Astrophysics (index)about

chromospheric activity index

(S-index)
(measure of magnetic activity of a star's chromosphere)

The chromospheric activity index (or S-index) is a measure of the chromospheric magnetic field activity of a star. It is derivable from the star's spectroscopy, and is of interest regarding the Sun, e.g., for comparison with other stars. A star's S-index changes over time, i.e., it is not a constant value.


(Sun,stars,magnetism,measure)
http://adsbit.harvard.edu//full/1995ApJ...438..269B/0000271.000.html
https://arxiv.org/abs/1803.11123

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