Measuring the mass and time available to form planets

行星在我们的银河系中无处不在，它们所在的系统通常与我们自己的太阳系不同，而且比最初理论模型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，这种多样性的部分原因是年轻恒星周围的恒星圆盘的性质，年轻恒星是行星的诞生地。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恒星周盘的两个基本性质，其中一个来自阿塔卡马大毫米阵列，这是NSF支持的一个国际设施。这项研究在获得的灵敏度和团队将应用于均匀计算恒星和盘性质的方法上都超出了最先进的水平。在解决美国2010年天文学和行星科学十年调查中发现的关键问题的同时，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。该小组将进一步促进增加目前代表不足的群体获得STEM教育的机会，开发一个K-12教师讲习班，将接触到西班牙裔和美洲原住民社区。环绕恒星的盘质量和盘物质在中央恒星上吸积的速度是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央恒星质量之间的标度定律。为了做到这一点，我们将分析用阿塔卡马大毫米阵列(ALMA)获得的一个独特的数据集，并测量星盘质量及其在恒星质量40英寸范围内的固有扩散。该团队还将分析每个ALMA目标的灵敏中分辨率光谱，并使用新开发的技术来确定准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。在推进研究的同时，该团队将培训学生，并开展K-12教师研讨会和动手活动，以调查教师可以在课堂上使用的宜居性和行星探测方法。

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.