Astronomers Unveil Secrets of V445 Puppis, the Milky Way's Only Helium Nova

• V445 Puppis, discovered in 2000, is the only confirmed helium nova in the Milky Way, erupting without hydrogen.
• A massive disc of dust generated during the explosion obscured the system for over two decades, but recent data has finally revealed its true nature.

System Architecture

• The system consists of a binary pair: a white dwarf siphoning material from a helium star.
• The helium star was stripped of its outer hydrogen envelope by the white dwarf.
• The pair orbits every 3.7 days, roughly double the previously assumed period.
• The white dwarf has begun siphoning material again, restarting the process that leads to future eruptions.

Mystery Features and Implications

• The explosion released oxygen-rich gas clumps traveling at up to 12 million km/h; this phenomenon has never been seen in other novae.
• Researchers are investigating whether repeated helium eruptions serve as a pathway to Type Ia supernovae.
• Because Type Ia supernovae are used as "standard candles" to measure cosmic acceleration, understanding this potential precursor is vital for cosmological research.