[Mesa-users] theta_co and time_co not reinitialised upon restarting

[Glenn-Michael Oomen]

Hi MESA,


I was having some trouble restarting a binary model from a photo in MESA version r-11701. After some digging, I found out that the problem was in the Tout_enhance_wind function, because theta_co contained completely random values and several NaNs. It turns out that theta_co and time_co are only properly initialised at the start of a binary model in binarydata_init of binary_evolve.f90, but not when restarting a model.


I applied a quick fix in my copy of the code by also reinitialising these arrays after restarting. I did this by adding the following to run_binary_support (just after theta_co and time_co are allocated):


         ! Set all parameters necessary for integration over the binary orbit
         ! 1) true anomaly = polar angle from periastron 0 -> 2pi
         if (doing_restart) then
            do i = 1,b% anomaly_steps
               b% theta_co(i) = (i-1) * (2 * pi) / b% anomaly_steps
            end do
            ! 2) time between periastron and polar angle theta 0 -> 1 (fraction of the
            !    orbital period)
            do i = 1,b% anomaly_steps ! time between periastron and polar angle theta
               b% time_co(i) = ( 2 * atan_cr( sqrt( (1-b% eccentricity)/(1 + b% eccentricity) ) * &
                               tan_cr(b% theta_co(i)/2d0) ) - b% eccentricity * &
                               sqrt(1 - b% eccentricity**2) * sin_cr(b% theta_co(i)) / &
                               (1 + b% eccentricity * cos_cr(b% theta_co(i)) ) ) /2. /pi
               if (i > b% anomaly_steps/2+1) then
                  b% time_co(i) = b% time_co(i) + b% time_co(b% anomaly_steps/2+1) * 2
               end if
            end do
         end if

I basically copied this piece of code from binary_evolve to run_binary_support.

Best regards,
Glenn-Michael Oomen


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