the Milky Way bar

At MW group meeting, Gail Zasowski (JHU) talked about work with Melissa Ness showing that the Milky Way has a kinematic bar. They see the bar very clearly in the distribution of stellar velocities projected onto the sky as a function of sky coordinates. It appears as a skewness or a second component in the velocity distribution. I wondered after the talk about the spiral structure: If it exists, shouldn't it also show up this way? There are hints of spiralness in the literature on stellar velocities, but nothing nearly as clear as what Zasowski and Ness see in the bulge for the bar.

Hans-Walter Rix suggested that I give my annual Königstuhl Colloquium here at MPIA on probabilistic graphical models, in part because he himself has found them so useful for clarifying our ideas about inference of stellar parameters, given data from Gaia, RAVE, Kepler, and so on. Late in the day, Dan Foreman-Mackey said just the opposite: His opinion is that PGMs merit either 10 minutes or else a semester course; nothing in-between makes sense! Might be too late.

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