EPJ Web of Conferences 152, 07001 (2017)
https://doi.org/10.1051/epjconf/201715207001

Pulsating stars and the distance scale

Mitchell Institute for Fundamental Physics & Astronomy and Department of Physics & Astronomy, Texas A&M University, College Station, Texas, United States of America

^* lmacri@tamu.edu

Published online: 8 September 2017

Abstract

I present an overview of the latest results from the SH0ES project, which obtained homogeneous Hubble Space Telescope (HST) photometry in the optical and near-infrared for ∼ 3500 and ∼ 2300 Cepheids, respectively, across 19 supernova hosts and 4 calibrators to determine the value of H₀ with a total uncertainty of 2.4%.

I discuss the current 3.4σ “tension” between this local measurement and predictions of H₀ based on observations of the CMB and the assumption of “standard” ΛCDM. I review ongoing efforts to reach σ(H₀) = 1%, including recent advances on the absolute calibration of Milky Way Cepheid period-luminosity relations (PLRs) using a novel astrometric technique with HST.

Lastly, I highlight recent results from another collaboration on the development of new statistical techniques to detect, classify and phase extragalactic Miras using noisy and sparsely-sampled observations. I present preliminary Mira PLRs at various wavelengths based on the application of these techniques to a survey of M33.