[mesa-users] A question related to gravitation constant G

Ehsan Moravveji e.moravveji at gmail.com
Wed Aug 24 07:45:51 EDT 2016


Dear Taghi,

Indeed, this is possible. If you take a look at the publicly accessible variables in your <mesa>/star/public/star_data.inc, you come across:

      ! gravitational constant (can be set by user and can be vary within model)
      real(dp), pointer :: cgrav(:)

I guess this cgrav vector is implemented for more and less the same purpose as yours.

You have access to this variable as a part of the “star_info" pointer: s% cgrav(1: s% nz).
To play around with it, you need to grab “star_info” pointer in any of your routines, e.g.

    type(star_info), pointer :: s
    call star_ptr(id, s, ierr) 

Best regards,
Ehsan

> On 24 Aug 2016, at 10:38, torabi <torabi at alzahra.ac.ir> wrote:
> 
> Dear Mesa Users
> 
> I know that it is possible to change the value of physical constant like newton gravitation constant, G, inside the mesa code and try stellar evolution with different value of G. I am working on stellar evolution in a modified gravity theory. The theory uses an effective G which depends on local mass density, then for different layer of star we have different value of G. The question is "is it possible to implement the code like this? or is it possible to define a local G(r), a gravitation constant depending on position.
> 
> Best regards
> Taghi Mirtorabi  
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