A team of astronomers has discovered a planet to be orbiting a star that is part of a solar twin, meaning it is identical to the Earth's sun in almost any way.
Using ESO's HARPS planet-hunting telescope in Chile, the researchers found three planets orbiting stars in the Messier 67 star cluster, according to a press release. With so many planets confirmed outside the solar system, only a small handful has been spotted in star clusters.
"In the Messier 67 star cluster the stars are all about the same age and composition as the Sun," study lead author Anna Brucalassi, of the Max Planck Institute for Extraterrestrial Physics, Garching, Germany, said in the release. "This makes it a perfect laboratory to study how many planets form in such a crowded environment, and whether they form mostly around more massive or less massive stars."
Given that many stars are born in clusters and knowing exoplanets to commonly orbit stars, it has been hard to find such planets in star clusters. Many exoplanets have been discovered in different sizes and compositions throughout the known universe and are usually found orbiting a star.
The M67 cluster is about 2,500 light years from Earth and lies in the Cancer constellation that consists of 500 stars. In total, three new planets were discovered. Two were orbiting stars similar to the sun and the last was revolving around a more mature giant red star.
The third planet was estimated to complete a revolution in 122 days and was more massive than Jupiter. The first two planets were about one-third the mass of Jupiter and orbited their stars in seven and five days, respectively.
The first of these planets was spotted orbiting a solar twin of our sun, meaning the two are identical is nearly every way. This is the first discovery of a planet orbiting a solar twin. None of the three planets orbited their stars in the habitable zone, a range of orbit where water could exist.
"These new results show that planets in open star clusters are about as common as they are around isolated stars -- but they are not easy to detect," study co-author Luca Pasquini, of ESO, Garching, Germany, said in the release. "The new results are in contrast to earlier work that failed to find cluster planets, but agrees with some other more recent observations. We are continuing to observe this cluster to find how stars with and without planets differ in mass and chemical makeup."
