Catch a Fading Star: Using Transient Dimming to Explore the Planet-Forming Zones of Young Stars

一群被称为“北斗七星”的低质量恒星会经历偶然的变暗事件，而这种变暗事件可能不是由行星凌日引起的。该团队将使用天文测量、成像和光谱数据来评估除磁盘或行星掩星之外的恒星变暗机制。他们将测试由圆盘风和外彗星在高度倾斜和偏心轨道上扬起的尘埃模型。他们还将进行多次带通光度测定，以检查星光变红的情况，并对尘埃大小分布进行限制。他们将利用之前的超新星调查经验，并使用机器学习开发一个自动化系统，以识别恒星变暗并消除误报。该小组将与民间科学家一起利用业余设备扩大对变暗恒星的调查。他们将利用夏威夷大学马诺阿分校（University of Hawaii at Manoa）现有的一个项目，将这项工作带给来自弱势群体的高中生，包括夏威夷原住民。高中生将与休斯敦大学的科学家和教授进行为期六个月的指导。这项工作的目的是检查结构，动力学，和组成的内部区域的原始磁盘。内盘与中心恒星交换质量和角动量。这些区域是行星形成和成长的地方。这项研究将补充用其他方法（例如ALMA）探测的外盘区域的研究。倾角和风之间的联系将为光蒸发和/或磁流体动力风提供新的探测，这些风可以控制圆盘的质量和角动量的演变，而这些又是行星形成和演化的重要因素。另一方面，与星子的联系将为这些系统中行星形成的关键阶段提供一个窗口。详细的光度和光谱学研究将使我们能够研究这些圆盘中气体和固体的组成，这些气体和固体也可能包含在行星中。该项目将创建一个北斗七星“警报”系统，将原行星盘的研究引入多波长瞬态天文学领域，并作为未来使用更强大的观测资源进行时间序列研究的基础。该奖项反映了美国国家科学基金会的法定使命，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。

A population of low-mass stars, called ‘dipper stars,’ experience episodic dimming events that might not arise due to planetary transits. The team will use astrometric, imaging, and spectroscopic data to evaluate mechanisms other than disk or planetesimal occultation for stellar dimming. They will test the model of dust lofted by disk winds and exocomets on highly inclined and eccentric orbits. They will also do multiple bandpass photometry to examine reddening of the starlight and put constraints on the dust size distribution. They will leverage prior experience with a supernova survey and use machine learning to develop an automated system to identify stellar dimming and eliminate false positives. The team will incorporate citizen scientists to expand the survey of dimming stars using amateur equipment. They will use an existing program at University of Hawaii at Manoa to bring the work to high school students from under-represented groups, including Hawaiian natives. High schoolers will work on this project with UH scientists and Professors on six-month mentorships.The purpose of this work is to examine the structure, dynamics, and composition of the inner regions of primordial disks. Inner disks exchange mass and angular momentum with the central star. These are the regions where planets form and grow. This research will complement studies of outer disk regions probed by other means, e.g. ALMA. A connection between dips and winds would provide a new probe of photoevaporative and/or magnetohydrodynamic winds that could control evolution of mass and angular momentum in disks, which in turn are important factors in planet formation and evolution. On the other hand, a link to planetesimals would provide a window on a critical stage of planet formation in these systems. Detailed photometric and spectroscopic investigations would allow studies of the composition of gases and solids in these disks that may also be incorporated in planets. This project will create a dipper “alerts” system that would usher studies of protoplanetary disk into the realm of multi-wavelength transient astronomy and serve as the basis for future time-series investigations using even more powerful observational resources.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.