[Mesa-users] Stellar Convective Zone Evolution

Chris Wang lwang178 at jhu.edu
Thu Feb 2 23:40:38 UTC 2023

Dear Radek,
Thanks for your kind reply! I will follow your suggestion and get back to you when I find whether that is the case!

From: Radek Smolec <smolec at camk.edu.pl>
Date: Thursday, February 2, 2023 at 18:05
To: Chris Wang <lwang178 at jhu.edu>
Cc: mesa-users at lists.mesastar.org <mesa-users at lists.mesastar.org>
Subject: Re: [Mesa-users] Stellar Convective Zone Evolution

      External Email - Use Caution

Dear Chris,

What you see is an artifact and not the deepening of the surface convection zone. Notice that conv_mx_1_*, conv_mx_2_* do not follow a boundary of the specific convective region (eg., of the convective core, or of the convective envelope), but the largest, by mass, convective region.
My guess is that a very thin convective shell develops in your models a top of the convective core and hence the spikes in your plot. I suggest to trace more convective regions, by using:
 mixing_regions <integer>
for your history.file, see $MESA_DIR/star/default/history_column.list for the description. Be careful with the plotting as these, again, will not follow a specific convective region, but consecutive convective regions starting from the center
Kind regards,

czw., 2 lut 2023 o 23:04 Chris Wang via Mesa-users <mesa-users at lists.mesastar.org<mailto:mesa-users at lists.mesastar.org>> napisał(a):
Dear MESA users,
I am a sophomore undergraduate physics/astronomy student from JHU, and I am using MESA to understand the convective zone evolution of main sequence stars of different masses. I simulated stellar models of different masses and solar metallicity to the TAMS stage with following command:
xa_central_lower_limit_species(1) = 'h1'
xa_central_lower_limit(1) = 1d-3
When I plotted the Kippenhaln diagram using conv_mx_1_top, conv_mx_1_bot, conv_mx_2_top, conv_mx_2_bot parameters from history.data files, there is some strange “deepening” of surface convective zone for stars of mass between 1.2 solar mass and 1.8 solar mass, which probably should not take place. For example, for 1.4 solar mass stellar model, there seems to be an “oscillation” of surface convective zone at ~1Myr. I have attached those Kippenhaln diagrams in this email. I am wondering if you can offer me some physical explanations for this phenomenon, or maybe point out some potential “bugs” in my simulation. Thank you so much!
Chris Wang
Johns Hopkins University

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