Effect of uncertainties of coefficients in steady-state equations for Ca II on temperature and electron density determination: A model problem

It is difficult to numerically solve steady-state equations for calcium, which are used to determine temperature and electron density in a sunspot umbra chromosphere. As a result, the coefficients of equations, obtained using inversion of the measured profiles of five Ca II lines, are to a certain degree uncertain. Never-theless, these insignificant uncertainties do not make it possible to consider that a unique solution of the set of equations, found using classical methods, is sufficiently reliable. Reasonable restrictions on desired variables are presented, which makes it possible to sufficiently accurately restore temperature variations in the specified (test) model of a sunspot umbra. Temperature variations in the studied region of the chromosphere are restored to an average relative error of ±14%.