AI 中文总结
本研究以两个成分基准褐矮星为对象，用Brewster框架反演其大气，结合JWST光谱数据，关联系统整体性质与大气参数，验证了云结构、元素丰度等结果的合理性。
AI 中文摘要
我们利用Brewster反演框架，对两个成分基准中型L型矮星——SDSSJ141659.78+500626.4和GJ 499 C开展了首次大气反演分析，这两个系统的宽基准特性可从其主星处获得年龄与整体成分的独立约束。这些目标由詹姆斯·韦布空间望远镜（JWST）利用近红外光谱仪（NIRSpec）棱镜模式和中红外仪器（MIRI）低分辨率光谱仪（LRS）观测，获得了0.6至14.0微米波段、低分辨率（R~100）且高信噪比（SNR~100至600）的光谱。对于SDSSJ141659.78+500626.4，反演得到的高空顽火辉石板和低空铁甲板云的组合，与基于主星Mg/Si比的相平衡预测相符；我们反演得到超太阳碳氧比C/O=0.71±0.01，以及略富金属的[M/H]=0.22±0.03，该碳氧比仅能在存在超出反演云质量的额外氧封存，或采用的不透明度存在不确定性、其他模型存在缺陷时，才与主星推断值相吻合；推断的[C/H]和[O/H]分别为0.31±0.03和0.19±0.03，与主星丰度的较大不确定性在误差范围内一致。对于GJ 499 C，反演得到的一氧化硅和镁橄榄石板云难以用简单的相平衡假设解释，得出Mg/Si~1.9；我们估算其碳氧比C/O=0.69±0.02，以及[M/H]=0.13±0.04+0.06。对于两个天体，推断的半径分别为0.85±0.01木星半径（R_Jup）和1.00±0.02木星半径，质量分别为73.7±4.9+9.2木星质量（M_Jup）和68.0±8.5+12.7木星质量，与演化模型和系统年龄相符，凸显了我们结果的合理性。
英文摘要
We present the first atmospheric retrieval analysis of two compositional benchmark mid-L dwarfs -- SDSSJ141659.78+500626.4 and GJ 499 C -- using the \textit{Brewster} retrieval framework, where the wide benchmark nature of these systems provides independent constraints on age and bulk composition from their stellar primaries. These targets were observed with JWST using NIRSpec Prism and MIRI LRS, providing low-resolution ($R$ $\sim$ 100) spectra between 0.6--14.0 $\mathrmμ$m with high signal-to-noise ratios (SNR $\sim$100 -- 600). For SDSSJ141659.78+500626.4, the retrieved cloud combination of a high-altitude enstatite slab and low-altitude iron deck clouds matches phase-equilibrium predictions based on the primary star's Mg/Si ratio. We retrieve a super-solar C/O = 0.71$^{+0.01}_{-0.01}$ and slightly metal-rich [M/H] = 0.22$^{+0.03}_{-0.03}$. This C/O ratio can only be reconciled with the value inferred for the primary if additional oxygen sequestration beyond the retrieved cloud mass is present, or if there are uncertainties in the adopted opacities or other model deficiencies. The inferred [C/H] and [O/H] are 0.31$\pm$0.03 and 0.19$\pm$0.03, respectively, which are consistent within the relatively large uncertainties of the host star abundances. For GJ 499 C, the retrieved silicon-monoxide and forsterite slab clouds are difficult to explain with simple phase-equilibrium assumptions, yielding Mg/Si $\sim$ 1.9. We estimate C/O = 0.69$^{+0.02}_{-0.02}$ and [M/H] = 0.13$^{+0.04}_{-0.06}$. For both objects, the inferred radii of 0.85$^{+0.01}_{-0.01}$ $R_{\mathrm{Jup}}$ and 1.00$^{+0.02}_{-0.02}$ $R_{\mathrm{Jup}}$ and masses of 73.7$^{+4.9}_{-9.2}$ $M_{\mathrm{Jup}}$ and 68.0$^{+8.5}_{-12.7}$ $M_{\mathrm{Jup}}$ are consistent with evolutionary models and system ages, highlighting the plausibility of our results.
Comments26 pages, 18 figures, accepted for publication in MNRAS
