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4d ago

Astronomers Spot Long-Lived Bow Shock Around Diskless White Dwarf, Defying Models

Spectral mapping ties the nebula to RXJ0528+2838, revealing a magnetic field too weak to sustain the thousand‑year outflow.

The central square image, taken with the MUSE instrument on ESO's Very Large Telescope, shows shock waves around the dead star RXJ0528+2838. When a star moves through space it can push away nearby material creating a so-called bow shock, which in this image is glowing in red, green and blue. The colours represent hydrogen, nitrogen and oxygen, respectively. These shocks are usually produced by a strong outflow expelled from the star. However, in the case of RXJ0528+2838 –– a white dwarf with a Sun-like companion –– astronomers discovered that the shock wave can’t be explained by any known mechanism. Some hidden energy source, perhaps magnetic fields, could be the answer to this mystery. European Southern Observatory (ESO)/K. Ilkiewicz and S. Scaringi et al./Handout via REUTERS
Image
The central square image, taken with the MUSE instrument on ESO's Very Large Telescope, shows shock waves around the dead star RXJ0528+2838. When a star moves through space it can push away nearby material creating a so-called bow shock, which in this image is glowing in red, green and blue. The colours represent hydrogen, nitrogen and oxygen, respectively. These shocks are usually produced by a strong outflow expelled from the star. However, in the case of RXJ0528+2838 –– a white dwarf with a Sun-like companion –– astronomers discovered that the shock wave can’t be explained by any known mechanism. Some hidden energy source, perhaps magnetic fields, could be the answer to this mystery. European Southern Observatory (ESO)/K. Ilkiewicz and S. Scaringi et al./Handout via REUTERS

Overview

  • The peer‑reviewed study, published January 12, 2026 in Nature Astronomy, reports a persistent bow shock around the white dwarf RXJ0528+2838 about 730 light‑years away.
  • The system shows no accretion disc despite driving a powerful outflow, challenging the standard view that sustained outflows in such binaries require disc‑fed accretion.
  • VLT/MUSE observations mapped the structure’s emission from hydrogen, nitrogen, and oxygen and confirmed it originates from the RXJ0528+2838 binary rather than an unrelated cloud.
  • The bow shock’s size implies a continuous outflow lasting at least 1,000 years, with the structure extending roughly 3,800 Earth–Sun distances.
  • MUSE data confirm a strong magnetic field channeling mass onto the white dwarf, yet calculations indicate the present field could power only a few hundred years, prompting searches for similar systems and further observations with future facilities.