Extreme Binary Stars: the fast, the hot, and the downright strange
While it is more common than not that stars are found in double or multiple systems, the presence of companions doesn’t generally change the stages of a star’s life cycle from that of isolated stars. In extreme cases, however, the most fundamental aspects of a star (size, mass, temperature, and composition) can be determined by its interaction with a companion. And while understanding the stages of isolated stars was one of the great scientific successes of the 20th century, many of the central secrets to binary star evolution have yet to be unraveled.
In this presentation we will report on studies made with the Calvin Observatory of several extreme examples of extreme binary stars. Contact binaries are stars that orbit each other so closely they share a common envelope. We will discuss the contact binaries with the fastest orbits and with the most time variable orbits. Subdwarf B stars are incredibly hot, compact helium stars that appear to result from ripping the outer layers off of a normal older star. We will discuss the subdwarf B star orbiting most closely to a normal stellar companion. These examples push the limit of the range of what is considered possible. We hope, therefore, that their study will give insight into how such systems form and interact.