  Broom and Rycht\'{a}\v{r} [Proc. R. Soc. A (2008) 464, 2609--2627] found an
exact solution for the fixation probabilities of the Moran process for a
structured population, in which the interaction structure among individuals is
given by the so-called star graph, i.e. one central vertex and $n$ leaves, the
leaves connecting only to the center. We generalize on their solution by
allowing individuals' fitnesses to depend on the population frequency, and also
by allowing a possible change in the order of reproduction and death draws. In
their cited paper, Broom and Rycht\'{a}\v{r} considered the birth-death (BD)
process, in which at each time step an individual is first drawn for
reproduction and then an individual is selected for death. In the death-birth
(DB) process, the order of the draws is reversed. It may be seen that the order
of the draws makes a big difference in the fixation probabilities. Our solution
method applies to both the BD and the DB cases. As expected, the exact formulae
for the fixation probabilities are complicated. We will also illustrate them
with some examples and provide results on the asymptotic behavior of the
fixation probabilities when the number $n$ of leaves in the graph tends to
infinity.
