CAREER: How does external photoevaporation shape planets?

观测显示，除了太阳以外，围绕恒星运行的行星种类繁多。行星在新生恒星周围形成由气体和尘埃组成的圆盘，但随着恒星的老化，圆盘消失，限制了行星形成的机会。圆盘可能螺旋进入中央恒星，或通过新生恒星的光子由内而外蒸发。然而，来自附近明亮得多的恒星的外部光蒸发可以更快地摧毁圆盘，减少制造行星的时间和材料。虽然在少数天体中观察到了这种现象，但这个项目将量化这种外部光蒸发是否是行星形成故事中的主要参与者。利用年轻星团的大型数据集，莱斯大学的梅根·赖特博士和她的研究伙伴们将自己测量这些星盘，测量照射到它们上面的星光，以及从它们流出的物质。与此同时，一项鼓励进入STEM领域并坚持下去的教育计划将分两部分实施：针对休斯顿K-12学校的主动学习教师培训和以天文学为灵感的课程，基本技能将被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。为了量化这种对行星形成的环境影响，赖特博士利用欧洲南方天文台甚大望远镜上的积分野外单元光谱仪缪斯获得了100多个小时的望远镜时间。目标是在质量至少是太阳1000倍的大质量恒星形成区观测数千颗低质量恒星及其圆盘--这个样本比现有研究大100倍。这些数据清楚地将恒星发射与明亮、多变的星云背景分开。光谱诊断显示活跃的外部光蒸发，并量化质量损失率。入射紫外光通量和外盘光蒸发之间的比例关系将被推导出来，这在理论家对行星的人口统计进行建模时很有用。当30米级地面望远镜问世时，这项工作所开发的方法和支持的天文学专业人员将受到高度需求。教育干预将包括价值参与评估，这是一种新的方式来测试更新的教学法是否提高了在莱斯和其他地方的STEM课程的留存率。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.