Alpha Omega Dynamo

The alpha-omega dynamo is an astrophysical theory that helps explain the magnetic field of the sun and stars ( active stars ).

The theory developed by the American astrophysicist Eugene N. Parker in 1955 predicts that sunspots ( star spots ) appear periodically and within a period - for the sun it is the 11-year Schwabe cycle - of a higher heliographic latitude, about 30 ° -35 °, walk to the equator ( Spörer's law ). The sunspots initiated by strong magnetic fields have a p main spot (p = preceeding ) and an f main spot (f = following ), the p spot is somewhat closer to the solar equator , the two main spots form a bipolar group in which magnetic field lines emanate from or enter the sun. Furthermore, bipolar groups correspond on the northern and southern hemisphere of the sun , whereby the magnetic orientation of the groups is opposite.

The Alpha-Omega-Dynamo explains the occurrence of a poloidal and toroidal magnetic field in the sun and stars from the differential rotation (rotation) of the star and from the convection zone of the celestial body (alpha and omega effect). If one also considers the overshoot region of a sun, i.e. the transition area between the convection zone and the radiative zone in the star's interior, the alpha-omega dynamo can be further developed into the theory of the magnetohydrodynamic dynamo with its magnetic flux tubes . Both theories explain in principle the change in polarity of the sun's magnetic orientation during successive Schwabe cycles.

literature

• Klaus G. Strassmaier: Active Stars. Solar Astrophysics Laboratories . Vienna, New York. 1997. p. 204ff.