Name/Affiliation: Sydney A. Barnes (Leibniz Institute for Astrophysics)
A unified model for rotation, coupling, desaturation, and angular momentum loss from cool stars
A model is presented for internal coupling in cool stars that also describes the rotational aspects of magnetic saturation, implying that the two phenomena (coupling and de-saturation) are equivalent. Correspondingly, rotational stellar models should not explicitly include both. The key transition in the model is also coincident with the transition in X-Ray flux from saturated to unsaturated regimes. The model provides a new formulation of the rate of loss of angular momentum from cool stars, significantly different from the Kawaler (1988) formulation and subsequent ones. The loss rate is maximal during the rotational transition in cool stars, and declines towards zero at the highest rotation rates. Correspondingly, the mass loss rates from cool stars are predicted to decline precipitously during their phase of fast rotation. The integrated mass loss is small enough that the masses of cool stars can be considered essentially constant on the main sequence. This further implies that the Faint Sun (or Warm Earth) Paradox cannot be resolved by postulating a more massive young Sun.