Secular Stability of the Magnetic Structures of Magnetic Stars. II
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SECULAR STABILITY OF THE MAGNETIC STRUCTURES OF MAGNETIC STARS. II
Yu. V. Glagolevskij
Numerous indications that the magnetic field structures in magnetic stars do not change with age are cited. The stars rotate like a solid. Keywords: stars: magnetic field - stars: magnetic structures - stars: ages
1. Introduction
This paper is a continuation of an article [1] in which it was shown that the magnetic field structures of chemically peculiar (CP) stars do not change over their entire lifetime. Here we introduce some additional data that are indicative of the secular stability of magnetic structures in stars of this type. The stability of the magnetic fields is a problem that has been discussed essentially over the entire time magnetic stars have been studied. In the earlier article data were cited which show that even in the earliest stages of research on magnetic stars, the idea of the secular stability of the magnetic field structures of CP stars arose. Theoretically, stable magnetic fields can exist for 1010-1011 years. The maximum age of magnetic stars is 109 years, or an order of magnitude below this value. The
Special Astrophysical Observatory, Russian Academy of Sciences, Russia; e-mail: [email protected]
Original article submitted January 31, 2020; accepted for publication June 24, 2020. Astrofizika, Vol. 63, No. 3, pp. 423-435 (August 2020) 376
0571-7256/19/6303-0376 ©2020 Springer Science+Business Media, LLC
Translated from
signs of secular stability of the magnetic field structures imply that there are no large scale movements of mass inside the stars. This result is extremely important for clarifying the physics and evolution of magnetic stars. In the previous article the age dependences of the inclinations D of the dipole axes relative to the equatorial plane and of the distances 'a of the dipoles from a star’s center were introduced. It turned out that these parameters do not vary with age. A certain conclusion, i.e., the structures of the magnetic fields are constant in time, can be reached from this fact alone. It has been shown [2] that even at times of an internal restructuring of the stars, the structures remain invariant
2. Early discussions of the problem of the stability of magnetic structures
In some of his first papers, Babcock [3] stated that, based on the profiles of spectral lines it may be concluded that the magnetic field in magnetic stars does not belong to separate magnetic regions, as on the sun. These stars are magnetized as a whole and the magnetic field structure has a clear dipole character. He stated [4] that differential rotation, which would rapidly destroy the observed dipole magnetic field structure, cannot exist in magnetic stars. It is possible that a strong field sustains the internal rigidity. In the following we show that the internal rigidity is sustained both by the magnetic field and by a slow rotation, with which differential rotation, meridional circulation, and other instabilities do not develop. Strittmatter and Norris [5] stated that, during compression of
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