发表机构
Nicolaus Copernicus University; Instituto de Astrofísica de Canarias (IAC); Universidad de La Laguna (ULL); INAF – Osservatorio Astrofisico di Torino; Instituto de Astrofísica de Andalucía (IAA-CSIC)（尼古拉·哥白尼大学; 加那利群岛天体物理研究所; 拉古纳大学; 意大利国家天体物理研究所都灵天文台; 安达卢西亚天体物理研究所）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
该研究通过HARPS-N和ESPRESSO的视向速度测量，得到K2-223系统两颗行星的质量约束，发现一颗候选长周期巨行星，其罕见结构对行星形成演化研究有重要价值。
AI 中文摘要
我们基于HARPS-N和ESPRESSO的高精度视向速度测量，给出了凌星恒星K2-223的两颗短周期类地行星的质量约束，还发现了一颗环绕G1V型矮星K2-223的外围类木星巨行星的候选迹象。K2-223 b的半径为$R_\text{b}=0.79\ud0b10.10\rm R_\u2295$，3σ质量上限为$M_\text{b}<2.8\rm M_\u2295$，属于已知的亚地球行星小群体，是目前已知环绕类太阳恒星的最小极短周期（USP）行星，其轨道周期$P_\text{b}\u22480.5$天。K2-223 c的半径为$R_\text{c}=1.41\ud0b10.15\rm R_\u2295$，质量为$M_\text{c}=4.2\ud0b11.3\rm M_\u2295$，密度为$\rho_\text{c}=8.3\ud0b13.7\rm g\thinspace cm^{-3}$，是一颗短周期超级地球，轨道周期$P_\text{c}\u22484.5$天。得益于用HARPS-N光谱仪对K2-223进行的近6.5年视向速度监测，我们识别出一颗候选巨行星，其轨道周期为$P_\text{d}=4.53^{+0.32}_{-0.34}$年，最小质量为$1.29^{+0.23}_{-0.17}\rm M_\text{Jup}$。两颗近距小行星伴随一颗遥远的候选类木星伴星，使K2-223成为具有罕见结构的系统，对检验行星形成与演化场景具有重要价值。K2-223 b与母星的极近距离需考虑相对论和潮汐对牛顿引力的摄动，我们在K2-223多行星系统的视向速度模型和动力学模拟框架下讨论了这些效应的时标与振幅。我们还对已直接测量质量、半径和整体密度的行星，以轨道周期与洛希周期的归一化形式进行参数化，在海王星沙漠的研究语境中提供了一种替代表征方式。
英文摘要
We present mass constraints of two short-period Earth-sized planets transiting K2-223 based on high-precision radial velocity measurements from HARPS-N and ESPRESSO, as well as a tentative indication of an outer Jupiter-like planet orbiting the G1V dwarf K2-223. With a radius of $R_\mathrm{b}=0.79\pm0.10$ $\mathrm{R_{\oplus}}$ and a 3$σ$ upper mass limit $M_\mathrm{b}<2.8$ $\mathrm{M_{\oplus}}$, K2-223 b belongs to the small group of known sub-Earth planets and is currently the smallest known ultra-short-period planet ($P_\mathrm{b}\approx$ 0.5 day) transiting a solar-type star. With a radius of $R_\mathrm{c}=1.41\pm0.15$ $\mathrm{R_{\oplus}}$, a mass of $M_\mathrm{c}=4.2\pm1.3$ $\mathrm{M_{\oplus}}$, and a density of $ρ_\mathrm{c}=8.3\pm3.7$ $\mathrm{g\,cm^{-3}}$, K2-223 c is a short-period ($P_\mathrm{c}\approx$ 4.5 days) super-Earth. Based on almost 6.5 years of radial velocity monitoring of K2-223 with the HARPS-N spectrograph, we identified a tentative giant planet with an orbital period of $P_\mathrm{d}=4.53^{+0.32}_{-0.34}$ $\mathrm{years}$ and a minimum mass of $1.29^{+0.23}_{-0.17}$ $\mathrm{M_{\rm Jup}}$. Two close-in small planets accompanied by a distant candidate Jupiter-like companion would make K2-223 a system with a rare architecture. This is valuable for testing scenarios of planetary formation and evolution. The extreme proximity of K2-223 b to the parent star means that relativistic and tidal perturbations to Newtonian gravity need to be considered. We discuss the timescales and amplitudes of these effects in the context of the radial velocity model and dynamical simulations of the K2-223 multiple-planet system. We also present a parametrisation of the planets with directly measured masses, radii, and bulk densities in terms of the orbital period normalised by the Roche period. This provides an alternative representation in the context of the Neptune desert.
Comments19 pages, 24 figures. Accepted for publication in A&A
