Three new exoplanets have been discovered inside a star cluster, which is a rare find as only a handful of such exoplanets are known to exist. However, one of the three new finds is even more remarkable - it orbits a star that appears to be "an almost perfect solar twin."
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The discovery was made by astronomers using the European Southern Observatory's HARPS exoplanet-hunting instrument attached to the 3.6-meter telescope at the La Silla Observatory in Chile and was confirmed by other collaborating observatories. The astronomers' attention was focused on the Messier 67 open star cluster, which is located approximately 2,600 light-years away in the constellation Cancer.
It is believed that all stars originated from within some kind of stellar cluster, including our sun. Clusters of stars are a consequence of a brood of stars emerging from a stellar nursery and, throughout their stellar evolution, remain gravitationally bound.
However, there is a mysterious lack of exoplanetary discoveries inside star clusters, leading astrophysicists to hypothesize that perhaps the planet-forming rules inside clusters are somehow different from stars that have gone on to disassociate themselves from their clusters. This is what inspired the focus on this particular star cluster.