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Angular momentum loss during pre-main sequence contraction

  • L. Mestel
1. Pre-Main Sequence Stars
Part of the Lecture Notes in Physics book series (LNP, volume 193)

Abstract

Current ideas on the early stages of star formation suggest strongly that proto-stars enter the pre-main sequence phase rotating rapidly. The subsequent rotational evolution of both single and binary stars is largely determined by angular momentum transport by a magnetically-controlled stellar wind. A massive star with a cool corona but with a modest relic magnetic field may be prevented from fragmenting into a binary system through the braking action of a centrifugally-driven wind. A late-type pre-main sequence star will generate by dynamo action a magnetic field of surface strength Bo that depends on the angular velocity Ω. The consequent braking can be powerful enough to cause spin-down in spite of the contraction. The predicted Ω(t) law depends on the Bo (Ω) relation, on whether the wind is thermal, thermo-centrifugal, or magneto-centrifugal, and on the fraction of the magnetosphere with open field-line. Angular momentum loss from a tidally locked binary pair can lead to the formation of late-type contact binaries with rapidly rotating members, and ultimately to their coalescence into one rapid rotator.

Keywords

Angular Momentum Wind Zone Star Formation Poloidal Field Centrifugal Acceleration 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer-Verlag 1984

Authors and Affiliations

  • L. Mestel
    • 1
  1. 1.Astronomy CentreUniversity of SussexFalmerEngland

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