Abundance measurements in M15 RGB stars

However, these data will have a high degree of heterogeneity and most will be low-resolution (R<10000), posing challenges to measuring consistent and reliable stellar labels. Here, we introduce a framework for identifying and remedying these issues.

By simultaneously fitting the full spectrum and Gaia photometry with the Payne, we measure ~30 abundances for eight metal-poor red giants in M15. From degraded quality Keck/HIRES spectra, we evaluate trends with resolution and signal-to-noise ratio (S/N) and find that (i) ~20 abundances are recovered consistently within <~0.1dex agreement and with <~0.05-0.15 dex systematic uncertainties from 10000<~R<~80000; (ii) for nine elements (C, Mg, Ca, Sc, Ti, Fe, Ni, Y, and Nd), this systematic precision and accuracy extends down to R~2500; and (iii) while most elements do not exhibit strong S/N-dependent systematics, there are nonnegligible biases for four elements (C, Mg, Ca, and Dy) below S/N~10/pixel.