Birth, Life And Death Of Stars

Question 1

What are Stars born in?

Answer 1

Stars are born in vast, slowly rotating, clouds of cold gas and dust called nebulae

Question 2

What are the masses of these nebulae

Answer 2

Between 100 thousand and 2 million times the mass of the sun

Question 3

What are the diameters of these nebulae

Answer 3

They range from 50 to 300 light year across

Question 4

What happens to the nebula over time

Answer 4

Over time the clouds contract, become denser and slowly heat up and break up into smaller clumps

Question 5

What happens to the clumps once they get smaller

Answer 5

They flatten out into disk shapes

Question 6

What happens to the center of each clump

Answer 6

It will eventually contain a star

Question 7

What happens to the outer disk of gas and dust

Answer 7

It may eventually form planets around the star

Question 8

What happens when the contracting clumps continue to heat up

Answer 8

A protostar is formed at the center

Question 9

What is a protostar?

Answer 9

A protostar is a dense ball of gas that is not yet hot enough at the center to start nuclear reactions

Question 10

How long does this stage last?

Answer 10

Roughly 50 million years

Question 11

What happens as the collapse continues?

Answer 11

The mass of the protostar increases

Question 12

What happens when the mass of the protostar increases

Answer 12

It squeezes it further and increases the temperature

Question 13

How hot does a protostar need to be in order for nuclear fusion to take place

Answer 13

10 million degrees Celsius

Question 14

What happens after nuclear fusion is able to take place

Answer 14

The protostar will technically be called a star

Question 15

How does a young star start converting hydrogen to helium

Answer 15

Via nuclear fusion reaction

Question 16

What type of energy is produced in vast amounts during nuclear reactions

Answer 16

Heat and light

Question 17

What does this energy production do?

Answer 17

Prevents the star from contracting any further

Question 18

What does the star do when it shines?

Answer 18

Blows away the disk of dust and gas surrounding the star

Question 19

What happens during nuclear fusion

Answer 19

2 or more nuclei combine to form a large, single nucleus

Question 20

What are star winds called?

Answer 20

Stellar winds

Question 21

When is a star considered to be born?

Answer 21

Once nuclear fusion reaction begins at its center

Question 22

What is a main sequence star

Answer 22

A star that is converting hydrogen to helium

Question 23

How long can a star remain a main sequence star

Answer 23

Millions or billions of years

Question 24

When are stars most stable?

Answer 24

During their main sequence stage

Question 25

Which type of star comes in many different sizes and colors?

Answer 25

Main sequence stars

Question 26

What determines their colours

Answer 26

Their surface temperature

Question 27

How do you get stars look

Answer 27

They are hotter and blue in colour

Question 28

What happens to them once they age

Answer 28

They become more yellow and orange and slowly cool down

Question 29

How do older stars appear

Answer 29

Red and are vastly cooler in temperature

Question 30

What determines how long a main sequence star lives

Answer 30

How massive it is

Question 31

What happens when the hydrogen in the center of the star is depleted

Answer 31

He stars core shrinks and heats up

Question 32

What happens to the outer parts of the star when this happens?

Answer 32

It starts to expand

Question 33

What happens when a star becomes larger and brighter

Answer 33

It’s surface temperature cools and it glows red

Question 34

What happens in the next nuclear reaction

Answer 34

Atoms of helium collide and fuse into heavier elements such as carbon and oxygen

Question 35

After the helium i know the core is depleted, what determines the fate of the star

Answer 35

It’s mass

Question 36

What happens to medium sized stars

Answer 36

The temperature in the center will never get hot enough for a second nuclear fusion and they don’t evolve any further

Question 37

What follows the red giant phase?

Answer 37

The star becomes unstable and will eventually die

Question 38

What are the three stages of the death of stars

Answer 38

* hydrogen starts to run out * other elements start to burn and give off more heat * star swells as surface cools —> red

Question 39

What are the stages of a medium sized star

Answer 39

* star swells and becomes red giant * outer layer of gas are shed to form a planetary nebula (dust clouds) * core contacts into white dwarf (dead star)

Question 40

What are the stages of a large star?

Answer 40

* turns yellow —> red —> super red giant * explodes as a supernova * a neutron star and a black hole are left behind

Question 41

What is a neutron star

Answer 41

Dense dead star

Question 42

What is a black hole?

Answer 42

Object with a large gravitational pull