Astronomers utilizing ESO’s Extremely Large Telescope (VLT) have captured images of SNR 0509-67.5.
This image, obtained with the multi-unit spectroscopic explorer (Muse) located on ESO’s Extremely Large Telescope (VLT), displays the supernova remnant SNR 0509-67.5. The Calcium shown in blue is arranged in two concentric shells, indicating a double explosion of the star. Image credits: ESO/DAS et al. / Noll et al.
“White dwarfs—small, inert cores resulting from the demise of sun-like stars—are capable of producing what astronomers classify as type Ia supernovae,” states a PhD student from the University of New South Wales University of Canberra.
“Our understanding of the universe’s expansion hinges on these supernovae, which also serve as the primary source of iron on Earth, including in blood.”
“Yet, despite their significance, the mechanisms driving their explosions are still not fully understood.”
All theories surrounding Type Ia supernovae begin with pairs of white dwarf stars.
When one of the stars’ orbits is sufficiently close to its counterpart, it can siphon material from its companion.
According to the most prevalent theory regarding Type Ia supernovae, the white dwarf accumulates matter until it hits a critical mass and then experiences a singular explosion.
However, new research indicates that at least some Type Ia supernovae could be better explained by a series of double explosions occurring before the stars reach this critical mass.
The recent VLT images of SNR 0509-67.5 confirm these predictions.
In this alternative model, the white dwarf forms a helium layer through theft, which becomes unstable and can ignite.
This initial explosion generates a shockwave that moves inward, resulting in another explosion at the core of the star, ultimately leading to the supernova.
Until now, there had been no clear visual proof supporting the occurrence of a double explosion in white dwarfs.
Recent studies have suggested that this process creates identifiable patterns or “fingerprints” on the still-glowing debris from the supernova, surfacing long after the primary explosion.
Research proposes that the remains of such supernovae contain two distinct calcium signatures.
Das and his colleagues have found these fingerprints on the supernova remnants.
“The findings clearly indicate that white dwarfs can explode well before reaching the famous Chandrasekhar limit, demonstrating that the ‘double explosion’ mechanism naturally occurs,” remarks Dr. Ibo Seitenzar, an astronomer at the Heidelberg Institute.
Astronomers were able to identify these calcium layers in SNR 0509-67.5 by employing VLT’s multi-unit spectroscopic explorer (Muse).
This provides compelling evidence that Type Ia supernovae can occur prior to their progenitor white dwarfs reaching critical mass.
“This tangible evidence of double explosions not only aids in resolving historical mysteries but also offers a visual interpretation,” explains Das.
“It’s incredibly satisfying to reveal the intricate workings behind such colossal cosmic explosions.”
The team’s results are published today in the journal Nature Astronomy.
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P. Das et al. Calcium in the remnants of the supernova as fingerprints of the sub-Chandrasekhar explosion. Nature Astronomy Published online on July 2, 2025. doi:10.1038/s41550-025-02589-5
Source: www.sci.news
