发表机构
Carnegie Institution for Science; University of California San Diego; Carnegie Science Observatories; Space Telescope Science Institute; University of Oxford; University of California, Santa Cruz; University of Hawai‘i（卡内基科学机构; 加州大学圣迭戈分校; 卡内基科学天文台; 太空望远镜科学研究所; 牛津大学; 加州大学圣克鲁兹分校; 夏威夷大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
该研究结合JWST和HST等数据，确认超热木星TOI-2109 b存在与轨道衰减一致的正弦和二次凌星时刻变化，并排除非行星解释，使其成为除WASP-12 b外唯一已知轨道衰减的系外行星。
AI 中文摘要
超热木星是系外行星中罕见而宝贵的子类，有助于阐明其宿主恒星的内部性质以及近距离行星的轨道演化。作为极端中的极端，TOI-2109 b是一颗超级木星（半径$1.347 \pm 0.047 R_{\rm Jup}$，质量$5.02 \pm 0.75 M_{\rm Jup}$），拥有已知巨行星中最短的轨道周期（0.67247479 $\pm$ 0.00000028天）和最快的预测轨道衰减率。先前观测暗示凌星时刻变化（TTVs）中存在与轨道衰减一致的二次长期趋势，以及与近共振行星伴星一致的短期正弦TTVs，后者表明存在动力学上静止的迁移路径。在此，我们将地基、TESS和CHEOPS的存档测光数据与HST和JWST的新凌星及掩星数据相结合，以更新TTV分析。我们发现相对于线性星历表，正弦TTVs有非常强的证据（$\Delta$BIC为33.6），与J.-V. Harre等人2024年提出的邻近行星伴星一致，并排除了几种可解释正弦TTVs的非行星情景。我们还发现了二次TTV趋势的强证据（$\Delta$BIC为6.75），与-3.46 $\pm$ 1.17 ms/yr的轨道衰减率和2.13$^{+1.18}_{-0.61} \times10^7$的恒星潮汐品质因子一致，尽管我们无法排除视线加速度作为二次趋势的原因。如果我们的结果得到证实，TOI-2109 b将成为除WASP-12 b之外唯一已知轨道衰减的系外行星，也是带有邻近伴星的近距离巨行星这一超罕见类别中最极端的成员。
英文摘要
Ultra-hot Jupiters are a rare yet valuable subset of exoplanets that can help elucidate both the internal properties of their host stars as well as the orbital evolution of close-in planets. An extreme among extremes, TOI-2109 b is a super-Jupiter ($1.347 \pm 0.047 R_{\rm Jup}$, $5.02 \pm 0.75 M_{\rm Jup}$) with the shortest orbital period (0.67247479 $\pm$ 0.00000028 days) and the fastest predicted orbital decay rate of any known giant planet. Previous observations hinted at a quadratic long-term trend in the transit timing variations (TTVs) consistent with orbital decay, as well as short-term sinusoidal TTVs consistent with a near-resonant planetary companion that would indicate a dynamically quiescent migration pathway. Here, we combine archival ground-based, TESS, and CHEOPS photometry with new transit and eclipse data from HST and JWST to update the TTV analysis. We find very strong evidence for sinusoidal TTVs over a linear ephemeris ($Δ$BIC of 33.6), consistent with a nearby planetary companion as suggested by J.-V. Harre et al. 2024, and rule out several non-planetary scenarios that could explain the sinusoidal TTVs. We also find strong evidence of a quadratic TTV trend ($Δ$BIC of 6.75) consistent with an orbital decay rate of -3.46 $\pm$ 1.17 ms/yr and a stellar tidal quality factor of 2.13$^{+1.18}_{-0.61} \times10^7$, though we cannot rule out line-of-sight acceleration as the cause of the quadratic trend. If our results are confirmed, TOI-2109 b would be the only known exoplanet besides WASP-12 b with a decaying orbit and the most extreme of an ultra-rare class of close-in giant planets with nearby companions.
CommentsSubmitted for publication in AAS Journals. 19 pages, 5 figures, 3 tables. Comments welcome
