Overview

• An international team led by Pasi Hakala reports the findings in Monthly Notices of the Royal Astronomical Society based on ESO Very Large Telescope X-shooter observations.
• V Sagittae, about 10,000 light-years away, is a 12.3-hour binary where a white dwarf strips hydrogen-rich gas from a larger companion, driving thermonuclear burning on its surface.
• Spectral lines fixed at the system’s velocity point to a luminous circumbinary ring formed from material the accretor cannot ingest.
• Researchers describe rapid, destabilizing mass transfer and predict a nova outburst within years that could be visible to the naked eye.
• Over longer timescales, continued mass gain or a merger could trigger a Type Ia supernova potentially visible in daylight, with the timing uncertain.