timothydmorton / isochrones

Pythonic stellar model grid access; easy MCMC fitting of stellar properties
http://isochrones.readthedocs.org
MIT License
117 stars 63 forks source link

potential issue with interpolation? #194

Open caseylam opened 5 days ago

caseylam commented 5 days ago

Hi,

I've found that when I use "get_eep", it fails to return an EEP where I think it should have no problem: for example, mist.get_eep(0.15, 10, 0, accurate=True)gives me RuntimeError: EEP minimization not successful: (0.15, 10, 0).

As a test, I ran get_eep on a grid of masses, logages, and Fe/H (mass_array = 10**np.linspace(np.log10(0.1), np.log10(20), 500), logage_array = np.arange(5, 10.2, 0.1), feh_array = np.arange(-3.5, 0.31, 0.1)).

I then plotted the resultant EEP of that for each value of Fe/H in a grid of mass vs age. If there is an EEP runtime error returned, that piece of the grid is white. The white region in the upper right makes sense (those stars are "dead" so they're not on the isochrones), but a lot of stars which I would expect to be on the MS are not there, especially at [Fe/H] > 0. There also looks to be some slightly weird behavior at low [Fe/H] around a solar mass (there is a "notch" in the distribution.)

Is this expected?

isochrones_feh_0 3 isochrones_feh_0 2 isochrones_feh_0 1 isochrones_feh_0 0 isochrones_feh_-0 1 isochrones_feh_-0 2 isochrones_feh_-0 3 isochrones_feh_-0 4 isochrones_feh_-0 5 isochrones_feh_-0 6 isochrones_feh_-0 7 isochrones_feh_-0 8 isochrones_feh_-0 9 isochrones_feh_-1 0 isochrones_feh_-1 1 isochrones_feh_-1 2 isochrones_feh_-1 3 isochrones_feh_-1 4 isochrones_feh_-1 5 isochrones_feh_-1 6 isochrones_feh_-1 7 isochrones_feh_-1 8 isochrones_feh_-1 9 isochrones_feh_-2 0 isochrones_feh_-2 1 isochrones_feh_-2 2 isochrones_feh_-2 3 isochrones_feh_-2 4 isochrones_feh_-2 5 isochrones_feh_-2 6 isochrones_feh_-2 7 isochrones_feh_-2 8 isochrones_feh_-2 9 isochrones_feh_-3 0 isochrones_feh_-3 1 isochrones_feh_-3 2 isochrones_feh_-3 3 isochrones_feh_-3 4 isochrones_feh_-3 5