[Mesa-users] problem with center-density calculation

[Ebrahim Hassani]

Dear Mesa-users


As a part of my PhD these, I need to calculate the center-density of stars
with different masses and when stars are in Intermediate age main sequence
phase (IAMS). IAMS is when the amount of Hydrogen in the center of a star
is X_c=0.3 [1]. For doing this, I used 1M_pre_ms_to_wd example in
~/star/test_suite folder. I made two changes:


1) I changed the mass of the star from “initial_mass = 1.0” to 0.5 , 1.0 ,
1.5 , 2.0 , 2.5 and 3.0 (6 stars).


2) In order to increase precision, I made upper-limit bound on timesteps
with “max_years_for_timestep” command for each star.


The results are:


for M=0.5 star ==> center-density is about 152

for M=1.0 star ==> center-density is about 166

for M=1.5 star ==> center-density is about 111

for M=2.0 star ==> center-density is about 73

for M=2.5 star ==> center-density is about 54

for M=3.0 star ==> center-density is about 41


Now, my question is why for M=1.0 star center-density is 166? It seems it
must be a number between 152 and 111. This problem also happens when I
don’t put an upper-limit bound on timesteps. Is there any other change that
I have to make on 1M_pre_ms_to_wd example?


I would be very grateful if you help me with more guidance about the problem
 that I encountered.
I would be pleased to hear from you soon.

Reference:
[1] - MESA Isochrones and Stellar Tracks (MIST) 0: Methods for the
Construction of Stellar Isochrones
http://adsabs.harvard.edu/abs/2016ApJS..222....8D


Sincerely yours,
Ebrahim,
Physics Department, University of Birjand,
Birjand, Iran
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.mesastar.org/pipermail/mesa-users/attachments/20181222/ea25af92/attachment.html>