The Cepheid Distance Scale: recent progress in fundamental techniques

TL;DR

This review discusses recent advances in fundamental techniques for measuring distances to Cepheid variable stars, emphasizing geometric methods and their agreement, which is crucial for cosmic distance scale calibration.

Contribution

It provides a comprehensive comparison of geometric and quasi-geometric techniques for Cepheid distance measurement, highlighting their agreement and the importance of the p-factor.

Findings

Surface brightness, interferometric pulsation, and trigonometric methods agree well for Galactic Cepheids.

The p-factor is essential and consistent between observations and theory.

Recent methods improve the accuracy of the Cepheid distance scale.

Abstract

This review examines progress on the Pop I, fundamental-mode Cepheid distance scale with emphasis on recent developments in geometric and quasi-geometric techniques for Cepheid distance determination. Specifically I examine the surface brightness method, interferometric pulsation method, and trigonometric measurements. The three techniques are found to be in excellent agreement for distance measures in the Galaxy. The velocity p-factor is of crucial importance in the first two of these methods. A comparison of recent determinations of the p-factor for Cepheids demonstrates that observational measures of p and theoretical predictions agree within their uncertainties for Galactic Cepheids.