At Milky Way group meeting, various projects were discussed. Marie Martig (MPIA) and Maria Bergemann (MPIA) are both looking at how we might extract stellar ages from stellar spectra. Martig is looking at the dredge-up of elements from the core into the stellar exterior. Bergemann is looking at how extremely weak chromospheric emission might adjust (minutely) the shapes of the Balmer lines. Both of these projects are directly relevant to what Ness and I are doing with The Cannon.
After lunch, the PSF coffee had two impressive presentations. In the first, Nestor Espinoza (PUC Santiago/Chile) showed very impressive transmission spectroscopy of transiting planets. He has some spectral features that are hard to explain, but he notes that they might be caused by some systematic problems with the pipelines. They are taking reasonably high resolution (few thousand) spectra, but binning them down for analysis; it is interesting to think about what could be done with non-trivial binnings of the spectra, that are customized to particular questions.
In the second presentation, Florian Rodler (MPIA) took time-domain spectra in the red side of the K band to find the forest of molecular CO lines in the inner planet in the Upsilon Andromeda multi-planet system. This system is amazingly complicated, with two super-Jupiters with huge mutual inclination, large eccentricity, and a (circular) hot Jupiter. It sure doesn't look like it could be stable! The system properties are known from a combination of radial-velocity monitoring (of the main star), astrometric monitoring (of the center of light), and direct detection (of the molecular lines from the hot Jupiter).