Chemical fingerprints reveal history of massive binary stars

Researchers have developed a method to identify whether massive stars were once part of a binary system by analyzing chemical fingerprints on their surfaces. While approximately 70 percent of massive stars are born in close binary systems, the surviving star often appears to be a single, solitary entity after mass exchange or mergers occur.

A study published in Nature Astronomy by Harim Jin and Norbert Langer demonstrates that transferred gas leaves a permanent mark. When a star gains material from a companion, its surface chemistry shifts: nitrogen and helium levels increase, while carbon and oxygen levels decrease. These specific ratios allow astronomers to distinguish mass gainers from truly single stars.

The researchers applied this model to Gamma Columbae, a star previously thought to be a stripped core that had lost its outer layers. The new chemical analysis reveals that Gamma Columbae was actually a mass gainer that swallowed approximately 0.8 solar masses from a companion star, fundamentally changing its understood evolutionary history.