CAREER: How does external photoevaporation shape planets?

观测显示，围绕太阳以外的恒星运行的行星种类繁多。行星形成于新生恒星周围的气体和尘埃盘，但随着恒星年龄的增长，盘会消失，这限制了行星形成的机会。圆盘可能会螺旋进入中心恒星，或者通过新生恒星的光子从内到外蒸发。然而，来自附近更亮的恒星的外部光蒸发可以更快地破坏圆盘，减少制造行星的时间和材料。虽然这种现象已经在一些物体上被观察到，但这个项目将量化这种外部光蒸发是否在行星形成的故事中起主要作用。莱斯大学（Rice University）的梅根·瑞特（Megan Reiter）博士和她的研究伙伴利用大量年轻星团的数据集，将测量这些圆盘本身、撞击它们的星光以及从它们流出的物质。与此同时，一项鼓励进入和坚持STEM领域的教育计划将分两部分实施：为休斯顿K-12学校提供主动学习的教师培训和天文学启发课程，并将基础技能添加到莱斯大学的观测实验室课程中；这些干预措施将优先帮助历史上代表性不足的群体。为了量化这种环境对行星形成的影响，瑞特博士使用欧洲南方天文台甚大望远镜上的积分场单位光谱仪MUSE获得了100多个小时的望远镜时间。其目标是在质量至少为太阳1000倍的高质量恒星形成区域中观测数千颗低质量恒星及其盘——这是一个比现有研究大100倍的样本。这些数据清晰地将恒星发射与明亮、多变的星云背景分离开来。光谱诊断显示活跃的外部光蒸发和量化质量损失率。将推导出入射紫外线通量和外盘光蒸发之间的比例关系，这在理论学家模拟行星的人口统计特征时很有用。当30米级的地面望远镜可用时，这项工作所开发的方法和支持的天文学专业人员将有很高的需求。教育干预将包括价值参与评估，这是一种测试更新的教学法是否能提高莱斯大学及其他学校STEM课程的保留率的新方法。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。

Observations have revealed a remarkable diversity of planets orbiting stars other than the Sun. Planets form in disks of gas and dust around newborn stars, but disks disappear as the stars age, limiting the opportunity for planets to form. Disks may spiral into the central star or evaporate from the inside-out via the newborn star’s photons. However, external photoevaporation from a nearby, much brighter star can destroy disks more quickly, reducing the time and materials to make planets. While this phenomenon has been observed in a few objects, this project will quantify whether such external photoevaporation is a major player in this story of planet formation. Leveraging a large dataset of young star clusters, Dr. Megan Reiter of Rice University and her research associates will measure the disks themselves, starlight impinging on them, and matter streaming away from them. In parallel, an educational program to encourage entrance and persistence in STEM fields will be implemented in two parts: an active-learning teacher training and astronomy-inspired curriculum for Houston K-12 schools, and foundational skills will be added to observational lab courses at Rice University; these interventions will preferentially help historically underrepresented groups.To quantify this environmental impact on planet formation, Dr. Reiter has secured more than 100 hours of telescope time using the integral field unit spectrograph MUSE on the European Southern Observatory's Very Large Telescope. The goal is to observe thousands of low-mass stars and their disks in high-mass star-forming regions of at least 1000 times the mass of the Sun – a sample 100 times larger than existing studies. These data cleanly separate stellar emission from the bright, variable nebular background. Spectral diagnostics indicate active external photoevaporation and quantify the mass-loss rate. A scaling relationship between incident UV flux and external disk photoevaporation will be derived, useful when theorists model the demographics of planets. The methods developed and astronomy professionals supported by this work will be in high demand when 30-meter class ground-based telescopes become available. The educational intervention will include value-engaged evaluation, a new way to test whether updated pedagogy improves retention in STEM courses at Rice and beyond.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.