Milky Way stars

It is a low-research week because of the move to Heidelberg for the summer (consult rules at right). But today I went to Rix's Milky Way group meeting, where Branimir Sesar (Caltech) told us about observations of red giant stars and RR Lyrae stars in the orphan stream. His work suggested a very small velocity dispersion for the stream, and also (apparently) points to a low mass for the Milky Way halo. Like Koposov, Rix, and me, he is fitting the stream with an orbit, not a tidal-stream model, which might lead to some biases.

At the same meeting, Rix showed predictions from Stinson and collaborators for chemical abundances for stars of different ages. They seem to confirm the picture we have been pushing with Bovy that the chemical abundance boxels (in Fe/H and alpha/Fe) are close to age boxels. He also noted that Sesar's work with red giants strongly endorses Rix and Xue's distance estimation work: In the stream, the RRL and K-giant distances seem to agree very well.

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