The European Southern Observatory (ESO) published a photograph revealing the remnants of a white dwarf star that ended its existence in a double explosion. This marks the first discovery of a stellar event involving a double detonation, according to Popular Science.
The breakthrough was published in Nature Astronomy on July 2, signifying an advancement in understanding Type Ia supernovae. Using the Very Large Telescope (VLT) and the Multi Unit Spectroscopic Explorer (MUSE) instrument, scientists at ESO observed the remains of supernova SNR 0509–67.5. This observation provided visuals for astronomy enthusiasts and certified that some stars can end their long lives violently through two chained explosions.
SNR 0509–67.5 is located more than 160,000 light-years away in the Large Magellanic Cloud and is believed to have formed more than 400 years ago. The researchers discovered two distinct layers of calcium arranged in concentric shells in the remnants, confirming the occurrence of a double detonation as predicted by models.
"The explosions of white dwarfs play a crucial role in astronomy," stated Priyam Das, a PhD student at the University of New South Wales Canberra and study leader. Das further described the findings as "tangible evidence of a double detonation" that solves a mystery and offers a "magnificent visual spectacle."
Type Ia supernovae are known for their consistent brightness, allowing scientists to calculate distances in space, making them crucial for measuring the universe's accelerating expansion.
"The findings provide a clear indication that white dwarfs can explode before reaching the Chandrasekhar mass limit and that the double detonation mechanism occurs in nature," stated Ivo Seitenzahl, one of the researchers who led the observations. This discovery confirms a theory that researchers had for years but had never been able to prove visually.
The study revealed that when the helium bubble on a white dwarf ignites, it causes a shock wave that travels around the white dwarf and inward, triggering a second detonation in the star's core that ultimately leads to the supernova.
White dwarfs are small, dense, and hot objects roughly the size of a planet like Earth. They remain as inactive cores after stars like our Sun exhaust their nuclear fuel and can give rise to Type Ia supernovae. In a binary system, a white dwarf can become a stellar vampire if it orbits too closely to a living star, siphoning material from its companion.
Once a white dwarf accumulates enough matter from its companion star and reaches the Chandrasekhar limit—around 1.4 times the mass of the Sun—it ignites in a thermonuclear explosion. This results in a Type Ia supernova that usually completely destroys the white dwarf. However, the new findings indicate that some white dwarfs can explode before reaching the critical mass through the double detonation mechanism.
The predictable brightness of Type Ia supernovae helps astronomers measure distances in space like a cosmic tape measure, leading to discoveries in modern astronomy. For instance, thanks to these supernovae, astronomers discovered the accelerated expansion of the universe, which contributed to the hypothesis of dark energy.
The observations of SNR 0509–67.5 were made possible thanks to the detailed analysis of the light emitted by the supernova remnant, observed with the VLT located in Chile and operated by ESO. The MUSE instrument allowed researchers to detect the characteristic calcium pattern in the remnant, confirming the double detonation model.
"This arrangement of calcium layers is exactly what computer simulations predict when a white dwarf undergoes a double detonation," according to Space.com. The discovery sheds new light on the role of supernovae in the evolution of the universe, contributing to solving a mystery in astronomy.
"Revealing the inner workings of such a spectacular cosmic explosion is incredibly rewarding," said Das. Understanding how these events work is essential for making sense of the universe. By collecting light from Type Ia supernovae, scientists can figure out how fast the universe has been expanding.
The discovery offers a new perspective on some of the universe's most important explosions. The researchers hope to deepen the study of how these objects explode by searching for other young supernova remnants with similar properties.
This finding confirms that some stars with mass similar to our Sun can suffer two chain explosions that ultimately destroy them completely. It also indicates that at least some stars do not need to hit a critical mass of matter before becoming supernovas, as evidenced by SNR 0509–67.5.
Understanding Type Ia supernovae will also help scientists learn about the role these explosions play in the formation of galaxies. The classical model for Type Ia supernovae did not explain all observations, particularly regarding the mechanisms of their explosions. The double detonation model offers an alternative explanation.
Written with the help of a news-analysis system.