Synthetic Cepheid Period-Luminosity & Period-Color Relations in Spitzer's IRAC Bands

Abstract

The mid-infrared period-luminosity (P-L) relation for Cepheids will be important in the JWST era, as it holds the promise of deriving the Hubble constant within 2% accuracy. We present the synthetic P-L and period-color (P-C) relations, derived from a series of stellar pulsation models with varying helium and metallicity abundance, in the Spitzer IRAC bands. Selected synthetic P-L and P-C relations were compared to the empirical relations derived from Galactic and Large Magellanic Cloud Cepheids. We also present the empirical P-L relations based on the latest distance measurements using infrared surface brightness techniques.

5 pages, 3 figures and 1 table. Proceeding submitted for the 20th Stellar Pulsation Conference (Impact of New Instruments and Insights in Stellar Pulsation), Granada, Spain, September 2011