Astronomers have studied the remnant of a Type Ia supernova to reveal in detail the mechanism of a cosmic explosion. Although supernovae of this type are known to occur in binary systems consisting of white dwarf and ordinary companion stars, many of the details of the process leading to a white dwarf explosion are still a mystery.
If a white dwarf and a normal star orbit too close to each other, the former starts to attract the matter of its companion, increasing its mass. If this mass reaches a critical value, known as the Chandrasekar limit, a supernova explosion will occur. In this case, the star's matter is thrown outward by the initial explosion, but then collides with the resistance of the surrounding gas and slows down, creating a reverse shock wave that travels toward the center of the explosion.
In the new work, astronomers observed the supernova remnant G344.7-0.1 using various telescopes, covering a wide range of radiation, including X-rays (Chandra Space Observatory), infrared light (Spitzer Space Telescope), and radio emission (VLA and ATCA antenna arrays). It is estimated that the remnant is as old as 3-6 thousand years. This means that the reverse shock wave has already had time to pass through the entire debris field, heating them to a temperature of millions of degrees and forcing them to emit X-rays.
It turned out that the region with the highest iron density was surrounded by arc-shaped structures containing silicon. Similar arc-like structures were also found for sulfur, argon, and calcium. This means that the region with the highest iron density was heated by the reverse shock wave later than the elements of the arc-like structures, and was located near the true center of the stellar explosion. The results confirm the predictions of the models of Type Ia supernovae explosions, according to which heavier elements are formed inside the exploding white dwarf.