London: Astronomers have found that there arefar more planets of the hot Jupiter type than expected in a cluster of stars called Messier 67, a finding that may help better understand planet formation. This open star cluster is about the same age as our Sun and it is thought that the Solar System arose in a similarly dense environment. The denser environment in a cluster causes more frequent interactions between planets and nearby stars, which may explain the excess of hot Jupiters, researchers said.
A hot Jupiter is a giant exoplanet with a mass of more than about a third of Jupiter’s mass. They are “hot” because they are orbiting close to their parent stars, as indicated by an orbital period that is less than ten days in duration. Researchers led by Roberto Saglia at the Max Planck Institute for Extraterrestrial Physics Germany, and Luca Pasquini at European Southern Observatory (ESO), spent several years collecting high-precision measurements of 88 stars in Messier 67.
The team looked for the signatures of giant planets on short-period orbits, hoping to see the tell-tale “wobble” of a star caused by the presence of a massive object in a close orbit, a kind of planet known as a hot Jupiters. This hot Jupiter signature has now been found for a total of three stars in the cluster alongside earlier evidence for several other planets. “We want to use an open star cluster as laboratory to explore the properties of exoplanets and theories of planet formation,” said Saglia.
“Here we have not only many stars possibly hosting planets, but also a dense environment, in which they must have formed,” he said. The study found that hot Jupiters are more common around stars in Messier 67 than is the case for stars outside of clusters. Astronomers think it highly unlikely that these exotic giants actually formed where we now find them, as conditions so close to the parent star would not initially have been suitable for the formation of Jupiter-like planets.
Rather, it is thought that they formed further out, as Jupiter probably did, and then moved closer to the parent star. PTI
For more news updates Follow and Like us on Facebook