The encyclopedia of variability
Every way a star can change its light
A page for every variability class — what it is, the physics behind the flicker, and archetype light curves pulled live from the archive.
The whole archive at a glance
A million variable stars, by family
Each tile is one variability class, its area set by how many stars it holds. Two families — eclipsing binaries and long-period red giants — fill most of the sky; the rarest are a sliver. Pick any tile to dive in.
Browse the families
Every class, one page each
How to read a light curve
Anatomy of a phase folded light curve
Folding stacks every observed cycle into one by wrapping time on the period. Pick an archetype to see what each feature means — and why the period-finder behaves the way it does for that shape. Drag the phase scrubber to trace one cycle.
Featured family · 158,902 stars
Rotational
Starspots carried across the disk by rotation.
Rotational variables aren't pulsating or eclipsing — they're spotted. Magnetic active regions, darker or brighter than the surrounding photosphere, sweep in and out of view as the star turns, modulating the light at the rotation period.
Spotted star
ROTGeneric spotted rotator; low-amplitude, quasi-sinusoidal modulation at the rotation period.
RS CVn
RSChromospherically active close binary — large spots, strong activity, often with eclipses too.
BY Draconis
BYSpotted, emission-line K–M dwarfs; the low-mass end of rotational variability.