Primordial differences responsible for differences between twin stars: Study

Astronomers have for the first time confirmed that chemical variations are responsible for the unexpected differences in binary stars’. The new research shows that these dissimilarities can originate from before the stars even began to form rather than resulting from later evolutionary processes.

Binary stars are born together out of the same molecular cloud from a shared abundance of chemical building blocks. Despite being born from the same cloud, they have many dissimilarities.

The researchers, led by Carlos Saffe of the Institute of Astronomical, Earth and Space Sciences (ICATE-CONICET) in Argentina, observed a binary consisting of two giant stars using the Gemini South telescope. The team utilized the new Gemini High Resolution Optical SpecTrograph (GHOST) to study a pair of giant binary stars and found significant differences in their chemical make-up.

Previous studies propose three potential explanations for these differences: atomic diffusion, planetary engulfment, and primordial inhomogeneities within the molecular cloud. The team focused on the third explanation which suggests that variations in the chemical distribution of the molecular cloud from which the stars formed can lead to inherent differences in their compositions.

Unlike previous studies that focused solely on main-sequence binary stars, Saffe and his team studied a binary consisting of two giant stars with extremely deep and strongly turbulent external layers. Based on the properties of these thick layers or convective zones, the team ruled out the first two explanations, leaving primordial inhomogeneities within the molecular cloud as the confirmed explanation.

"By showing for the first time that primordial differences really are present and responsible for differences between twin stars, we show that star and planet formation could be more complex than initially thought. The Universe loves diversity," Saffe said.

These findings not only provide a new understanding of how binary stars can exhibit different chemical compositions and planetary systems despite their common origins but also challenge the current models of stellar and planet formation.