🔭 This shock wave should not exist

It's a true cosmic oddity: around the star RXJ0528+2838, researchers have identified a bright arc-shaped shock wave. This type of structure is a sign of powerful matter ejections, but it manifests here in an environment where everything indicates it cannot occur.

This stellar system, located some 730 light-years away, is composed of a white dwarf paired with a Sun-like star. As it moves through space, this duo should normally disturb the surrounding interstellar gas. However, the intensity and morphology of the detected shock wave do not match any phenomenon catalogued for this category of star.


The striking element of this white dwarf is the absence of the traditional accretion disk, that rotating gaseous structure that forms around the star. Such a disk, formed from matter stolen from the companion star, is typically the source of significant ejections.

The team behind the study spotted this unusual nebula using the Isaac Newton Telescope in Spain. Additional examinations conducted with the MUSE instrument on the Very Large Telescope allowed for a detailed mapping of this shock wave.

The gathered information confirms that the structure indeed originates from the binary system and not from an isolated interstellar cloud. Its shape and extent suggest that the phenomenon has been ongoing for at least a thousand years.

Subsequently, scientists detected a particularly strong magnetic field around the white dwarf. It is considered that this field could guide matter from the neighboring star directly to the surface of the compact star, thus avoiding the creation of a disk. However, this hypothesis does not fully explain the power and longevity of the observed shock wave.

This discovery thus offers new avenues for thought on the energetic mechanisms at work in binary systems. The future Extremely Large Telescope (ELT) should allow the examination of other similar systems to unravel the workings of this phenomenon. The study was published in the journal Nature Astronomy.