Sudden and Steady Orbital Period Changes Across Six Classical Nova Eruptions; The End of Hibernation and Two Serious Challenges for the Magnetic Braking Model of Cataclysmic Variable Evolution

Abstract

I report on two new measures of the sudden change in the orbital period ($P$) across the nova eruption ($\Delta$P) and the steady period change in quiescence ($\dot{P}$) for classical novae (CNe) RR Pic and HR Del, bringing a total of six such measures for CNe, all in a final report of my large and long observing program. The fractional changes ($\Delta$P/P) in parts-per-million (ppm) are -290.71$\pm$0.28 (QZ Aur), -472.1$\pm$4.8 (HR Del), -4.46$\pm$0.03 (DQ Her), +39.6$\pm$0.5 (BT Mon), -2003.7$\pm$0.9 (RR Pic), and -273$\pm$61 (V1017 Sgr). These results are in stark opposition to the Hibernation Model for the evolution of cataclysmic variables (CVs), which requires $\Delta$P/P$>$+1000 ppm to get the required drop in the accretion rate to produce hibernation. The Hibernation Model cannot be salvaged in any way. My program has also measured the first long-term $\dot{P}$ for classical novae, with -2.84$\pm$0.22 (QZ Aur), +4.0$\pm$0.9 (HR Del), +0.00$\pm$0.02 (DQ Her), -2.3$\pm$0.1 (BT Mon), and +1.25$\pm$0.01 (RR Pic) in units of $10^{-11}$ days/cycle. These can be directly compared to the predictions of the Magnetic Braking Model, where the long-term average $\dot{P}$ is a single universal function of $P$. The measured values are +5.3, $-$94, 0.00, +6.9, and $-$190 times that predicted by the model, so the predictions are always greatly wrong. Further, the effects of the $\Delta$P averaged over the eruption cycle are usually much larger than the magnetic braking effects. To get a realistic model of CV evolution, we must add the physics of the $\Delta$P and $\dot{P}$ variations.

MNRAS in press. Companion paper gives details of photometry, physics of period changes, and results for BT Mon and DQ Her

References in corpus (2)

• Precise Measures of Orbital Period, Before and After Nova Eruption for QZ Aurigae
• RR Pictoris: an old nova showing superhumps and QPOs

Cited by in corpus (4)

• A Catalogue of Potential Post Common Envelope Binaries
• Asymmetrical mass ejection from proto-white dwarfs and the formation of eccentric millisecond pulsar binaries
• A Speckle-Imaging Search for Close Triple Companions of Cataclysmic Binaries
• Searching for nova shells around cataclysmic variables -- II. A second campaign