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arXiv · 0811.2533

The Cepheid Period-Luminosity Relation at Mid-Infrared Wavelengths: II. Second-Epoch LMC Data

Barry F. Madore·Wendy L. Freedman·Jane Rigby·S. E. Persson·Laura Sturch·Violet Major
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Abstract

We present revised and improved mid-infrared Period-Luminosity (PL) relations for Large Magellanic Cloud (LMC) Cepheids based on double-epoch data of 70 Cepheids observed by Spitzer at 3.6, 4.5, 5.8 and 8.0um. The observed scatter at all wavelengths is found to decrease from +/-0.17 mag to +/-0.14 mag, which is fully consistent with the prediction that the total scatter is made up of roughly equal contributions from random sampling of the light curve and nearly-uniform samplings of stars across the instability strip. It is calculated that the Cepheids in this sample have a full amplitude of about 0.4 mag and that their fully-sampled, time-averaged magnitudes should eventually reveal mid-infrared PL relations that each have intrinsic scatter at most at the +/-0.12 mag level, and as low as +/-0.08 mag after correcting for the tilt of the LMC.

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Barry F. Madore, Wendy L. Freedman, Jane Rigby, S. E. Persson, Laura Sturch, Violet Major. 2008-11-15. The Cepheid Period-Luminosity Relation at Mid-Infrared Wavelengths: II. Second-Epoch LMC Data. https://doi.org/10.1088/0004-637x/695/2/988

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