space physics (paper 2) Flashcards
what do stars initially form from
a cloud of dust and as called a nebula
the force of gravity pulls the dust and the as together to form a protostar
what happens as the star gets denser and the temperature rises and more particles collide with each other
when the temperature gets high enough , hydrogen nuclei undergo nuclear fission to form helium nuclei. this gives out huge amounts of energy which keeps the core of the star hot, as star is born
what is the long stable period of a star
where the outward pressure caused by the nuclear fission that tries to expand the star balances the force of gravity pulling everything inwards
what is the star called in its long stable period
a main sequence star
how long does a stars stable period typically last
several billion years
what happens when the hydrogen begins to run out in a star
the star then swells into a red giant (if it is a small star ) or a red super giant ( if it is a larger star )
it becomes red because the surface cools
fusion of helium occurs
heavier elements (up to iron) are created in the core of the star
what is the difference between red giants and red super giants sizes
red giants are stars about the same size as the sun
red super giants are much bigger than the sun
how does a small to medium size star become a white dwarf
it becomes unstable and ejects its outer layer of dust and gas , this leaves behind a hot, dense, solid core - a white dwarf
how does a white dwarf become a black dwarf
as a white dwarf cools down , it emits less and less energy . when it no loner emits a significant amount, it is called a black dwarf
how does a red super giant become a supernova
big stars start to glow brightly as they undergo more fusion and expand and contract several times , forming elements as heavy as iron in various nuclear reactions
eventually they will explode in a supernova, forming elements heavier than iron and ejecting them into the universe to form new planets and stars
stars and their life cycles produce and distribute all naturally occurring elements
how do supernovas become a neutron star or a black hole
the exploding supernova throws the outer layers of dust and as into space , leaving a very dense core called a neutron star
if the star is massive enough it will become a black hole - a super dense point in space that not even light can escape from
what are planets
large objects that orbit a star
have to be large enough to have ‘cleared their neihbourhoods’ - which means their gravity is strong enough to have pulled in any nearby objects apart from their satellites
what are dwarf planets
these are planet like objects that orbit stars , but they do not meet all of the rules for bein a planet - Pluto
what are moons
these orbit planets
they are a type of natural satellite which means they are not man made
what are artificial satellites
satellites that humans have built - they generally orbit the earth
