Orbital period of the stars as a function of their distance from the galactic center. There are small galaxies orbiting the Milky Way. The element that is produced when this limit is reached is a. uranium. The main sequence lifetime of a star half the mass of the Sun a. is the same as that of the Sun, because mass does not affect the lifetime of a star. Differential rotation on the Sun creates vortices, or eddies, which are cooler and darker than the rest of the solar surface.
Solar flares cause the photosphere to expand and cool in the vicinity of the flare.
Magnetic fields breaking through the photosphere inhibit gas motion where the field is strong.