Running Single Stars with POSYDON

Single stars, hydrogen or helium main sequence stars (HMS; HeMS), can be run with POSYDON specifying the single_star_grid = True option in the ini file. This function takes care of setting up the MESA simulation to run a single star instead of a binary star system.

Creating the Initialization File

You can reuse your HMS-HMS.ini file from the previous tutorials. Simply make a copy of it and call it for example single_HMS.ini. Now change the line

single_star_grid = False

to

single_star_grid = True

Creating the Initial Simulation Points CSV File

We now need to generate the grid.csv containing 10 initial values for 10 stars, in this case the initial values are just the mass and metallicity paramters. You can do this by running the following code cell. The code that follows was copied from $PATH_TO_POSYDON/grid_params/POSYDON-MESA-INLISTS/r11701/running_scripts/parameter_space_v2/create_csv.ipynb an adopted to the needs here.

[1]:

import os
import csv
import numpy as np

def log_range(x_min,x_max,x_n):
    return 10**np.linspace(np.log10(x_min),np.log10(x_max), x_n)

# digit rounding pick 10 to be sure we resolve 10^-4Zsun
NDIG = 10

Zsun = 0.0142
m1_min = 5.0
m1_max = 100.0
m1_n = 10
m1 = log_range(m1_min,m1_max,m1_n)
met = [0.1*Zsun]

with open('./grid_test.csv', 'w', newline='') as file:
    writer = csv.writer(file)
    writer.writerow(['initial_z','Zbase','initial_mass'])
    for Z in met:
        for i in range(m1_n):
            writer.writerow([round(Z,NDIG),round(Z,NDIG),round(m1[i],NDIG)])

[2]:

!cat ./grid_test.csv

initial_z,Zbase,initial_mass
0.00142,0.00142,5.0
0.00142,0.00142,6.9747539698
0.00142,0.00142,9.7294385879
0.00142,0.00142,13.572088083
0.00142,0.00142,18.9323950471
0.00142,0.00142,26.4097595025
0.00142,0.00142,36.8403149864
0.00142,0.00142,51.3904266401
0.00142,0.00142,71.6871164437
0.00142,0.00142,100.0

Runing the MESA Grid with the POSYDON Submission Script

We are now ready to run the simulation, with the following commands (Please remember to have the POSYDON and MESA variables being set before):

posydon-setup-grid --grid-type fixed --inifile single_HMS.ini --submission-type slurm
./run_grid.sh

Sit back relax, and wait for the grid to finish. Check out the advanced tutorial on how to generate the PSyGrid object for single stars.