Re: [mesa-users] Change in evolutionary timescale between r8118 and r9575

[Aaron D. <aar...@gm...>]

Hi Matteo,

Somewhere between r8118 and r9575 there was a change to the internal EOS
code that switched from cubic to linear interpolation in X.

I was able to reproduce your results between 8118 and 9575 by switching
back and forth between linear and cubic interpolation in the EOS.

Can you continue to use r8118?  If not, you might want to wait for the next
public release and update again.

Aaron


On Tue, Mar 28, 2017 at 11:03 AM, Matteo Dell'Omodarme <mat...@fa...
> wrote:

> Dear All,
>
> I'm performing some basic comparisons in order to extend (using MESA
> r9575) a
> dataset computed by means of MESA r8118.
> I'm noticing some differences in the evolutionary timescale between the two
> releases.
>
> The case study I'd like to discuss is M = 1.40 Msun, Z = 0.01894, Y =
> 0.2674.
> The inlist for the computations are attached to this message (inlist,
> inlist_default, and inlist-nr) [the control  photo_interval in r9575
> replaces
> the old photosteps], as well as the .net adopted.
>
> It turns out that the stellar evolution computed by r9575 is 2% faster than
> the one by r8118 (see attached plots). This is a very notable difference --
> all input being the same -- and it
> will have a relevant impact on grid-based estimates of stellar mass,
> radius, and age.
>
> I've no clue to trace the origin of the difference, since the release
> notes do
> not highlight some changes which could alter so much the evolutionary
> timescale.
>
> Could someone help by pointing out the changes (algorithms or default
> values) occurred between the two versions?
>
> Thanks in advance,
> Matteo Dell'Omodarme
>
> Sezione di Astronomia
> Università di Pisa
>
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