Rainbow bow shock around a nearby white-dwarf binary challenges stellar physics

Astronomers using the VLT have spotted a rainbow-colored bow shock around RXJ0528+2838, a white dwarf in a binary about 730 light-years away. The nebula, extending ~4,000 AU and at least 1,000 years old, surrounds a diskless system that is actively pulling material from its companion. Researchers believe an extremely strong magnetic field powers an unusual, outflow-like phenomenon—the so-called mysterious engine—without a traditional accretion disk, challenging current models of mass transfer in binary systems. The finding, published in Nature Astronomy, suggests more such systems may exist and could be studied in detail with the upcoming ELT set to go online by 2028.