Clues to Globular Cluster Formation

David M. Nataf

Assistant Research Scientist
Department of Physics and Astronomy
The Johns Hopkins University

Globular clusters, which are among the oldest and most compact stellar systems known, are now well-established to host “second-generation” stars, which show anomalous abundances in some or all of He, C, N, O, Na, Al, Mg, etc. The simplest explanations for these phenomena typically require the globular clusters to have been ~20x more massive at birth, and to have been enriched by processes which are not consistent with the theoretical predictions of massive star chemical synthesis models. The library of observations is now a vast one, yet there has been comparatively little progress in understanding how globular clusters could have formed and evolved. In this talk I discuss two new insights into the matter. First, I report on a meta-analysis of globular cluster abundances that combined APOGEE and literature data for 42 globular clusters, new trends with globular cluster mass are identified. I discuss the chemical properties of former globular cluster stars that are now part of the field population, and what can be learned. Finally, use updated state-of-the-art massive star stellar evolution models from the Padova group to make predictions for the upcoming and inevitable James Webb Space Telescope observations of young globular cluster progenitors in their starburst phase.