MICROLENSING ZONE OF PLANETS DETECTABLE THROUGH THE CHANNEL OF HIGH-MAGNIFICATION EVENTS
MICROLENSING ZONE OF PLANETS DETECTABLE THROUGH THE CHANNEL OF HIGH-MAGNIFICATION EVENTS
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可通过高倍率事件通道探测到的行星微透镜区
DOI：
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发表时间：
2008
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通讯作者：
C. Han
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文献类型：
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作者：
C. Han
微透镜区指的是行星与恒星之间的距离，在这个距离内，探测到行星信号的概率很高。它的传统定义是主透镜的爱因斯坦半径在0.6到1.6之间，这是基于行星引起的主焦散应位于主透镜的爱因斯坦环内的标准。然而，目前的行星透镜搜索的重点是高放大率的事件，以检测扰动引起的另一个焦散总是位于爱因斯坦环非常接近的主要透镜（恒星焦散），因此需要一个新的定义的透镜区。在本文中，我们确定这个透镜区。通过应用一个标准，可检测的行星应产生信号的105%，我们发现，新的透镜区不同的行星/星星质量比的固定范围的经典区，无论质量比。对于行星/星星质量比为q 3 × 10−4的行星来说，透镜区相当于经典区，而对于较重的行星来说，透镜区会变得更宽。对于木星质量的行星，透镜区的范围为0.25至3.9爱因斯坦半径，对应于典型银河系事件的物理范围在0.5至7.4 Au之间。巨行星中心摄动的透镜区较宽，这意味着微透镜方法为探测由多颗冰巨行星组成的行星系统提供了重要工具。
A microlensing zone refers to the range of planet–star separations where the probability of detecting a planetary signal is high. Its conventional definition as the range between ∼0.6 and 1.6 Einstein radii of the primary lens is based on the criterion that a major caustic induced by a planet should be located within the Einstein ring of the primary lens. However, current planetary lensing searches focus on high-magnification events to detect perturbations induced by another caustic always located within the Einstein ring very close to the primary lens (stellar caustic) and thus a new definition of a lensing zone is needed. In this paper, we determine this lensing zone. By applying a criterion that detectable planets should produce signals ⩾5%, we find that the new lensing zone varies depending on the planet/star mass ratio unlike the fixed range of the classical zone regardless of the mass ratio. The lensing zone is equivalent to the classical zone for a planet with a planet/star mass ratio q ∼ 3 × 10−4 and becomes wider for heavier planets. For a Jupiter-mass planet, the lensing zone ranges from 0.25 to 3.9 Einstein radii, corresponding to a physical range between ∼0.5 and 7.4 AU for a typical Galactic event. The wider lensing zone of central perturbations for giant planets implies that the microlensing method provides an important tool to detect planetary systems composed of multiple ice-giant planets.