Hipparcos Parallaxes and the Cepheid Distance Scale
Abstract
Hipparcos parallaxes have recently become available for a sample of Galactic Cepheids, and we have used these new distances to calibrate the Cepheid period-luminosity (PL) relation at six wavelengths (BVIJHK). Comparing these calibrations with previously published multiwavelength PL relations we find agreement to within 0.07 +/- 0.14 mag, or 4 +/- 7% in distance. Unfortunately, the current parallax errors for the fundamental pulsators (ranging in signal-to-noise = pi /sigma_pi from 0.3 to 5.3, at best) preclude an unambiguous interpretation of the observed differences, which may arise from a combination of true distance modulus, reddening and/or metallicity effects. We explore these effects and discuss their implications for the distance to the Large Magellanic Cloud (LMC) and the Cepheid-based extragalactic distance scale. These results suggest a range of LMC moduli between 18.44 +/-0.35 and 18.57 +/-0.11 mag; however, other effects on the Cepheid PL relation (e.g., extinction, metallicity, statistical errors) are still as significant as any such reassessment of its zero point.
Cite
@article{arxiv.astro-ph/9707091,
title = {Hipparcos Parallaxes and the Cepheid Distance Scale},
author = {Barry F. Madore and Wendy L. Freedman},
journal= {arXiv preprint arXiv:astro-ph/9707091},
year = {2014}
}
Comments
15 pages, 4 figures, Ap. J. Letters, in press