Variable Stars
First published: 2010
Brief summary
AAVSO guide to variable stars and their periodic/light-curve behaviour.
Article
Variable stars are stars whose observed brightness changes with time. The changes may be periodic, semiregular or irregular and can arise from physical changes within a star or from one object passing in front of another.
Intrinsic variables include pulsating stars, eruptive stars and systems whose luminosity changes because of stellar activity or mass transfer. Extrinsic variables include eclipsing binaries and rotating stars whose surface features produce brightness changes as different regions face the observer.
A light curve plots measured brightness against time. Its period, amplitude, shape and changes from one cycle to another help identify the type of variable and reveal properties such as stellar size, temperature, orbital geometry and evolutionary state.
Long-term observations are important because many variables change on timescales ranging from minutes to years. Professional and amateur measurements contribute to databases used to refine periods, detect unusual events and support follow-up observations with other instruments.
Source details and credits
- Source / publisher: AAVSO
- Source type: Educational article
- URL type: WWW
- Credits: AAVSO
- URL: https://www.aavso.org/variable-stars