A survey published this Monday (30) in the scientific journal Nature Astronomy reveals that at least a quarter of stars similar to the Sun cannibalize the planets that orbit them. The discovery may help to understand the possible evolutionary paths of planetary systems.
The Galaxy we inhabit has many planetary systems, and it was already known that most of them are quite different from our Solar System.
But now scientists have discovered that, unlike our Solar System – which has preserved an orderly architecture of planets orbiting the Sun – a significant number of neighboring planetary systems have had a very dynamic past. In at least 25% of them, the central star may have “devoured” some of the planets that orbited it.
Conducted by researchers from the University of São Paulo (USP) and centers in Italy, Australia and the United States, the study observed the chemical composition of solar-type stars in more than 100 binary systems – systems formed by two twin stars with the same chemical composition. For this, the telescope of the La Silla Observatory, administered by the European Southern Observatory (ESO) and located in the Atacama Desert, in Chile, was used.
To the amazement of scientists, in some binary systems analyzed the sister stars did not have the same chemical composition, since one of them had a greater amount of lithium and iron, elements abundant in rocky planets.
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Timelapse shows the sky from La Silla Observatory in Chile
The conclusion, according to the professor at the USP Astronomy Department and one of the authors, Jorge Meléndez, is that the stars rich in these elements had dissolved some of the planets in their own system in their outermost region. Hence the nickname of “cannibal star”.
“An abnormally high abundance of this chemical element in a star [lítio e ferro] it may indicate that planetary material was swallowed by it,” says Meléndez.
The publication points out that the chemically inhomogeneous binary stars discovered by the study “represent one of the most contradictory examples in stellar astrophysics and a source of tension between theory and observations.” Furthermore, it is still unclear what caused the differences in the composition of these twin stars.
3.6-meter telescope from the La Silla Observatory, European Southern Observatory (ESO), in the Atacama Desert, Chile. — Photo: Yuri Beletsky (LCO)/ESO
“It is still unclear whether chemical abundance variations are the result of inhomogeneities in proto-stellar gas clouds [da formação estrelar] or are they due to planet engulfing events (…) The first scenario undermines the general belief that the chemical composition of stars provides the fossil information on the environment in which they formed, while the second scenario sheds light on possible evolutionary pathways planetary systems,” states the publication.
However, scientists say there is compelling evidence in favor of the scenario of the planets being engulfed by the system’s central star.