Demographics of the Youngest Protostars and their Disks

帕特里克·希恩被授予美国国家科学基金会天文学和天体物理学博士后奖学金，在西北大学开展一个研究和教育项目。他将研究圆盘的结构和性质，圆盘是在太空中的气体和尘埃云坍缩形成原恒星时形成的。观测证据表明，行星及其前体在恒星形成初期就形成了，这个项目的结果将使天文学家了解行星形成的速度有多快。除了这项研究，Sheehan还将开展一个暑期教育项目，旨在为高中生提供编程、数据分析和天文研究方面的经验。最近对几乎每颗1-5迈前主序星周围的原行星盘的亚结构的观察表明，这些盘可能已经经历了大量的行星或星子的形成。为了了解重大尘埃处理或行星形成之前的初始条件，该项目将利用从厘米到亚毫米波长的非常高的角分辨率进行观测，研究较年轻的圆盘（1 Myr）及其中心原恒星的结构。观测将包括金牛座恒星形成区域的每一个已知的原恒星盘，使Sheehan能够对气体和尘埃的结构以及早期尘埃颗粒的生长进行限制。希恩还将利用高分辨率成像技术研究猎户座恒星形成区域中已知的年轻盘群，这些盘的亚结构可能与早期行星形成有关。最后，他将直接测量年轻原恒星的动态质量，将这些圆盘置于其恒星的背景下，并对主序前演化轨迹进行强有力的约束。这个项目将产生最大的直接测量原恒星质量的样本，测量结果将提供关于磁盘质量如何依赖于原恒星质量的信息。由此产生的综合图像将促进我们对行星在圆盘中形成的可能性的理解，以及形成行星的精确位置。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。

Patrick Sheehan is awarded an NSF Astronomy and Astrophysics Postdoctoral Fellowship to conduct a program of research and education at Northwestern University. He will study the structures and properties of disks, which are formed when clouds of gas and dust in space collapse to form protostars. Observational evidence suggests that planets and their precursors are formed very early during the onset of star formation, and the results from this project will allow astronomers to understand just how soon planet formation begins. Along with this research, Sheehan will conduct a summer educational program designed to provide experience in programming, data analysis, and astronomical research to high school students.Recent observations of substructures in protoplanetary disks surrounding nearly every 1-5 Myr-old pre-main sequence star suggest that these disks may already have undergone a significant amount of planet or planetesimal formation. To understand the initial conditions before significant dust processing or planet formation has occurred, this project will investigate the structures of younger disks ( 1 Myr old) and their central protostars using observations done at very high angular resolution from centimeter to submillimeter wavelengths. The observations will include every known protostellar disk in the Taurus star-forming region, enabling Sheehan to place constraints on the structure of gas and dust and on the growth of early dust grains. Sheehan will also use high-resolution imaging to study a known population of young disks in the Orion star-forming region with substructures possibly related to early planet formation. Finally, he will directly measure the dynamical masses of young protostars to place these disks within the context of their stars and place robust constraints on pre-main sequence evolutionary tracks. This project will generate the largest sample of directly measured protostellar masses, and the measurements will provide information on how disk mass depends on protostellar mass. The resulting comprehensive picture will advance our understanding of the potential for planet formation in disks, as well as the precise location of the forming planets.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.