论文标题
K2-111：一个旧系统，有两个近气的行星
K2-111: an old system with two planets in near-resonance
论文作者
论文摘要
本文报告了具有K2，WASP和ASAS-SN光度法以及Harps-N和Espresso的高分辨率光谱数据的K2-111行星系统的详细表征。主机K2-111被确认是一个轻微的进化（$ \ log g = 4.17 $），贫困（[fe/h] $ = -0.46 $），但是alpha-inhanced（[$α$/fe] $ = 0.27 $），非常安静，非常古老的圆盘G2 G2恒星。通过使用Pyorbit执行的全球拟合表明，具有$ p_b $ p_b = 5.3518 \ pm0.0004 $ d的过渡行星K2-111b，轨道，并且具有$ 1.82^{+0.11} _ { - 0.09} $ r $ _ \ r $ _ \ oplus $的行星半径为$ 1.82^{+0.11} $ 5.29^{+0.76} _ { - 0.77} $ m $ _ \ oplus $，导致散装密度略低于地球。恒星化学成分和行星性能与K2-111的陆地质量分数低于地球是一致的。我们宣布，我们将第二个信号存在于径向速度数据中，我们将其归因于非运输行星K2-111c，其轨道周期为$ 15.6785 \ pm 0.0064 $ 0.0064 $天数，在接近3：1绕过3：1的旋转，与跨越行星的平均值共鸣，$ $ $ $ $ $ 1.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3 osl。单独拟合时，在HARPS N中独立检测到两个行星信号。在这个共振系统中，可能会有更多的行星，但是需要更多的数据来确认其存在和物理参数。
This paper reports on the detailed characterisation of the K2-111 planetary system with K2, WASP, and ASAS-SN photometry as well as high-resolution spectroscopic data from HARPS-N and ESPRESSO. The host, K2-111, is confirmed to be a mildly evolved ($\log g=4.17$), iron-poor ([Fe/H]$=-0.46$), but alpha-enhanced ([$α$/Fe]$=0.27$), chromospherically quiet, very old thick disc G2 star. A global fit, performed by using PyORBIT shows that the transiting planet, K2-111b, orbits with a period $P_b=5.3518\pm0.0004$ d, and has a planet radius of $1.82^{+0.11}_{-0.09}$ R$_\oplus$ and a mass of $5.29^{+0.76}_{-0.77}$ M$_\oplus$, resulting in a bulk density slightly lower than that of the Earth. The stellar chemical composition and the planet properties are consistent with K2-111b being a terrestrial planet with an iron core mass fraction lower than the Earth. We announce the existence of a second signal in the radial velocity data that we attribute to a non-transiting planet, K2-111c, with an orbital period of $15.6785\pm 0.0064$ days, orbiting in near-3:1 mean-motion resonance with the transiting planet, and a minimum planet mass of $11.3\pm1.1$ M$_\oplus$. Both planet signals are independently detected in the HARPS-N and ESPRESSO data when fitted separately. There are potentially more planets in this resonant system, but more well-sampled data are required to confirm their presence and physical parameters.
