[Mesa-users] difficulty with custom mass loss

Tue Jul 16 18:59:54 EDT 2019

There could be several use cases, but the first one I see is that 
other_wind is called before any enhancements due to super Eddington 
luminosities or rotation, whereas adjust_mdot is the end-all be-all way to 
change the mass of the star.
Also, if you look at that lab Frank posted, I use adjust_mdot to 
preferentially turn off mass accretion when approaching a wind regime to 
ease the transition from accretion to mass loss. That would be much harder 
to do in other_wind on its own.
Regards,
Bill

On Tue, Jul 16, 2019 at 12:06 AM, Warrick Ball <W.H.Ball at bham.ac.uk> wrote:
While reading the start of this thread, I started to wonder why there are
then two ways of changing the mass-loss rate. From Bill's description, it
sounds like `other_wind` allows you to set a (wind) mass loss rate that
will be combined with other sources, whereas `other_adjust_mdot` allows
you to change the total mass loss rate once it's calculated (which
includes the option of overwriting it completely). Have I got that right?

W

------------
Warrick Ball
Postdoc, School of Physics and Astronomy
University of Birmingham, Edgbaston, Birmingham B15 2TT
W.H.Ball at bham.ac.uk
+44 (0)121 414 4552

On Tue, 16 Jul 2019, mesa-users at lists.mesastar.org wrote:

