Binary and Variable Stars
Binary stars and variable stars are two extremely important groups of celestial objects. Observations of binary stars have allowed astronomers to determine the masses of stars and provided a wealth of information on the density, atmosphere and evolution of stars. Variable stars too provide information about the interiors and evolution of stars. They are also extremely useful as distance indicators, allowing astronomers to measure the distance to the clusters and galaxies where they are found. Historically the study of binaries and variables has changed our understanding of the scale of the Universe.
Observing variable stars is one branch of astronomy that even amateurs can make a valuable contribution. Some can even be observed using the unaided eye and simple comparison charts. Organisations such as the American Association of Variable Star Observers (AAVSO) collect and collate observations on hundreds of stars from amateurs around the world and provide them to professional researchers. Many keen amateurs use computer-controlled telescopes and CCDs in partnerships with professional astronomers in long-term research programs.
Syllabus Requirements
5. The study of binary and variable stars reveals vital information about stars
- describe binary stars in terms of the means of their detection: visual, eclipsing, spectroscopic and astrometric
- explain the importance of binary stars in determining stellar masses
- classify variable stars as either intrinsic or extrinsic and periodic or non-periodic
- explain the importance of the period-luminosity relationship for determining the distance of cepheids
- perform an investigation to model the light curves of eclipsing binaries using computer simulation
- solve problems and analyse information by applying: