Secrets of the Stellar Blast: CHARA Array Nova Explosion Imaging Reveals Cosmic Chaos

It's no longer just a dot in the night sky. For the first time, astronomers have captured the violent birth of a stellar explosion in unprecedented detail. The CHARA Array at Georgia State University has produced direct images of two nova explosions from 2021, fundamentally changing our understanding of how these cosmic events evolve. Using near-infrared interferometry, they've turned what were once indirect inferences into clear visual evidence.

V1674 Herculis: The Blazing Speed of Non-Spherical Ejecta

One of the subjects, V1674 Herculis, shattered records by reaching peak brightness in less than 16 hours after discovery. Images taken just 2.2 days post-explosion revealed that the blast wasn't a perfect sphere. Instead, it featured a distinct elliptical structure with two ejecta flows shooting toward the northwest and southeast.

This asymmetry is more than just a visual curiosity. According to the research team, these flows collided to form a powerful shock wave. This physical interaction perfectly timed with the detection of high-energy gamma rays by NASA's Fermi Telescope, proving that novae act as massive particle accelerators in space.

V1405 Cassiopeiae: The Mystery of the Common Envelope

The second subject, V1405 Cassiopeiae, followed a much slower path, taking 53 days to peak. Surprisingly, the expansion radius was measured at only 0.85 au—a far cry from the expected 23-46 au if the gas had been ejected immediately.

This massive discrepancy suggests a "common envelope" phase, where the expanded outer layers swallow the entire binary star system for weeks. Gail Schaefer, director of the CHARA Array, noted that catching these transient events requires extreme flexibility. Such observations provide a rare look into how closely orbiting stars interact—a phenomenon believed to occur in over 10% of the stars in our universe.