University of Auckland astrophysicist Jan Eldridge and her international collaborators have identified two stars as vanishingly rare among hundreds of billions of stars in the galaxy.

Located in a constellation near Sirius, the brightest star in the night sky, the pair may be one of only about 10 such pairs in the galaxy, according to Eldridge on Friday.

Making computer models of how stars are born, live and die, what one could call a "synthetic universe," Eldridge's research helps to establish the meaning of astronomers' observations, according to Eldridge's article published in the Journal of Nature.

"Stars make the elements needed for life, so understanding stars is to understand where we come from," Eldridge said.

As an expert on the evolution of binary stars, pairs of stars which orbit each other, Eldridge's computer modeling helped establish the stars' story, the article said, adding the research was carried out with colleagues including at Embry-Riddle Aeronautical University in the United States.

Many people know of supernova, massive stars exploding with colossal force as they run out of nuclear fuel in their cores. The cores collapse and the explosions create neutron stars, the article said.

"What Eldridge and colleagues have found is something much rarer, a scenario where the supernova was a fizzer, like a damp firecracker... a wimpy supernova," it said.

With a regular supernova, the force of the explosion gives the neutron star a big kick, so it flies off at hundreds of kilometers per second and develops an elliptical orbit. But that didn't happen in this case.

The gravitational pull of the neighboring star stole most of the mass of the exploding star, leading to a weaker explosion, called an "ultra-stripped supernova." So there was no big kick, and consequently no elliptical orbit, Eldridge said.

"What really sets this system apart is the circular orbit, much like the Earth going around the Sun," she said, adding this star system has evolved in a very rare and strange way.

The two stars will eventually create a kilonova, as the pair collide and explode, releasing gold and other elements, Eldridge said.