The Carnegie Hubble Program: The Leavitt Law at 3.6 μm in NGC 300
Authors:Ivan Aguilar, David Buickians
- Jeniffer Krestow, Professor of Astronomy & Planetarium Director, Glendale Community College
- Victoria Scowcroft, Postdoctoral Research Associate, Carnegie Observatories
The Carnegie Hubble Program (CHP) is designed to calibrate the extragalactic distance scale using data from the post-cryogenic era of the Spitzer Space Telescope. The ultimate goal of the CHP is a determination of the Hubble constant to an accuracy of 2%. We focus on the measurement and calibration of the extragalactic Cepheid period-luminosity (PL, Leavitt) relation using the warm Spitzer/IRAC 1 band at 3.6 μm. We present photometric measurements of 10 NGC 300 Cepheids with a range of 11-53 days in period. A PL relationship of the form M = a(logP −1)+b is derived. The slope a, -3.31, is taken from the Spitzer Large Magellanic Cloud (LMC) data of Scowcroft et al. We use a calibrated 3.6 μm PL zero point of -5.80. With the calibrated zero point, we determine a distance modulus of 26.23 mag to NGC 300.