ABSTRACT
The first variable to be positively identified as such was Mira in 1638. Mira variables, often called long-period variables; Mira Ceti is the brightest member of the class. Mira has a binary companion, which is itself variable and has been given a variable star designation. Mira has a binary companion, which is itself variable and has been given a variable star designation. The Hubble Space Telescope has also detected a small, hook-like appendage extending from Mira in the direction of the companion, and Mira is itself rather football-shaped instead of spherical. Unlike Mira stars, Cepheids are perfectly regular, and the cycles repeat each other, so that the magnitude at any particular moment can be predicted. A nova is a binary system, made up of a low-density red star with a white dwarf companion. The white dwarf pulls material away from the giant star, and this material builds up into an accretion disk round the white dwarf.
