Two concentric rings appear around the supernova remnant SNR 0509-67.5, indicating that it exploded twice
ESO/P. Das et al. Background stars (Hubble): K. Noll et al.
Astronomers have made a groundbreaking discovery of a white dwarf star located approximately 160,000 light years away, suggesting that it may have exploded twice in a rare phenomenon known as a double detonation. This finding provides the first concrete evidence that certain supernovae involve a dual explosion event, shedding light on the mysterious mechanisms behind these cosmic events.
White dwarf stars, remnants of dead stars that were once similar to our sun, undergo a cataclysmic explosion when they accumulate enough mass from a neighboring star, resulting in a type Ia supernova. The exact process by which a white dwarf transforms into a supernova has long been a subject of speculation among astronomers, with some proposing the possibility of a two-step detonation process.
Researchers, led by Priyam Das from the University of New South Wales in Canberra, Australia, utilized data from the European Southern Observatory’s Very Large Telescope in Chile to analyze a supernova remnant in the Large Magellanic Cloud known as SNR 0509-67.5. Their observations revealed the presence of two concentric shells surrounding the remnant, indicating a double explosion event.
According to Das, the white dwarf in question likely accreted helium from a nearby source, such as another helium white dwarf or a helium-rich massive star. Once a critical mass of helium had accumulated on its surface, the white dwarf underwent an initial helium detonation followed by a second detonation within a matter of seconds.
“We get a very initial helium detonation and, within tens of seconds, we get the second detonation, so it happens all in the blink of an eye,” explains Das. Despite the rapid succession of explosions, the material ejected from the first blast was initially traveling at a staggering speed of 25,000 kilometers per second, resulting in significant separation between the two detonation events.
The light from this extraordinary cosmic event is estimated to have reached Earth between 310 and 350 years ago. Although it would have been one of the brightest objects in the southern hemisphere night sky at the time, there are no historical records of any human witnesses, possibly due to the supernova being obscured by the sun.
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