Double Explosion May Explain โฃOrigin of Hyper-Fast White โDwarfs
HAIFA,Israel – September 9,2025 – A newly proposed scenario involving a double detonation could solve the mystery of how some white dwarfs achieve extraordinarily โฃhigh velocities,potentially reshaping our understandingโค of stellar evolution within the Milky Way. Researchers at the Technion-Israel Institute of Technology suggest these “hyper-velocity” dwarfs aren’t simply ejected, but propelled by a unique chain of events.
The process begins with a binary star system consisting of a larger, โprimary white dwarf and a smaller companion. As the โstars interact, โmass transfer ignites a helium detonation on the surface of the โprimary white dwarf. This initial explosion generates a shock wave that penetrates to the core, triggering a second, more powerful detonation โwithin the carbon-oxygen core, ultimately resulting in a supernova explosion.
“The mass transfer triggers a โขhelium detonation on the surface of the primary white dwarf,”โฃ explain the โขastronomers.This explosion spreads around the entire star and creates a shock wave that extends to the core of this white dwarf. “The shock waveโค thenโ causes a secondary detonation in theโข carbon oxygen core,which leads to a supernova explosion,” said Glanz and her โteam.
Crucially, the smaller companion star is partially disrupted โ before the second explosion, receiving a particularly strong “kick” from the event. the resulting debris is ejected at speeds exceeding 2,000 kilometers per second,leaving behind only the core of the former โคcompanion.”This solves the puzzle about the origin of these stellarโข outliers,” says researcherโ Glanz. The dramatic destructionโค and double explosion explain how these hyper-velocity dwarfs maintain such high speeds and temperatures. “It is indeed the first timeโ that we see a path of origin, accelerated throughโฃ the hot โคwhite dwarfs to the hyper-speeds that we have observed in the Halo ofโ the Milky Way,” Glanz added.
The model may also explain the existence of unusually weak โฃType 1Aโ supernovae, which release less energy and eject less material then typical. “This scenario opens up a window in new types of stellar explosions,” says Glanz’s colleague, Hagai Perets.
However, the โฃscenario remainsโ theoretical. Astronomers emphasize thatโ future observations are needed to confirm whether these double-detonation events actually occur. ( Nature Astronomy, 2025; DOI: 10.1038/S41550-025-02633-4)
Quelle: Technion-Israel Institute of Technology