A nonextensive approach to the stellar rotational evolution I. F and G type stars

Abstract

The pioneering study by Skumanich (1972) showed that the rotational velocity of G-type Main-Sequence (MS) stars decreases with stellar age according to $<v\sin i>$ $\propto$ $t^{-1/2}$. This relationship is consistent with simple theories of angular momentum loss from rotating stars, where an ionized wind is coupled to the star by a magnetic field. The present study introduces a new approach to the study of stellar rotational braking in unsaturated F and G type stars limited in age and mass, connecting angular momentum loss by magnetic stellar wind with Tsallis nonextensive statistical mechanics. As a result, we show that the rotation-age relationship can be well reproduced using a nonextensive approach from Tsallis nonextensive models. Here, the index $q$, which is related to the degree of nonextensivity, can be associated to the dynamo process and to magnetic field geometry, offering relevant information on the level of stellar magnetic braking for F- and G-type Main-Sequence stars.

8 pages, 3 figures, MNRAS accepted

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• Stellar age dependence of the nonextensive magnetic braking index: a test for the open cluster $\alpha$Per
• Strong evidences for a nonextensive behavior of the rotation period in Open Clusters
• A nonextensive view of the stellar braking indices
• The limit behavior of the evolution of Tsallis entropy in self-gravitating systems
• Non-extensive processes associated with heating of the Galactic disc
• New Suns in the Cosmos V: Stellar rotation and multifractality in active \textit{Kepler} stars
• Crab pulsar spectrum: a non-extensive approach
• Hemispheric asymmetry in the sunspot cycle as a nonextensive phenomenon