Related papers: Strong evidences for a nonextensive behavior of th…
Using a generalized function of the stellar spin-down law, we investigate the age dependence of the magnetic braking index ($q$). Our survey includes 9 open clusters aged lower than 1 Gyr and ranged in mass from 0.7 to 1.1$M_{\odot}$. Our…
Nonextensive formalism is a generalization of the Boltzmann-Gibbs statistics. In this formalism the entropic index q is a quantity characterizing the degree of nonextensivity, and is interpreted as a parameter of long-memory or long-range…
The present work is based on a description for the angular mometum loss rate due to magnetic braking for main-sequence stars on the relationship between stellar rotation and age. In general, this loss rate denoted by $\mathrm dJ/\mathrm dt$…
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…
In this first work attempts to analytically explain the effects on the magnetic braking index, $q$, caused by the evolution of stellar velocity in main-sequence stars, and estimated by de Freitas \& De Medeiros (2013). We have found that…
The present work attempts to analytically explain the effects on the moment of inertia, $I$, caused by the evolution of stellar velocity in main-sequence stars. We have found that the effects linked to stellar oblateness can be estimated…
Studies using asteroseismic ages and rotation rates from star-spot rotation have indicated that standard age-rotation relations may break down roughly half-way through the main sequence lifetime, a phenomenon referred to as weakened…
Stellar rotation is a complex function of mass, metallicity, and age and can be altered by binarity. To understand the importance of these parameters in main sequence stars, we have assembled a sample of observations that spans a range of…
The connection between stellar rotation, stellar activity, and convective turnover time is revisited with a focus on the sole contribution of magnetic activity to the Ca II H&K emission, the so-called excess flux, and its dimensionless…
Rotation and magnetic activity are intimately linked in main-sequence stars of G or later spectral types. The presence and level of magnetic activity depend on stellar rotation, and rotation itself is strongly influenced by strength and…
The aim of this work is to determine the deviation of the value of magnetic braking index $q$ from Skumanich $q=3$ canonical value for giant and main-sequence stars. In this context, the present work attempts to analytically calculate the…
We present 75 new stellar rotation periods in the young cluster IC348. Stars estimated to be less massive than 0.25 Mo show a unimodal distribution with a peak at P ~1-2 d) and a tail of slower rotators, while stars estimated to be more…
The analysis of the distribution of stars in open clusters may yield important information on the star formation process and early dynamical evolution of stellar clusters. Here we address this issue by systematically characterizing the…
Our ability to determine stellar ages from measurements of stellar rotation, hinges on how well we can measure the dependence of rotation on age for stars of different masses. Rotation periods for stars in open clusters are essential to…
We report rotation periods, variability characteristics, gyrochronological ages for ~950 of the Kepler Object of Interest host stars. We find a wide dispersion in the amplitude of the photometric variability as a function of rotation,…
Recent analyses of FGK stars in open clusters have helped clarify the precision with which a star's rotation rate and lithium content can be used as empirical indicators for its age. Here we apply this knowledge to stars observed by Kepler.…
The association of starspots with magnetic fields leads to an expectation that quantities which correlate with magnetic field strength may also correlate with {starspot} coverage. Since younger stars spin faster and are more magnetically…
In low-mass stars, the connection between magnetic activity, rotation period, and age provides key insights into the functioning of dynamos. Fully understanding the activity-rotation-age relationship requires stars with precise fundamental…
The rotation rate, level of magnetic activity and surface lithium abundance are age-dependent quantities in stars of about a solar mass and below. The physical reasons for the evolution of these phenomena are qualitatively understood, but…
Kepler ultra-high precision photometry of long and continuous observations provides a unique dataset in which surface rotation and variability can be studied for thousands of stars. Because many of these old field stars also have…