For this lesson you will need:
Let's take a look at a more massive star, in this case one of 60 solar masses. If you run the above model and data file, you will get a model that happily ascends the giant branch and even gets a long way through carbon burning. However, this model is not very physical as it does not include any mass loss. We should probably include some. The code currently has 5 different mass-loss laws to choose from. For a single star, we switch on mass loss by setting IML1 to some non-zero value. We can either choose the Reimer's mass loss law (IML1=1), the Blöcker mass loss law (IML1=2), the Vasilliadis and Wood formula (IML1=3) and two versions for massive stars, IML1=4 and 5. These both use the de Jager et al. (1988) mass loss rates with a metallicity scaling for pre-WR phases, while they use differing rates for the Wolf-Rayet phases. We will apply the latter, so our data file must be modified as shown below:
where the number you need to change is the highlighted one. Now run the model with the same input file -- you will notice that as the star ascends the giant branch, it moves back over to the blue. Have a look at its mass (column 6 in the plot file). The stellar wind we've applied has stripped lots of mass of this model as it evolved.
Unfortunately, the model is still not close enough to physical reality. In order to reproduce observed stellar properties, such as the width of the main sequence, modellers apply `convective overshooting' to their models. This is just mixing beyond the normal convective boundaries. It has been determined that the appropriate overshooting parameter to use in this code is 0.12, so let's now apply this to our stellar model. Our data file is modified as follows:
Again, the number you need to change (the parameter OS) is highlighted. If you run this model with the original input file, you'll get something slightly different to what you had before. Plotting up all three evolutionary tracks should give you something like this:
