Period-finding methods, techniques and applications to variable stars observations

Abstract

The problem of finding periods of variable stars is considered and it's main methods are generally reviewed. Special attention has been devoted to three methods based on Fourier transform. These methods have been coded in Fortran and have been applied to data of three eclipsing binaries (AD Cnc, UZ Pup andβ Per), threeδ Scuti stars (HR 1170, HR 1223 and RY Lep) and one spectroscopic binary (RS Sag). The methods have been tested, compared and evaluated concerning their speed, resolution and sensitivity. It has been found that data exhibiting irregular variations lead to erroneous periods. To save computing time and to avoid any spurious period a practical procedure for period finding is proposed with an effective approach for period refinement. The revised and refined periods for the above stated variables have been discussed with comparison to the ones given in literatures and they can be adopted for future work. Some of these variables have been found to show variations in both their periods and amplitudes.