The life cycle of a star is already known to all. Born gas accumulation and diverse material gravity collapsing until it starts melting at its core while its gravity attracts more material grows passing hydrogen to helium and other heavy materials when it runs out of hydrogen is unable to retain its gravity and the materials begin to escape until it collapses, breaks (throwing stuff out) was disintegrates or form a neutron star or a black hole.
The material spewing is dedicated to form new stars.
The most usual is that when the star collapses and explodes in a supernova throw great material, increasing its size (due to lack of gravity) before finishing collapsing altogether (its core, of course). It is not a standard, but it is more usual. So in the visible universe ever “you can see” exploding stars.
Barring a curious, Cygnus X-1 is now a black hole and I think that collapsed directly dud.
And say: why is that if you have told us otherwise?. Well, like everything in life there are exceptions and thought that was so because the material that should have expelled has not formed new stars around it.
In the image it can be seen as there are clusters of hot gas and new stars being formed in another part of the constellation Cygnus (Cygnus for friends) while single Cygnus X-1 is more than about one.
That is why it is thought that collapsed directly unexploded besides practically gas is observed around because of explosions.
It is also thought that simply bursts of Cygnus OB3 and her companions could expel Cygnus X-1 long ago in the time of explosion, especially because in the image not only the situation but the velocity vector of shows star, can see that is not altered, which should have happened by gravity to become a black hole and begin to “suck” all I had around. This is very curious. Since neither a supernova has pushed him or has modified its vector to become a black hole.
Whatever it is, it’s a mystery as physic, we would love to discover.