Benoit Coté (Victoria & MSU) came to NYU for the day. He gave a great talk about nucleosynthetic models for the origin of the elements. He is building a full pipeline from raw nuclear physics through to cosmological simulations of structure formation, to get it all right. There were many interesting aspects to his talk and our discussions afterwards. One was about the i-process, intermediate between r and s. Another was about how r-process elements (like Eu) put very strong constraints on the rate at which stars form within their gas. Another was about how we have to combine nucleosynthetic chemistry observations with other kinds of observations (of, say, the PDMF, and neutron-star binaries, and so on) to really get a reliable and true picture of the nucleosynthetic story.
Late in the afternoon, I met with Ruth Angus (Columbia) to further discuss our project on cross-calibrating (or really, self-calibrating) all stellar age indicators. We wrote down some probability expressions, designed a rough design for the code, and discussed how we might structure a Gibbs sampler for this model, which is inherently hierarchical. We also drew a cool chalk-board graphical model (in this tweet), which has overlapping plates, which I am not sure is permitted in PGMs?