Galactic archaeology

It's a long story, but we have been experimenting continuously with the rules and principles underlying the weekly Stars and Exoplanets Meeting that we run at Flatiron for the NYC astrophysics community. One of the things I say about it is that if you want a meeting to be open, supportive, easy, and community-building, it has to have a strong set of draconian rules! In our most recent set of discussions, we have been talking about theming the meetings around specific science themes. Today was our first experiment with that! Joss Bland-Hawthorn (Sydney) is in town, so we themed the meeting around Galactic Archaeology. We had five short discussions; here are some highlights:

Megan Bedell (Flatiron) showed her incredibly precise 35-element (?) abundance measurements vs stellar age for her Solar twin sample. The abundances are very closely related to the age (for this sample that is selected to have Solar [Fe/H]). Suroor Gandhi (NYU) showed her results on the dependence on dynamical (or really kinematic) actions on [Fe/H] and age for low-alpha and high-alpha stars in the local Milky Way disk. These show that the two different sequences (high and low alpha) have different origins. And Rocio Kiman (CUNY) showed her M dwarf kinematics as a function of magnetic activity that could be used to constrain a disk heating model. All three of these presentations could benefit (for interpretation) from a forward model of star formation and radial migration in the Milky Way disk, along with heating! This is related to things I have done with Neige Frankel (MPIA) but would require extensions. Simple extensions, though.

Adam Wheeler (Columbia) showed us abundances he has measured all over the Milky Way from LAMOST spectroscopy, training a version of The Cannon with GALAH abundances. It's an amazing data set, and he asked us to brainstorm ideas about what we could do with it. He seems to have features in his catalog that look similar to the midplane issues that were causing me existential angst this past August. Bland-Hawthorn said that he sees similar things in the GALAH data too.

And Bland-Hawthorn himself talked about the possibility that some future instrument could measure stellar accelerations and get the Milky Way acceleration field directly! He started by commenting on the conclusions of the Bonaca et al work on a possible dark-matter perturber acting on the GD-1 stellar stream. His remarks played very well with things Bonaca and I have been discussing around making a non-parametric acceleration map of the Milky Way.

In summary: A great experiment!