The Binary Zoo
Observationally Based Classification
- Visual Binaries - the two stars are resolved and we can see them orbit each other.
Example: Xi Boo
- Spectroscopic Binaries - spectral lines of one or both stars show Doppler shifts.
Examples:Alpha Gem and Kappa Ari
- Astrometric Binaries - one star traces a sinusoidal path on the sky due to the influence
of the unseen companion.
- Eclipsing Binaries - the stars pass in front of each other as seen from Earth, causing
the brightness to drop.