Young and active stars usually have regular, almost sinusoidal, patterns of variability attributed to their rotation. At the same time the majority of older and less active stars, including the Sun, have more complex and non-regular light-curves which do not have a clear rotational modulation signal. Consequently, the rotation periods have been successfully determined only for a small fraction of the Sun-like stars (mainly the active ones) observed by transiting planet-hunting missions, such as CoRoT, Kepler and TESS. This indicates that only a small fraction of analogous solar-like systems have been properly analyzed. We propose GPS, a new method for determining rotation periods of low-activity stars, like the Sun. The method is based on calculating the gradient of the power spectrum (GPS) of stellar brightness variations and identifying the inflection point in such a spectrum. The rotation frequency is then proportional to the frequency of the inflection point. We show that the GPS method returns accurate values of solar rotation independently of the level of solar activity. GPS method has been successfully applied to the retrieval of periods of stars with both regular and non-regular light-curves.
2020 January 22, 13:30
Centro de Astrofísica da Universidade do Porto (Auditorium)
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