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Journal of Physical Studies 22(2), Article 2902 [5 pages] (2018)
DOI: https://doi.org/10.30970/jps.22.2902 ARE CHANGES IN THE PARAMETERS OF FRAUNHOFER LINES ON THE 11-YEAR SOLAR CYCLE TIME SCALE REAL?M. Koval'chuk{1}, M. Hirnyak{1}, M. Stodilka{1}, I. Laushnyk{2}
1The Ivan Franko National University of Lviv, Astronomical Observatory, |
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The study of the reality of the observed changes in the parameters of Fraunhofer lines, depending on the phase of the solar activity cycle, is important for establishing possible patterns in the evolution of the solar and stellar atmospheres. An extensive series of high-precision observations of the fine structure of the Fraunhofer lines of the Sun have been carried out. However, the question about long-period changes of Fraunhofer lines intensity remains open and contradictory. The purpose of this work was to clarify the statistical significance of the variations in Fraunhofer lines parameters depending on the phase of the solar activity cycle.
The most suitable material for solving this problem was the homogeneous high-precision observation of the profiles of Fraunhofer lines obtained at the Main Astronomical Observatory of the Russian Academy of Sciences (Pulkovo) during the 19th-21th cycles of the solar activity. About 70 uncovered lines were selected with different conditions of formation in a wide range of heights of the solar atmosphere -- from the deep photosphere to the lower chromosphere near the temperature minimum. The equivalent widths and central residual intensities were most sensitive to the time changes of absorption lines.
To answer the questions about the statistical significance of the variations in the parameters of the studied lines on the 11-year solar cycle time scale, we applied a method based on $t$-distribution, whose main idea is to compare the zero hypothesis and a competing hypothesis. It is shown that we may confirm with 95\ onfidence that the differences in the values of the Fraunhofer line parameters in the years of minima and maxima of a 11-year Solar cycle are not statistically significant.
PACS number(s): 95.75.Wx