The TIME Table: rotation and ages of cool exoplanet host stars
The TIME Table: rotation and ages of cool exoplanet host stars
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时间表：冷系外行星主恒星的自转和年龄
DOI：
10.1093/mnras/stad343
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发表时间：
2023
影响因子：
4.8
通讯作者：
Feiden, Gregory A.
中科院分区：
文献类型：
--
作者：
Gaidos, Eric;Claytor, Zachary;Dungee, Ryan;Ali, Aleezah;Feiden, Gregory A.
年龄是一个恒星参数，既基本又难以确定。在中年M矮星中，最丰富的近距离和可探测的系外行星宿主，陀螺仪年表是最有希望确定年龄的方法，但需要在已知年龄的星团中通过旋转温度序列（陀螺仪）进行校准。我们编制了249颗具有确定自转周期的晚期K型和m型（Teff= 3200-4200 K）系外行星宿主恒星的目录，并基于相关已发表的陀螺仪（包括4-Gyr-old疏散星团M67的观测数据）应用了经验的、温度相关的旋转年龄关系。我们对其中227颗恒星的年龄进行了估计，并对另外8颗恒星的年龄进行了上限估计，但不包括14颗旋转太快或在我们的陀螺年表的有效参数范围之外的恒星。我们根据观测到的年轻星团旋转周期的散射、陀螺仪的误差、温度和非太阳金属丰度的不确定性来估计不确定性。对于那些测量过金属丰度的恒星，我们提供但不包含对偏离太阳金属丰度的影响的修正。我们样本的年龄分布在10 Gyr（银河盘的年龄）下降到接近零，只有少数异常值可以用很大的不确定性来解释。继续增加或扩展星团旋转序列，以更彻底地校准时间和温度空间上的陀螺年表，更精确和可靠的旋转周期测量，以及更准确的恒星参数测量，将使这些重要的系外行星宿主恒星的年龄估计不断改进。
Age is a stellar parameter that is both fundamental and difficult to determine. Among middle-aged M dwarfs, the most prolific hosts of close-in and detectable exoplanets, gyrochronology is the most promising method to assign ages, but requires calibration by rotation-temperature sequences (gyrochrones) in clusters of known ages. We curated a catalogue of 249 late K- and M-type (Teff= 3200–4200 K) exoplanet host stars with established rotation periods, and applied empirical, temperature-dependent rotation–age relations based on relevant published gyrochrones, including one derived from observations of the 4-Gyr-old open cluster M67. We estimated ages for 227 of these stars, and upper limits for eight others, excluding 14 which are too rapidly rotating or are otherwise outside the valid parameter range of our gyrochronology. We estimated uncertainties based on observed scatter in rotation periods in young clusters, error in the gyrochrones, and uncertainties in temperature and non-solar metallicity. For those stars with measured metallicities, we provide but do not incorporate a correction for the effects of deviation from solar-metallicity. The age distribution of our sample declines to near zero at 10 Gyr, the age of the Galactic disc, with the handful of outliers explainable by large uncertainties. Continued addition or extension of cluster rotation sequences to more thoroughly calibrate the gyrochronology in time and temperature space, more precise and robust measurement of rotation periods, and more accurate stellar parameter measurements will enable continued improvements in the age estimates of these important exoplanet host stars.