Authors: Jesper Storm Nicolas Nardetto Wolfgang Gieren Pascal Fouqué Thomas G Barnes
Publish Date: 2012/04/04
Volume: 341, Issue: 1, Pages: 115-121
Abstract
We have applied the nearinfrared surfacebrightness method to 111 Cepheids in the Milky Way and in the Large and the Small Magellanic Clouds determining distances and luminosities for the individual stars We find that the Kband PeriodLuminosity PLrelations for Milky Way and Large Magellanic Cloud Cepheids are almost identical whereas the zero point of the Wesenheit relation depends significantly on metallicity metal poor Cepheids being fainterWe determine empirically the relation between the projection factor p and pulsational period P used for converting the observed radial velocities into the pulsational velocities necessary for applying the nearinfrared surfacebrightness method We also determine the pfactor relation on a theoretical basis and find a significantly shallower slope than from our empirical determination suggesting that there is still some physics related to the method which deserves further investigationUsing the empirical pfactor relation we redetermine the Cepheid PLrelation in the Kband using all 111 Cepheids We argue that this is the currently best PLrelation for distance determination being largely independent of both metallicity and reddening
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