White Dwarfs Can Propel Each Other Out of Galaxies at Millions of Kilometers per Hour

Recent research has uncovered that white dwarf stars can achieve astonishing speeds exceeding 8 million kilometers per hour, potentially ejecting them from their galaxies. This phenomenon is attributed to the explosive interactions between two specific types of white dwarf stars, as revealed by simulations conducted by a collaborative study involving German and Israeli researchers.

The simulations indicate that a collision between two white dwarfs can trigger a double explosion, propelling one of the stars at incredible velocities. These startling findings provide an explanation for the existence of hyperspeed white dwarfs, which had been observed in data from the Gaia space telescope.

Hyperspeed white dwarfs have recently gained attention, with several discovered in the last two years. They are characterized by their remarkable speeds, surpassing 1300 kilometers per second (4.7 million kilometers per hour), with the fastest recorded white dwarf reaching 8.5 million kilometers per hour. Such speeds are sufficient to escape the gravitational pull of the Milky Way, a phenomenon that had puzzled astronomers until now.

The research team, which includes experts from the University of Potsdam and the Max Planck Institute for Astrophysics, has outlined that a specific set of conditions must occur for these stars to be expelled from their galaxies. The process begins with the collision of two white dwarfs of a particular type, where the smaller star is partially disintegrated while the larger one undergoes two explosions. This sequence of events leads to the smaller star being thrust into space at extreme velocities, along with an increase in its temperature.

The team is now advocating for further exploration of the Gaia data to identify additional examples of these stellar phenomena. Their comprehensive findings have been published in the journal Nature Astronomy.