A repeating nova eruption in the Large Magellanic Cloud has shattered temperature records, revealing unexpected chemical signatures and offering fresh insight into stellar evolution. The findings were published in the Monthly Notices of the Royal Astronomical Society.
Most Intense Nova Ever Detected Beyond the Milky Way
A recurrent nova called LMCN 1968-12a, located in the Large Magellanic Cloud—a satellite galaxy of the Milky Way—has erupted again, and this time, astronomers are calling it one of the hottest nova explosions ever recorded.
This eruption, observed in August 2024, is part of a repeating pattern that occurs roughly every four years. But unlike previous observations, scientists have now conducted the first-ever near-infrared analysis of a recurrent nova outside our galaxy. The data was gathered using the Magellan Baade and Gemini South telescopes in Chile, with a focus on the light emitted 9 and 22 days after the eruption.
The observations uncovered temperatures reaching up to 5.4 million degrees Fahrenheit (3 million degrees Celsius). The brightness and chemical profile of this nova set it apart from similar events observed in the Milky Way.
Unusual Chemistry Points to Unique Stellar Conditions
What astonished researchers wasn’t just the heat. The nova’s spectral fingerprint showed an unusually high presence of ionized silicon, glowing at 95 times the brightness of the entire sun across all wavelengths. Strikingly absent, however, were other high-energy elements that usually appear in such events : “We would’ve expected to also see signatures of highly energized sulfur, phosphorus, calcium and aluminum,” noted Geballe.
This anomaly suggests a rarified and extremely hot environment, which the researchers’ models confirmed. According to Tom Geballe, emeritus astronomer at NOIRLab, and Sumner Starrfield, astrophysics professor at Arizona State University, this absence of expected elements hints at a deeper link between local galactic chemistry and eruption intensity.
One contributing factor is metallicity—the presence of heavy elements in a star system. The Large Magellanic Cloud has lower metallicity than the Milky Way, allowing more hydrogen and helium to accumulate on the white dwarf before it detonates in a nova. In contrast, higher-metallicity environments like our galaxy tend to produce less violent eruptions.
Anatomy of a Recurrent Nova
A nova occurs when a white dwarf, the dense core left behind after a star’s death, pulls in gas from a nearby companion star—often a subgiant. As this material builds up, it forms an accretion disk, gradually piling onto the white dwarf’s surface. Once enough material collects, pressure and temperature spike, igniting a thermonuclear runaway reaction.
The result is a powerful burst of energy, ejecting gas and causing a dramatic brightening in the night sky. In recurrent systems like LMCN 1968-12a, this process happens repeatedly. Though the core stars survive, each outburst sheds material and alters the system’s dynamics.
The regularity of these eruptions has made LMCN 1968-12a a benchmark object since its first detection in 1968. Observations since 1990 have revealed a roughly four-year cycle, giving astronomers a rare chance to study the effects of time, composition, and eruption physics across decades.
