The Mass Function and Galactic Distribution of Cool Planets from Microlensing

对围绕其他恒星运行的行星(系外行星)的搜索发现了数千个围绕各种恒星运行的行星系统。这些调查中的大多数只能探测到与木星轨道类似或更小的相对较小轨道上的行星。此外，到目前为止，已知的拥有行星的恒星中的绝大多数都离太阳相对较近。因此，人们对行星系统的外部区域知之甚少，对银河系中更远的行星的分布也几乎一无所知。微透镜可以解决这个问题。微透镜可以解决这个问题。微透镜是指一颗遥远的恒星与一个巨大而致密的前景物体充分对准，由于其引力场而使其光线弯曲，从而产生可观察到的放大倍数。另一方面，对系外行星的微透镜观测对太阳系外部的冷的、低质量的行星很敏感。此外，微透镜对我们银河系中各种环境中的行星都很敏感。这可能是检测自由漂浮行星是否存在的唯一方法。该团队将开发微透镜方法，并使用它们来确定不围绕主星运行的行星的性质和银河系分布。这项工作依赖于业余天文学社区的观测，该团队将组织一个国际研讨会，将业余和专业社区聚集在一起。该计划是理论和观测工作的结合，旨在开发测量大量和广泛微透镜行星样本的质量和距离的方法。COPIS和他们的学生将：1)开发测量微透镜视差效应的方法，这为测量微透镜的质量和距离提供了最可靠的方法。使用两个斯皮策运动的结果，总计超过900小时，他们将研究所有类型的微透镜视差测量方法的现象学。(2)发展对微透镜视差效应的统一、全面的认识。这种各种方法的综合将使视差测量成为可能，从而能够对大范围的行星系统样本进行质量和距离估计。(3)继续领导微透镜后续网络通过监测高倍率微透镜事件寻找太阳系外行星的工作。

Searches for planets orbiting other stars (exoplanets) have discovered thousands of planetary systems orbiting a wide variety of stars. Most of these surveys are only able to detect planets on relatively small orbits similar to that of Jupiter or smaller. Furthermore, the vast majority of the stars so far known to host planets are relatively close to the Sun. Therefore, little is known about the outer regions of planetary systems, and almost nothing is known about the distribution of planets farther away in the galaxy. Microlensing, which occurs when a distant star gets sufficiently aligned with a massive compact foreground object to bend its light due to its gravitational field, resulting in an observable magnification, can address this. Microlensing surveys for exoplanets, on the other hand, are sensitive to cool, low-mass planets in the outer parts of solar systems. Furthermore, microlensing is sensitive to planets in a range of environments in our Milky Way galaxy. It is perhaps the only way to detect whether free-floating planets exist. This team will develop microlensing methods and use them to determine the properties and Galactic distribution of planets that do not orbit close to a host star. This work relies on observations from the amateur astronomy community, and this team will organize an international workshop to bring the amateur and professional communities together.This program is a combination of theoretical and observational work to develop methods to measure the mass and distance to a large and broad sample of microlens planets. The CoPIs and their students will: 1) Develop methods to measure the microlens parallax effect, which provides the most robust way to measure the mass of and distance to microlenses. Using the results from two Spitzer campaigns totalling over 900 hours, they will study the phenomenology of all types of microlens parallaxes measurement methods. (2) Develop a unified, comprehensive understanding of the microlens parallax effect. This synthesis of various methods will enable parallax measurements, and thus mass and distance estimates, for a large and broad sample of planetary systems. (3) Continue to lead the Microlensing Follow Up Network effort to find extra-solar planets by monitoring high-magnification microlensing events.