 > Careful, there. In other_adjust_mdot, you want to change s% mstar_dot. 
But in other_wind, you only need to set w.
 >
 > Why the difference? When in doubt about how an "other" hook works, go to 
$MESA_DIR/star/private and grep for something like "call s% 
other_blah_blah_blah". In this case,
 >
 > cd $MESA_DIR/star/private
 > grep "call s% other_adjust_mdot" *.f90
 >
 > You'll see that it's in evolve.f90. The call happens right after a call 
to set_mdot, which sounds promising. That subroutine is located in 
winds.f90. It's a pretty long subroutine, but you'll see its
 > ultimate effect is to change the value of s% mstar_dot, so that's a 
strong indication that you'll want to do the same in your other_adjust_mdot 
routine.
 >
 > HOWEVER, you'll note that in set_mdot, the actual wind calculation is 
done by eval_wind_for_scheme. In that subroutine, we finally call s% 
other_wind. So what? Well, if you set s% mstar_dot in other_wind, it
 > will ultimately be overwritten by the end of set_mdot (probably the 
value of w, whatever that ends up being in your wind routine, if anything). 
In short, setting s% mstar_dot in the wind routine will have no
 > effect.
 >
 > Figuring out when these hooks are actually called is very useful (read: 
necessary), because it helps you know which variables have already been set 
and which ones you should leave alone, because they'll just
 > be overwritten later. The other_* hooks are extremely powerful, but you 
can be burned by them quite easily if you don't know the context in which 
they are called. I say that after being burned in just such a
 > way during a summer school lab.
 >
 > Regards,
 >
 > Bill
 >
 >
 >
 > From: TUCHOW, NOAH WOLFE <nxt5109 at psu.edu>
 > Reply: TUCHOW, NOAH WOLFE <nxt5109 at psu.edu>
 > Date: July 15, 2019 at 7:38:44 PM
 > To: Bill Wolf <wmwolf at asu.edu>
 > Cc: Aaron Dotter <aaron.dotter at gmail.com>, mesa-users at lists.mesastar.org 
<mesa-users at lists.mesastar.org>
 > Subject: Re: [Mesa-users] difficulty with custom mass loss
 >
 > I suppose that makes sense. I was wondering why there were potentially 
two variables for mdot. I'll try using s% mstar_dot and use other_wind 
instead.
 >
 > Thanks,
 > Noah
 >
 > Noah Tuchow
 >
 > Penn State University
 >
 > Department of Astronomy and Astrophysics
 >
 > 532C Davey Lab
 >
 > University Park, PA 16802
 >
 >
 >
 > On Mon, Jul 15, 2019 at 10:28 PM Bill Wolf <wmwolf at asu.edu> wrote:
 > Try setting s% mstar_dot instead of s% star_mdot. I've made this mistake 
before, and it took me a bit to figure out what was going wrong.
 >
 > To reduce the surprise factor, other_wind is probably what you want to 
use, but in most cases that I can think of, other_adjust_mdot should work.
 >
 > Bill
 >
 >
 > From: TUCHOW, NOAH WOLFE <nxt5109 at psu.edu>
 > Reply: TUCHOW, NOAH WOLFE <nxt5109 at psu.edu>
 > Date: July 15, 2019 at 7:18:47 PM
 > To: Aaron Dotter <aaron.dotter at gmail.com>
 > Cc: mesa-users at lists.mesastar.org <mesa-users at lists.mesastar.org>
 > Subject: Re: [Mesa-users] difficulty with custom mass loss
 >
 > The main reason why I wasn't using other_wind is that the mass loss 
which I wanted to model wasn't exclusively due to wind. If I were to use an 
other_wind hook, would it matter if the
 > mass loss isn't actually wind? Would I still modify s% star_mdot to set 
the mass loss rate, or is there another variable I should change? If I 
wanted to set a custom wind for main
 > sequence evolution would that be setting hot_wind_scheme= 'other' in the 
inlist?
 >
 > Thanks,
 > Noah Tuchow
 >
 >
 > Noah Tuchow
 >
 > Penn State University
 >
 > Department of Astronomy and Astrophysics
 >
 > 532C Davey Lab
 >
 > University Park, PA 16802
 >
 >
 >
 > On Mon, Jul 15, 2019 at 9:47 PM Aaron Dotter <aaron.dotter at gmail.com> 
wrote:
 > Hi Noah,
 > Just a suggestion: Have you tried using other_wind? I've used that 
successfully a number of times over the years. It might be what you're 
looking for rather than other_adjust_mdot.
 >
 > Aaron
 >
 > On Mon, Jul 15, 2019 at 9:34 PM TUCHOW, NOAH WOLFE <nxt5109 at psu.edu> 
wrote:
 > Hello everyone,
 >
 > I've been having a bit of difficulty trying to implement a custom mass 
loss rate for a main sequence star. I've started off simple, just slightly 
modifying the default work
 > folder's inlists to make a 1 solar mass star losing mass with a mass 
loss rate given as a function of time. Since I want to specify a function 
for a custom mass loss mechanism,
 > I have been trying to use the "other" hooks in run_star_extras to do so. 
However, I can't seem to get even the simplest example, a constant mass 
loss rate, working via run star
 > extras. I made a simple subroutine called const_mdot, and I direct MESA 
to use it in extras_controls as an other_adjust_mdot. I am trying to set s% 
star_mdot to be a value that
 > I specify in the inlist, but, when I run MESA, I find that the mass of 
the star doesn't change at all. I noticed that setting mass_change in the 
inlist controls does what I
 > thought this would be doing, but I would eventually like to implement 
more complicated mass loss rates.
 >
 > Am I not implementing mass loss in the correct manner? Should I not put 
my mass loss subroutine as an other_adjust_mdot, or is s% star_mdot not the 
right quantity to be
 > modifying? I know there is an other_wind option, but I'm dealing with 
mass loss from other sources such as CMEs not only wind. I've attached my 
inlists and run_star_extras.f
 > which I've been using in MESA r10398. How does one specify a custom mass 
loss rate in MESA?
 >
 > Thanks,
 > Noah Tuchow
 >
 > Noah Tuchow
 >
 > Penn State University
 >
 > Department of Astronomy and Astrophysics
 >
 > 532C Davey Lab
 >
 > University Park, PA 16802
 >
 >
 > _______________________________________________
 > mesa-users at lists.mesastar.org
 > https://lists.mesastar.org/mailman/listinfo/mesa-users
 >
 > _______________________________________________
 > mesa-users at lists.mesastar.org
 > https://lists.mesastar.org/mailman/listinfo/mesa-users
 >
 >
 >
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.mesastar.org/pipermail/mesa-users/attachments/20190716/56dfbaef/attachment-0001.html>