Delta Cephei’s hidden companion

To measure distances in the Universe, astronomers use Cepheids, a family of variable stars whose luminosity varies with time. Their role as distance calibrators has brought them attention from researchers for more than a century. While it was thought that nearly everything was known about the prototype of Cepheids, named Delta Cephei, a team of researchers have now discovered that this star is not alone, but that it has a hidden companion. —> Read More