Astronomers have utilized the unparalleled capabilities of ESO’s Very Large Telescope (VLT) to detect a remarkable shock wave enveloping the white dwarf star 1RXS J052832.5+283824, colloquially known as RXJ0528+2838. This phenomenon deviates significantly from current theoretical frameworks, potentially necessitating a revision of our comprehension of stellar evolutionary pathways.
This image, captured by the MUSE instrument aboard ESO’s Very Large Telescope, illustrates a shock wave surrounding RXJ0528+2838. Credit: ESO / Iłkiewicz et al.
RXJ0528+2838 is situated approximately 730 light-years distant within the celestial confines of the constellation Auriga.
Similar to our Sun and other stellar bodies, this white dwarf traverses its orbit around the Galactic Center of the Milky Way.
“As it navigates its orbital path, it experiences interactions with the interstellar medium, the diffuse gas that populates the space between stars, consequently generating a specific type of shock wave denominated a bow shock. This manifests as a curvilinear formation of matter, analogous to the wave preceding a moving vessel,” explained Dr. Noel Castro Segura, a distinguished astronomer affiliated with the University of Warwick.
“Typically, these bow shocks are a consequence of material ejected outward from the central star; however, in the specific instance of RXJ0528+2838, none of the established astrophysical mechanisms adequately account for the observed phenomena.”
RXJ0528+2838 is known to host a companion star in orbital conjunction. Within such binary configurations, material transfer from the companion star to the white dwarf is a common occurrence, frequently leading to the formation of an accretion disk around the latter.
While this disk provides sustenance to the white dwarf, a portion of the accreted material is also propelled outward into space, engendering potent outflows.
Nevertheless, RXJ0528+2838 exhibits no discernible evidence of an accretion disk, rendering the genesis of the outflow and the resultant nebular structure surrounding the star a perplexing enigma.
“The unexpected revelation that a seemingly quiescent, disk-absent system could be responsible for driving such a remarkable nebula was a profound ‘eureka’ moment,” remarked Dr. Simone Scaringi, an astronomer based at Durham University.
Initial indications of an anomalous nebulosity around RXJ0528+2838 were first detected by the research team in imagery acquired by the Isaac Newton Telescope situated in Spain.
Subsequent to observing its peculiar morphology, further in-depth investigations were conducted utilizing the MUSE instrument, an integral component of the VLT.
The geometry and scale of the observed bow shock suggest a sustained period of vigorous outflow from the white dwarf, persisting for a minimum of 1,000 years.
While the precise mechanism by which a diskless white dwarf could sustain such an enduring outflow remains unknown, scientists have posited a potential explanation.
RXJ0528+2838 is recognized for possessing a potent magnetic field, a characteristic substantiated by the data procured from the MUSE observations.
It is theorized that this magnetic field acts as a conduit, directing material siphoned from the companion star directly onto the surface of the white dwarf, thereby circumventing the formation of an accretion disk.
“Our findings underscore the capacity of these systems to generate substantial outflows even in the absence of an accretion disk, thereby elucidating a process that remains largely enigmatic. This observation challenges the conventional paradigm governing the dynamics and interplay of matter within these extreme binary stellar environments,” stated Dr. Krystian Iłkiewicz, a postdoctoral researcher at the Nicolaus Copernicus Astronomical Center.
“The implications of these results suggest the presence of an underlying energy source, most plausibly the robust magnetic field; however, this ‘enigmatic engine’ warrants further intensive investigation.”
The analyzed data indicate that the currently detectable magnetic field strength is insufficient to sustain a bow shock for durations exceeding a few hundred years, thus only partially accounting for the observed phenomenon.
“We have unearthed a discovery that is both unprecedented and, critically, entirely unanticipated,” declared Dr. Scaringi.
This significant scientific revelation has been formally documented in a publication released today in the esteemed journal Nature Astronomy.
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K. Iłkiewicz et al. A persistent bow shock in a diskless magnetized accreting white dwarf. Nat Astron, published online January 12, 2026; doi: 10.1038/s41550-025-02748-8
