🌠 Discovery of a dead star traversing the Universe like a ship cutting through water

Recent observations conducted by the Very Large Telescope (VLT) have revealed a singular phenomenon around the white dwarf RXJ0528+2838, located 730 light-years away. This discovery offers a new perspective on the behavior of these stellar relics.

Thanks to the VLT's MUSE instrument, researchers have detected a luminous bow shock around this dead star. It orbits a companion, but contrary to what is usually observed, no disk of matter accompanies this system.


This absence of a disk makes the presence of a shock wave particularly astonishing. Usually, matter stripped from the companion star forms a disk before falling onto the white dwarf, sometimes generating outflows into space. In this case, nothing of the sort is visible here, leaving scientists puzzled by this unexpected structure.

The detailed mapping carried out by MUSE established that this shock wave, similar to that created by a ship cutting through water, originates from the white dwarf's movement through the interstellar gas. The analysis confirms that the structure is indeed associated with the binary system and not with an isolated cosmic cloud.

The data indicates that this outflow has been persisting for at least a millennium. Such longevity is difficult to explain, because in the absence of a disk, the energy source should be depleted quickly. One hypothesis suggests that the white dwarf's magnetic field could play a crucial role by channeling matter directly towards its surface.

However, the duration of the outflow exceeds the predictions of current models. This persistence likely implies the existence of another, as yet unidentified, mechanism that fuels the phenomenon. To elucidate this question, the future Extremely Large Telescope (ELT) will prove invaluable, by allowing the examination of other similar systems with increased acuity.


This discovery, published in Nature Astronomy, broadens our understanding of the interaction of dead stars with their environment. It demonstrates that even seemingly stable stellar objects can reveal unexpected behaviors, inviting astronomers to reevaluate some established scenarios.

White dwarfs: the end of life for stars

White dwarfs are the remnants of stars similar to the Sun after they have exhausted their nuclear fuel. When a medium-mass star ends its life, it expels its outer layers, leaving behind a dense, hot core. This stellar core, called a white dwarf, slowly cools over billions of years, becoming fainter and fainter.

These objects are extremely dense, with a mass comparable to that of the Sun but a volume similar to that of Earth. Their gravity is so strong that the matter composing them is in a degenerate state, supported by electron pressure. This makes them stable without internal nuclear reactions, with only the radiation of their residual heat.

In binary systems, white dwarfs can interact with a companion star. If they are close enough, their gravity can strip matter from the other star, sometimes forming an accretion disk. This disk allows matter to spiral towards the white dwarf's surface, releasing energy in the form of light and sometimes outflows.

Understanding white dwarfs helps to grasp stellar evolution and the final fate of most stars in our galaxy. Their study reveals processes such as Type Ia supernovae, which are important for measuring cosmic distances.