Science:
Cool giant stars spin slowly on their surfaces, but what about
their cores? Paul Beck of the Catholic University of Leuven in
Belgium and colleagues have
reported
that the cores of three yellow giant stars, each 20% to 50%
more massive than our Sun, spin at least ten times faster than
their surfaces. Beck's team studied data from NASA's
Kepler spacecraft, which monitors the variations in
starlight that occur when planets pass in front of their star.
Oscillations within a star—called asteroseismological
vibrations—can also cause starlight to vary, and they
provide information about stars' internal structure. The
discovery implies that our Sun's core will also spin faster
than its surface when it becomes a giant; this may affect how
it sheds its outer atmosphere and transforms from a red giant
into a white dwarf.
