AI 中文总结
研究确认并描述了HD 148797恒星的两颗中等周期次木星行星，利用TESS和CHEOPS数据确定其轨道周期、半径、质量和密度等参数，发现其结构常见，多行星系统比例及相邻行星周期比有规律，该系统有望用于比较大气特征描述。
AI 中文摘要
我们报告了两颗中等周期次木星行星凌越明亮F型恒星HD 148797（G = 9.4星等，有效温度Teff = 6441±51 K）的确认和特征描述。利用凌日系外行星勘测卫星（TESS）和 CHEOPS的光度时间序列，我们确定HD 148797 b的轨道周期为42.1天，HD 148797 c的轨道周期为68.2天，周期比非常接近黄金分割比1.619，因此接近几个强谐波，并分别测量出行星半径为8.25±0.37倍地球半径和8.37±0.38倍地球半径。我们检测到两颗行星都有显著的反相关凌星时间变化，其中包含足够的谐波信息，得出HD 148797 b的光动力学质量为39.3 +13 -8.5倍地球质量，HD 148797 c的光动力学质量为39.6±9.3倍地球质量。相应的平均密度为0.39±0.12和0.377±0.084 g/cm³，这两颗行星都属于海王星区域的低密度次木星行星。HD 148797的结构在这个范围内并不罕见：我们发现该区域中探测到的多系统比例保持在~70 - 90%，并且大多数多行星系统至少包含一对相邻行星，其Pout/Pin < 3。这种模式表明，海王星区域的次木星行星通常存在于动态冷系统中，这与诸如盘驱动迁移等更平滑的迁移路径一致，而不是破坏性的高偏心率潮汐迁移。作为一个明亮的、共同演化的系统，拥有两颗半径和质量相似的温暖海王星区域次木星行星，HD 148797也是进行比较大气特征描述的一个有前景的目标。
英文摘要
We report the confirmation and characterisation of two moderate-period sub-Jovian planets transiting the bright F-type star HD 148797 (G=9.4 mag, Teff=6441 +/- 51 K). Using photometric time series from TESS and CHEOPS, we determine orbital periods of 42.1 d for HD 148797 b and 68.2 d for HD 148797 c, putting the period ratio very close to the golden mean at 1.619 and therefore near several strong harmonics, and measure planetary radii of 8.25 +/- 0.37 RE and 8.37 +/- 0.38 RE, respectively. We detect significant anti-correlated transit-timing variations for both planets, which contain enough harmonic information to yield photodynamical masses of 39.3 +13 -8.5 ME for HD 148797 b and 39.6 +/- 9.3 ME for HD 148797 c. The corresponding bulk densities, 0.39 +/- 0.12 and 0.377 +/- 0.084 g/cm3, place both planets among the low-density sub-Jovians of the Neptunian savanna. The architecture of HD 148797 is not unusual within this regime: we find that detected multi-system fractions in the savanna remain at ~70-90%, and that most savanna multi-planet systems contain at least one adjacent planet pair with Pout/Pin < 3. This pattern suggests that savanna sub-Jovians are commonly found in dynamically cold systems, consistent with smoother migration pathways such as disk-driven migration rather than disruptive high-eccentricity tidal migration. As a bright, co-evolved system hosting two warm savanna sub-Jovians with similar radii and masses, HD 148797 is also a promising target for comparative atmospheric characterisation.
Comments17 pages, 16 figures, submitted
