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Observations on seemingly identical ‘twin’ stars suggests one of the pair ingests planets, which could explain more about planet formation.
A new study of the cosmos suggests that some stars have appetites for entire planets, which causes slight differences compared to their more famished counterparts.
The researchers in the study looked at co-moving stars that appear to be identical twins, but upon closer observation contain slight differences. One possibility could be that these differences occurred during the birth of these stars, as they accumulated material from their surrounding discs.
But this international team – including Prof Bertram Bitsch of University College Cork – believes the differences exist because one star ingested planets. If correct, the researchers said this would change our understanding of planetary systems.
The research focused on 91 pairs of twin stars, which had a shared origin and a well-defined selection function. The team claims to have identified at least seven instances of planetary ingestion from this batch of twin stars.
Stars are able to ingest planets when certain gravitational interactions cause the planets to be pulled very close to the star. After this point, the force of the star’s gravity leads to the planet being dragged in and ingested, which can influence the star’s composition.
“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,” Bitsch said.
“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.”
Bitsch said the theory that the differences between these twin stars unlikely to be come from their birth, as the observed stars “evolved for billions of years” after that period, which would have wiped out those 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 researchers said these results could explain more about planet formation and provide new insights into the long-term evolution of planetary systems.
The study used data collected with the Magellan Telescopes in Chile, the WM Keck Observatory and the European Southern Observatory’s (ESO) Very Large Telescope. Researchers recently used this ESO telescope to complete a massive survey of 86 stars and claim this revealed unique insights on the formation of planets.
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