Astronomers have discovered a star system unlike anything seen before: a greedy white dwarf star is feasting on its much larger stellar companion at a record-breaking rate.
The double-star system, known as V Sagittae, is burning so brightly that scientists believe it may one day explode in a dazzling display visible from Earth.
White dwarfs are the dense remnants of stars that have burned through their fuel.
In this case, the white dwarf’s partner star is much larger, but instead of dominating the relationship, it is being slowly consumed.
As the two orbit each other every 12.3 hours, the white dwarf pulls in streams of material from its companion, creating a cosmic feeding frenzy.
An international team of astronomers, led by Dr. Pasi Hakala from the University of Turku in Finland, investigated this unusual system with colleagues from Spain’s Instituto de Astrofisica de Canarias and the University of Southampton in the UK.
Their study, soon to be published in the Monthly Notices of the Royal Astronomical Society and already available on the arXiv preprint server, may finally solve a mystery that has puzzled astronomers for more than a century.
“V Sagittae is no ordinary star system,” explained Southampton’s Professor Phil Charles. “It’s the brightest of its kind, and our study shows that its brilliance comes from the white dwarf sucking the life out of its companion.
The matter it steals fuels thermonuclear reactions on its surface, making it shine like a beacon in the night sky.”
Using the European Southern Observatory’s Very Large Telescope in Chile, researchers also spotted a striking new feature: a vast ring of glowing gas surrounding both stars. This ring, formed from the material the white dwarf cannot fully consume, is a sign of the extreme energy being generated inside the system.
According to Dr. Hakala, the halo of gas may force astronomers to rethink what they know about how stars evolve and die.
The violent relationship between these two stars may end in catastrophe. Dr. Pablo Rodríguez Gil of the Instituto de Astrofisica de Canarias explained that the accumulating matter on the white dwarf could soon trigger a nova—an explosive burst of energy that would make V Sagittae visible to the naked eye.
Eventually, the two stars are expected to collide and merge, producing a spectacular supernova explosion. Such an event would be so bright it could be seen from Earth even during the daytime.
Though V Sagittae is about 10,000 light-years away, its dramatic behavior offers a rare glimpse into the fate of close binary stars. For now, scientists are keeping a close eye on this doomed system as it spirals toward its fiery end.
Source: University of Southampton.
