Rare Star Blast Fires Cosmic Gas Bullets Across Space At 20 Million MPH

by Aaron Leong — Friday, July 24, 2026, 11:09 AM EDT

Astronomers have used the Hubble Space Telescope to capture cosmic 'bullets' streaming from V445 Puppis, a unique stellar explosion in the Milky Way firing clumps of gas into space at a blistering 20 million miles per hour.

When V445 Puppis erupted in late 2000, it instantly stood out as the only confirmed helium nova ever detected within our galaxy. Standard novas occur when a white dwarf sucks hydrogen off a nearby binary companion until a runaway thermonuclear blast sets off on its surface (due to temperature and pressure changes). V445 Puppis is different: its companion star is a rare helium star that has already been stripped of its outer hydrogen layer, forcing the white dwarf to feed almost exclusively on helium instead.

For more than two decades, the full nature of this binary system remained behind a shroud of thick, expanding dust launched during the initial blast. As that circumstellar dust cloud dispersed, an international research team led by John Mills at the University of Warwick turned a suite of instruments, including Hubble, NASA’s Transiting Exoplanet Survey Satellite (TESS), and the European Southern Observatory’s Very Large Telescope (VLT), back onto the remnant.

puppis ejecta — *Expansion of the bipolar shell ejected from 2005 (upper left) to 2007 (lower right) Credit: ESO/P.A. Woudt*

Peering through the clearings, the team detected distinct, highly concentrated clumps of potentially oxygen-rich gas hurtling through space. These fast-moving knots (or bullets) appear to have formed after the main outburst, traveling outward along twin debris plumes that resemble gigantic butterfly wings spanning over a trillion miles across. Similar structures have never been observed around any conventional hydrogen nova, leaving experts eager to decipher the exact mechanism that launched them at roughly 3% of light speed.

Further observations also revealed that the white dwarf has survived its explosive indigestion and resumed siphoning helium from its stripped companion. It's safe to say that this resumed feeding routine could mean V445 Puppis is heading toward another helium nova in the near future.

A repeated helium blast would be a fantastic phenomenon to study in the world of astrophysics. If a white dwarf such as Puppis continues to accumulate mass from its companion without shedding too much during outbursts, it could eventually breach the critical mass threshold required to trigger a Type Ia supernova. Because Type Ia supernovas explode with consistent intrinsic brightness, astronomers rely on them as standard rulers of sorts to gauge galactic distances and track the accelerating expansion of the universe.

Main image: Image from HST showing the bipolar outflow of material ejected by the helium nova V445 Puppis. (Credit: John Mills / University of Warwick)