A caldera
yes it is true
Traditionally there are two different structures that can be left behind. Although both structures are a type of hole, there are general size requirements for each. If a smaller volcano suffers a collapse and the hole is less than 1 mile in diameter, it is called a crater. If a larger volcano collapses and the hole is larger than 1 mile in diameter, it is called a caldera.
The large hole at the top of a volcano is called a "crater." It is formed when explosions or collapses create a depression at the summit of the volcano.
Such a hole is called a fumarole.
It is called a volcano.
The name of the hollow landform, found at the top of the volcano is called crater.
it's called a crater.
it is called a caldera a caldera is formed when a volcano erupts and it it such a big eruption that the volcano has no magma left in its chamber and since there is nothing left to support it, it caved in on itself.
Vent .
It seems you are referring not to any collapsed star, but a black hole. The "event horizon" is the area from which nothing can escape.
If the Sun collapsed into a black hole, it would be about 3 kilometers in diameter.
It is called a crater.