A study of the open cluster Messier 67 has found an excess of the planets known as “hot Jupiters”, gas giants that orbit very close to their parent stars. The discovery suggests this category of planets can be produced by interactions between nearby stars, possibly resolving a major debate in planetary studies.
Back when the only system of planets we knew was our own, it all seemed so simple. Rocky planets like Earth and Venus were close to the Sun, farther out lay the gas giants like Jupiter and Saturn. Big planets were dependent on the accumulation of ice grains beyond the “frost line”.
However, once our telescopes became sensitive enough to detect the influence of planets around other stars, we got a surprise. Explorations repeatedly turned up giant planets, too massive to be solid, orbiting close in. Although hot Jupiters are easier to detect than smaller or more distant worlds, their abundance remains a puzzle.
In Astronomy and Astrophysics (preprint on ArXiv) a team led by Dr Anna Brucalassi of the Max Planck Institute for Extraterrestrial Physics has revealed that hot Jupiters are even more common in the star cluster known as Messier 67.
M67 contains more than 500 stars. A study of 66 of these found three hot Jupiters. Two Micron All Sky Survey