Our solar system is a single star system. But that’s not necessarily true for all star systems in our own galaxy, the Milky Way. There are several multiple star systems in this galaxy. While most of these are binary star systems consisting of two stars, there are others. A topic related to stars is a supernova, the final stage in the evolution of a massive star, when it explodes with a bright stellar explosion. Astronomers are always on the lookout for any potential supernova explosions, because these have ramifications for the entire universe. In this work, a team of researchers discovered that a four-star system — dubbed HD 74438 — could represent a new channel through which thermonuclear supernova explosions could occur in the universe.
The HD 74438 system was discovered in 2017 and is a quad-core system. It consists of a pair of stars orbiting each other while orbiting another two stars in close proximity (2+2 configuration). Subsequent research showed that HD 74438 was the youngest of all such systems, only 43 million years old. Now, astronomers at the Mount John Observatory at the University of Canterbury in New Zealand have discovered that the quad is made up of four gravitationally bound stars.
In their study, published in the journal Nature Astronomy, they show that the gravitational effects of the outer binary system are changing the orbit of the inner binary, making it more eccentric. So the researchers tried to simulate the orbits of future stars. They found that this gravitational dynamics can lead to one or more collisions and merger events, resulting in evolved death stars, or white dwarfs, with masses slightly below the Chandrasekhar limit. As a result, these white dwarfs can lead to thermonuclear supernovae.
Named after Indian-born astrophysicist Subrahmanyan Chandrasekhar, this limit is the maximum mass for a stable white dwarf. The currently accepted Chandrasekhar limit is about 1.4 solar masses.