Cepheid variable stars pulsate in brightness over regular periods. That’s one reason astronomers use them as a standard candle to judge distances–even for stars well outside our galaxy. In this image, researchers display a simulation of convection inside a Cepheid eight times more massive than our sun. The colors represent vorticity, with zero vorticity in white.(Image credit: M. Stuck and J. Pratt)
Gorgeous visualization, and the vorticity map really sells how “messy” the inside of a Cepheid has to be for such a clean light curve on the outside. I always wonder how much the convection–pulsation coupling (and that partial ionization zone driving the κ-mechanism) nudges the period–luminosity relation once you move off idealized 1D models. Do these sims suggest any systematic bias in inferred distances, or is it mostly extra scatter?
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