Collaborative Research: The Evolution of Magnetic Complexity in Old Sun-like Stars

首席研究员梅特卡夫和货车萨德斯将采取恒星样本的偏振光谱，以评估其磁场的强度和复杂性。 对于像我们的太阳这样的恒星，恒星风会沿着星星的磁场线慢慢逃逸，并在数十亿年的时间里减缓星星的旋转速度。这个过程称为磁制动。旋转减慢导致中年危机，磁场产生开始失败。恒星从活动期（强磁场伴随着许多耀斑、太阳黑子和爆发）转变为不活动期（较弱的更复杂的磁场伴随着减少的活动）。确定这些转变何时以及如何发生将有助于我们了解恒星的年龄。为了扩大参与范围，研究小组计划在科罗拉多大学举办一个为期15周的“科学家生存技能”研讨会，并在夏威夷大学为教师举办一个夏季研究体验活动。研究小组将使用波茨坦中阶梯偏振和光谱仪（PEPSI）观测12颗恒星。在大型双筒望远镜结合同期光谱使用拉斯坎布雷斯天文台的网络机器人中阶梯光谱仪（NRES）以确定活动水平。将使用加拿大-法国-夏威夷望远镜（CFHT）上的用于恒星观测的中阶梯分光偏振装置（ESPaDOns）获得后续详细磁场图。由此产生的关于恒星磁性如何依赖于旋转和质量的限制，将对磁化恒星风的角动量损失的理论模型，陀螺年代学作为推断恒星年龄的技术的使用，并将为长期的“太空天气”预测提供信息。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Principal Investigators Metcalfe and van Saders will take polarized spectra of a sample of stars to assess the strength and complexity of their magnetic fields. For stars like our Sun, the stellar wind slowly escapes along the star’s magnetic field lines and slows down the rate at which the star rotates over a period of billions of years. This process is called magnetic braking. Slowing rotation leads to a mid-life crisis and the magnetic field generation starts to fail. Stars switch from periods of activity (strong magnetic field with many flares, sunspots, and outbursts) to in-activity (weaker more complex magnetic field with reduced activity). Determining when and how these switches occur will improve our understanding of how stars age. To broaden participation the team plan to lead a 15-week "Survival Skills for Scientists" seminar at the University of Colorado and a summer Research Experience for Teachers at the University of Hawaii.The team will observe 12 stars using the Potsdam Echelle Polarimetric and Spectroscopic Instrument (PEPSI) at the Large Binocular Telescope combined with contemporaneous spectra using Las Cumbres Observatory's Network of Robotic Echelle Spectrographs (NRES) to determine the level of activity. Follow-up detailed magnetic field maps will be obtained using the Echelle SpectroPolarimetric Device for the Observation of Stars (ESPaDOnS) on the Canada-France-Hawaii Telescope (CFHT). The resulting constraints on how the properties of stellar magnetism depend on rotation and mass beyond middle-age will have implications for theoretical models of angular momentum loss from magnetized stellar winds, the use of gyrochronology as a technique for inferring stellar ages, and will inform predictions of long term "space weather" for the Sun and other planetary systems.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.