标题： 2012-2014年凯克望远镜和Gemini自适应光学成像的高信噪比观测：新云模式、活跃度增加以及风速测量的改进 显示英文标题

标题： High S/N Keck and Gemini AO imaging of Uranus during 2012-2014: New cloud patterns, increasing activity, and improved wind measurements

摘要： 我们使用凯克/NIRC2相机和双子座/NIRI相机（两者均配备自适应光学系统）于2012年至2014年期间对天王星的近红外波段进行了成像。通过在与行星固定坐标系相关的平均8到16次单独曝光，我们获得了极高的信噪比。去噪后的图像揭示了许多之前未见的低对比度离散特征和大规模云模式，包括赤道以南出现的锯齿状波形。在三年中的每一年里，在北极地区（北纬55\deg 以上）都观测到了许多主要为明亮的小型（直径约600-700公里）离散特征。共进行了超过850次风速测量，其中绝大多数是在北半球进行的。这些测量结果显示，在北纬62\deg 至至少北纬83\deg 范围内存在一个广大的刚体旋转区域，相对于行星内部（无线电）自转速度20.88\deg /小时向西旋转，该区域以4.08$\pm0.015$\deg /小时的速度向西旋转。 在赤道附近以高精度测量到的速度对波和小的离散特征给出了不同的结果，东向漂移率分别为 0.4\deg /h 和 0.1\deg /h。 极地刚体旋转区域与小尺度极地云特征区域非常吻合，表明两者存在动力学关系。 虽然南半球高纬度地区（50\deg S - 90\deg S）的风速无法通过地面观测约束，但 Karkoschka（2015年，Icarus 250, 294-307）对1986年旅行者2号观测数据的重新分析揭示了该区域存在极大的南北不对称性，这可能是季节性的。 2014年观察到了显著增强的活动，包括在 K' 波段图像中观测到的最亮特征（de Pater 等人，2015年，Icarus 252, 121-128）。 在2012年至2014年期间，我们识别出了六个持续存在的离散特征。其中三个被追踪超过两年，另外两个被追踪超过一年，还有一个至少被追踪了五个月并且仍在继续追踪。 显示英文摘要

摘要： We imaged Uranus in the near infrared from 2012 into 2014, using the Keck/NIRC2 camera and Gemini/NIRI camera, both with adaptive optics. We obtained exceptional signal to noise ratios by averaging 8-16 individual exposures in a planet-fixed coordinate system. noise-reduced images revealed many low-contrast discrete features and large scale cloud patterns not seen before, including scalloped waveforms just south of the equator. In all three years numerous small (600-700 km wide) and mainly bright discrete features were seen within the north polar region (north of about 55\deg N). Over 850 wind measurements were made, the vast majority of which were in the northern hemisphere. These revealed an extended region of solid body rotation between 62\deg N and at least 83\deg N, at a rate of 4.08$\pm0.015$\deg/h westward relative to the planet's interior (radio) rotation of 20.88\deg/h westward. Near-equatorial speeds measured with high accuracy give different results for waves and small discrete features, with eastward drift rates of 0.4\deg/h and 0.1\deg/h respectively. The region of polar solid body rotation is a close match to the region of small-scale polar cloud features, suggesting a dynamical relationship. While winds at high southern latitudes (50\deg S - 90\deg S) are unconstrained by groundbased observations, a recent reanalysis of 1986 Voyager 2 observations by Karkoschka (2015, Icarus 250, 294-307) has revealed an extremely large north-south asymmetry in this region, which might be seasonal. Greatly increased activity was seen in 2014, including the brightest ever feature seen in K' images (de Pater et al. 2015, Icarus 252, 121-128). Over the 2012-2014 period we identified six persistent discrete features. Three were tracked for more than two years, two more for more than one year, and one for at least 5 months and continuing.