0 Assigned ID: 3923 ----- Attempting Submission 1 (Fri May 12 19:29:22 GMT 2023) ----- HST Phase I Proposal 3923 successfully submitted. Receipt: # 3923-1 ----- Attempting Submission 2 (Fri May 12 19:41:11 GMT 2023) ----- HST Phase I Proposal 3923 successfully submitted. Receipt: # 3923-2 ----- Attempting Submission 3 (Thu May 18 22:01:34 GMT 2023) ----- HST Phase I Proposal 3923 successfully submitted. Receipt: # 3923-3 ----- Attempting Submission 4 (Tue May 23 17:56:26 GMT 2023) ----- HST Phase I Proposal 3923 successfully submitted. Receipt: # 3923-4 ----- Attempting Submission 5 (Wed May 24 20:04:30 GMT 2023) ----- HST Phase I Proposal 3923 successfully submitted. Receipt: # 3923-5 ----- Attempting Submission 6 (Wed May 24 21:02:24 GMT 2023) ----- HST Phase I Proposal 3923 successfully submitted. Receipt: # 3923-6 ----- Attempting Submission 7 (Wed May 24 21:45:47 GMT 2023) ----- JAGB stars, a subset of carbon-rich AGB stars, have well-defined, low-dispersion absolute magnitudes in the near infrared, making them excellent standard candles. The JAGB star extragalactic distance indicator has been shown to be as precise and accurate as the Cepheid and TRGB methods in measuring distances to nearby galaxies (Lee et al. 2021, 2022). However, because the JAGB method is still relatively novel, it has not undergone the same level of comprehensive testing across diverse stellar environments as the Cepheid and TRGB distance indicators. Lee (2023) was the first to empirically quantify environmental effects on the JAGB method by using archival HST data of M31 from the PHAT survey to show that while internal reddening had a significant effect on the mode of the JAGB star luminosity function, metallicity and age had negligible effects. We now propose to leverage archival data from the PHATTER survey in M33 to extend this analysis to a wider range of stellar environments as M33 has a lower metallicity and 10x higher SFR than M31. The JAGB method has already been shown to be highly precise; understanding the systematics of even these small effects will further increase its precision. Once the potential systematics of the JAGB method have been thoroughly investigated, the JAGB method can be used to provide an independent local measurement of H0, and cross-check TRGB and Cepheid distances. As a bonus, this proposal will help provide observational constraints on the carbon star luminosity function in different stellar environments, directly guiding theoretical models of carbon star evolution which includes winds, dredge-ups, and hot-bottom burning. Ms. Abigail Lee has years of expertise in HST data analysis for ACS and WFC3. As a graduate student at UChicago, she has published three papers on the JAGB method, the distance indicator discussed in this proposal. Professor Wendy L. Freedman and Dr. Barry F. Madore share a long-standing mutual interest and applied expertise in determining the expansion rate of the Universe, having pioneered the use of Cepheid variables and the TRGB Method, in the optical and in the near infrared. Both were founding members of the original HST Key Project on the Hubble constant and they have over 100 refereed papers on this topic. Dr. Jang is a postdoctoral fellow at the University of Chicago and has upwards of 10 years of experience analyzing HST ACS and WFC3 data. Ms. Kayla Owens is a graduate student working with Prof. Freedman and Dr. Madore at the University of Chicago. She has considerable experience working with HST imaging data. All of the people listed above have been active participants in the Carnegie-Chicago Hubble Constant Program and have years of experience reducing, analyzing and using HST imaging data. With specific regard to this program, Lee, Freedman, and Madore have pioneered the calibration and application of the JAGB Method to the extragalactic distance scale. Stellar Populations and the Interstellar Medium Large Scale Structure of the Universe 0 Regular false false false false false false SUPPORTED