The Cepheid Period-Luminosity Relation at Mid-Infrared Wavelengths: II. Second-Epoch LMC Data
نویسندگان
چکیده
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 8.0 μm. 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 nearlyuniform 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.
منابع مشابه
The Cepheid Period-Luminosity Relation at Mid-Infrared Wavelengths: I. First-Epoch LMC Data
We present the first mid-infrared Period-Luminosity (PL) relations for Large Magellanic Cloud (LMC) Cepheids. Single-epoch observations of 70 Cepheids were extracted from Spitzer IRAC observations at 3.6, 4.5, 5.8 and 8.0 μm, serendipitously obtained during the SAGE (Surveying the Agents of a Galaxy’s Evolution) imaging survey of the LMC. All four mid-infrared PL relations have nearly identical...
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