AI 中文总结
本研究采用统一线理论计算极端密度下的Na、K D线轮廓，发现其会提升Rosseland平均不透明度，使巨行星辐射-对流边界向低压移动、核心质量增加，且木星大概率无稳定辐射层。
AI 中文摘要
碱金属线，尤其是钠Na D线（5891Å、5897Å）和钾K D线（7667Å、7701Å）共振双线，是温度大于1000K的宽范围区间内巨行星的主要不透明度源。它们强的压力致宽翼显著影响巨行星的热结构，尤其是在高压条件下。迄今为止，大多数详细的线轮廓计算仅限于扰动体密度高达10²¹cm⁻³的情况。然而，巨行星的深层大气和内部的条件可达到显著更高的密度，这使得温度梯度愈发不确定。我们确定了极端密度下Na D线和K D线物理一致的碰撞致宽如何影响不透明度计算，进而影响推断出的巨行星内部结构。我们采用统一线理论计算了详细的Na D线和K D线轮廓，将分子氢扰动体密度延伸至n_H₂ = 5×10²²cm⁻³，这对应压力高达约20kbar。修正后的截面被纳入Rosseland平均不透明度表，随后用于评估它们对行星热结构的影响。在n_H₂大于10²¹cm⁻³的密度下，统一线理论预测的线轮廓表现出比常用Voigt轮廓强得多的翼，以及密度相关的线位移，这大幅提高了Rosseland平均不透明度。因此，温暖巨行星和热巨行星的辐射-对流边界可向更低压力移动，产生更温暖的内部绝热线，并增加推断出的核心质量。我们进一步发现，木星当前或其演化的大部分时间内都不太可能拥有稳定的辐射层，因为实现这一点所需的Na和K丰度远低于观测约束。
英文摘要
Alkali lines, in particular the sodium Na $D$ (5891$Å$, 5897$Å$) and potassium K $D$ (7667$Å$, 7701$Å$) resonance doublets, are dominant opacity sources in giant planets over a wide range of temperatures ($\gtrsim$1000K). Their strong pressure-broadened wings significantly influence the thermal structure of giant planets, especially at high pressures. Most detailed line-profile calculations have so far been limited to perturber densities up to $10^{21}$cm$^{-3}$. However, conditions in the deep atmospheres and interiors of giant planets can reach significantly higher densities, making the temperature gradients increasingly uncertain. We determined how physically consistent collisional broadening of the Na $D$ and K $D$ lines at extreme densities affects opacity calculations and consequently the inferred interior structure of giant planets. We computed detailed Na $D$ and K $D$ line profiles using unified line theory, extending to molecular hydrogen perturber densities of $n_{\rm H_2} = 5 \times 10^{22}$cm$^{-3}$, which translates to pressures up to $\sim$ 20kbar. The revised cross sections were incorporated into Rosseland mean opacity tables, which were then used to evaluate their effect on planetary thermal structures. At densities $n_{\rm H_2} > 10^{21}$cm$^{-3}$, the line profiles predicted by unified line theory exhibit significantly stronger wings than commonly used Voigt profiles, as well as density-dependent line shifts, which substantially increases Rosseland mean opacities. Consequently, the radiative-convective boundary of warm and hot giant planets can shift to lower pressures, producing warmer interior adiabats and increasing inferred core masses. We further find that Jupiter is unlikely to host a stable radiative layer at the present time or throughout most of its evolution, as the required Na and K abundances for this are well below observational constraints.
CommentsAccepted for publication in A&A, 14 pages, 11 figures
DOI：10.1051/0004-6361/202661682
