发表机构
The University of North Carolina at Chapel Hill; The University of Texas at Austin; Center for Astrophysics | Harvard & Smithsonian（北卡罗来纳大学教堂山分校; 德克萨斯大学奥斯汀分校; 哈佛-史密森天体物理中心）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
通过分析17 Myr双行星系统HIP 67522的凌星时间变化，测得两行星低质量与低偏心率，支持气体矮星形成模型，为年轻行星演化理论提供关键数据。
AI 中文摘要
幼年（<100 Myr）凌星行星系统为理解塑造观测到的成熟行星种群的过程提供了线索。这些行星的质量是检验行星形成与演化理论的有力数据点。由于年轻系统往往处于平均运动共振（MMR）中，并表现出更高的凌星时间变化（TTVs）发生率，我们可以利用行星间引力相互作用导致的预期与实际凌星时间的偏差来确定行星质量和轨道偏心率。在此，我们报告了对HIP 67522的TTV分析，这是一个17 Myr、接近2:1轨道共振的双行星系统。该分析基于来自11个设施的55次行星b凌星观测（50个历元）和29次行星c凌星观测（22个历元）。假设圆形轨道，我们确定质量为$M_b=25.0^{+7.6}_{-7.8}M_\oplus$和$M_c=11.2\pm1.4M_\oplus$。允许偏心轨道时，我们得到$M_b=23.1^{+15.4}_{-12.4}M_\oplus$和$M_c=11.8^{+3.0}_{-2.3}M_\oplus$，且两颗行星的偏心率均较低（<0.1）。采用来自JWST透射光谱的$M_b$高斯先验，将行星c的偏心解质量收紧至$9.7^{+1.9}_{-1.6}M_\oplus$，这是我们推荐的解。低质量和大半径与收缩大气行星形成模型（如气体矮星形成）一致。鉴于径向速度质量的挑战以及年轻系统中高TTV发生率，TTV质量对于检验超级地球和亚海王星的形成与演化理论，以及确定银河系中最常见行星类型的形成条件至关重要。
英文摘要
Infant ($<$100\,Myr) transiting planet systems provide glimpses into the processes that shape the observed mature planet population. Masses for these planets are powerful data points for testing theories of planet formation and evolution. Because young systems tend to be in mean-motion resonances (MMR) and show higher rates of transit timing variations (TTVs), we can take advantage of deviations in the expected versus observed transit timings due to gravitational interactions between the planets to determine the planetary masses and orbital eccentricities. Here we report the TTV analysis of HIP\,67522, a 17\,Myr two-planet system near a 2:1 orbital resonance. The analysis is based on 55 transit observations (50 epochs) of planet b and 29 transit observations (22 epochs) of planet c, taken across 11 facilities. Assuming circular orbits, we determine masses of $M_b=25.0^{+7.6}_{-7.8}M_\oplus$ and $M_c=11.2\pm1.4M_\oplus$. Allowing for eccentric orbits, we find $M_b=23.1^{+15.4}_{-12.4}M_\oplus$ and $M_c=11.8^{+3.0}_{-2.3}M_\oplus$, and low eccentricities ($<0.1$) for both planets. Adopting a Gaussian prior on $M_b$ from the JWST transmission spectrum tightens the eccentric-solution mass for planet c to $9.7^{+1.9}_{-1.6}M_\oplus$, which is our recommended solution. The low masses and large radii are consistent with a contracting atmosphere planet formation model, such as Gas Dwarf formation. Given the challenge of radial-velocity masses and the high rate of TTVs seen in young systems, TTV-masses will be essential for testing theories of the formation and evolution of super-Earths and sub-Neptunes and determining the conditions that create the most common types of planets in the Galaxy.
CommentsUnder review for the AAS Journal
