0 Assigned ID: 1060 ----- Attempting Submission 1 (Sat Mar 07 00:55:47 GMT 2020) ----- HST Phase I Proposal 1060 successfully submitted. Receipt: # 1060-1 ----- Attempting Submission 2 (Sat Mar 07 00:59:40 GMT 2020) ----- The discrepancy between local measurements of the Hubble constant (H0) and the value inferred from observations of the CMB under the assumption of a Lambda-CDM cosmological model may be our strongest indication of new physics. Direct, distance-ladder measurements of the H0 rely primarily on Cepheids and the Tip of the Red Giant Branch (TRGB) to calibrate the luminosity of Type Ia supernovae (SN Ia). An independent approach using Mira variables can check existing Cepheid and TRGB measurements while extending the distance ladder in the era of infrared space missions such as JWST and WFIRST, which will have difficulty discovering Cepheids. Miras are pulsating variable stars that follow tight (~0.12 mag scatter) Period-Luminosity Relations (PLRs) in the near-infrared (NIR). Short-period Miras (P < 400 days) have NIR luminosities up to 2 mag brighter than TRGB and are a ubiquitous older population that have already been used to calibrate H0 with 5% uncertainty. Long-period Miras (P > 400 days) are highly luminous and follow a different PLR from short-period Miras. Using archival observations obtained to study the late-time lightcurve of SN 2011fe, we will (1) derive a new distance measurement to this galaxy using short-period Miras, resulting in a sub-3% calibration of H0 with Miras when combined with existing Mira-SN Ia hosts; (2) search long-period Miras with HST for the first time in a SN Ia host galaxy; (3) cross-correlate long-period variables discovered in HST with Spitzer IR observations. Dr. Caroline Huang is an expert in Mira variables and their application as distance indicators using HST data. She has calibrated the absolute luminosity of Miras in NGC 4258 and derived a Hubble constant using observations of Miras in NGC 1559. Dr. Nadia Zakamska is an expert in extragalactic astronomy and time-variability surveys and has worked on a Hubble constant calibration using Miras and the Gaia calibration of Mira variables. Dr. Wenlong Yuan is an expert in HST data reduction, crowded-field photometry, and time-series analysis. He has worked on Hubble constant calibrations using Cepheids, Miras, and TRGB with HST data. Large Scale Structure of the Universe 0 Regular false false false false false SUPPORTED