New study led by Dr. Hila Glantz and Prof. Hagai Peretz uncovers explosive pathway to hypervelocity white dwarfs, space faster than 2000 km/s, and unusual
Type Ia supernovae.
The international team performed state-of-the-art three-dimensional hydrodynamic simulations of a merger between two rare hybrid helium–carbon–oxygen white dwarfs. The results reveal a dramatic sequence of events: as the lighter star is partially disrupted, the heavier one undergoes a double-detonation explosion, slingshotting the surviving remnant of its companion into space at hypervelocity speeds exceeding 2000 kilometers per second — fast enough to escape the gravitational grip 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.”
Unlike previously proposed scenarios, the new model accounts for both the extreme velocities and unusual temperatures and brightness of known HVWDs, such as the stars J0546 and J0927. It also offers insight into underluminous thermonuclear explosions, which are crucial tools for measuring the universe’s expansion and for understanding how elements are formed in galaxies.
“This discovery doesn’t just help us understand hypervelocity stars — it gives us a window into new kinds of stellar explosions,” said co-author Prof. Hagai Perets, also of the Technion.
The study was conducted by researchers from the Technion, Universität Potsdam, and the Max Planck Institute for Astrophysics, combining high-performance simulations with new theoretical modeling.
The work has implications for upcoming transient surveys and Gaia data releases, which may uncover more of these elusive stellar cannonballs flying through the galaxy.
Nature article: https://www.nature.com/articles/s41550-025-02633-4
Ynet article: https://www.ynet.co.il/environment-science/article/rkbmu0011qgl
In the photos:
Prof. Hagai Perets
Dr. Hila Glanz
Illustration showing the remnant of a star being ejected at tremendous speed into space from the site of a supernova explosion caused by the interaction between a pair of white dwarfs.
Credit: Technion Spokesperson’s Office
