2018-09-19

dynamics and chemistry

Today Kathryn Johnston (Columbia) test-drove a group meeting at Flatiron on Dynamics, to which I was honored to be invited. We went around the table and described our current dynamics-related projects. After that, it was Stars Meeting, which was its usual hugeness. At the suggestion of its (rotating) organizers, we are experimenting with different ways of making sure many voices are all involved in the conversation. That's a hard problem!

As Stars meeting many interesting things happened. A highlight for me was Adrian Price-Whelan (Princeton) describing work done at Aspen in the last few weeks on the Orphan stream. It looks for dynamical and chemical reasons like a disrupted dwarf galaxy, and it may fully wrap the Galaxy. Another highlight was a contribution from Victor Debattista (UCLAN) looking at chemical abundances in toy (that is, non-cosmological) simulations of star-forming disk galaxies. He has a new explanation for the bimodality between alpha-rich thick disk and alpha-poor thin disk, and his explanation is general, so it implies (as he explicitly predicts in his new paper) that the bimodality will be observed in all disk galaxies! That's exciting. Of course it is hard to observe.

In other news, Matthew Buckley (Rutgers) showed me really beautiful results, in which he can measure the mass of a globular cluster by using phase-space density or volume information, even in the presence of real data issues. The reason it is hard is that the data quality is extremely anisotropic in phase space. It looks extremely promising. I want to figure out how this relates to old-school methods, like virial methods and caustic methods.

No comments:

Post a Comment