Example 4: Get abundance from REW

About

This example will show you how to derive the lithium abundance given a REW by using the Rew class in breidablik.interpolate.rew.

Example

Lets assume we want to find the 3D NLTE abundance for a REW of -6 for LP 815-43.

REW = -6
# stellar parameters for LP 815-43
t_eff = 6400 # K
log_g = 4.17 # cgs
met = -2.74 # dex

Next, we load in the models by initialising the class, then call the function find_abund with the parameters we just defined.

from breidablik.interpolate.rew import Rew
# initialise model
model = Rew()
# find abundance
abund = model.find_abund(t_eff, log_g, met, REW)
print(abund)

Which returns an abundance of 1.70 dex.

find_abund accepts a parameter: center, that determines which model is used: there are 3 models, 1 for each Li line. The 3 lithium lines are centered at 610.5298, 670.9659, and 812.8606 nm. The input center value will snap to the closest value out of those 3. By default, the 670.9 nm model is used.

The 3D stagger grid does not go to low temperatures. For M-type stars, we can calculate 1D NLTE A(Li) trained on the marcs grid.

# initialise model trained on 1D NLTE A(Li)
model = Rew(dim = 1)

This 1D model was only trained on the 670.9 nm line. If you call find_abund using a different Li line, a warning will be raised and find_abund will return a 3D NLTE abundance for the specified line.