Stellar rotation

Stellar rotation is the <a href="/facts/Angular_motion/r4YaTspL">angular motion</a> of a <a href="/facts/Star/PFbd6ICx">star</a> about its axis. The <a href="/facts/Rate_of_rotation/DAVXQgXj">rate of rotation</a> can be measured from the spectrum of the star, or by timing the movements of active features on the surface.
The rotation of a star produces an <a href="/facts/Equatorial_bulge/8CIPWl0I">equatorial bulge</a> due to <a href="/facts/Centrifugal_force/CWgvMw6w">centrifugal force</a>. As stars are not solid bodies, they can also undergo <a href="/facts/Differential_rotation/e1dhGsBV">differential rotation</a>. Thus the <a href="/facts/Equator/CjaxbVaN">equator</a> of the star can rotate at a different <a href="/facts/Angular_velocity/2n8JljAT">angular velocity</a> than the higher <a href="/facts/Latitudes/IBYqkjhU">latitudes</a>. These differences in the rate of rotation within a star may have a significant role in the generation of a <a href="/facts/Stellar_magnetic_field/TEsF7BxY">stellar magnetic field</a>.
In its turn, the magnetic field of a star interacts with the <a href="/facts/Stellar_wind/bn5J6vpx">stellar wind</a>. As the wind moves away from the star its angular speed decreases. The magnetic field of the star interacts with the wind, which applies a <a href="/facts/Drag_(physics)/vdl4jF7I">drag</a> to the stellar rotation. As a result, <a href="/facts/Angular_momentum/7TuSVFxq">angular momentum</a> is transferred from the star to the wind, and over time this gradually slows the star's rate of rotation.

Stellar rotation open-in-new

Stellar rotation