Stars can explode twice: A major discovery in cosmology

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Creation Date: July 04, 2025 10:53

USING THE VERY LARGE TELESCOPE (VLT) OF THE European Southern Observatory (ESO), the study focused on the supernova remnant SNR 0509-67.5, located in the Large Magellanic Cloud, approximately 160 thousand light-years away. The lead author of the study, published in the journal Nature Astronomy, Priyam Das from the University of Canberra in Australia, stated that some supernovas of this type can experience two separate explosions.

According to Sciencealert, this phenomenon, called "double explosion", is observed in Type 1a supernovas. These supernovas occur in binary systems consisting of a white dwarf star and another star. White dwarfs are the dense remnants of stars left behind by small stars that have died out. The white dwarf, which draws gas from the stars around it, first experiences a helium explosion on its surface when this gas reaches a certain level. This first explosion sends a shock wave inward, triggering a second, larger explosion in the star's core.

IMPORTANCE OF NEW FINDINGS

Scientists found evidence for the binary explosion model by analysing the chemical signatures left by the explosion. Two distinct calcium layers were discovered in the remnant of SNR 0509-67.5 using ESO's telescope. "These findings clearly show that white dwarfs can explode without reaching the famous Chandrasekhar limit (around 1.4 solar masses)," said co-author Ivo Seitenzahl.

WHAT IS CHANDRASEKHAR LIMIT?

The Chandrasekhar limit is a critical threshold for the mass of white dwarf stars. Above this limit, which is approximately 1.4 times the mass of the Sun, the pressure and temperature inside the star initiate a chain reaction that leads to the star exploding.

The discovery is seen as a major step in explaining the differences in the brightness and structure of supernovae, and will provide critical information in understanding the nature of dark energy that drives the expansion of the universe and the origin of iron in the universe.