Overview

• Astronomers used the Multi Unit Spectroscopic Explorer on the Very Large Telescope in Chile to examine SNR 0509-67.5 in the Large Magellanic Cloud.
• They identified two concentric shells rich in calcium, marking the first direct observational proof of a double detonation sequence.
• In this mechanism, an initial thermonuclear shell detonation compresses the underlying white dwarf and triggers a secondary explosion.
• The results, led by Priyam Das of the University of New South Wales, appear in the July 2025 issue of Nature Astronomy.
• This breakthrough resolves a decades-old puzzle about Type Ia triggers and may enhance the precision of cosmological distance measurements.