| Do bright stars have secular brightness variations Although this problem has been studied by some astronomers during the last centuries, no serious answer has been given to it. A hundred years ago, C. Flammarion collected old stars brightness estimates and published them in his book "Les étoiles et les curiosités du cie1". It was obvious to him that a great number of stars had secular variations. Since that time, Pickering (1895) and Zinner (1926) published two other compilations of star catalogues. They did not agree with Flammarion's opinion, but they were not really able to analyze the amount of genuine information the old data contained. No other study has been published since then. New data analysis methods have been created in the last years, such as Correspondence Factorial Analysis, that allow further studies of large data tables. The aim of the work here presented is to appraise whether those methods can help us to solve this secular variations problem. Some of those methods have already been tested on the basis of data published by Flammarion. They tend to prove that the real problem is to get rid of notation differences between observers. Therefore, special data coding methods must be used. It also seems that expected effects, such as Color observers' equations, cannot be visible. To improve the results of the analysis, we are now rebuilding the table of data, extracting them from original sources. After the completion of this work, new factorial analyses will be performed, thanks to new data coding methods. In order to draw astrophysical conclusions, it can be then useful to test some statistical treatment combining factorial and Fourier analyses. Such treatment could allow to get rid of phase information and open the way for periods correlation studies. |
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