  In the previous paper [Harada, Cardoso, and Miyata, Phys.\ Rev.\ D {\bf 99}
(2019), 044039], it is shown that a hollow transmissive shell collapsing to an
ultracompact object of radius very close to its horizon radius generally emits
transient Hawking radiation followed by a couple of bursts separated each other
by a long time interval. In the current paper, we expand the previous work in
two independent directions: changing boundary conditions and specifying the
equations of state of the matter. First, we introduce a perfectly reflective
surface collapsing to an ultracompact object and find that this model also
emits transient Hawking radiation that is followed only by a single burst.
Second, we introduce two different collapse dynamics to an ultracompact object
and specify the corresponding matter equations of state. We find that transient
Hawking radiation is quite commonly seen in early times, while the subsequent
bursts strongly depend on the boundary condition and the equation of state or
the braking behavior of the surface.
