KMT-2021-BLG-1898: Planetary microlensing event involved with binary source stars
KMT-2021-BLG-1898: Planetary microlensing event involved with binary source stars
复制标题
KMT-2021-BLG-1898：涉及双源恒星的行星微透镜事件
DOI：
10.1051/0004-6361/202243102
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发表时间：
2022
影响因子：
6.5
通讯作者：
Shin, In-Gu
中科院分区：
文献类型：
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作者：
Han, Cheongho;Gould, Andrew;Kim, Doeon;Jung, Youn Kil;Albrow, Michael D.;Chung, Sun-Ju;Hwang, Kyu-Ha;Lee, Chung-Uk;Ryu, Yoon-Hyun;Shin, In-Gu
微透镜事件KMT-2021-BLG-1898的光变曲线表现出短期的中心异常，具有双凸特征，无法用通常的二元透镜或二元源解释来解释。为了解释这一异常现象，我们分析了各种复杂models.MethodsWe下的透镜光变曲线，发现这一异常现象可以用一个模型来解释，其中透镜和光源都是双星（2L 2S模型）。根据这种解释，透镜是一个行星系统，行星/宿主质量比为q ~ 1.5 × 10−3，而源是一个由一颗关闭或亚巨星星星和一颗中K矮星组成的双星。异常的双凸特征也可以用三重透镜模型（3L 1 S模型）来描述，其中的透镜是一个包含两颗行星的行星系统。在这两种解释中，2L 2S模型比3L 1 S模型更受青睐，不仅因为它产生了更好的数据拟合，即2 × 2=[14.3−18.5]，而且从双星源的两颗恒星独立得出的爱因斯坦半径也得到了一致的值。根据2L 2S解释，KMT-2021-BLG-1898是继MOA-2010-BLG-117和KMT-2018-BLG-1743之后发生在双星系统中的第三个行星透镜事件。根据贝叶斯分析，我们估计这颗行星的质量约为0.7 - 0.8 MJ，它围绕着一颗质量约为0.5 M的早期M矮星。根据封闭解和宽解，预计行星与宿主的距离分别为~1.9 Au和~3.0 Au。
AimsThe light curve of the microlensing event KMT-2021-BLG-1898 exhibits a short-term central anomaly with double-bump features that cannot be explained by the usual binary-lens or binary-source interpretations. With the aim of interpreting the anomaly, we analyze the lensing light curve under various sophisticated models.MethodsWe find that the anomaly is explained by a model, in which both the lens and source are binaries (2L2S model). For this interpretation, the lens is a planetary system with a planet/host mass ratio ofq~ 1.5 × 10−3, and the source is a binary composed of a turn off or a subgiant star and a mid K dwarf. The double-bump feature of the anomaly can also be depicted by a triple-lens model (3L1S model), in which the lens is a planetary system containing two planets. Among the two interpretations, the 2L2S model is favored over the 3L1S model not only because it yields a better fit to the data, by ∆χ2=[14.3−18.5], but also the Einstein radii derived independently from the two stars of the binary source result in consistent values. According to the 2L2S interpretation, KMT-2021-BLG-1898 is the third planetary lensing event occurring on a binary stellar system, following MOA-2010-BLG-117 and KMT-2018-BLG-1743.ResultsUnder the 2L2S interpretation, we identify two solutions resulting from the close-wide degeneracy in determining the planet-host separation. From a Bayesian analysis, we estimate that the planet has a mass of ~0.7−0.8MJ, and it orbits an early M dwarf host with a mass of ~0.5M⊙. The projected planet-host separation is ~1.9 AU and ~3.0 AU according to the close and wide solutions, respectively.