Latitudinal differential rotation in the solar analogues 16 Cygni A and B
Latitudinal differential rotation in the solar analogues 16 Cygni A and B
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DOI：
10.1051/0004-6361/201834594
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发表时间：
2019-03-19
影响因子：
6.5
通讯作者：
Sreenivasan, K. R.
中科院分区：
文献类型：
--
作者：
Bazot, M.;Benomar, O.;Sreenivasan, K. R.
语境。继 CoRoT 和开普勒太空任务之后，星震学作为一个科学领域经历了深刻的转变。后者现在正在产生直接从振荡频率获得的纬度差分旋转的第一个测量结果。差分旋转是恒星发电机效应的基本机制。我们的目标是测量太阳类似物 16 Cyg A 和 B 的差分旋转量，它们是双星系统的组成部分。这些恒星是开普勒观测到的最亮的恒星，因此被广泛观测，其振荡频率具有极高的精度。方法。我们使用考虑了差分旋转对旋转频率分裂的贡献的模型对 16 Cyg A 和 B 的声功率谱进行了建模。该估计是在贝叶斯设置中进行的。然后我们对这些结果进行反演，以获得在类太阳函数形式假设下两颗恒星的旋转轮廓。结果。我们观察到，两颗恒星的纬度差异旋转的幅度很有可能与太阳相似，它们的旋转速率在赤道处比在极点处更高。测得的纬度差自转（定义为赤道和极点之间的自转速率之差）对于16 Cyg A和B分别为320 +/- 269 nHz和440(-383)(+363 )nHz，证实这些恒星的自转速率几乎与太阳相似。它们的赤道自转速率为 535 +/- 75 nHz 和 565(-129)(+150) nHz。我们的结果与分光偏振法、光谱学和光度测定法获得的测量结果非常一致。结论。我们提出了太阳类比纬度差自转的第一个结论性测量。它们的旋转轮廓非常接近太阳的旋转轮廓。这些结果在很大程度上取决于恒星参数的不确定性。
Context. Asteroseismology has undergone a profound transformation as a scientific field following the CoRoT and Kepler space missions. The latter is now yielding the first measurements of latitudinal differential rotation obtained directly from oscillation frequencies. Differential rotation is a fundamental mechanism of the stellar dynamo effect.Aims. Our goal is to measure the amount of differential rotation in the solar analogues 16 Cyg A and B, which are the components of a binary system. These stars are the brightest observed by Kepler and have therefore been extensively observed, with exquisite precision on their oscillation frequencies.Methods. We modelled the acoustic power spectrum of 16 Cyg A and B using a model that takes into account the contribution of differential rotation to the rotational frequency splitting. The estimation was carried out in a Bayesian setting. We then inverted these results to obtain the rotation profile of both stars under the assumption of a solar-like functional form.Results. We observe that the magnitude of latitudinal differential rotation has a strong chance of being solar-like for both stars, their rotation rates being higher at the equator than at the pole. The measured latitudinal differential rotation, defined as the difference of rotation rate between the equator and the pole, is 320 +/- 269 nHz and 440(-383)(+363 )nHz for 16 Cyg A and B, respectively, confirming that the rotation rates of these stars are almost solar-like. Their equatorial rotation rates are 535 +/- 75 nHz and 565(-129)(+150) nHz. Our results are in good agreement with measurements obtained from spectropolarimetry, spectroscopy, and photometry.Conclusions. We present the first conclusive measurement of latitudinal differential rotation for solar analogues. Their rotational profiles are very close to those of the Sun. These results depend weakly on the uncertainties of the stellar parameters.