Exoplanets Discovered Orbiting Stars in Messier 67 Cluster

Three planets were discovered by scientists orbiting three different stars in the Messier 67 star cluster, which is approximately 2,500 light-years away from Earth, according to CNN.

The discovery is the first time scientists have been able to find an exoplanet circling a solar twin in a star cluster, according to European Southern Observatory officials, who spoke with SPACE.com. Scientists used ESO's HARPS telescope instrument to help find the planets.

The first planet discovered is just a little smaller than Jupiter and takes around seven days to orbit its star.

"In the Messier 67 star cluster the stars are all about the same age and composition as the sun," Anna Brucalassi of the Max Planck Institute for Extraterrestrial Physics, leader of the study, said in a statement, according to SPACE.com. "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."

Two additional planets were discovered orbiting stars in the cluster as well. Researchers used HARPS instrument on the 3.6-meter telescope at the La Silla Observatory in Chile, according to SPACE.com.

Thanks to the instrument, the scientists were able to observe approximately 88 stars in Messier 67 over a six year period.

ESO confirmed that at least two of the three planets are considered "hot Jupiters" or planets that are similar in size to Jupiter but orbit closer to their host stars. Scientists believe that the planets are too close to their stars for liquid water to exist, according to CNN.

"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," Luca Pasquini of ESO, co-author of the new study to appear in the journal Astronomy & Astrophysics, said in a statement, according to SPACE.com. "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."

There are over 500 stars located in Messier 67, according to SPACE.com.