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Wesenheit function for Galactic Cepheids: Application to the projection factors

Published online by Cambridge University Press:  26 February 2013

Chow-Choong Ngeow ,
Hilding Neilson ,
Nicolas Nardetto  and
Massimo Marengo
Chow-Choong Ngeow
Affiliation:
Graduate Institute of Astronomy, National Central University, Jhongli City, 32001, Taiwan email: [email protected]
Hilding Neilson
Affiliation:
Argelander Institute for Astronomy, Auf dem Huegel 71, 53121 Bonn, Germany
Nicolas Nardetto
Affiliation:
Laboratoire Lagrange, UMR7293, UNSA/CNRS/OCA, 06300 Nice, France
Massimo Marengo
Affiliation:
Department of Physics and Astronomy, Iowa State University, Ames, IA 50010, USA
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Abstract

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Galactic Cepheids are necessary tools for calibrating the period–luminosity relation, but distances to individual Galactic Cepheids are difficult to measure precisely and their application is limited to a small number of techniques, such as direct parallax measurements, main-sequence fitting to open clusters that host Cepheids, and Baade–Wesselink (BW)-type methods. Here, we re-examine the application of Wesenheit functions in determining distances to more than 300 Galactic Cepheids by taking advantage of the fact that the Wesenheit function is extinction-free by definition. Wesenheit distances are used to calibrate the projection (p) factor for Galactic Cepheids that also have BW distances. Based on ~ 70 Cepheids, we find that the period–p-factor relation may exhibit a nonlinear trend with a considerable scatter. We found discrepant p factors for δ Cephei in the literature. This may be due to inconsistent measurements of its angular diameter using different empirical techniques. We discuss the reason for the inconsistency in angular-diameter measurements and offer a possible remedy.

Keywords

Cepheidsstars: distancesdistance scale
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 8 , Symposium S289: Advancing the Physics of Cosmic Distances , August 2012 , pp. 134 - 137
Copyright
Copyright © International Astronomical Union 2013

References

Bono, G., Caputo, F., Marconi, M., & Musella, I. 2010, ApJ, 715, 277Google Scholar
Caccin, R., Onnembo, A., Russo, G., & Sollazzo, C. 1981, A&A, 97, 104Google Scholar
Madore, B. F. 1982, ApJ, 253, 575Google Scholar
Madore, B. F. & Freedman, W. L. 2009, ApJ, 696, 1498Google Scholar
Majaess, D., Turner, D., & Gieren, W. 2011, ApJ, 741, L36CrossRefGoogle Scholar
Mérand, A., Kervella, P., Coudé du Foresto, V., et al. 2005, A&A, 438, L9Google Scholar
Nardetto, N., Mourard, D., Kervella, P., et al. 2006, A&A, 453, 309Google Scholar
Neilson, H. R., Nardetto, N., Ngeow, C.-C., Fouqué, P., & Storm, J. 2012, A&A, 541, A134Google Scholar
Ngeow, C.-C., Kanbur, S. M., Neilson, H. R., et al. 2009, ApJ, 693, 691Google Scholar
Ngeow, C.-C. 2012, ApJ, 747, 50Google Scholar
Ngeow, C.-C., Neilson, H. R., Nardetto, N., & Marengo, M. 2012, A&A, 543, A55Google Scholar
Opolski, A. 1983, IBVS, 2425, 1Google Scholar
Storm, J., Gieren, W., Fouqué, P., et al. 2011, A&A, 534, A94Google Scholar