Measuring the mass and time available to form planets

行星在我们的银河系中无处不在，它们所在的系统往往与我们的太阳系不同，而且比理论模型最初预测的要多样化得多。这种多样性的起源是什么？目前的数据表明，这种多样性部分源于年轻恒星（行星的诞生地）周围的星周盘的特性。作为NSF调查的一部分，该团队将通过分析两个独特的数据集来测量星周盘的两个基本特性，其中一个数据集来自由NSF支持的国际设施阿塔卡马大型毫米波阵列。这项研究在达到的灵敏度和团队将应用于均匀计算恒星和磁盘属性的方法方面都超越了最先进的技术。在解决美国2010年天文学和行星科学十年调查中确定的关键问题的同时，这项工作将通过让研究生和本科生参与拟议的活动来促进教育和培训。该团队将通过开发一个面向西班牙裔和美洲原住民社区的K-12教师研讨会，进一步为目前代表性不足的群体提供更多接受STEM教育的机会。星周圆盘的质量和圆盘物质吸积到中心恒星上的速率是圆盘演化和行星形成模型的两个最基本的参数。作为这项研究的一部分，我们将建立这两个量与中心恒星质量之间的标度定律。为此，我们将分析由阿塔卡马大型毫米波阵列（ALMA）获得的独特数据集，并测量磁盘质量及其在40倍恒星质量范围内的固有分布。该团队还将分析每个ALMA目标的敏感的中分辨率光谱，并采用新开发的技术来确定精确的恒星质量和吸积率。这些结果将为行星形成的理论模型提供关键的输入，并有助于理解系外行星系统的多样性。随着研究的推进，该团队将培训学生并开发K-12教师研讨会和实践活动，以调查教师可以在课堂上使用的可居住性和行星探测方法。

Planets are ubiquitous in our Galaxy, in systems often different from our own Solar System and far more diverse than originally predicted by theoretical models. What is the origin of this diversity? Current data suggest that part of this diversity arises from the properties of circumstellar disks around young stars, the birth sites of planets. As part of this NSF investigation the team will measure two fundamental properties of circumstellar disks by analyzing two unique datasets, one of which comes from the Atacama Large Millimeter Array, an international facility supported by NSF. This investigation goes beyond the state-of-the-art both in the achieved sensitivity and in the methods the team will apply to homogeneously compute stellar and disk properties. While addressing key questions identified in the United States' 2010 Astronomy and Planetary Science Decadal surveys, the work will advance education and training by involving both graduate and undergraduate students in the proposed activities. The team will further contribute to increasing access for currently underrepresented groups to STEM education by developing a K-12 teacher workshop that will reach out to Hispanic and Native American communities.The masses of circumstellar disks and the rate at which disk material is accreted onto the central star are the two most fundamental parameters of disk evolution and planet formation models. As part of this investigation we will establish the scaling laws between these two quantities and the mass of the central star. To do that we will analyze a unique dataset obtained with the Atacama Large Millimeter Array (ALMA) and measure disk masses and their intrinsic spread over a range of 40 in stellar mass. The team will also analyze sensitive medium-resolution optical spectra for each of the ALMA targets and employ newly developed techniques to determine accurate stellar masses and accretion rates. The results will provide critical inputs to theoretical models of planet formation and help understanding the diversity of exoplanetary systems. Along with advancing research, the team will train students and develop a K-12 teacher workshop and hand-on activities to investigate habitability and methods for planet detection that teachers can use in the classroom.