A new planetary system has been discovered with a host star similar to the Earth’s Sun but its unusual composition indicates that it has ‘eaten’ some of its planets.
The study that was published in the journal “Astronomy and Astrophysics” suggest that this new discovery can provide clues to researchers about how planetary systems evolve over time.
“It does not mean that the Sun will ‘eat’ the Earth any time soon,” said Jacob Bean, Assistant Professor University of Chicago. However, “our discovery provides an indication that violent histories may be common for planetary systems, including our own” Bean said.
In 1995, astronomers discovered the first planet orbiting a star other than the sun. Two thousand exoplanets were identified since then including some rare planets that orbit a star similar to Earth’s Sun.
Researchers at University of Chicago studied star HIP68468, which is 300 light years away, as part of a multi-year project to discover planets that orbit solar twins.
“It is tricky to draw conclusions from a single system to study more stars like this to see whether this is a common outcome of the planet formation process,” cautioned Megan Bedell, co-author of the study.
The researchers said that the study of HIP68468 was a post-mortem of this process happening around another star similar to our sun and that the discovery deepened their understanding of the evolution of planetary systems.
“HIP68468’s composition points to a history of ingesting planets. It contains four times more lithium than would be expected for a star that is six billion years old, as well as a surplus of refractory elements — metals resistant to heat that are abundant in rocky planets,” the research found. Scientists used the 3.6-meter telescope at La Silla Observatory in Chile to discover their first exoplanet in 2015.
“The more recent discovery needs to be confirmed, but includes two planet candidates — a super Neptune and a super Earth. Their orbits are surprisingly close to their host star, with one 50 per cent more massive than Neptune and located at a Venus-like distance from its star.
“The other, the first super Earth around a solar twin, is three times the Earth’s mass and so close to its star that its orbit takes just three days,” the study noted. The scientists said that these two planets most likely did not form where they see them today.
“Instead, they probably migrated inward from the outer parts of the planetary system. Other planets could have been ejected from the system — or ingested by their host star,” the researchers added.
Researchers continue to explore more than 60 solar twins, eyeing for more exoplanets.