2006/07/04 by Chow‐Choong Ngeow, C. Ngeow, Shashi M. Kanbur +1
Mathematics · Physics and Astronomy · #Astrophysics #Astrophysics and Star Formation Studies #Cepheid variable #Computer science #Large Magellanic Cloud #Mathematics #Nonlinear system #Physics #Quantum mechanics #Relation (database) #Solar and Space Plasma Dynamics #Stars #Statistics #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1086/507419
published as Astrophys.J.650:180-188,2006 · 22 pages, 8 figures, 1 table, ApJ accepted
arxiv created 2006/07/04 · openalex publication_date 2006/10/10 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
In this paper we discuss and examine various issues concerning the recent findings that suggest that the observed period-luminosity ( P-L ) relation for the Large Magellanic Cloud (LMC) Cepheids is nonlinear. These include (1) visualizing the nonlinear P-L relation; (2) long-period Cepheids and sample selection; (3) outlier removal; (4) issues of extinction; (5) nonlinearity of the period-color ( P-C ) relation; (6) nonlinear P-L relations in different passbands; and (7) the universality of the P-L relation. Our results imply that a statistical test is needed to detect the nonlinear P-L relation. We then show that sample selection, number of long-period Cepheids in the sample, outlier removal, and extinction errors are unlikely to be responsible for the detection of the nonlinear P-L relation. We also argue for the existence of a nonlinear P-L relation from the perspective of the nonlinear P-C relation and the nonuniversality of the P-L relation. Combining the evidence and discussion from these aspects, we find that there is a strong indication that the observed LMC P-L relation is indeed nonlinear in the optical bands (however, the K -band LMC P-L relation is apparently linear). This could be due to internal physical reasons or to external hidden/additional factors. Compared to the nonlinear P-L relation, the systematic error in distance scale introduced from using the (incorrect) linear P-L relation is at most at the few percent level. While this is small compared to other systematic errors, it will be important in future efforts to produce a Cepheid distance scale accurate to 1% in order to remove degeneracies presented in CMB results.