  We consider evaporation alongside collapse for a dustball in standard (not
comoving) coordinates. A classical analysis gives the main result: an explicit
metric (joined to the exterior) for the collapse. The metric then provides the
causal structure: light cones corresponding to the coordinate speed of light,
c. If the problem is perturbed from a pure dustball collapse, the solution can
only be altered within the future light cones of such perturbations.
  The metric tells us that c_{interior} << c_{exterior}. Importantly, the speed
at which the Schwarzschild radius shrinks during evaporation is intermediate
between the two. Thus a perturbation at the (shrinking) surface will only
influence the exterior in finite time. For example, if we assume evaporation to
be a process located at the dustball's surface, we can model it as a series of
perturbations to the classical solution. In this modified solution, the
interior is not altered as the evaporation process eats into a frozen interior
from the outside in; the singularity and a region near it are no longer
present; infalling particles don't cross the (shrinking) dustball boundary; the
metric coefficients don't change sign with time, and therefore timelike world
lines can exist at constant radius inside the (shrinking) Schwarzschild radius
and emerge at late times (no absolute horizon forms).
  Research on evaporation alongside collapse typically study collapsing shells
and apply quantum field theory. This paper differs in that it studies an entire
dustball and uses classical general relativity to constrain evaporation models.
