The mass of whatever the impactor is has to be brought to a halt and for a 100 km chunk massing as much as you've computed, that's not happening in an instant in the photosphere of the Sun. Computing exactly how long is a non trivial task and at that speed is more like the injection of a supersonic fluid through a much lower density medium since the internal strength, heat capacity and even the ionization energy of the object is trivial against the kinetic energy it is dissipating.