Variable stars as standard candles
{"Image DocumentName": "Variable stars as standard candles", "Image ImageDescription": "Care is needed: Cepheids in the disk of the MW, where the metal abundance is high, are brighter than stars with the same period but fewer metal. Correct for the effect of interstellar dust in dimming and reddening the stars. RR are useful within 2-3 Mpc; Cepheids are useful to about 30 Mpc.", "Image XResolution": "37", "Image YResolution": "37", "Image ResolutionUnit": "Pixels/Centimeter", "Image Software": "SlidePlayer", "Image YCbCrPositioning": "Centered"}