Classical novae are the most common astrophysical thermonuclear explosions, occurring on the surfaces of white dwarf stars accreting gas from companions in binary star systems. Novae typically expel about 10(-4) solar masses of material at velocities exceeding 1,000 kilometres per second. However, the mechanism of mass ejection in novae is poorly understood, and could be dominated by the impulsive flash of thermonuclear energy, prolonged optically thick winds or binary interaction with the nova envelope. Classical novae are now routinely detected at gigaelectronvolt γ-ray wavelengths, suggesting that relativistic particles are accelerated by strong shocks in the ejecta. Here we report high-resolution radio imaging of the γ-ray-emitting nova V959 Mon. We find that its ejecta were shaped by the motion of the binary system: some gas was expelled rapidly along the poles as a wind from the white dwarf, while denser material drifted out along the equatorial plane, propelled by orbital motion. At the interface between the equatorial and polar regions, we observe synchrotron emission indicative of shocks and relativistic particle acceleration, thereby pinpointing the location of γ-ray production. Binary shaping of the nova ejecta and associated internal shocks are expected to be widespread among novae, explaining why many novae are γ-ray emitters.
Novae. Fermi Establishes Classical Novae as a Distinct Class of Gamma-Ray SourcesFermi-LAT Collaboration. Science 345 (6196), 554-8. PMID 25082700.A classical nova results from runaway thermonuclear explosions on the surface of a white dwarf that accretes matter from a low-mass main-sequence stellar companion. In 20 …
An Ancient Nova Shell Around the Dwarf Nova Z CamelopardalisMM Shara et al. Nature 446 (7132), 159-62. PMID 17344847.Cataclysmic variables (classical novae and dwarf novae) are binary star systems in which a red dwarf transfers hydrogen-rich matter, by way of an accretion disk, to its w …
Proper-motion Age Dating of the Progeny of Nova Scorpii AD 1437MM Shara et al. Nature 548 (7669), 558-560. PMID 28858302.'Cataclysmic variables' are binary star systems in which one star of the pair is a white dwarf, and which often generate bright and energetic stellar outbursts. Classical …
A Recurrent Nova Super-Remnant in the Andromeda GalaxyMJ Darnley et al. Nature 565 (7740), 460-463. PMID 30626965.The accretion of hydrogen onto a white dwarf star ignites a classical nova eruption1,2-a thermonuclear runaway in the accumulated envelope of gas, leading to l …
Gamma-ray Emission Concurrent With the Nova in the Symbiotic Binary V407 CygniFermi-LAT Collaboration et al. Science 329 (5993), 817-21. PMID 20705855.Novae are thermonuclear explosions on a white dwarf surface fueled by mass accreted from a companion star. Current physical models posit that shocked expanding gas from t …