Challenge: Measuring the spin rates for old stars.
05/23/2011
A star's spin period is determined from measurements of periodic
fluctuations in its brightsness due to dark spots on its surface. Young
stars spin fast and have many and large spots and show large fluctuations
of short duration (left). As stars spin slower with age they have fever
and smaller spots and smaller fluctuations of longer duration (middle and
right).
