Abstract
Most massive stars live in pairs. Often, since their birth, they have lived close to another star. During their life as a couple, certain events in the life of a star will bring them so close together that they will exchange matter, a phenomenon that gives rise to the emission of X-rays, hence their name. And then, at the end of their lives, they will merge, in catastrophic events that will shake the entire universe. It's these paired stars that we'll be discovering in this lecture.
