标题： 奥尔特云探测的有效观测策略 显示英文标题

标题： An efficient observational strategy for the detection of the Oort cloud

摘要： 奥尔特云可能是太阳系形成过程中遗留下来的原始遗迹。探测奥尔特云可能提供有关太阳诞生时的恒星环境以及外行星形成阶段星子群体的信息。目前最被推荐的探测奥尔特云天体的方法是通过这些天体对遥远恒星的亚秒级掩食来寻找它们。我们按照布朗和韦伯斯特的研究方向，讨论了通过观测接近正交方向来探测奥尔特云天体的可能性。由于地球的投影速度，在正交方向上的掩食时间较长，因此更容易探测到，但发生频率较低。我们表明，对于直径小于1米的望远镜，增加曝光时间将导致可探测恒星数量增加大约一到三个数量级，这些恒星的角直径小于弗雷斯内尔尺度，因此适合用于掩食搜索。我们讨论了这种方法使用现有巡天望远镜探测奥尔特云天体的能力，并估计了检测率作为奥尔特云天体大小分布幂律指数和它们与太阳距离的函数。我们显示，在正交点附近的最优区域内，使用直径小于1米的望远镜以约1秒积分时间检测到的掩食将主要由奥尔特云天体而非柯伊伯带天体主导。 显示英文摘要

摘要： The Oort cloud is presumably a pristine relic of the Solar System formation. Detection of the Oort cloud may provide information regarding the stellar environment in which the Sun was born and on the planetesimal population during the outer planets' formation phase. The best suggested approach for detecting Oort cloud objects in situ, is by searching for sub-second occultations of distant stars by these objects. Following Brown & Webster, we discuss the possibility of detecting Oort cloud objects by observing near the quadrature direction. Due to the Earth's projected velocity, the occultations are longer near the quadrature direction and are therefore easier to detect, but have lower rate. We show that, for <1-m size telescopes, the increased exposure time will result in about one to three orders of magnitude increase in the number of detectable stars that have an angular size smaller than the Fresnel scale and are therefore suitable for an occultation search. We discuss the ability of this method to detect Oort cloud objects using existing survey telescopes, and we estimate the detection rate as a function of the power-law index of the size distribution of the Oort cloud objects and their distance from the Sun. We show that occultations detected using ~1-s integration by <1-m telescopes at the optimal region near the quadrature points will be marginally dominated by Oort cloud objects rather than Kuiper belt objects.