Stellar age dependence of the nonextensive magnetic braking index: A test for the open cluster αPer

Freitas, D. B. de

doi:10.1209/0295-5075/ac0dfb

Cited by 4 publications

(3 citation statements)

References 39 publications

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“…At present, some literatures focus on metallicities, age spread, fast rotating, the amplitude of photometric variability and so on, which can affect the age determination of star clusters. Some comments can be found in the papers (e.g., Gossage et al 2018;Catelan 2018;Wang et al 2020a;Anders et al 2021;de Freitas 2021). Li & Han (2008) investigated the effects of binary interactions on age and metallicity of star clusters based on the isochrone and spectral energy distribution fittings, but its results were mainly obtained from the theoretical side on account of the limitation of computing ability.…”

Section: Introductionmentioning

confidence: 99%

Effects of Binaries on Open Cluster Age Determination in Bayesian Inference

Li¹,

Zhang²,

Chen³

et al. 2022

Res. Astron. Astrophys.

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We investigate the effects of binaries on the cluster age determination for 561 open clusters in the Galactic disk via the Bayesian statistical framework. Stellar properties of these star clusters, including age, metallicity, distance modulus, color excess, binary fraction and rotating star fraction, are derived from color magnitude-diagrams (CMDs) via isochrone fitting to high-precision Gaia EDR3 data. Across the simple stellar population of binary and single-star, age differences can be found with the same star cluster. A Bayesian applied regression modeling software, Stan, is employed to explore how much binaries affect the age determination of open clusters. Our results present less statistically significant difference between the binary-star simple populations (bsSSPs) and the single-star simple populations (ssSSPs) for cluster age determination. For all clusters in our sample, the ages estimated using the bsSSPs models are younger than those estimated using the ssSSPs, with a mean value of ∼ 70 Myr. However, it is found that for 52.5% clusters in our sample, ages are relatively sensitive to the presence of binaries, at least ∼ 25% younger. This suggests that in studies of open cluster age determinations, the effects of binary interactions on the whole sample are not prominent, but its effects on some clusters should still be included as an essential ingredient.

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Section: Introductionmentioning

confidence: 99%

Effects of Binaries on Open Cluster Age Determination in Bayesian Inference

Li¹,

Zhang²,

Chen³

et al. 2022

Res. Astron. Astrophys.

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“…Modeling the stellar magnetic braking index. -First of all, the present paper is the second one (Paper I: [22]) of a series of three papers which brings a new approach to the non-extensive magnetic braking as a determining factor for understanding the delicate mechanisms that control the spin-down of stars in different luminosity classes. By using the equation proposed in [22] to describe the behavior of the rotational velocity, we have that:…”

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confidence: 99%

“…As cited in Paper I, the non-extensive formalism reveals to be a powerful theory for studying stellar systems, among them open clusters and field stars as will be seen here. Several studies (e.g., [13,22]) have shown that the stellar rotational braking mechanism can be explained by investigating the behavior of the entropic index q. As a result, de Freitas and De Medeiros [13] suggested that increasing index q behavior between the saturated (q = 1) and unsaturated (1 < q < 3) magnetic field regimes as a function of spectral type may explain the process of magnetic transition that occurs in the stellar dynamo dynamics.…”

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confidence: 99%

Measuring deviation from Skumanich braking index in active stars observed by Kepler mission

Freitas

Cavalcante²,

Santiago³

2022

EPL

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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 braking index based on the balance of gravitational and centrifugal forces, a determining factor for understanding the delicate mechanisms that control the spin-down of stars in these evolutionary phases. In the present study, we used a wide sample of stellar targets from the Kepler mission with well-deﬁned mass, radius, and rotation period. As a result, Kepler stellar parameters provide rather precise values of q index limited in the range 1 q 3, which is consistent with the predictions of the model of magnetic stellar wind. Our results show conclusively that, within the model used in this work, any signiﬁcant deviation of the braking index away from the value q = 3 occurs at masses higher than the Kraft break.

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Hemispheric Asymmetry in the Sunspot Cycle as a Nonextensive Phenomenon

et al. 2023

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The appearance of dark sunspots over the solar photosphere is not considered to be symmetric between the northern and southern hemispheres. Among the different conclusions obtained by several authors, we can point out that the North-South asymmetry is a real and systematic phenomenon and is not due to random variability. In the present work, we selected the sunspot area data of a sample of 13 solar cycles divided by hemisphere extracted from the Marshall Space Flight Centre (MSFC) database to investigate the behavior of probability distributions using an out-of-equilibrium statistical model a.k.a nonextensive statistical mechanics. Based on this statistical framework, we obtained that the non-extensive entropic parameter q has a semi-sinusoidal variation with a period of ∼22 year (Hale cycle). Among the most important results, we can highlight that the asymmetry index q(A) revealed the dominance of the northern hemisphere against the southern one. Thus, we concluded that the parameter q(A) can be considered an effective measure for diagnosing long-term variations

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Stellar age dependence of the nonextensive magnetic braking index: A test for the open cluster αPer

Cited by 4 publications

References 39 publications

Effects of Binaries on Open Cluster Age Determination in Bayesian Inference

Effects of Binaries on Open Cluster Age Determination in Bayesian Inference

Measuring deviation from Skumanich braking index in active stars observed by Kepler mission

Hemispheric Asymmetry in the Sunspot Cycle as a Nonextensive Phenomenon

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