ASTRONOMY COURSE - Lesson 29 - Supernovae
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- Опубліковано 6 лют 2025
- ASTRONOMY COURSE - Lesson 29 - Supernovae
Supernovae: incredibly powerful cosmic explosions
A supernova is a truly spectacular and violent astronomical event. Imagine a massive star, much larger than our Sun, that at the end of its life collapses on itself. This implosion generates a shock wave that causes a titanic explosion, capable of emitting an amount of energy greater than that which our star will emit throughout its existence.
Why do they happen?
There are two main mechanisms that can trigger a supernova:
Gravitational collapse: Very massive stars, at the end of their life cycle, run out of nuclear fuel and are no longer able to support their outer layers against the force of gravity. The core collapses on itself, giving rise to the explosion.
Accretion of matter: A white dwarf, the remnant of a medium-low mass star, can accrete matter from a companion star. When it reaches a critical mass, a nuclear fusion reaction is triggered that causes the explosion.
What happens during a supernova explosion?
Extreme luminosity: During the explosion, the supernova becomes so luminous that it outshines that of an entire galaxy.
Emission of heavy elements: Supernovae are veritable "cosmic factories" of heavy elements, such as oxygen, carbon and iron, which are dispersed into interstellar space.
Formation of neutron stars or black holes: Depending on the initial mass of the star, the explosion can leave a neutron star or, in the case of very massive stars, a black hole as a residue.
Why are supernovae important for astrophysics?
The study of supernovae is fundamental to understanding:
Stellar evolution: Supernovae represent the final phase in the life of many massive stars.
The origin of elements: Supernovae are the main source of heavy elements in the universe.
The expansion of the universe: Type Ia supernovae are used as "standard candles" to measure cosmic distances and study the expansion of the universe.
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Grazie !
Sono solo un amatoriale del cosmo e solo adesso mi sono accorta delle sue lezioni, professore. Spero di capire bene il linguaggio tecnico, ma è evidente che devo partire dalla prima lezione. Mi appresterò a farlo immediatamente a recuperare le altre lezioni. Grazie Prof.
@@antonellavassallo7016 e tutto on line lo puoi fare quando vuoi...
C'è un motivo per cui sembrano non esistere stelle con massa enorme (ad esempio 10⁶ masse solari) mentre buchi neri si?
perché le stelle ad una certa evaporano per grande T... quindi spazzano via il materiale circostante. i buchi neri supermassicci si formano quando le galassie si scontrano, le dinamiche sono diverse... LO SPIEGO NELLA LEZIONE DEDICATA AI BUCHI NERI. la numero 4..
Chissà quante stelle stanno collassando in questo momento nell'Universo
@@giuseppegiadone8348 in media in miliardo all'anno in tutto l universo
@@AntonioLoiacono Ma non lo possiamo stabilire con certezza
@giuseppegiadone8348 e una stima .. si studio l'universo intorno a noi e poi lo si moltiplica per quanto in teoria dovrebbe essere grande... a conti fatti un miliardo l anno non e tantissimo... ci sono almeno 100 miliardi di galassie