an easy target in an SHG.


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Re: Mg (b2) absorption line

Post by marktownley »

Will be interesting to see the disks you get in Mg Ken. I purchased (and sent back) an Mg Quark a few years ago.


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Re: Mg (b2) absorption line

Post by Montana »

Thanks for the info Ken, I look forward to the images :hamster:

A quick question, how do you know which line you are imaging in?

Alexandra


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Re: Mg (b2) absorption line

Post by Merlin66 »

Alexandra,
The whole of the solar spectrum can accessed by rotating the diffraction grating. The higher the rotation angle the further into the Red and NIR, so you can have a marked “dial” showing the approximate wavelength after calibration.
This is the setup with the Sol’Ex. (https://i.ibb.co/YD8BFjn/IMG-5212.jpg)
Calibration means working your way through the solar spectrum and comparing the view (usually around 100-200A wide) to a reference solar spectrum. I use the BASS spectrum (https://bass2000.obspm.fr/solar_spect.php). Once you recognise the main Fraunhofer lines it’s pretty easy to home in on any nominated line/wavelength.


"Astronomical Spectroscopy - The Final Frontier" - to boldly go where few amateurs have gone before
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"Astronomical Spectroscopy for Amateurs" and
"Imaging Sunlight - using a digital spectroheliograph" - Springer
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