标题： 微引力透镜中环双星行星的焦散结构与探测性 显示英文标题

标题： Caustic Structures and Detectability of Circumbinary Planets in Microlensing

摘要： 开普勒数据中近期发现的环绕双星的行星表明，在主序双星周围存在可行的行星形成通道。 受这些发现的启发，我们研究了微引力透镜事件中环绕双星的行星的焦散结构和可探测性。 我们生成了一系列焦散结构的动画，作为双星宿主投影分离度和角度的函数，以高效地探索整个环绕双星参数空间中的焦散结构。 借助这些动画，我们推导出了一个半经验的解析表达式，用于计算环绕双星透镜中行星焦散的位置，这些位置与单宿主行星的焦散位置不同。 我们利用这个表达式证明，焦散运动的主要来源将是行星的轨道运动，而非双星宿主的运动。 最后，我们估计，在爱因斯坦半径单位范围内投影分离度为0.1到0.5的环绕双星微引力透镜事件中，能够被识别为这类事件的比例是显著的（5%-50%）。 显示英文摘要

摘要： Recent discoveries of circumbinary planets in Kepler data show that there is a viable channel of planet formation around binary main sequence stars. Motivated by these discoveries, we have investigated the caustic structures and detectability of circumbinary planets in microlensing events. We have produced a suite of animations of caustics as a function of the projected separation and angle of the binary host to efficiently explore caustic structures over the entire circumbinary parameter space. Aided by these animations, we have derived a semi-empirical analytic expression for the location of planetary caustics, which are displaced in circumbinary lenses relative to those of planets with a single host. We have used this expression to show that the dominant source of caustic motion will be due to the planet's orbital motion and not that of the binary star. Finally, we estimate the fraction of circumbinary microlensing events that are recognizable as such to be significant (5-50 percent) for binary projected separations in the range 0.1-0.5 in units of Einstein radii.