This dead star with a light shockwave should not exist

A vibrant show of glowing gas around a dead star is being powered by a mysterious source that scientists can’t explain, in an unprecedented phenomenon.

As stars move through space, they push aside matter and create what is called a bow shock in front of them, similar to a curved ridge of water that forms in front of a moving boat. Using the European Southern Observatory’s Very Large Telescope, a team of astronomers discovered a shock wave that should not exist.

The star RXJ0528+2838 is a white dwarf, the remains of a dead star that no longer generates energy through nuclear fusion. And yet the white dwarf is surrounded by a shock wave of light that glows red, green and blue – and its origin is unknown. The discovery, published Monday in natural astronomy, cannot be explained by any known mechanism of the universe.

Cosmic mystery

The white dwarf star is located about 730 light years from Earth, which is pretty close in cosmological terms. The remaining core of the low-mass star has a stellar companion, a Sun-like star that orbits it. In these types of binary systems, material from the companion star is often transferred to its dead neighbor, forming a disk around the white dwarf. The disk powers the white dwarf, while some of the material is ejected into space to form an outflow.

The newly discovered star, however, shows no signs of a disk. “We discovered something never seen before and, more importantly, completely unexpected,” said Simone Scaringi, an associate professor at the University of Durham, England, and co-senior author of the study. statement. “The surprise that a supposedly quiet, quiet system could drive such a spectacular nebula was one of those rare ‘wow’ moments.”

As the white dwarf orbits the center of the Milky Way, it interacts with the surrounding gas to form a vibrating arc in front of it. These arc shocks are usually created by matter flowing out of the star, but the white dwarf shows no evidence of any type of matter being generated.

“Our observations reveal a powerful outflow that, according to our current understanding, should not be there,” Krystian Ilkiewicz, a postdoctoral researcher at the Nicolaus Copernicus Astronomical Center in Warsaw, Poland, and co-leader of the study, said in a statement.

Origin unknown

The scientists behind the discovery mapped the arc shock in detail and analyzed its composition, confirming that it originates from the binary star system. They found that the shape and size of the arc shock suggest that the white dwarf has been expelling this material for at least 1,000 years, furthering the mystery of how a lifeless, diskless star produces such a long-lasting outflow.

Although it’s a unique cosmic mystery, the team of scientists has some clues as to how it might have happened. The results point to a possible hidden energy source, likely a strong magnetic field. The white dwarf’s magnetic field could channel material stolen from its companion star directly onto its dead stellar remnants without forming a disk around it.

However, the theory still requires some work. A magnetic field would only be enough to power an arc shock for a few hundred years, thus solving only part of the cosmic mystery.

“This discovery challenges the standard picture of how matter moves and interacts in these extreme binary systems,” Ilkiewicz said. “Our discovery shows that even without a disk, these systems can generate powerful outflows, revealing a mechanism that we do not yet understand.”