Binary Star Light Curve

- Explain the causes of variability in the light curve of a binary star
- Identify a binary star from the light curve and deduce its period

Eclipsing binaries are a pair of stars that orbit each other. One will move in front and behind the other as seen from Earth.

Frequently one star is brighter than another and we can see the stars wink and dip as the darker star moves in front and behind it.

By charting the brightness of a binary star you can find its period. In the chart on the right the period would be from the 'dips' at 24 and 64 leading to a period of 30 hours.


Animation New Window

Light Curves Animation Light Curves

Image New Window

Links New Window

Imagine the Universe

Light curves


How could an astronomer measure the period of an eclipsing binary star?


A well known eclipsing binary star is Algol in Perseus.