Institution(s): 1. Massachusetts Institute of Technology
Studying old, metal-poor stars allows for connecting the present state of the Galactic halo with its long-lasting assembly history. By retaining the chemical information from their formation time in their atmospheres, these low-mass (M < 0.8 M_sun) stars also enable the reconstruction of the chemical evolution, early star formation, and galaxy evolution. Taken altogether, they are an exceptionally versatile tool for investigating the conditions of the early universe and the assembly process(es) of large galaxies. Examples in this context include studies on the formation of the first stars (Pop III), supernova (SN) nucleosynthesis, early metal and gas mixing processes, chemical evolution, assembly processes of galaxies. I will review the current state of the field, report on the most recent discovery of a star with [Fe/H] < -7.0 and describe prospects for upcoming surveys to find more of these relic ancient stars.