The research, led by Dr. Hila Glanz of the Technion - Israel Institute of Technology, used advanced three-dimensional hydrodynamic simulations to model the merger of two rare hybrid helium - carbon - oxygen white dwarfs. The team found that as the lighter star is disrupted, the heavier one detonates in a double explosion, flinging the surviving remnant away at extraordinary speeds - fast enough to break free of the Milky Way.
"This is the first time we've seen a clean pathway where the remnants of a white dwarf merger can be launched at hypervelocity, with properties matching the hot, faint white dwarfs we observe in the halo," said Dr. Glanz. "This solves the mystery about the origin of these stellar runaways - and also opens up a new channel for faint and peculiar Type Ia supernovae."
The model explains not only the extreme velocities but also the unusual brightness and temperature of known hypervelocity white dwarfs, including J0546 and J0927. It further provides insight into underluminous thermonuclear supernovae, which play a key role in cosmology and chemical enrichment.
"This discovery doesn't just help us understand hypervelocity stars - it gives us a window into new kinds of stellar explosions," noted co-author Prof. Hagai Perets of the Technion.
The international collaboration included researchers from the Technion, Universitat Potsdam, and the Max Planck Institute for Astrophysics. Their findings could shape the interpretation of future Gaia data releases and transient surveys, which are expected to uncover additional hypervelocity stellar remnants.
Research Report:The origin of hypervelocity white dwarfs in the merger disruption of He-C-O white dwarfs
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Technion-Israel Institute of Technology
Stellar Chemistry, The Universe And All Within It
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