GYRE physical constants

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GYRE physical constants

Postby ehsan » Thu Feb 06, 2014 1:25 pm

Hello Rich,
Pieter Degroote and I were discussing today about the impact of various options on seismic results. One is indeed different choices of physical constants used in evolutionary and seismic codes, which must be compatible, which is not the case essentially. So, I noticed that GYRE uses the same value for the gravitational constant G as of MESA, but the solar mass, radius and luminosity are different. For book keeping, I quote from GYRE:
Code: Select all
  real(WP), parameter :: M_SUN = 1.9891E33_WP             ! Solar mass
  real(WP), parameter :: R_SUN = 6.96E10_WP               ! Solar radius
  real(WP), parameter :: L_SUN = 3.826E33_WP              ! Solar luminosity (Allen, 1973)

and also from MESA
Code: Select all
         msol = 1.9892d33  ! solar mass (g)  <<< gravitational mass, not baryonic
         rsol = 6.9598d10 ! solar radius (cm)
         lsol = 3.8418d33  ! solar luminosity (erg s^-1)


As varying the gravitational constant is already possible through the &coeffs namelist, I believe it will be a very nice support if user can tweak the constants like above through the input inlist.
So, I would like to ask for the inclusion of the above three constants in the inlist.

Thanks for your consideration
Ehsan.
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Re: GYRE physical constants

Postby rhtownsend » Fri Feb 21, 2014 1:30 pm

Hi Ehsan --

The latest development version of GYRE now includes this functionality. Constants are now expressed in the &constants namelist (which has to be present, even if it is empty). Right now, you can change the following constants:

G_GRAVITY
C_LIGHT
A_RADIATION
M_SUN
R_SUN
L_SUN

The default values are the ones given in core_constants.

Note that the &coeffs namelist is now named &model, and the coeffs_type parameter is named model_type.

cheers,

Rich
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