AI 中文总结
通过测量V1405 Cas的轨道周期变化和抛射/吸积质量，证明其质量减小且非Ia型超新星前身星，并反驳了五项传统CV演化主张。
AI 中文摘要
2021年仙后座新星（V1405 Cas）是一颗普通的J(175)型氖新星，其白矮星质量估计为 $M_{\rm WD}$=0.60$\pm$0.10 $M_{\odot}$。我发现其轨道周期为 $P$=0.1884天，并追踪了2013年至2025年间20次光度极小的时间。我测量到周期在爆发前后发生了变化，爆发前 $P_{\rm pre}$=0.1883919$\pm$0.0000018天，爆发后 $P_{\rm post}$=0.1884043$\pm$0.0000018天，对应的 $\Delta P$/$P$=66$_{-18}^{+21}$ ppm（百万分率）。在考虑了双星在爆发期间角动量损失的修正后，我推导出新星抛射质量为 $M_{\rm ejecta}$=7.5$\times$10$^{-4}$ $M_{\odot}$，极端范围为 (2.9--40)$\times$10$^{-4}$ $M_{\odot}$。上一次爆发周期中吸积的质量由触发质量决定，为 $M_{\rm accreted}$=(1.6$\pm$0.4)$\times$10$^{-4}$ $M_{\odot}$。V1405 Cas为自20世纪80年代以来主导密近双星（CV）演化的五项主张提供了反例。第一，V1405 Cas具有正的 $\dot{P}$，这与磁制动模型相矛盾。第二，$\Delta P$ 太小，比使系统进入冬眠状态所需的值小20倍。第三，$M_{\rm WD}$ 随时间减小，这由 $M_{\rm ejecta}$$>$$M_{\rm accreted}$ 以及它是氖新星的事实所表明。第四，基于同样的原因，V1405 Cas不是Ia型超新星前身星。第五，V1405 Cas的轨道周期在2013年至2025年间增加了$+$75 ppm，这反驳了激变变星周期普遍随演化而下降的普遍观点。V1405 Cas是近期对52颗激变变星和25颗X射线双星的 $\Delta P$ 和 $\dot{P}$ 测量的最新结果，这些测量共同反驳了上述全部五项主张。
英文摘要
Nova 2021 Cassiopeia (V1405 Cas) was an ordinary J(175) neon nova with the white dwarf mass estimated to be $M_{\rm WD}$=0.60$\pm$0.10 $M_{\odot}$. I found an orbital period of $P$=0.1884 days, and have tracked 20 times of photometric minima from 2013--2025. I measure that $P$ increased from before to after the eruption with $P_{\rm pre}$=0.1883919$\pm$0.0000018 days and $P_{\rm post}$=0.1884043$\pm$0.0000018 days, for $ΔP$/$P$=66$_{-18}^{+21}$ parts-per-million. With correction for the angular momentum loss by the binary during the eruption, I derive that the nova ejected $M_{\rm ejecta}$=7.5$\times$10$^{-4}$ $M_{\odot}$, with an extreme range of (2.9--40)$\times$10$^{-4}$ $M_{\odot}$. The mass accreted during the previous eruption cycle comes from the trigger mass, and is $M_{\rm accreted}$=(1.6$\pm$0.4)$\times$10$^{-4}$ $M_{\odot}$. V1405 Cas provides counterexamples against five claims about CV evolution that have dominated since the 1980s. First, V1405 Cas has positive $\dot{P}$, and this is contrary to the Magnetic Braking Model. Second, the $ΔP$ is 20$\times$ too small to allow the system to fade into a hibernation state. Third, $M_{\rm WD}$ is decreasing over time, as shown by $M_{\rm ejecta}$$>$$M_{\rm accreted}$ and by being a neon nova. Fourth, V1405 Cas is not a Type Ia supernova progenitor, for the same reasons. Fifth, the orbital period of V1405 Cas increased by $+$75 ppm from 2013--2025, as a counterexample to the pervasive idea that cataclysmic variables are universally declining in period from evolution. V1405 Cas is the latest of recent measures of $ΔP$ and $\dot{P}$ for 52 cataclysmic variables and 25 X-ray binaries that have together refuted all five claims.
Comments7th in a series of ApJ papers, each proving that popular progenitor candidates cannot become Type Ia supernovae: 1. V445 Pup (arXiv:2412.17286), 2. T CrB (arXiv:2510.01587), 3. U Sco (arXiv:2510.01589), 4. FQ Cir (arXiv:2511.16594), 5. all symbiotic stars (arXiv:2511.19948), 6. T Pyx (arXiv:2602.09377), 7. V1405 Cas (ApJ in press)
