Life Cycle of Stars Flashcards
What do stars initially form as?
Nebulas- a cloud of gas and dust.
How does gas and dust spiral together?
The force of gravity.
What does the force of gravity do to a nebula?
Pull together the gas and dust.
What causes the temperature of a nebula to rise?
Gravitational energy being converted into heat energy
When the temperature gets high enough, what happens to the hydrogen nuclei?
it undergoes thermonuclear fusion to form helium nuclei and gives out massive amounts of energy.
How is a star born?
- the force of gravity creates a nebula by pulling
together the dust and gas
*gravitational energy is converted to heat energy
*when temperature rises enough, hydrogen nuclei undergo thermonuclear fusions to form a helium nuclei and give out massive amounts of energy.
When a star is born, what does it immediately enter?
it enters a long stable period where the hear created by nuclear fusion provides an outward pressure to balance the force of gravity pulling everything inwards.
What is a star called when it enters a long stable period and how long does it last?
Called a main sequence star and this period can last several billion years.
In the core of a star what eventually runs out?
Hydrogen
What happens when the hydrogen in the core of a star begins to run out?
the star swells into a red giant
why does a red giant star become red?
because the surface cools
how does a red giant star form?
when a main sequence star eventually begins to run out of hydrogen in the core, it swells into a red giant
is the sun classified as a big or small star?
small
after becoming a red giant star, what kind of star does it become?
planetary nebula and white dwarf
how does a red giant become a planetary nebula?
it becomes unstable and ejects layers of dust and gas as a planetary nebula
why does a white dwarf eventually disappear?
because it cools down
what is a white dwarf star?
a hot dense solid core that is left behind when a small star becomes unstable and ejects its outer layers of dust and gas
what do BIG stars become after a red giant?
A supernova star
How does a asupernova form?
they undergo more fusion and expand and contract several more times, forming heavier elements in various nuclear reactions. eventually they explode in a supernova.
If a star is big enough, what will it become after a neutron star?
a black hole
when do black holes form?
when a star is big enough to become one
what is a neutron star and how is it formed?
is a very dense core which is left after an exploding supernova throws the outer layers of dust and gas into space.
What is the life cycle of a small star? ( size of sun)
Nebula Prostar Main sequence star Red giant Planetary nebula White dwarf Black dwarf
Life cycles of big star ( bigger than sun)
nebula main sequence star red super giant supernova black hole or neutron star
A constellation is
a group of stars that make an image in the sky
