News Release 

A census of star brightness: The sun is less active and variable than similar stars

American Association for the Advancement of Science

By analyzing the brightness variations of 369 solar-like stars, researchers have concluded that the Sun is less magnetically active and shows less variability in its brightness than similar stars in the Galaxy. "Why does the Sun seem to differ so much from other stars that appear to be the most similar to it?" asks a related Perspective from Angela Santos and Savita Mathur. Like other main-sequence stars, the Sun possesses a powerful magnetic field that generates dark sunspots, bright solar flares, and other visible features. These magnetic imprints vary over time and temporarily affect the variability of the star's light output, causing the Sun to go through an 11-year cycle of higher and lower activity. Understanding the Sun's magnetic field is critical for predicting the star's future, but scientists debate whether the Sun's activity will diminish or may still become more magnetically active. Timo Reinhold and colleagues compared the Sun's brightness variations to observations of 369 stars with similar masses, temperatures, compositions and rotational properties, which they selected from four years of observations from the Kepler space telescope and combined with data from the Gaia spacecraft. By quantifying the brightness variations of the stars, the authors found that most were more active than the Sun, often being five times more variable than the Sun was over the last 140 years. Reinhold et al. discuss several potential explanations for their observations, including possibilities that the Sun can have higher variability over long timescales, or differs from similar stars in ways that haven't yet been recognized. Santos and Mathur also discuss how stellar variability has implications for the operation of satellites in orbit around E


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