Link to the science paper
This study confirms that the bright star Nunki (Sigma Sagittarii) is the closest known candidate to the Sun that could eventually explode as a core-collapse supernova.
Using high-resolution interferometric observations from multiple instruments, the authors determine that Nunki is a close binary system made of two nearly equal-mass stars (about 6.5 and 6.3 times the Sun’s mass) orbiting each other every ~135 days at a distance of about 1.26 astronomical units.
The orbit is highly elliptical, which strongly affects how the system will evolve. As the primary star expands later in its life, the stars are expected to interact through mass transfer at closest approach. Because of the eccentric orbit, this process is unstable and may lead to a “common envelope” phase, where both stars share gas, likely ending in a merger into a single, more massive star (greater than 10 solar masses). This merged star would be massive enough to eventually collapse and explode as a supernova.
The study also explains why such binaries are hard to detect spectroscopically due to rapid rotation. Overall, Nunki, located about 69 parsecs away, is now considered the nearest likely future supernova progenitor, surpassing previous candidates like Spica and Bellatrix.
Image Credit: E. Slawik/NOIRLab/NSF/AURA/M. Zamani/Milky Way
by Busy_Yesterday9455