Depending on the mass of the original star it will either end up as a neutron star (< 20 solar masses) or a black hole (> 20 solar masses).
It is an adverb phrase, although in forms such as "The period after a supernova is marked by stellar collapse" it seems to be an adjective phrase.
Dangerous. Novas, or supernovas. Tycho Brahe coined the phrase "nova stellarum" when a "new star" appeared in the night sky. We now know that he was observing a supernova, the death throes of a very massive star.
Adverb: "A black hole forms when a supermassive star collapses after a supernova explosion."
Elements present in a star just before it forms a supernova would include hydrogen, helium, carbon, oxygen, and iron. The star undergoes nuclear fusion to produce heavier elements in its core, leading to the buildup of iron which triggers the supernova explosion.
Neutron star
Remember that Supernovas are great contributors to interstellar material that forms new stars. The star which explodes to supernova will leave either a pulsar or a black hole depending on its mass. Part of the supernova will scatter into space.
Neutron Star
When a large star collapses in a supernova, it can produce either a neutron star or a black hole, depending on the mass of the original star. A neutron star forms when the core of the star collapses but the outer layers are ejected, while a black hole forms when the core collapses completely.
The leftover material from a supernova explosion forms either a neutron star or a black hole, depending on the mass of the collapsing core. A neutron star is extremely dense and composed mostly of neutrons, while a black hole is a region of spacetime where gravity is so strong that not even light can escape.
When a star explodes, it releases an immense amount of energy, creating a supernova. This explosion can outshine an entire galaxy for a short period of time. Supernovae are crucial for the formation of heavy elements and can also cause the star to collapse and form a black hole or neutron star.
The Vela Supernova is the remnant of a supernova explosion that occurred in the Vela constellation about 11,000 to 12,300 years ago. It is located about 800 light-years away from Earth and is one of the closest known supernova remnants to us.
"after a supernova" is the adverb phrase in the sentence.