SOUTHAMPTON, UK — Astronomers have discovered a white dwarf star locked in a deadly dance with its stellar companion—devouring it at a rate never seen before. The doomed pair, known as V Sagittae, lies around 10,000 light-years from Earth and has long puzzled scientists with its unusual brightness.

The new study, led by Dr Pasi Hakala from the University of Turku (Finland) and involving Professor Phil Charles from the University of Southampton (UK) and Dr Pablo Rodríguez Gil from the Instituto de Astrofísica de Canarias and the University of La Laguna (Spain), reveals that the white dwarf is siphoning vast amounts of material from its larger partner star.

“V Sagittae is no ordinary star system—it’s the brightest of its kind and has baffled experts since its discovery in 1902,” said Professor Charles. “Our study shows that this extreme brightness is caused by the white dwarf sucking the life out of its companion, turning it into a blazing inferno. It’s going thermonuclear on its surface, shining like a beacon in the night sky.”

A Cosmic Feeding Frenzy

White dwarfs are the dense, burnt-out cores of dead stars. In V Sagittae, the white dwarf and its companion orbit each other once every 12.3 hours, spiralling gradually closer. As the white dwarf rips matter from its partner, it burns with intense heat and brightness, unleashing powerful radiation.

Using the European Southern Observatory’s Very Large Telescope in Chile, the researchers also discovered a striking ring of gas encircling both stars. This halo of debris appears to form from the material the white dwarf cannot consume.

“The white dwarf cannot swallow all the mass being transferred, so it creates this bright cosmic ring,” explained Dr Hakala. “The sheer speed and energy of this system are frantic signs of its imminent, violent end.”

A Future Supernova Visible from Earth

Dr Rodríguez Gil said the growing layer of stolen material could soon trigger a nova outburst—a dramatic explosion that would make V Sagittae visible to the naked eye from Earth. Ultimately, when the two stars finally collide, the event will produce a supernova so bright it could even be seen in daytime skies.

The findings, published in the Monthly Notices of the Royal Astronomical Society, solve a century-old mystery around V Sagittae’s extraordinary luminosity and offer new insights into the life and death cycles of stars.

Original Publication
Authors: Pasi Hakala, Phil Charles and Pablo Rodríguez-Gil.
Journal: Monthly Notices of the Royal Astronomical Society
DOI: 10.48550/arXiv.2507.22637
Method of Research: Meta-analysis
Subject of Research: Not applicable
Article Title: V Sge: Supersoft Source or Exotic Hot Binary? I. An X-Shooter campaign in the high state
Article Publication Date: 10-Sep-2025