K2-264: a transiting multiplanet system in the Praesepe open cluster
K2-264: a transiting multiplanet system in the Praesepe open cluster
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DOI：
10.1093/mnras/sty3464
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发表时间：
2018-09
影响因子：
4.8
通讯作者：
J. Livingston;F. Dai;T. Hirano;D. Gandolfi;A. Trani;G. Nowak;W. Cochran;M. Endl;S. Albrecht;O. Barragán;J. Cabrera;S. Csizmadia;J. D. de Leon-J.-D.-de Leon-2126297755;H. Deeg;P. Eigmüller;A. Erikson;M. Fridlund;A. Fukui;S. Grziwa;E. Guenther;A. Hatzes;J. Korth;M. Kuzuhara;P. Montañés;N. Narita;D. Nespral;E. Pallé;M. Pätzold;C. Persson;J. Prieto-Arranz;H. Rauer;M. Tamura;V. Van Eylen-V.-Van Eylen-2126247821;J. Winn
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文献类型：
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作者：
J. Livingston;F. Dai;T. Hirano;D. Gandolfi;A. Trani;G. Nowak;W. Cochran;M. Endl;S. Albrecht;O. Barragán;J. Cabrera;S. Csizmadia;J. D. de Leon-J.-D.-de Leon-2126297755;H. Deeg;P. Eigmüller;A. Erikson;M. Fridlund;A. Fukui;S. Grziwa;E. Guenther;A. Hatzes;J. Korth;M. Kuzuhara;P. Montañés;N. Narita;D. Nespral;E. Pallé;M. Pätzold;C. Persson;J. Prieto-Arranz;H. Rauer;M. Tamura;V. Van Eylen-V.-Van Eylen-2126247821;J. Winn
年龄受到很好限制的主行星恒星为了解行星形成和演化的时间域提供了一个罕见的窗口。美国国家航空航天局的K2任务已经发现了绝大多数已知的恒星凌日星团，为已知年龄和半径的行星提供了一个宝贵的样本。这两颗行星的轨道周期分别为5.8d和19.7d，半径分别为2.22±0.2R⊕和2.7R±0.2K，平衡温度分别为496±10K和331±7K。当放在已知行星围绕与K2-264质量相似的场星运行的背景下时，这些行星的半径似乎并没有像以前注意到的一些星系团行星那样显著膨胀。作为第二个已知的多行星凌日星团系统，K2-264对于测试多行星系统中的光蒸发理论应该是有价值的。用目前的近红外光谱仪进行后续观测可能会产生行星质量测量结果，这将提供有关小行星的平均密度和组成的信息，这些信息预计将在光蒸发完成后不久完成。使用斯皮策或大型地面望远镜进行的后续近红外凌日观测可能会改进半径估计，进一步加强对这些有趣行星的描述。
Planet host stars with well-constrained ages provide a rare window to the time domain of planet formation and evolution. The NASA K2 mission has enabled the discovery of the vast majority of known planets transiting stars in clusters, providing a valuable sample of planets with known ages and radii. We present the discovery of two planets transiting K2-264, an M2 dwarf in the intermediate age (600-800 Myr) Praesepe open cluster (also known as the Beehive Cluster, M44, or NGC 2632), which was observed by K2 during Campaign 16. The planets have orbital periods of 5.8 and 19.7 d, and radii of 2.2 ± 0.2 and 2.7 ± 0.2R⊕, respectively, and their equilibrium temperatures are 496 ± 10 and 331 ± 7 K, making this a system of two warm sub-Neptunes. When placed in the context of known planets orbiting field stars of similar mass to K2-264, these planets do not appear to have significantly inflated radii, as has previously been noted for some cluster planets. As the second known system of multiple planets transiting a star in a cluster, K2-264 should be valuable for testing theories of photoevaporation in systems of multiple planets. Follow-up observations with current near-infrared (NIR) spectrographs could yield planet mass measurements, which would provide information about the mean densities and compositions of small planets soon after photoevaporation is expected to have finished. Follow-up NIR transit observations using Spitzer or large ground-based telescopes could yield improved radius estimates, further enhancing the characterization of these interesting planets.