Possible next steps in XP spectra & the Milky Way

 These are literally only notes-to-self by HW

The Rich Heart of the Milky Way

[see also the Jupyter notebook: Metal Rich Stars from Andrae+2023]

I just made the plot using the Andrae+2023 giant table

We can then identify the most metal-rich stars in it [M/H]>0.47.

Their CMD's look "normal"; but iffy [M/H]-estimates and imprecise parallaxes

prevent clear age-dating.

We then look at the all-sky distribution, in different metallicity slices, which looks remarkable

 To do's:

• plot [M/H]_XP vs DR17 APOGEE - get new metallicities from Andy Casey (?)
• check whether there are any RV's (few?)
• get good distances (a la Hogg...) or from Xiangyu
• with good/assumed distances, say something about the ages
• build a model to constrain the level of rotation using only proper motions (that needs good distances). -- get proper motions!! (the notebook is set up for that)
• all this requires a clean-up/augmentation of the Jupyter notebook.

Giant Ages within 3 kpc

For giants with XP metallicities and very good parallaxes (5%?) we can get ages, as in the LMC, using HWR's sped-up code.   We should do that..  perhaps suggest to to Josh?

Calibration of the stellar mass scale on the lower MS

I have taken the Hwang et al 2023 code that calculates (and dynamically calibrates) M_*(absG,B-R) from the wide-binary dynamics and applied it to M-dwarfs. Compared to the what the Carmenes DR1 folks use, there is a serious offset.