The MACHO Project Interactive P-L Relation

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Click on a point to see its lightcurve

This graph portrays the P-L relation for about 1500 variables in 22 LMC fields observed by the MACHO Project. The two well-populated bands are due to classical Cepheids. The brighter sequence at a given period are Cepheids pulsating in the first overtone radial mode. The fainter sequence, extending to longer periods, are Cepheids pulsating in the fundamental mode. A handful of other variables, including some Type II (low mass) Cepheids are seen in the lower right. Only about 10 percent of the lightcurves are available in this map. The photometric calibration is only preliminary - zeropoint differences of 0.2 mags are known to exist between fields.

Doug Welch