Information about the spin state of asteroids is important for our understanding of the dynamical processes affecting them. However, spin properties of asteroids are known for only a small fraction of the whole population. To enlarge the sample of asteroids with a known rotation state and basic shape properties, we combined sparse-in-time photometry from the Lowell Observatory Database with flux measurements from NASA's WISE satellite. We applied the light curve inversion method to the combined data. The thermal infrared data from WISE were treated as reflected light because the shapes of thermal and visual light curves are similar enough for our purposes. While sparse data cover a wide range of geometries over many years, WISE data typically cover an interval of tens of hours, which is comparable to the typical rotation period of asteroids. The search for best-fitting models was done in the framework of the Asteroids@home distributed computing project. By processing the data for almost 75,000 asteroids, we derived unique shape models for about 900 of them. Some of them were already available in the DAMIT database and served us as a consistency check of our approach. In total, we derived new models for 662 asteroids, which significantly increased the total number of asteroids for which their rotation state and shape are known. For another 789 asteroids, we were able to determine their sidereal rotation period and estimate the ecliptic latitude of the spin axis direction. We studied the distribution of spins in the asteroid population. We revealed a significant discrepancy between the number of prograde and retrograde rotators for asteroids smaller than about 10 km. Combining optical photometry with thermal infrared light curves is an efficient approach to obtaining new physical models of asteroids.
Inversion of asteroid photometry from Gaia DR2 and the Lowell Observatory photometric database
小行星的自转特性（自转轴方向和自转周期）和粗略的形状模型，可以从它们的磁盘集成的亮度时，从各种观察几何测量重建。这些物理特性对于创建主带的结构和动力学演化的全球图像至关重要。形状和自旋模型的数量不仅可以在新数据可用时增加，而且可以通过组合独立的数据集并将它们反演在一起来增加。我们的目标是通过处理现有的光度测定法得出新的小行星模型。我们使用Lowell天文台测光数据库中编译的小行星测光，并使用Gaia Data Release 2中的测光。这两个数据源都可用于大约5400颗小行星。在Asteroids@home分布式计算项目的框架下，我们对每颗小行星应用光变曲线反演方法，以找到符合观测光度学的凸形模型和自旋状态。由于盖亚DR 2数据点数量有限，洛厄尔数据的光度精度较差，我们只能为大约1100颗小行星推导出独特的模型。然而，其中762个是新模型，大大扩大了目前约1600个小行星模型的数据库。我们的研究结果表明，一个综合的方法来反演小行星测光的重要性。虽然我们的模型一般同意通过单独反演洛厄尔和盖亚数据，组合反演更强大，模型参数更受约束，独特的模型可以重建在许多情况下，单独的数据集是不够的。
Asteroid shape inversion with light curves using deep learning
School of Physics, Zhejiang University of Technology（浙江工业大学物理学院）；Zhejiang University of Technology（浙江工业大学）；National Astronomical Observatories, Chinese Academy of Sciences（中国科学院国家天文台）
Asteroids@home - A BOINC distributed computing project for asteroid shape reconstruction
我们提出了Asteroids@home项目，该项目使用分布式计算来解决小行星形状重建的耗时逆问题。该项目使用Berkeley Open Infrastructure for Network Computing（BOINC）框架来分发、收集和验证小型计算单元，这些计算单元在连接到该项目的志愿者的个人计算机上独立求解。通过光变曲线反演方法，从小行星的盘积分测光中重建了小行星的自转、自转周期和自转轴方向。
Binary asteroid (31) Euphrosyne: Ice-rich and nearly spherical
小行星（31）Euphrosyne是小行星主带中最大的天体之一，Euphrosyne家族占据了主带外部一个高度倾斜的区域，成员数量非常多，这被解释为一次破坏性撞击事件的结果。这项自适应光学成像研究的目标有三个方面：描述Euphrosyne的形状，限制其密度，并寻找可能与家族形成事件相关的大型陨石坑。作为我们大型项目（ID：199.C-0074，PI：Vernazza）的一部分，我们在ESO的8.2 m VLT上使用SPHERE/ZIMPOL获得了Euphrosyne的磁盘分辨率图像。我们重建了它的三维形状使用亚当形状建模算法的基础上SPHERE图像和可用的光变曲线的小行星。我们分析了卫星的动力学与基因型元启发式算法。最后，我们用流体静力学平衡模型研究了Euphrosyne的形状。我们的SPHERE观测表明，Euphrosyne具有近似球形的形状，球度指数为0.9888，其表面没有大型撞击坑。Euphrosyne的直径为268+/-6公里，使其成为十大主带小行星之一。我们探测到Euphrosyne的一颗卫星-- S/2019（31）1--直径约4公里，位于圆形轨道上。由卫星轨道确定的质量和由形状模型计算的体积意味着其密度为1665+/-242 kg/m^3，这表明Euphrosyne内部可能含有很大一部分水冰。我们发现，Euphrosyne的球形形状是撞击后再积累过程的结果，就像（1…
