A spin-down clock for cool stars from observations of a 2.5-billion-year-old cluster
A spin-down clock for cool stars from observations of a 2.5-billion-year-old cluster
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DOI：
10.1038/nature14118
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发表时间：
2015-01
期刊：
影响因子：
64.8
通讯作者：
S. Meibom;S. Barnes;I. Platais;R. Gilliland;D. Latham;R. Mathieu
中科院分区：
文献类型：
--
作者：
S. Meibom;S. Barnes;I. Platais;R. Gilliland;D. Latham;R. Mathieu
最常见的恒星--像太阳这样的低质量（冷）恒星，以及更小的恒星--的年龄很难推导出来，因为传统的定年方法使用的恒星属性要么随着恒星年龄的变化而变化很小，要么很难测量。所有冷恒星的自转速率都随着时间的推移而大幅下降，因为恒星会稳定地失去它们的角动量。如果正确校准，旋转因此可以作为一个可靠的决定因素，他们的年龄的基础上的方法gyrochronology，，。为了校准陀螺年代学，必须确定不同质量的冷恒星的自转周期和年龄之间的关系，这最好通过测量已知年龄的星团中恒星的自转周期来完成。迄今为止，这样的测量只有在年龄小于10亿年的星团中才有可能，而较老恒星的陀螺年代学年龄是从模型预测中推断出来的。在这里，我们报告了25亿年前的星系团NGC 6819中30颗冷恒星的旋转周期测量结果。的周期揭示了一个明确的关系之间的旋转周期和恒星质量的集群年龄，这表明年龄的精度为10%的顺序可以推导出大量的冷银河场恒星。
The ages of the most common stars—low-mass (cool) stars like the Sun, and smaller—are difficult to derive,because traditional dating methods use stellar properties that either change little as the stars age,or are hard to measure,,,. The rotation rates of all cool stars decrease substantially with time as the stars steadily lose their angular momenta. If properly calibrated, rotation therefore can act as a reliable determinant of their ages based on the method of gyrochronology,,,. To calibrate gyrochronology, the relationship between rotation period and age must be determined for cool stars of different masses, which is best accomplished with rotation period measurements for stars in clusters with well-known ages. Hitherto, such measurements have been possible only in clusters with ages of less than about one billion years,,,,, and gyrochronology ages for older stars have been inferred from model predictions,,,. Here we report rotation period measurements for 30 cool stars in the 2.5-billion-year-old cluster NGC 6819. The periods reveal a well-defined relationship between rotation period and stellar mass at the cluster age, suggesting that ages with a precision of order 10 per cent can be derived for large numbers of cool Galactic field stars.