A team of U.S. astronomers has discovered that small planetary systems with multiple planets are more likely to form around stars that have lower amounts of ‘metals’ (elements heavier than helium, including iron, silicon, magnesium, and carbon) than our own Sun. An illustration of a compact, multi-planet system. Image credit: Michael S. Helfenbein / Yale University. For the study, Yale University researcher John Michael Brewer and colleagues looked...
