[Mesa-users] Questions about MLT++ and center variables

[Josiah Schwab]

Hi Matheus,

> I'm an undergraduate student and I'm using MESA to study the evoltion of
> massive stars up to the oxigen burning.
>
> 1) On MESA's second paper (section 7.3.1) it's shown different results
> depending if one choose MLT or MESA's MLT++. Which result should I prefer
> as 'the most correct'?

Well, they're both wrong.  Which one you would choose depends on what
questions you're asking of the models.

> 2) How can I switch between MLT and MLT++ on my MESA models?

The relevant control is named okay_to_reduce_gradT_excess

http://mesa.sourceforge.net/controls_defaults.html#okay_to_reduce_gradT_excess

> 3) How the center variables (T_c, rho_c,etc) are defined, in the most
> central cell or  as a region composed by a given amount of cells near the
> center?

The center quantities are defined as averages over a certain size
region.  However, this is defined by fractional mass, not by cell
number, so in a converged model the answer should be resolution
independent.

http://mesa.sourceforge.net/controls_defaults.html#center_avg_value_dq

Hope that helps,
Josiah