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

[Matteo Dell'O. <mat...@fa...>]

Hi Aaron,
thanks for the quick reply.
Indeed this is an impressive demonstration of how our age estimates are 
prone to systematic effects due to the choices we made internally in our 
codes!

Cheers
Matteo


On 03/28/2017 07:25 PM, Aaron Dotter wrote:
> 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... <mailto: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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