Astronomers had pictured novae, violent explosions that occur on the surface of white dwarf stars, as simple spherical fireballs. You can think of them as cosmic flashbulbs. One loud pop, a bright light, and then it slowly fades away. But when researchers recently pointed the powerful CHARA array telescope at the two erupting Mars, they saw something quite different.

New high-resolution images of these stellar cataclysms reveal that novae are actually messy, complex events with vertical gas jets and delayed eruptions that engulf entire star systems.

“The fact that we can watch a star explode and instantly see the structure of the material being blown into space is remarkable,” said John Monnier, a professor of astronomy at the University of Michigan.^.

This leap in imaging technology is changing our understanding of stellar evolution. “It opens a new window on some of the most dramatic events in the universe,” Monnier said.

From grainy photos to high-resolution videos

This breakthrough comes from the Center for High Angle Resolution Astronomy (CHARA) array in California.

By linking six telescopes using a technique called interferometry, the observatory can achieve the resolution needed to observe small, rapidly expanding debris fields in stars thousands of light-years away. The CHARA array is essentially a giant distributed eye made up of six individual telescopes dotted atop Mount Wilson, all linked together to act like one giant 330-meter instrument.

When we look at a nova, we’re not just looking at one star. We are looking at a high-stakes celestial heist. These phenomena occur in interacting binary stars, where a small, incredibly dense white dwarf star (about the size of Earth but with the mass of the Sun) siphons hydrogen-rich gas from its larger companion star. As this gas builds up, it triggers a thermonuclear runaway, a nuclear explosion on the white dwarf’s surface, which we see as a “new” star in the sky.

“We’re not just seeing flashes of light, we’re uncovering the true complexity of how these explosions unfold,” says Elias Eidi, the study’s lead author and an astrophysicist at Texas Tech University.^{. “It’s like going from grainy black and white photography to high-definition video.”}

This clarity allowed the research team to track two very different outbursts in 2021. V1674 Hercules is a “speed demon” that flashed and disappeared within a few days, and V1405 Cassiopeia is a “slow burn” that lasted for several months.

speed demon and shockwave

This new clarity allowed the team to track two very different outbursts that occurred in 2021. The first was V1674 Hercules, a “speed demon” that flashes on and off in a matter of days.

V1674 Herculis was a record breaker. It erupted in the constellation Hercules on June 12, 2021, and rapidly rose to its maximum brightness within 16 hours. When the CHARA team took images just two days after the explosion, they found something unexpected.

When the CHARA team took images just two days after the explosion, they found something unexpected. The explosion was not a uniform round shell. Instead, the star expelled material in two distinct vertical streams.

“These images provide a close-up look at how material is ejected from a star during an explosion,” says CHARA Array Director Gail Schaefer.^.

These conflicting gas flows created a violent environment. The streams of ejecta collided with each other, creating shock waves powerful enough to emit gamma rays. NASA’s Fermi Gamma-ray Space Telescope captured a high-energy signal from the star at the exact same time that CHARA images showed the appearance of the outflow.

This confirmed our main hypothesis. This means that the gamma rays detected from these explosions are not only produced by the blast waves that hit interstellar space, but also by internal collisions within the debris field.^.

Slow burn and common envelope

If the V1674 Hercrys is a sprint, the V1405 Cassiopeia is a marathon. Discovered in March 2021, the nova took an astonishing 53 days to reach its maximum brightness.

For almost two months, the star baffled astronomers. The first CHARA image showed a bright, compact central source with a radius of about 0.85 astronomical units (AU), or the distance from the Sun to Venus.

This was strange. If the star had blown its outer layer into space on its first day, the debris shell would have been huge by day 53, measuring between 23 and 46 AU. But the shell was gone.

The best explanation is a phenomenon known as the “common envelope” phase. Instead of immediately expelling material, the white dwarf would have expanded, swallowing the companion star in a cloud of hot gas. The two stars orbited inside this shared atmosphere, stirring like a blender, until material finally sloshed outward after several weeks.

Extreme Physics Laboratory

These discoveries turn these dying stars into local physics laboratories.

“Novaes are more than just fireworks in our galaxy; they are laboratories for extreme physics,” says study co-author Laura Chomiuk of Michigan State University.

“By observing when and how material is ejected, we can ultimately connect the dots between nuclear reactions on the star’s surface, the shape of the ejected material, and the high-energy radiation detected from space.”

Understanding these shock waves can help us understand phenomena far beyond our galaxy, from ultra-bright supernovae to stellar mergers that ripple through the fabric of space-time.^.

We used to think of novae as a simple on/off switch. We now know that they are complex engines of creation and destruction, driven by binary mechanics and fluid dynamics, which we are only beginning to map.

“Capturing these temporary events requires the flexibility to adapt nightly schedules as new targets of opportunity are discovered,” Schaefer said.^{. As telescopes become sharper and their response times faster, the night sky begins to look more like an unstable, evolving frontier than a static backdrop.}

The survey results were published in a magazine natural astronomy.