A brief survey of chromospheric and photometric variability among sunlike stars

Abstract

It is widely believed that the cyclic variation of about 0.1% in the Sun's total irradiance arises from the presence of sunspots and faculae on its surface. While it has been known for decades that other sunlike stars can harbor activity cycles reminiscent of the 11-yr solar cycle, it is only recently that precision photometry suitable for comparing solar brightness variability with its stellar analogs has become available. This comparison indicates that the Sun's behavior is fairly typical for a star of its age and mass. In contrast, young stars tend to be significantly more variable than the present-day Sun, and the relationship between chromospheric and photometric variability for such stars is also different than for the Sun. Using the sunlike star HD10476, I illustrate that inclination effects may become significant when using solar models to interpret stellar observations.