Identification of the OGLE-2003-BLG-235/MOA-2003-BLG-53 Planetary Host Star
Identification of the OGLE-2003-BLG-235/MOA-2003-BLG-53 Planetary Host Star
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DOI：
10.1086/507585
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发表时间：
2006-06
期刊：
影响因子：
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通讯作者：
D. Bennett;Jay Anderson;I. Bond;A. Udalski;A. Gould
中科院分区：
文献类型：
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作者：
D. Bennett;Jay Anderson;I. Bond;A. Udalski;A. Gould
我们介绍了HST观测到的第一颗由微透镜探测到的太阳系外行星的主恒星的结果。该事件的光曲线模型预测，在HST成像时，透镜星应该与源星相隔约6 mas。如果透镜恒星是晚期G， K或早期M矮星，那么它将在HST图像中作为与源图像混合的额外光源可见。除非透镜和光源具有完全相同的颜色，否则它的存在也将通过在不同滤光带中源和透镜的质心之间的系统移动而显示出来。HST数据表明了这两种效应：与源星位置匹配的HST源在ACS/HRC F814W滤光片中比微透镜模型预测的要亮0.21等，并且该源的质心在F814W和F435W滤光片波段之间存在~0.7 ma的偏移。我们的结论是，在这些HST图像中已经检测到行星主恒星，并且这种透镜恒星的识别使得透镜系统的完整解决方案成为可能。透镜参数是通过贝叶斯分析确定的，平均测量参数的不确定性，星际消光，并考虑到源星的双星伴星的可能性。这产生了恒星质量M* = 0.63 M☉和行星质量Mp = 2.6MJ，轨道距离为4.3 AU。因此，透镜系统类似于我们自己的太阳系，有一颗~3MJ的行星在类似木星的轨道上围绕一颗M☉恒星运行。这些结论可以用未来的HST图像进行验证，这些图像应该会显示出由于透镜-光源的相对固有运动，混合源-透镜点扩展函数的展宽。
We present the results of HST observations of the host star for the first definitive extrasolar planet detected by microlensing. The light-curve model for this event predicts that the lens star should be separated from the source star by ~6 mas at the time of the HST images. If the lens star is a late G, K, or early M dwarf, then it will be visible in the HST images as an additional source of light that is blended with the source image. Unless the lens and source have exactly the same colors, its presence will also be revealed by a systematic shift between centroids of the source plus lens in different filter bands. The HST data indicate both of these effects: the HST source that matches the position of the source star is 0.21 mag brighter in the ACS/HRC F814W filter than the microlensing model predicts, and there is an offset of ~0.7 mas between the centroid of this source in the F814W and F435W filter bands. We conclude that the planetary host star has been detected in these HST images, and this identification of the lens star enables a complete solution of the lens system. The lens parameters are determined with a Bayesian analysis, averaging over uncertainties in the measured parameters, interstellar extinction, and allowing for the possibility of a binary companion to the source star. This yields a stellar mass of M* = 0.63 M☉ and a planet mass of Mp = 2.6MJ at an orbital separation of 4.3 AU. Thus, the lens system resembles our own solar system, with a planet of ~3MJ in a Jupiter-like orbit around a star of M☉. These conclusions can be tested with future HST images, which should reveal a broadening of the blended source-plus-lens point-spread function due to the relative lens-source proper motion.