The Near-infrared Period-luminosity Relations of Cepheids in the Large Magellanic Cloud

Abstract

We present near-infrared (J & Ks) observations of Cepheids in the Large Magellanic Cloud. The goals of these observations are to better characterize the Cepheid Period-Luminosity relation at these wavelengths, especially for periods below 10 days, and to determine if the relation is linear or non-linear in these bandpasses. We observed approximately 1,200 fundamental and first-overtone Cepheids originally discovered by the OGLE-II survey. We used the CTIO 1.5-m telescope and the CPAPIR camera to image 49 separate fields within the LMC in the J & Ks filters. Observations were collected from November 2006 to December 2007 and each field was imaged approximately 10 times. The images were analyzed using standard astronomical software (IRAF and the DAOPHOT suite of photometry programs). We used the 2MASS Point Source Catalog to derive astrometric and photometric calibrations for our measurements. We present color-magnitude diagrams (CMDs) for all fields and period-luminosity relations for the Cepheid variables. Future work will ascertain the (non)-linearity of these P-L relations and make use of our CMDs for stellar population studies.