Comparison of multi-band period-luminosity relations for classical Cepheids in the Magellanic Clouds

Chow-Choong Ngeow & Shashi Kanbur

National Central University, Taiwan

The period-luminosity (PL) relation for classical fundamental mode Cepheids (hereafter Cepheids) is an important astrophysical tool in distance scale applications. In this Poster, we present the multi-band PL relations, from optical to infrared, for Cepheids in both of the Magellanic Clouds. Catalogs of Cepheids in the two Clouds were adopted from the third phase of Optical Gravitational Lensing Experiment (OGLE-III), which provide the position, pulsation period and the mean VI band photometry. The OGLE-III catalogs were cross-matched to the 2MASS point source catalogs to derive the mean JHK band photometry (after applying the random-phase corrections), as well as to the Spitzer IRAC band data available from SAGE and SAGE-SMC projects. Extinction corrections to these multi-band photometry were done using the Zaritsky's extinction maps. We also derived the extinction free Wesenheit function in the form of W=I-1.55(V-I). When compared the slopes of the multi-band PL relations for Cepheids in the two Clouds, we found that these PL slopes agree with each others except in the V- and J-band. We also found an excellent agreement of the P-L slopes in Wesenheit function, hence we calibrate the Period-Wesenheit relation by combining the data from both Clouds, together with an accurate LMC distance based on measurement from late-type eclipsing binaries.

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