The findings have been hailed as ‘groundbreaking’.

A study by an international team of astrophysicists, some based at University College Cork, has uncovered a stunning cosmic phenomenon – co-moving stars thought to be identical to their “twins” have differences.

The research sheds light on a celestial phenomenon where binary co-moving stars, once thought to be identical twins due to their shared molecular origins, show subtle compositional differences, hinting at the absorption of planets.

The study, the cover story in this week’s issue of the prestigious academic journal Nature, delves into the findings derived from data collected with the 6.5-meter Magellan Telescopes in Chile and the W. M. Keck Observatory. The data was also collected from the European Southern Observatory’s Very Large Telescope.

New insights into the evolution of planetary systems

“Co-moving stars come from the same molecular cloud, indicating that they should have the same composition, similar to identical twins.” explains Bertram Bitsch, Professor of Astrophysics at the College of Science, Engineering and Food Science at UCC, co-author of the study.

“Stars consist mostly of hydrogen and helium; they also contain all other elements like iron, silicate, magnesium, oxygen, and carbon, which are the materials that form terrestrial planets like our own Earth.

“However, detailed new high-precision observations of these stars have revealed small compositional differences between co-moving pairs, indicating that another effect is at play. The measured compositional differences in the different elements could be attributed to differences in their accretion history during the protoplanetary disc phase of the first few millions of years of their life, but this is unlikely considering that the star evolved for billions of years afterwards, wiping out these differences.

“It seems more likely that one of the components of the co-moving pair ingested planets, giving important constraints on the stability of planetary systems around stars,” he said.

The results have far-reaching implications for the scenarios of planet formation and engulfment and provide new insights into the long-term evolution of planetary systems.