Abstract
The present work is based on the effects of the magnetic braking for the
angular mometum loss evolution and, consequently, the relationship
between stellar rotation and age. In general, this loss rate denoted by
dJ/dt depends on the angular velocity Omega in the form dJ/dt alpha
Omega(q), where q is a parameter from nonextensive statistical
mechanics. In the context of the stellar rotation, this parameter is
directly related to the braking index. For q equal to unity, the
scenario of the saturation of the magnetic field is recovered. Such an
approach was proposed and investigated by de Freitas and De Medeiros for
unsaturated field stars. We propose a new nonextensive approach for the
stellar rotational evolution based on the Reiners and Mohanty model. We
developed a nonextensive version of Reiners and Mohanty torque, and
compare it with the model proposed in de Freitas and De Medeiros, by
using a sample of velocity v sin i for similar to 16000 field F- and G-
stars. As a result, we show that the Kawaler and Reiners-Mohanty models
exhibit strong discrepancies in relation to the domain of validity of
the entropic index q. These discrepancies are mainly due to sensitivity
on the stellar radius. Our results also showed that the modified Kawaler
prescription is consistent in a wider mass ranges, while the Reiners and
Mohanty model is restricted to masses less than from G6 stars. Copyright
(C) EPLA, 2015
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