论文标题

解开银河系。 iv。对田间年轻恒星的角动量进化和旋律的经验约束

Untangling the Galaxy. IV. Empirical Constraints on Angular Momentum Evolution and Gyrochronology for Young Stars in the Field

论文作者

Kounkel, Marina, Stassun, Keivan G., Bouma, Luke G., Covey, Kevin, Hillenbrand, Lynne A., Curtis, Jason Lee

论文摘要

我们在该系列的先前论文中,在苔丝FFI数据中介绍了一个约100,000个周期性可变星的目录。通过将归因于旋转的目录的周期与基准开放簇的先前旋转周期相结合,我们开发了角动量进化的经验跨越人类学关系,该关系对10-1000 MYR的恒星有效。排除旋转速度比2天快的恒星,我们发现这主要是二进制的恒星,我们达到了典型的年龄精度约为0.2-0.3 DEX,并且在老年时代提高了。重要的是,与旋转周期分布相比,这些经验关系不仅适用于FGK型星,而且适用于M型恒星,因为角动量分布比旋转周期分布相比更平滑,更简单,连续和单调。结果,我们还能够详细地详细地追踪低质量恒星中角动量损失的性质,作为质量和年龄的功能。我们将酷星的恒星变异性幅度表征为质量和年龄的功能,这可能与覆盖分数的星点相关。我们还确定了目录中较热的恒星之间的脉动变量,包括$δ$ SCUTI,$γ$ dor和SPB型变量。这些数据代表了能够估算田间FGK和M型恒星精确年龄的重要一步,最早从进化的前序列阶段开始。

We present a catalog of ~100,000 periodic variable stars in TESS FFI data among members of widely distributed moving groups identified with Gaia in the previous papers in the series. By combining the periods from our catalog attributable to rotation with previously derived rotation periods for benchmark open clusters, we develop an empirical gyrochronology relation of angular momentum evolution that is valid for stars with ages 10-1000 Myr. Excluding stars rotating faster than 2 days, which we find are predominantly binaries, we achieve a typical age precision of ~0.2-0.3 dex and improving at older ages. Importantly, these empirical relations apply to not only FGK-type stars but also M-type stars, due to the angular momentum distribution being much smoother, simpler, continuous and monotonic as compared to the rotation period distribution. As a result, we are also able to begin tracing in fine detail the nature of angular momentum loss in low-mass stars as functions of mass and age. We characterize the stellar variability amplitudes of the cool stars as functions of mass and age, which may correlate with the starspot covering fractions. We also identify pulsating variables among the hotter stars in the catalog, including $δ$ Scuti, $γ$ Dor and SPB-type variables. These data represent an important step forward in being able to estimate precise ages of FGK- and M-type stars in the field, starting as early as the pre-main-sequence phase of evolution.

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