A new calibration of Galactic Cepheid
Period-Luminosity relations from B to K bands, and a comparison to LMC
PL relations
P. Fouque, P. Arriagada, J. Storm, T.
G. Barnes, N. Nardetto, A. Merand, P. Kervella, W. Gieren, D. Bersier,
G. F. Benedict, B. E. McArthur
A&A, 476, pg.71-83 (2007)
Abstract
The universality of the Cepheid Period-Luminosity relations has been
under discussion since metallicity effects have been assumed to play a
role in the value of the intercept and, more recently, of the slope of
these relations. The goal of the present study is to calibrate the
Galactic PL relations in various photometric bands (from B to K) and to
compare the results to the well-established PL relations in the LMC. We
use a set of 59 calibrating stars, the distances of which are measured
using five different distance indicators: Hubble Space Telescope and
revised Hipparcos parallaxes, infrared surface brightness and
interferometric Baade-Wesselink parallaxes, and classical
Zero-Age-Main-Sequence-fitting parallaxes for Cepheids belonging to
open clusters or OB stars associations. A detailed discussion of
absorption corrections and projection factor to be used is given. We
find no significant difference in the slopes of the PL relations
between LMC and our Galaxy. We conclude that the Cepheid PL relations
have universal slopes in all photometric bands, not depending on the
galaxy under study (at least for LMC and Milky Way). The possible
zero-point variation with metal content is not discussed in the present
work, but an upper limit of 18.50 for the LMC distance modulus can be
deduced from our data.
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