A peer-reviewed study published January 12, 2026, reported a resolved bow shock around RXJ0528+2838, a diskless white dwarf in a binary system. The shock’s energy requirements point to a persistent power source beyond the system’s accretion energy output, but the researchers did not identify that source.
A curved shock around a diskless white dwarf
RXJ0528+2838 is a high-proper-motion, magnetically accreting white dwarf about 730 light-years from Earth. It has a Sun-like companion. A white dwarf is the remnant core of a low-mass star.
A bow shock is a curved arc of material formed as an object moves through surrounding gas, much like a wave building ahead of a moving ship. Images from the Isaac Newton Telescope first revealed the structure around RXJ0528+2838. MUSE, an instrument on the European Southern Observatory’s Very Large Telescope (VLT), mapped it in detail and linked it to the binary system.
Why the familiar explanations fall short
The system has no observed accretion disk, and the study found that the bow shock is inconsistent with either a past thermonuclear explosion on the white dwarf or a wind from its companion. Those explanations do not account for the structure in this system.
The study’s energy modelling indicates that the shock requires a persistent power source whose luminosity significantly exceeds the system’s accretion energy output. The white dwarf’s magnetic field is estimated at approximately 42–45 megagauss (MG), but magnetic activity remains a possible connection—not an identified explanation for the required power.
A long-lived structure, two different timescales
ESO estimates that the bow shock’s size and shape imply an outflow lasting at least 1,000 years. Separately, ESO estimates that the white dwarf’s present magnetic field could power a bow shock for only a few hundred years.
| Estimate | What it describes |
| At least 1,000 years | Inferred duration of the outflow, based on the shock’s size and shape |
| A few hundred years | How long the present magnetic field could power a bow shock, according to ESO |
One estimate concerns the duration inferred from the structure; the other concerns the sustaining power of the present magnetic field. The study does not identify the persistent source needed to meet the shock’s energy requirement. Researchers expect ESO’s Extremely Large Telescope (ELT) to help map more systems, including fainter ones, and investigate the energy source.
