Flashcards in Life Cycle Of Stars Deck (8):
Gravitational energy is converted into heat energy so temperature rises. When the temperature gets Hugh enough hydrogen nucli undergo nuclear fission to form helium nuclei and give out massive amounts of heat and light. A star is born. Smaller mass of gass and dust may also pull together to make the the planets that orbit the star.
Nuclear fission of hydrogen ➡️helium (once hot enough)
Main sequence star
Star enters lining stable period where heat from nuclear fusion provides an outward pressure to balance force of gravity pulling everything inwards. Maintains it energy output for millions of years due to massive amounts of hydrogen it consumes.
Eventually hydrogen begins to run out. Heavier elements such as iron are made by nuclear fusion of helium. The star then swells into a RED GIANT if it's a small star or a RED SUPER GIANT if it's a big star. Becomes red because surface cools.
Small/medium sized star like sun then becomes unstable and ejects its outer layer of dust and gas as a PLANETARY NEBULA
Leaves behind a hot dense solid core -A WHITE DWARF which cools down to a BALCK DWARF and eventually disappears.
Big stars however start to flow brightly again as they undergo more fusion and expand and contract several times forming elements as heavy as iron. Eventually explode in a SUPERNOVA forming elements heavy than iron and ejecting them into the universe to form new planets and stars.
The exploding supernova throws out layers of dust and gas into space leaving a very dense core called a NEUTRON STAR. If the star is big enough it will become a black hole