Summary of Zeeman Lines by Three Amateurs     Fredrick Veio, Aug. 16, 2003


Most photospheric lines in the solar spectrum have a dark core about 0.03A wide. Most  Zeeman sensitive lines will thicken to about 0.06A wide with high linear dispersion of about 2A/mm, or less. Just barely seen with the human eye. Not too many but some photospheric lines are very sensitive to the Zeeman effect, having the line thicken from about 0.1A to 0.3A, sometimes showing a split. Very easy to see.


Leonard Higgins and I first made visual observations of the Zeeman effect in the solar spectrum in the summer of 1999 with his spectrohelioscpe in the spectroscope mode. Two different days and two different sun spot groups were studied. The Zeeman sensitive lines in the green were not identified. The lines with dark core of 0.03A were observed to thicken to 0.6A. Then in September of 2002 we looked for and identified some Zeeman lines, also in October of 2002 and in the spring of 2003.


Leonard's  instrument has a telescope concave mirror of 125mm (5 inch) diameter of 2.7 meters f.l. (9 feet), used with a -500mm Barlow to give about 6 meters equivalent f.l. (20 feet), producing a 2.2 inch (55mm) sun image on the entrance slit. The spectroscope is one concave mirror of 200mm diameter (8 inch), Ebert design, has 2.5 meter f.l. (8 feet). Grating is 50x50mm ruled area byDiffraction  Products, 1200 gr/mm. Linear dispersion in the first order is 3.2 A/mm, second order 1.4A/mm in the green and third order 1.0A/mm in the green.


I met Philippe Rousselle, France, on the Internet about two years ago. He has a spectroheliograph with a linear array, pixels 14 microns. His telescope is an achromat of 90/1300, and the Arcetri spectroscope is two achromats of 60/900mm. Grating is 1800 gr/mm, about 50x50mm area. Linear dispersion is about 3.8A/mm.He gets excellent H alpha and violet calcium photos of the solar disk.


In 2002 I gave Phil information on the detection of the solar rotation at the solar limb for the Doppler shift. Brian Manning of England did it first with his shs in 1975. Also Phil received technical details for the solar disk in yellow helium light with plage (not need a flare), and he captured  the molecular bands in a large umbra of a spot. He obtained excellent spectrograms and spectroheliograms. He can not observe in the winter months. But in the spring of 2003 he observed  Zeeman lines in a large umbra of a spot. He was successful.


In the winter of  2002, Leonard and I gladly shared our list of Zeeman photospheric lines with Phil. In the spring of 2003 he confirmed all the lines that we saw. Also I sent Phil xerox of all the pages of the Monograph no. 61 from the National Bureau of Standards, USA, edited by Dr. C. E. Moore, published 1966. The book has about 25,000 solar wavelengths from the violet to the red. About 4000 of these lines are visible to the human eye with a good spectroscope. A few hundred of the spectral lines are sensitive to the Zeeman effect, and many of them are very sensitive. Not all spectral lines are equally sensitive. Here is a list of the  Zeeman lines so far observed.


September of 2002, visual by Veio and Higgins

Ca I  6572.8A, widen to 0.3A, easy to see

Fe I  6574.3A,  widen to 0.2A, easy

Fe I  6575.0A, nearby water line, not sure


October of 2002, visual by Veio and Higgins

5224A or 5225A, not sure which wavelength, easy to see

Ti I    5426.3A, seen in the umbra only

Mn I  5432.6A


April of 2003, spectrogram and visual by Rousselle

Ti I   6554.2A

Ti I   6556.1A

Ca I  6572.8A

Fe I  6574.3A

Fe I  6575.0A, confirmed ok, not easy to see


July of 2003, visual and ccd by Veio and Higgins

Fe I  5225.5A, easy and split

Two other lines nearby at about 5245A, easy to see, not identified


August of 2003, spectrogram, web cam and visual by Rousselle

Fe I  5225.5A

Cr I  5247.6A

Fe I  5250.2A  


Amateur Telescope Making, vol. I, edited by Ingalls, has an H alpha drawing of nearby lines of a sun spot spectrum, and some lines are slightly thickened. Same drawing in The Sun by Young as seen in 1872. Use a 3x loupe to see the lines better.  Le Soleil by  Secchi, about 1875, has a composite drawing of a slightly sensitive and a very sensitive Zeeman line as seen in a sun spot drawing. In the Astrophysical Journal, 1905, Dr. Mitchell authored a list of 680 lines visually seen in sun spot spectra.