AR 15024 (Archival Research)

Thu Jul 25 13:21:12 GMT 2024

Principal Investigator: Michael Gregg
PI Institution: University of California - Davis
Investigators (xml)

Title: Serendipitous WFC3 Infrared Color Magnitude Diagrams of NGC4472
Cycle: 25

This proposal requests support for analysis of deep, four filter, wide-band WFC3/IR archival imaging data, serendipitously taken in the halo of the brightest galaxy in the Virgo cluster, the giant elliptical NGC4472. The data resolve stars well below the tip of the red giant branch with S/N of 5. These data will produce various IR color magnitude diagrams of the upper red and asymptotic giant branch populations. Comparison of the location and width of the red giant branch locus with theoretical isochrones will yield mean metallicity and abundance spread measurements of the halo population of NGC4472. These data will also determine a secure distance from the luminosity of the observed giant branch tip in the IR. Detection or limits on intermediate age populations will be extracted from analysis of the asymptotic giant branch population. The resulting mean metallicity, metallicity distribution function, and constraints on intermediate age populations will be the first such data for a luminous elliptical in a rich cluster of galaxies. The results will provide meaningful input and testing of massive elliptical galaxy formation. This program also serves as a preparatory project for a JWST Early Release Science program which shares some of the same science goals and analysis methods.