stars, although the difference of spectral class for the maximum of the two lines (
,
) and the presence of a solar iron line at 4215, suggest a blend for the latter in stars cooler than about
. It is also to be remarked that the head of a “cyanogen” band falls at 4216.
(2) Abnormal Conditions.—Abnormal conditions permit of no direct observational test, but it would be anticipated that they would also affect other lines to a degree greater than is observed. The change of temperature that would be required to raise the Sr+ lines to their maximum strength at
