In the context of black hole formation, consider the following statements:
1. Supernova explosions are the only known mechanism for stellar-mass black hole
formation.
2. "Direct collapse" formation involves a star imploding without a supernova explosion.
3. The presence of distant companion stars in a black hole system always indicates
supernova formation.
4. V404 Cygni provides observational evidence challenging the supernova-only
formation theory.
Which of the statements given above are correct?
Explanation: Statement 1 is incorrect as the discovery suggests alternative formation
mechanisms. Statement 2 is correct, describing "direct collapse". Statement 3 is
incorrect as V404 Cygni has distant companions despite likely forming without a
supernova. Statement 4 is correct as V404 Cygni challenges the supernova-only theory.
Explanation: Statement 1 is incorrect as the discovery suggests alternative formation
mechanisms. Statement 2 is correct, describing "direct collapse". Statement 3 is
incorrect as V404 Cygni has distant companions despite likely forming without a
supernova. Statement 4 is correct as V404 Cygni challenges the supernova-only theory.