The detailed forms of the LMC Cepheid PL and PLC relations
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Date
2007
Authors
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Journal ISSN
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Publisher
Oxford University Press
Abstract
Possible deviations from linearity of the Large Magellanic Cloud Cepheid period–luminosity
(PL) and period–luminosity–colour (PLC) relations are investigated. Two data sets are studied,
respectively from the Optical Gravitational Lensing Experiment (OGLE) and MACHO
projects. A non-parametric test, based on linear regression residuals, suggests that neither
PL relation is linear. If colour dependence is allowed for, then the MACHO PL relation is
found to deviate more significantly from the linear, while the OGLE PL relation is consistent
with linearity. These findings are confirmed by fitting ‘Generalized Additive Models’
(non-parametric regression functions) to the two data sets. Colour dependence is shown to
be non-linear in both data sets, distinctly so in the case of the MACHO Cepheids. It is also
shown that there is interaction between the period and the colour functions in the MACHO
data.
Description
Keywords
Methods: statistical, Cepheids, Distance Scale
Citation
Koen, C. Kanbur, S. Ngeow, C (2007). The detailed forms of the LMC Cepheid PL and PLC relations. Monthly Notices of the Royal Astronomical Society, 380: 1440–1448