AI 中文总结
研究高质量比激变变星中出现正超峰的问题，通过三维流体动力学模拟等方法，发现即使共振半径在盘外，盘结构也会影响偏心率增长及超峰出现，解释了正超峰现象。
AI 中文摘要
以前人们认为，激变变星（CV）盘只有在3:1共振位于盘内时才会变得偏心并显示超峰。这要求双星质量比$q = M_2/M_1 \lesssim 0.33$，其中$M_1$是白矮星质量，$M_2$是伴星质量。然而，几个更高质量比的系统被观测到呈现正超峰，对这一图景构成挑战。我们进行了首次三维流体动力学模拟，表明即使共振半径位于盘外，CV盘中也会发生偏心率增长。3:1共振的有限宽度延伸到盘的外部并驱动偏心率。虽然高质量比CV更常显示负超峰，但我们的线性分析表明，轨道进动方向对盘外半径和表面密度分布高度敏感。光滑粒子流体动力学模拟倾向于抑制偏心率梯度并有利于正向进动。这些结果为高质量比CV中的正超峰提供了自然解释，并表明盘结构而非仅共振位置控制超峰的出现。
英文摘要
Previously it has been assumed that a cataclysmic variable (CV) disk can only become eccentric and display superhumps if the 3:1 resonance is located within the disk. This requires the binary mass ratio to be $q=M_2/M_1\lesssim 0.33$, where $M_1$ is the mass of the white dwarf and $M_2$ is the mass of the companion star. However, several systems with higher mass ratios have been observed to exhibit positive superhumps, posing a challenge to this picture. We present the first 3D hydrodynamic simulations to show that eccentricity growth can occur in CV disks even when the resonance radius lies outside the disk. The finite width of the 3:1 resonance extends into the outer parts of the disk and drives eccentricity. While high mass ratio CVs more commonly show negative superhumps, our linear analysis reveals that the direction of apsidal precession is highly sensitive to the disk outer radius and surface density distribution. Smoothed particle hydrodynamic simulations tend to suppress eccentricity gradients and favor prograde precession. These results provide a natural explanation for positive superhumps in high mass ratio CVs and show that disk structure, rather than the resonance location alone, controls the emergence of superhumps.
CommentsAccepted for publication in ApJL
