Masses, revised radii, and a third planet candidate in the 'Inverted' planetary system around TOI-1266
Masses, revised radii, and a third planet candidate in the 'Inverted' planetary system around TOI-1266
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TOI-1266 周围“倒置”行星系统中的质量、修正后的半径和第三颗候选行星
DOI：
10.1093/mnras/stad3450
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发表时间：
2024
影响因子：
4.8
通讯作者：
Cloutier R
中科院分区：
文献类型：
--
作者：
Cloutier R
围绕M矮星运行的近距离行星群是由热驱动的逃逸所塑造的，还是行星形成过程的直接结果？最近的一些实证结果强烈表明后者。然而，TOI-1266系统的独特结构对行星形成和大气逃逸的模型提出了挑战，因为它似乎是一个大型亚海王星（Pb= 10.9 d）的“倒置”结构，轨道内部是该系统的较小行星（Pc= 18.8 d）。在这里，我们提出了修订的行星半径的基础上新的TESS和扩散器辅助的地面过境观测，并使用一组145个径向速度测量HARPS-N（$M_{p，B}=4.23\pm 0.69\，\mathrm{M}_{\oplus }，M_{p，c}=2.88\pm 0.80\，\mathrm{M}_{\oplus }$）的特征的行星质量。我们的分析还揭示了第三颗行星候选者（Pd= 32.3 d，），如果真实的，将形成一个周期比接近5：3的链，尽管该系统可能不是在平均运动共振。我们的研究结果表明，TOI-1266 B和C是M矮星周围密度最低的亚海王星之一，可能表现出不同的整体组成的气体包裹的陆地（Xenv，B= 5.5 ± 0.7%）和水丰富的世界（WMFc= 59 ± 14%），这是支持的流体动力学逃逸模型。如果通过大气特征确定了不同的散装成分，该系统独特的结构将代表一个有趣的测试案例，即在卵石陷阱中由内而外的次海王星形成。
Is the population of close-in planets orbiting M dwarfs sculpted by thermally driven escape or is it a direct outcome of the planet formation process? A number of recent empirical results strongly suggest the latter. However, the unique architecture of the TOI-1266 system presents a challenge to models of planet formation and atmospheric escape given its seemingly ‘inverted’ architecture of a large sub-Neptune (Pb= 10.9 d,) orbiting interior to that of the system’s smaller planet (Pc= 18.8 d,). Here, we present revised planetary radii based on new TESS and diffuser-assisted ground-based transit observations, and characterize both planetary masses using a set of 145 radial velocity measurements from HARPS-N ($M_{p,b}=4.23\pm 0.69\, \mathrm{M}_{\oplus }, M_{p,c}=2.88\pm 0.80\, \mathrm{M}_{\oplus }$). Our analysis also reveals a third planet candidate (Pd= 32.3 d,), which if real, would form a chain of near 5:3 period ratios, although the system is likely not in a mean motion resonance. Our results indicate that TOI-1266 b and c are among the lowest density sub-Neptunes around M dwarfs and likely exhibit distinct bulk compositions of a gas-enveloped terrestrial (Xenv,b= 5.5 ± 0.7 per cent) and a water-rich world (WMFc= 59 ± 14 per cent), which is supported by hydrodynamic escape models. If distinct bulk compositions are confirmed through atmospheric characterization, the system’s unique architecture would represent an interesting test case of inside-out sub-Neptune formation at pebble traps.