Variable Stars

Abstract

Our Milky Way Galaxy contains an estimated 10¹¹ stars in a variety of evolutionary stages and in two major zones or populations. Those stars generally in elliptical orbits high above the galactic plane are termed Population II stars, while Population I types lie in the plane of the Galaxy. Stars showing a measurable change of brightness are classed as variable stars; these provide clues to the nature of stars which range from hypergiants to white dwarfs. Their study may help the understanding of the Solar System’s formation, and perhaps of life itself. For cosmologists, variable stars provide distance indicators which are fundamental to measurements of the Universe. Astronomers for the last few centuries have observed and classified these stars using a host of observational techniques and analytical methods. With so many galactic stars available, some 45,000 catalogued variables (including stars suspected of variability) and only several hundred variable star specialists world-wide, it is obvious there is much work to do. In recent years links between professional and amateur astronomers have brought about a rapid exchange of information (e.g. the discovery of Nova Cygni in 1992), resulting in new findings about stellar phenomena.