Bridging the Gap—The Disappearance of the Intermediate Period Gap for Fully Convective Stars, Uncovered by New ZTF Rotation Periods
Bridging the Gap—The Disappearance of the Intermediate Period Gap for Fully Convective Stars, Uncovered by New ZTF Rotation Periods
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DOI：
10.3847/1538-3881/ac9bee
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发表时间：
2022-10
期刊：
影响因子：
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通讯作者：
Y. Lu;J. Curtis;R. Angus;T. David;S. Hattori
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作者：
Y. Lu;J. Curtis;R. Angus;T. David;S. Hattori
开普勒发现的中间周期间隙是在温度-周期图中观察到的恒星自转周期的缺失，G 矮星约为 20 天，早期 M 矮星可达约 30 天。然而，由于开普勒主要针对类太阳恒星，因此缺乏对 M 型矮星的周期测量，尤其是那些处于完全对流极限的矮星。因此，中、晚期M矮星是否存在中间周期间隙尚不清楚。在这里，我们提出了一个包含 40,553 个旋转周期（9535 个周期 >10 天）的周期目录，使用 Zwicky 瞬态设施 (ZTF) 进行测量。为了测量这些周期，我们开发了一个简单的管道，可以直接改进 ZTF 档案光曲线，并将光度散射平均减少 26%。这个新目录涵盖了一系列恒星温度，将开普勒的样本与 MEarth（对明亮 M 型矮星进行的地面时域勘测）连接起来，并揭示了中间周期间隙在理论预测的全对流边界位置（GBP - GRP ∼ 2.45 mag）处闭合。这一结果支持了间隙是由核心-包膜相互作用引起的假设。利用陀螺运动年龄，我们还发现恒星在这个周期间隙中可能会快速旋转。
The intermediate period gap, discovered by Kepler, is an observed dearth of stellar rotation periods in the temperature–period diagram at ∼20 days for G dwarfs and up to ∼30 days for early-M dwarfs. However, because Kepler mainly targeted solar-like stars, there is a lack of measured periods for M dwarfs, especially those at the fully convective limit. Therefore it is unclear if the intermediate period gap exists for mid- to late-M dwarfs. Here, we present a period catalog containing 40,553 rotation periods (9535 periods >10 days), measured using the Zwicky Transient Facility (ZTF). To measure these periods, we developed a simple pipeline that improves directly on the ZTF archival light curves and reduces the photometric scatter by 26%, on average. This new catalog spans a range of stellar temperatures that connect samples from Kepler with MEarth, a ground-based time-domain survey of bright M dwarfs, and reveals that the intermediate period gap closes at the theoretically predicted location of the fully convective boundary (G BP − G RP ∼ 2.45 mag). This result supports the hypothesis that the gap is caused by core–envelope interactions. Using gyro-kinematic ages, we also find a potential rapid spin-down of stars across this period gap.