• DOI:10.1209/0295-5075/108/39001
• Corpus ID: 118459168

Strong evidences for a nonextensive behavior of the rotation period in Open Clusters

@article{Freitas2014StrongEF,
  title={Strong evidences for a nonextensive behavior of the rotation period in Open Clusters},
  author={D. B. de Freitas and Mackson M. F. Nepomuceno and Br'aulio B. Soares and J. R. P. Silva},
  journal={arXiv: Solar and Stellar Astrophysics},
  year={2014}
}

• D. B. D. Freitas, M. M. F. Nepomuceno, +1 author J. R. P. Silva
• Published 4 August 2014
• Physics
• arXiv: Solar and Stellar Astrophysics

Time-dependent nonextensivity in a stellar astrophysical scenario combines nonextensive entropic indices $q_{K}$ derived from the modified Kawaler's parametrization, and $q$, obtained from rotational velocity distribution. These $q$'s are related through a heuristic single relation given by $q\approx q_{0}(1-\Delta t/q_{K})$, where $t$ is the cluster age. In a nonextensive scenario, these indices are quantities that measure the degree of nonextensivity present in the system. Recent studies reveal that the index $q$ is correlated to the formation rate of high-energy tails present in the distribution of rotation velocity. On the other hand, the index $q_{K}$ is determined by the stellar rotation-age relationship. This depends on the magnetic field configuration through the expression $q_{K}=1+4aN/3$, where $a$ and $N$ denote the saturation level of the star magnetic field and its topology, respectively. In the present study, we show that the connection $q-q_{K}$ is also consistent with 548 rotation period data for single main-sequence stars in 11 Open Clusters aged less than 1 Gyr. The value of $q_{K}\sim$ 2.5 from our unsaturated model shows that the mean magnetic field topology of these stars is slightly more complex than a purely radial field. Our results also suggest that stellar rotational braking behavior affects the degree of anti-correlation between $q$ and cluster age $t$. Finally, we suggest that stellar magnetic braking can be scaled by the entropic index $q$.