  We study the pressureless Navier--Stokes-Poisson equations of describing the
evolution of the gaseous star in astrophysics. The isothermal blowup solutions
of Yuen, to the Euler-Poisson equations in R2, can be extended to the
pressureless Navier-Stokes-Poisson equations with density-dependent viscosity
in R3. Besides some remarks, about the meaning of the blowup solutions and the
applicability of such solutions to the the drift-diffusion model in
semiconductors, are discussed in the end.
