Researchers at the University of Notre Dame have identified the first eclipsing magnetic propeller in a cataclysmic variable star system, according to research forthcoming in the Astrophysical Journal.

The star system, referred to as J0240, is only the second of its kind on record. It was identified in 2020 as an unusual cataclysmic variable—a binary system consisting of a white dwarf star and a mass-donating red star. Normally, the compact white dwarf star collects the donated gas and grows in mass. In J0240, however, the fast-spinning, magnetic white dwarf rejects the donor's gas and propels it out of the binary system.

"It takes a rapidly spinning dwarf with a strong magnetic field in order to create a propeller," said Peter Garnavich, professor of astrophysics and cosmology physics and chair of the Department of Physics at Notre Dame, and lead author of the study that presented evidence of the propeller system.

In a dramatic, multi-staged eruption, the sun has revealed new clues that could help scientists solve the long-standing mystery of what causes the sun's powerful and unpredictable eruptions. Uncovering this fundamental physics could help scientists better predict the eruptions that cause dangerous space weather conditions at Earth.

This explosion contained components of three different types of solar eruptions that usually occur separately—making it the first time such an event has been reported. Having all three eruption types together in one event provides scientists with something of a solar Rosetta Stone, allowing them to translate what they know about each type of solar eruption to understand other types and uncover an underlying mechanism that could explain all types of solar eruptions.

"This event is a missing link, where we can see all of these aspects of different types of eruptions in one neat little package," said Emily Mason, lead author on the new study and solar scientist at NASA's Goddard Space Flight Center in Greenbelt, Maryland. "It drives home the point that these eruptions are caused by the same mechanism, just at different scales.