A rare binary star with an oddly round orbit

By studying the binary star system CPD-29 2176, researchers are unraveling new clues about our earliest beginnings as stardust. -NOIRLAB/NSF/AURA/J. DA SILVA/SPACE ENGINE

A study from Embry-Riddle Aeronautical University describes a high-mass, X-ray-luminous twin star system with an oddly circular orbit, a rarity among binaries. This system seems to have formed when an exploding or supernova star faded without the usual explosion, as published in the journal ‘Nature’.

After processing a mountain of astronomical data, Clarissa Pavao, a student at Embry-Riddle Aeronautical University, presented her preliminary analysis to her mentor about this strange binary star system with unusual features. The round orbit of the binary was a key clue that helped researchers identify the second star in the binary system as a depleted or “ultra-exploded” supernova.

Normally, when a star uses up all its nuclear fuel, its core collapses before exploding into space as a supernova. In this case, according to Richardson, “the star was so depleted that the explosion did not even have enough energy to give the orbit the more typical elliptical shape seen in similar binaries.” The researchers estimate that there are currently only about 10 such star systems in the Galaxy. By studying it, they are unraveling new clues about our early beginnings, like stardust.

“When we look at these objects, we look back in time,” Pavao explains in a statement. “We come to know more about the origins of the universe, which will tell us where our solar system is headed. As humans, we start with the same elements as these stars. Richardson adds that without binary systems like CPD-29 2176, life on Earth would be very different. “Systems like this are likely to evolve into neutron binary stars, which eventually merge and form heavy elements that are spewed out into the universe,” he says.