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Weakened magnetic braking supported by asteroseismic rotation rates of Kepler dwarfs
Nature Astronomy ( IF 12.9 ) Pub Date : 2021-04-22 , DOI: 10.1038/s41550-021-01335-x
Oliver J. Hall , Guy R. Davies , Jennifer van Saders , Martin B. Nielsen , Mikkel N. Lund , William J. Chaplin , Rafael A. García , Louis Amard , Angela A. Breimann , Saniya Khan , Victor See , Jamie Tayar

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 magnetic braking. Although rotation rates from spots can be difficult to determine for older, less active stars, rotational splitting of asteroseismic oscillation frequencies can provide rotation rates for both active and quiescent stars, and so can confirm whether this effect really takes place on the main sequence. We obtained asteroseismic rotation rates of 91 main sequence stars showing high signal-to-noise modes of oscillation. Using these new rotation rates, along with effective temperatures, metallicities and seismic masses and ages, we built a hierarchical Bayesian mixture model to determine whether the ensemble more closely agreed with a standard rotational evolution scenario, or one where weakened magnetic braking takes place. The weakened magnetic braking scenario was found to be 98.4% more likely for our stellar ensemble, adding to the growing body of evidence for this stage of stellar rotational evolution. This work presents a large catalogue of seismic rotation rates for stars on the main sequence, which opens up possibilities for more detailed ensemble analysis of rotational evolution with Kepler.



中文翻译:

开普勒矮星的星震自转率支持弱磁制动

使用星-斑自转的星震年龄和自转速率的研究表明,标准的年龄-自转关系可能在主序带寿命的大约一半时崩溃,这种现象被称为磁制动减弱。虽然对于较老的、不太活跃的恒星来说,来自点的自转率很难确定,但星震振荡频率的自转分裂可以为活跃和静止的恒星提供自转率,因此可以确认这种效应是否真的发生在主序星上。我们获得了 91 颗主序星的星震自转速率,它们显示出高信噪振荡模式。使用这些新的旋转速率,以及有效温度、金属丰度和地震质量和年龄,我们建立了一个分层贝叶斯混合模型,以确定该系综是否更接近标准旋转演化场景,或者发生弱磁制动的场景。我们发现,对于我们的恒星系综,磁制动减弱的可能性要高出 98.4%,这增加了这一阶段恒星旋转演化的证据。这项工作提供了主序星上恒星的地震自转率的大型目录,这为使用开普勒对自转演化进行更详细的集合分析开辟了可能性。为这一阶段的恒星旋转演化增加了越来越多的证据。这项工作提供了主序星上恒星的地震自转率的大型目录,这为使用开普勒对自转演化进行更详细的集合分析开辟了可能性。为这一阶段的恒星旋转演化增加了越来越多的证据。这项工作提供了主序星上恒星的地震自转率的大型目录,这为使用开普勒对自转演化进行更详细的集合分析开辟了可能性。

更新日期:2021-04-22
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