Wednesdays at Flatiron are pretty fun! Today Kathryn Johnston (Columbia) convened a discussion of dynamics that was pretty impressive. In that discussion my only contribution was to briefly describe the project that Adrian Price-Whelan (Princeton) and I have started called MySpace. This project is to find (in a data-driven way) the local transformation of velocity as a function of position that makes the local disk velocity structure more coherent over a larger patch of the disk.
At first we thought we were playing around with this idea, but then we realized that it produces an unsupervised, data-driven classification of all the stars: Stars in velocity-space concentrations locally in the disk are either in concentrations that extend in some continuous way over a larger patch of the disk or they do not. And this ties into the origins of the velocity substructure. While I was talking about this, Robyn Sanderson (Flatiron) pointed out that if the substructure is created by resonances or forcing by the bar, there are specific predictions of how the local transformation should look. That's great, because it is a data-driven way of looking at the Milky Way bar. Sanderson also gave us relevant references in the literature.
Late in the day, I wrote down some ideas about how we might tease apart metallicity, age, and kinematics in local samples of stars. The sample of Solar Twins from Megan Bedell (Flatiron) have empirical properties that suggest that a lot of the chemical (element-abundance-ratio) diversity of the stars is strongly related to stellar age. So is there information left for chemical taggging? Maybe not. I tried to write down a framework for asking these questions.
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