Exploring the Galaxy: 3-Dimensional Structure and Stellar Streams

研究人员使用了对近10亿颗恒星的泛星一号探测(PS1)绘制了我们银河系中的尘埃和气体地图。基于这些恒星的颜色，研究人员开创了一种非常准确地测量银河系旋臂中尘埃和气体的方法。尘埃使星光变红，原因与落日是红色的原因相同。天文学家使用这张地图来确定到各种物体的距离，并校正尘埃对他们数据的影响。研究人员将在北部天空扩展他们的第一项工作，使用一种新的南方天空测量来绘制整个银河系的三维结构。研究人员计划通过以一种新的方式平均数据来提高他们地图的准确性。所有地图都将公开发布，并将为3-D变红估计、恒星流搜索和其他银河系结构工作提供具有巨大价值的遗留数据集。在创建第一代三维尘埃地图的过程中，研究人员发现了一些技术改进，如空间正则化，这将增强地图的定量可靠性。下一个贴图不是单独计算贴图的每个像素，而是组合来自相邻像素的信息以稳定适配，并允许较小的像素(角度和距离)和较低的噪波。新的地图还将包括关于观测选择功能和银河系先例的详细信息，以便能够估计每个体积元素中每种类型的恒星的数量。加入盖亚的自然运动和视差将稳定3-D拟合并增加地图的保真度。数据的及时发布促进了知识的进步，研究人员拥有追溯到第一张尘埃地图的数据发布的良好记录。第一代三维地图已经导致了分子云距离目录的发布。综合(沿着每一条视线)地图已经与基于排放的地图进行了测试，发现两者吻合得很好。这里提出的改进的尘埃和恒星的“第二代”地图将是一个强大的银河系结构探测器，并可能导致发现新的潮汐流、圆盘扭曲和其他有助于我们理解银河系动力学的特征。此外，这些地图将为直接计算6-D辐射场(每个地方、每个方向、每个能量的辐射量)的长期目标提供基础。

The investigators have used the Pan-STARRS-1 survey (PS1) of nearly 1 billion stars to map the dust and gas in our galaxy. Based on the colors of these stars, the investigators have pioneered a method to very accurately measure the dust and gas in the spiral arms of our galaxy. Dust reddens starlight, for the same reason that sunsets are red. Astronomers use this map to determine distances to various objects, and to correct for the effects of dust on their data. The investigators will expand their first work, over the northern sky, using a new southern sky survey to map the 3-dimensional (3-D) structure of the entire galaxy. The investigator has a plan for improving the accuracy of their map, through averaging the data in a new way.All maps will be publicly released and will provide a legacy dataset of enormous value for 3-D reddening estimates, stellar stream searches, and other Galactic structure work. They will be available to the general public via the World-Wide Telescope interface, which has over 10 million unique users.In the process of creating the first-generation 3-D dust map the investigator has identified technical improvements, such as spatial regularization, that would enhance the quantitative reliability of the map. Rather than computing each pixel of the map independently, the next map will combine information from neighboring pixels to stabilize the fit and allow smaller pixels (both angle and distance) with lower noise. The new map will also incorporate detailed information on the observational selection function and Galactic priors to make possible an estimate of the number of stars of every type in every volume element. Inclusion of proper motions and parallaxes from Gaia will stabilize the 3-D fit and increase the fidelity of the map.Timely data releases spur the advancement of knowledge, and the investigator has a strong record of data releases date back to the first dust maps. The first-generation 3-D map has already resulted in the release of a molecular cloud distance catalog. The integrated (along each line of sight) map has been tested against emission-based maps and found to agree well. The improved "second-generation" maps of dust and stars proposed herein will be a powerful probe of Galactic structure, and may lead to discoveries of new tidal streams, disk warps, and other features that help us understand Galactic dynamics. Additionally these maps will provide a foundation for the longer-term goal of a direct calculation of the 6-D radiation field (amount of radiation at every place, in every direction, at every energy).